Journal articles on the topic 'Sand limit state'
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1
I.P, Ukwoma,, Akpokodje, E.G., and Nwankwoala, H.O. "TEXTURE AND CEMENT STABILIZATION OF DREDGED SAND USED FOR OGBIA – NEMBE ROAD, BAYELSA STATE, NIGERIA." Engineering Heritage Journal 6, no. 1 (2022): 06–13. http://dx.doi.org/10.26480/gwk.01.2022.06.13.
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This paper is aimed at determining the texture, compaction, and cement stabilization properties of the dredged sand used in the Ogbia-Nembe road construction in Bayelsa State, Nigeria. Both field and laboratory studies were undertaken. Results from the laboratory tests revealed the various properties as follows: moisture content (41.3 – 58.2%), Liquid limit (45.5 – 50.5%), Plastic limit (26.2 – 33.7%), Plasticity Index (16.8 – 20.6%), Cu (2,15 – 3.16), Optimum moisture content (OMC) and Maximum dry densities (MDD) for the dredged sands are (9.2 – 9.4) and (1600 – 1620kN/m3 respectively. The OMC, MDD and California bearing ratio (CBR) of the sand-cement mixture are 10.2 – 12.6%, 1830 – 1880kN/m3, 177 -313% and 1140 -2905kN/m2 respectively. The dredged sands are classified as A-3 according to the AASHO classification system. However, the average MDD of the dredged sand is 1620kN/m3 which is below the Federal Ministry of Works (FMW) specification for pavement construction, therefore the need for stabilization. Stabilization of the sand with 6% – 10% cement increased the MDD, CBR, UCS to 1880kN/m3, 313% and 2905kN/m2, respectively. The results of this study revealed that the minimum percentage of cement required to stabilize the dredged sand used for the construction of the road is 6%. Also, particle size of cohesionless soil affects the density and sand-cement stabilization is more economical than paying for additional maintenance cost if the pavement fails. This study also revealed that increasing the percentage of cement of a sample does make the soil brittle as well as increases the strength of the material/soil.
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Sun, Dongning, Xin Liu, Yuhao Cao, Junjie Gong, and Baoning Hong. "Determination of Cost-Effective Sand Mixing Ratio for Improvement of High Liquid Limit Soil Based on Fuzzy Comprehensive Evaluation." IOP Conference Series: Materials Science and Engineering 1203, no. 3 (November 1, 2021): 032060. http://dx.doi.org/10.1088/1757-899x/1203/3/032060.
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Abstract In order to save soil resources and increase the utilization range of high liquid limit soil, the high liquid limit soil was improved by mixing sand, and the cost-effective sand mixing ratio was determined with the help of fuzzy comprehensive evaluation method. It is shown that the sand-mixing improvement method can significantly reduce the liquid limit and plasticity index of high liquid limit soil, and increase its value of California bearing ratio to meet the property requirements for embankment filling. The fuzzy comprehensive evaluation results show that the improvement effect and cost of sand-mixed high liquid limit soil reach a comprehensive optimal state when the sand mixing ratio is 20%.
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Ikoko, N. L. A., M. A. Briggs-Kamara, F. B. Sigalo, A. R. C. Amakiri, and H. N. Ude. "Spatial Distribution of Radiometric and Dosimetric Parameters in Soil Samples from Selected Areas in Bayelsa State, Nigeria." Journal of Applied Sciences and Environmental Management 26, no. 5 (May 31, 2022): 975–81. http://dx.doi.org/10.4314/jasem.v26i5.27.
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Radiation from radioactive materials/radionuclides in the environment enhanced by anthropogenic activities is presently of a great concern globally. The objective of this study is to determine the radiometric and dosimetric parameters from soil samples collected randomly from the study area of Bayelsa State, Nigeria. The samples were prepared using standard methods and analyzed with a high resolution Hyperpure Germanium Detector configuration (HPGe). The results showed the clay samples to have higher activity concentration to the sands samples with activity concentration of clay samples ranging between 68.99±9.05 –189, 42±21.11Bq/kg and the sand samples with activity concentration range of 17.95±5.87 – 38.59±7.43Bq/kg. The activity concentration spatial distribution map in clay lithologies showed 2 peak values trending north-west, while the sand lithology showed a single peak central distribution. The result also showed the values of the absorbed doses with the 8 clay samples values ranging between 59.09 - 155.25nGy/h and sand samples values between 17.90 – 33.92nGy/h. The spatial distribution of the dose showed 2 peak central distribution in clay samples and north-east trending distribution of high peak values for samples with sand lithologies. In addition, the results showed an effective absorbed dose of range of 0.235-0.0616mSv/y for samples with clay lithology and 0.0071-0.0135mSv/y for samples with sand lithology The activity concentration of all the samples studied are below the 1000Bq/kg international reference limit for Radium 226, Thorium 232, uranium 238 and 10,000Bq/kg for potassium 40. The absorbed dose rate and annual effective absorbed dose are also below the international reference limits published by ICRP, 2007 and UNSCEAR, 2000 publications. Also, effective activity maximum limit of 370Bq/kg for input raw materials for public building is not exceeded.
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Łucarz, M. "State of Spent Molding Sands in the Mold Large-Size Cast." Archives of Foundry Engineering 16, no. 4 (December 1, 2016): 69–74. http://dx.doi.org/10.1515/afe-2016-0086.
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Abstract The results of investigations of spent moulding sands taken from the mould at various distances from the surface of the produced casting, are presented in the paper. The casting mould was made with an application of the cooling system of the metal core in order to increase the cooling rate of the ladle casting. As temperature measurements in the mould indicated the heat flow from the metal did not create conditions for the complete burning of a moulding sand. The analysis was performed to find out changes of spent moulding sands caused by degradation and destruction processes of organic binders. Conditions occurring in the casting mould were discussed on the bases of testing: ignition losses, dusts contents, pH reactions and the surface morphology of the moulding sand samples. Factors limiting the effective mould degassing were pointed out. Operations, possible for realization, which can limit the reasons of a periodical occurrence of increased amounts of casting defects due to changing gas evolution rates being the result of the technological process, were also indicated.
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Vicedo, Jorge Soriano, Javier García Barba, Jorge Luengo Frades, and Vicente Negro Valdecantos. "Scale Tests to Estimate Penetration Force and Stress State of the Silica Sand in Windfarm Foundations." Energies 14, no. 18 (September 17, 2021): 5904. http://dx.doi.org/10.3390/en14185904.
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The analysis of the soil behavior when the pile is driving into the seabed in offshore wind platforms is one of the major problems associated with this new form of clean energy generation. At present, there are no scaled studies carried out analyzing the mechanical and deformational behavior of both the material of the pile supporting the engine (large steel hollow piles with a diameter of 8 m and a thickness of 15–20 cm) and the soil where the pile is driven. Usually, these elements are installed on sands with a very small grain size displaced from the limits of dry–wet beach (water limit) toward the offshore limits, which prevents them from returning to their previous location in a natural way. This paper presents results obtained from scale tests in a steel pool to analyze the behavior of the sand where the piles were installed. First, the California Bearing Ratio (CBR) test was carried out to estimate the soil behavior in similar conditions to the steel pool. The scale tests consisted of the penetration of the steel tube into the sand using a hydraulic press. The objective was to compare the results for three tubes with different diameters, three different speeds, and two kinds of ending on the extreme of the tested element.
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Kechkar, Chiraz, Leila Kherraf, Assia Abdelouahid, and Houria Hebhoub. "THE COMPARATIVE STUDY OF THE PERFORMANCE OF CONCRETE MADE FROM RECYCLED SAND." Stavební obzor - Civil Engineering Journal 31, no. 3 (October 30, 2022): 415–26. http://dx.doi.org/10.14311/cej.2022.03.0031.
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The main objective of this study of research is to initiate and develop a comparative study of fresh and hardened properties of concretes made from recycled sand from three types of waste: marble waste, tiling waste and cinder block waste. And this, in the intention of contributing to the world effort relating to the preserve of natural aggregate resources and limit landfill to the ultimate waste thresholds.
To do this, in the composition of a current concrete with a water / cement ratio equal to 0.55, an equivalent volume of sand from the three wastes respectively replaced a volume of 15% of the ordinary sand. The properties in the fresh state: workability, air content and density and in the hardened state: compressive strength, Flexural tensile strength, compressive strength determined with non-destructive tests, water absorption by immersion, absorption by capillarity and chloride penetration of the various concretes produced are analyzed, and compared to those of the control concrete.
The results obtained show that the concretes containing the waste sands have acceptable characteristics. However, tiling waste sand performs better than the other two recycled sands.
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Uzielli, Marco, and Paul W. Mayne. "Serviceability limit state CPT-based design for vertically loaded shallow footings on sand." Geomechanics and Geoengineering 6, no. 2 (June 2011): 91–107. http://dx.doi.org/10.1080/17486025.2010.531146.
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T. V, Nwosu, Nwaiwu C.J, and Egboka N.T. "ANALYSIS OF WATER QUALITY DETERIORATION IN NWORIE RIVER, OWERRI- IMO STATE, SOUTHEAST, NIGERIA." Journal CleanWAS 5, no. 2 (July 1, 2021): 58–61. http://dx.doi.org/10.26480/jcleanwas.02.2021.58.61.
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Due to indiscriminate activities of man through sand excavation, sand mining and illegal waste disposal within the watershed the study evaluated the effect of these activities on selected water quality parameters of Nworie River in Owerri -Imo State, Southeast Nigeria. The study area was divided into Upstream, Midstream and downstream. The river was sampled and the raw data from water sampling were subjected to laboratory analysis; results obtained were matched with standards. The results showed that the average pH of the river was 7.4; upstream and midstream had higher pH values than the downstream with low pH and these were within the permissible limit. Biological oxygen Demand (BOD) of the river were 75mg/l, 60mg/l and 56mg/l at the Upstream, Midstream and downstream with an average value of 64 mg/l . The river had a mean turbidity value of 76NTU and mean Total Dissolved solids (TDS) value of 272mg/l which were above the permissible limit. Calcium (Ca2+) did not exceed the standard limit while magnesium exceeded the standard limit by 68% at the Upstream. Nworie river had mean water conductivity value of 93S/cm; water conductivity at the Midstream and downstream were within the permissible limits while the Upstream had 6% increase above the acceptable limit. It was observed from this study that Nworie river exhibited three different colours of light-green, dark-green and brownish-muddy colour respectively at the Upstream, Midstream and Downstream which could be attributed to the level of erosional deposits and sediment loads from the degraded watershed. Further degradation of the watershed should be avoided by practising good soil conservation measures, ensuring that indiscriminate activities of inhabitants of the area are stopped and since environmental balance, land degradation, water management and food security are strongly linked, each must be addressed in the context of the other to have a measurable impact to the society.
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Matvienko, Maxim, Vladimir Dyba, and Julia Matvienko. "Combined soil foundation analysis based on ultimate limit state." E3S Web of Conferences 371 (2023): 02023. http://dx.doi.org/10.1051/e3sconf/202337102023.
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The paper defines an updated method for “soil – reinforced concrete foundation” calculation that takes into account their mutual interaction. In this method, both the foundation structure and the footing structure are represented by a rigid-plastic model, which makes it possible to determine the bearing capacity of the system. This method eliminates the possibility of destruction of the reinforced concrete foundation from punching to the exhaustion of its bearing capacity. It further presents the results of the test conducted by the authors at Novocherkassk School for Soil Mechanics Research to validate the theoretical calculations attained with the use of the proposed method, as well as the results of tray testing of reinforced concrete foundation models. The calculation of the bearing capacity by the modernized method gives values close to the results of experimental studies. The authors discuss the challenge of determining the strength of sand base, which is known to affect the calculation of load-bearing capacity, and further propose a solution that uses piecewise linear limit line of shear strength of soil and has been developed in an attempt to increase the accuracy of calculations.
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Mirakhmedov, Mahamajon M. "The problem of sand drifts on railways." Innotrans, no. 1 (2021): 32–36. http://dx.doi.org/10.20291/2311-164x-2021-1-32-36.
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The sand drift of the railway track and the blowing of the roadbed negatively affect the elements of the track infrastructure to such an extent that they reach the limit states at which it becomes impossible for them to continue functioning. This leads to a violation of train safety. To assess the negative impact of sand and determine the necessary protective measures, a method of visual monitoring of the state of the track is proposed.
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Altaee, Ameir, and Bengt H. Fellenius. "Physical modeling in sand." Canadian Geotechnical Journal 31, no. 3 (June 1, 1994): 420–31. http://dx.doi.org/10.1139/t94-049.
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Small-scale testing under 1 g conditions as well as in the centrifuge presupposes that a model and prototype have comparative behavior. The chief condition for agreement between model and prototype is that the initial soil states of both must be at equal proximity to the steady state line. Then, when stresses are normalized to the initial mean stress, the model will in all aspects behave similarly to the prototype. Scaling rules are presented that indicate the relations between stress, strain, and displacement for the model and the prototype in terms of geometric scale and stress scale. An obvious limit of scales is imposed by that the soil in the model can be no looser than the maximum void ratio. Similarly, it must not be denser than a value that corresponds to a prototype soil at the minimum void ratio. Three main areas of application of the approach in engineering practice are identified: design of representative 1 g small-scale model tests; reanalysis of data from conventional small-scale tests; and improving the versatility of centrifuge facilities in recognition of the fact that the centrifuge test does not need to be performed at equal levels of stress, when designed according to the new approach. Key words : physical modeling, sand, scaling relations, steady state, centrifuge testing.
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Azhim, Abdul, and Widjojo A. Prakoso. "Construction cost optimization of shallow foundation for sand soil in Indonesia." MATEC Web of Conferences 270 (2019): 05005. http://dx.doi.org/10.1051/matecconf/201927005005.
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In designing foundation, there are three fundamental requirements namely: ultimate limit state (ULS), serviceability limit state (SLS), and economics. Generally, the ULS and SLS are the focus of the design process, while the cost factors are not explicitly considered. This paper deals with the three requirements with the minimum construction cost as the controlling objective. A wide range of sand density conditions are considered, while the typical ULS and SLS design checks available in the literature are employed. The optimization tool used is the Solver add-in function available in MS-Excel™. The effects of different construction cost structures in four Indonesia's provinces are examined in this paper. The purpose of this research is to be able in designing the shallow foundation with 3 aspects consideration at once, namely ULS, SLS and economic. On the other hand, this research is to analyse the sensitivity's factor which influence the design, namely work unit price, soil properties and design's requirements.
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Sanchez, P. S., E. G. Agudo, F. G. Castro, M. N. Alves, and M. T. Martins. "Evaluation of the Sanitary Quality of Marine Recreational Waters and Sands from Beaches of the São Paulo State, Brazil." Water Science and Technology 18, no. 10 (October 1, 1986): 61–72. http://dx.doi.org/10.2166/wst.1986.0112.
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In order to evaluate the sanitary quality of marine recreational waters and sand at some beaches of São Paulo State, Brazil, a 19-month study (1984-1985) was undertaken at nine sampling stations, and a total of 342 samples of sea water and sand were analysed for total and faecal coliforms, faecal streptococci, Pseudomonas aeruginosa and Salmonella. In sand samples Candida albicans, dermatophytes, Pitryrosporum, helminth eggs and protozoan cysts were also researched. Sea water samples were also analysed for enteroviruses and, in the second part of this study, for enterococci also. The results have shown some areas with high levels of faecal contamination in sea water and sand. The Brazilian recommended faecal coliform limit was exceeded in 31% of the sea water samples. Out of 171 sea water samples analysed, 10.5% were positive for Salmonella and 3.5% for enteroviruses. Positive results for C. albicans were observed in 18.7% of the sand samples and helminth eggs were detected in 12.9% of these 171 samples; Pityrosporum, dermatophytes and protozoan cysts were not detected.
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Ubuoh, E. A., I. U. Uzonu, U. I. Uchendu, and F. C. Ndukauba. "Soil Nutrient Dynamics and Potentially Toxic Elements of Sand Mining Impacted Agrarian Land in Obowo, Southeastern Nigeria." March 2022 6, no. 1 (March 2022): 84–100. http://dx.doi.org/10.36263/nijest.2022.01.0329.
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The study assessed the effect of inland sand mining activities on the physicochemical properties and potentially toxic elements in soils in Umuna, Obowo LGA, Imo State, and Southeastern Nigeria. Triplicate soil samples were collected from soil depths ranging from 0-15, 15-30 cm) in eight traverse points and control. Points were designated soil sampling point (SSP) ranging between SSP1-SSP8 and control sample point (CSP1). The results of the particle distribution were in order of Sand ≥ Clay ≥ Silt, with Textural class ranging from sandy loams to loamy sandy. Chemical tracers: Soil pH ranged from 4.8 – 5.7 signifying moderate to strong acidity. The available P, Total N., SOC,SOM and BS ≤ control and Maximum Tolerable limits and FAO /World Reference Base. Effective cation exchange capacity (ECEC) (cmol/kg) (Ca2+, Mg2+, K+ and Na+), with mean Ca2+ 3.02, Mg2+, 0.64, K+ 0.09, Na+ 0.10 ≤ control respectively. Exchangeable acidity recorded 1.04 ≥ control, and CEC: 6.22 ≤ the control. Based on the ratings of soil nutrients for agricultural soil, the soil nutrients status of the sand mined sites ranged from very low to low status for total N(0.02 -0.04), avail. P (6.55-9.96), exchangeable K, (0.07-0.14), exchangeable Ca (2.25-3.55), and exchangeable Mg (0.25-0.85). Copper the mean value of 15.21, Lead: 12.20 and Cadmium (1.80) ≥ control (zero) above the FAO/WHO permissible levels respectively. Chromium (2.65) ≤ the FAO/WHO, limit. The potentially toxic heavy metals are in order of abundance in sand –mined soil: Cu ≥ Pb ≥ Cr ≥ Cd, with copper dominating the soil. The conservation of the area requires ecological restoration and regeneration of degraded mining site and the prohibition of mining activities as well as strict local control and enforcement of mining laws.
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Sladen, J. A., R. D. D'Hollander, and J. Krahn. "The liquefaction of sands, a collapse surface approach." Canadian Geotechnical Journal 22, no. 4 (November 1, 1985): 564–78. http://dx.doi.org/10.1139/t85-076.
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Recent large-scale slides occurring during the hydraulic placement of an artificial island berm in the Beaufort Sea resulted from the liquefaction of the berm sand. Subsequent laboratory tests and back analyses have led to advancements in the understanding of the liquefaction potential of sand. Analyses of undrained triaxial tests, undertaken to measure steady state parameters, suggest that there is a "collapse surface" in three-dimensional void ratio – shear stress – normal stress space. A necessary condition for liquefaction is that the soil state lie on this surface. This collapse surface concept is fundamentally an extension of the steady state concepts proposed by others, and in many respects follows the principles of critical state soil mechanics. Replotted published tests support the concept. Parameters used to describe the position of the surface are termed collapse parameters. These can be converted into parameters analogous to Mohr–Coulomb failure parameters and can therefore be used in conventional limit equilibrium stability analyses. Utilizing these parameters overcomes limitations inherent in previously proposed undrained steady state analysis methods. These concepts also provide a basis for a rational explanation of the Beaufort Sea hydraulic fill slides. Key words: liquefaction, sand, hydraulic fill, slope stability, steady state testing.
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Tong, Huai Feng. "Analysis of Small Non-Sand Concrete Pile Grouting Pressure Based on Unified Strength Theory." Applied Mechanics and Materials 166-169 (May 2012): 3095–99. http://dx.doi.org/10.4028/www.scientific.net/amm.166-169.3095.
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Analysis of stress state of soil around the pile and grouting pressure of small non-sand concrete pile is given based on the expansion elastic theory of cylindrical cavity and the unified strength theory, the grouting pressure formula is obtained in the elastic limit state and elastic-plastic state of soil around the pile considered the intermediate principal stress, and the relationship is obtained between the grouting pressure and the plastic radius; When the soil around the pile is in different stress state, the correlativity of crack and densification of grouting is analyzed, and the relationship between the grouting pressure and the plastic radius is discussed with the right coefficient of the intermediate principal stress and initial press under different values. The obtained results have provided efficient analysis means for grouting optimal design of post-processing technology with small non-sand concrete pile.
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Li, Qian Qian, Li Xin Liu, and Sheng Dong He. "Experimental Study on Fatigue Behavior of Prestressed Concrete Beams with Manufactured Sand." Key Engineering Materials 517 (June 2012): 595–600. http://dx.doi.org/10.4028/www.scientific.net/kem.517.595.
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This paper presents the test results of 2 prestressed concrete beams with manufactured sand under cyclic loading, the concrete is made of manufactured sand to replace natural sand with different replacement rates of 50% and 100%. The stress of re-bars and prestressed strands and the strain of manufactured sand concrete are discussed, the rigidity and cracking of the prestressed beams under cyclic loading are analyzed, and the flexural behavior of the beams after 2.5 million times cyclic loading are also discussed and analyzed. The results show that the fatigue behavior of the prestressed concrete beams with manufactured sand to replace the natural sand under cyclic loading is satisfied, the flexural bearing capacity of the prestressed beams after 2.5 million times cyclic loading is still sufficient. The results also show that the crack width and the mid-span deflection of the prestressed beams are in the allowable range at the serviceability limit state. This may be regarded as a reference for the applications of manufactured sand in the prestressed concrete structure .
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Sosa, Marìa Eva, Andrés Chirillano, Yury Andrés Villagrán Zaccardi, and Claudio Javier Zega. "Optimizing manufactured sand content in mortars and its influence on fresh and hardened state." DYNA 87, no. 214 (July 1, 2020): 196–203. http://dx.doi.org/10.15446/dyna.v87n214.84553.
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The shape and roughness of aggregates play a predominant role in the properties of cement mixes. Due to that, some regulations limit the content of manufacture fine aggregate at 30% of the total of fine aggregate in concrete. However, few design methods consider the shape and roughness surface of aggregates in the mix proportioning. This study presents an optimization method to increase the percentage of manufactured fine aggregates to be used, based on the void volume of the aggregates and their correlation with the fresh properties of mortars. To achieve that, the characteristics of the fresh and hard state were evaluated in order to carry out a comprehensive analysis on the influence of the method on the performance of mortars. From the results emerges that it is possible to maximize the content of manufactured aggregates without detrimental effects on compressive strength.
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Chijioke Nwachukwu, Martin, Chikwado Godwin Aleke, Okechukwu Pius Aghamelu, and Ezea Uchenna Joesph. "Geotechnical Evaluation of the Causes of Road Pavement Failure Along the Mbaitoli-Ikeduru-Mbaise Highway, Southeastern Nigeria." Asian Review of Civil Engineering 11, no. 1 (June 10, 2022): 21–26. http://dx.doi.org/10.51983/tarce-2022.11.1.3302.
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The incessant failed spots in the road pavement along the 27.61km Mbaitolu-Ikeduru-Ahiara Mbaise highway in Imo state, southeastern Nigeria, has necessitated this geotechnical study to evaluate the impact of the subgrade material quality on the road pavement failure. The study entailed both physical and geological assessment of the predominantly sandy to clayey silt Benin Formation underlying the area, as well as field and laboratory engineering tests on the subgrade materials underlying the road alignment. The engineering tests carried out included the grain size distribution, specific gravity, natural moisture content, Atterberg (liquid and plastic) limits, compaction (to determine maximum dry density and optimum moisture content), California bearing ratio (CBR), and shear strength (to determine cohesion and angle of internal friction). The engineering test results indicate that the natural moisture content values range between 10.4 and 18.9%, liquid limit between 36.0 and 48.6%, plastic limit ranges from 26.1 to 31.6, with corresponding plasticity index values that range from 9.2 to 17.0%. The grain size distribution test results connote the predominance of sand, with number of fines-sized particles that ranges from 22 to 38% and amount coarse to medium sand-sized particles ranging from 62 to 78%.Maximum dry density ranges from 1.29to 1.93 kg/m3. (CBR) ranges from 3.7 and 91.9%. Specific gravity ranges between 2.56and 2.61, while cohesion and angle of internal friction range from 39 to 42 kPa, and 14 to 20°, respectively. Some failed portion especially in Inyishi area were likely due to moisture fluctuation in the subgrade due to closeness of the water table. Proper compaction, chemical stabilization, and appropriate drainage would likely boost the efficiency of the subgrade material and the durability of the road pavement.
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Royer, John R., and Paul M. Chaikin. "Precisely cyclic sand: Self-organization of periodically sheared frictional grains." Proceedings of the National Academy of Sciences 112, no. 1 (December 23, 2014): 49–53. http://dx.doi.org/10.1073/pnas.1413468112.
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The disordered static structure and chaotic dynamics of frictional granular matter has occupied scientists for centuries, yet there are few organizational principles or guiding rules for this highly hysteretic, dissipative material. We show that cyclic shear of a granular material leads to dynamic self-organization into several phases with different spatial and temporal order. Using numerical simulations, we present a phase diagram in strain–friction space that shows chaotic dispersion, crystal formation, vortex patterns, and most unusually a disordered phase in which each particle precisely retraces its unique path. However, the system is not reversible. Rather, the trajectory of each particle, and the entire frictional, many–degrees-of-freedom system, organizes itself into a limit cycle absorbing state. Of particular note is that fact that the cyclic states are spatially disordered, whereas the ordered states are chaotic.
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Drucker, D. C., and Devo Seereeram. "Remaining at Yield During Unloading and Other Unconventional Elastic-Plastic Response." Journal of Applied Mechanics 54, no. 1 (March 1, 1987): 22–26. http://dx.doi.org/10.1115/1.3172965.
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A rather special time-independent or elastic-plastic response is proposed in which, although there is elastic response to unloading, the material remains at yield for all or a significant portion of the unloading path following plastic deformation. In the most elementary form, the material exhibits no memory of prior plastic deformation; the current state of the material is given solely by the current state of stress. A simple but unconventional field of plastic moduli then can be chosen to produce a limit surface that cuts through a nested set of yield surfaces and to model critical aspects of the behavior of sand.
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CHISHOLM, COLIN, NAEEM JAN, PETER GIBBS, and AYŞE ERZAN. "SELF-ORGANIZED CRITICALITY IN AN ASEXUAL MODEL?" International Journal of Modern Physics C 11, no. 06 (September 2000): 1257–62. http://dx.doi.org/10.1142/s0129183100001073.
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Recent work has shown that the distribution of steady state mutations for an asexual "bacteria" model has features similar to that seen in Self-Organized Critical (SOC) sandpile model of Bak et al. We investigate this coincidence further and search for "self-organized critical" state for bacteria but instead find that the SOC sandpile critical behavior is very sensitive; critical behavior is destroyed with small perturbations effectively when the absorption of sand is introduced. It is only in the limit when the length of the genome of the bacteria tends to infinity that SOC properties are recovered for the asexual model.
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Yang, Minghui, Hutao Gong, and Bo Deng. "DEM Analysis and Simplified Calculation of Passive Earth Pressure on Retaining Walls Backfilled with Sand Considering Strain-Softening Behavior." Geofluids 2022 (June 9, 2022): 1–12. http://dx.doi.org/10.1155/2022/1880502.
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Common calculation methods of passive earth pressure, such as the Rankine or Coulomb earth pressure theory, assume that the width of the fill behind the wall is sufficient for the development of the slip surface and that after the passive earth pressure reaches the limit state, its value remains unchanged with the increase of displacement of the retaining wall. Nevertheless, cases with narrow backfill width should be considered when retaining walls must be built close to existing stabilization walls in urban areas or near rock faces in mountainous areas. Furthermore, for sand, especially dense sand, when the displacement of the retaining wall is large, a strain-softening behavior similar to the triaxial test will appear, resulting in a decrease in passive earth pressure. In this regard, a practical model for strain-softening of dense sand is proposed firstly and verified by the discrete element method (DEM) using the Particle Flow Code (PFC-2D) software. Then, based on the sliding surface shape obtained by DEM, a simplified method for determining the passive earth pressure distribution of retaining walls using limit equilibrium analysis was proposed. Finally, the passive earth pressures calculated by the proposed method agree well with those from PFC results, and the effects of the width of the backfill and displacement of retaining wall on the distribution of active earth pressure were discussed.
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Jiang, Jiafei, Jie Luo, Jiangtao Yu, and Zhichen Wang. "Performance Improvement of a Fiber-Reinforced Polymer Bar for a Reinforced Sea Sand and Seawater Concrete Beam in the Serviceability Limit State." Sensors 19, no. 3 (February 5, 2019): 654. http://dx.doi.org/10.3390/s19030654.
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Fiber-reinforced polymer (FRP) has supreme resistance to corrosion and can be designed with optic fibers. FRP can be an alternative to steel reinforcement for concrete structures, and can serve as a sensor for smart concrete structures. Due to poor cracking control and bond performance, the limit of flexural capacity in the serviceability limit state has not been determined, which has obstructed the wider application of FRP bars in smart structures. In this study, in order to overcome these shortcomings, a new engineering cementitious composite (ECC) with superior tensile strain capacity was used to replace the cover around the FRP bars in the tensile zone. To investigate the anti-cracking performance of the new composite beam, seven simply supported beams were designed. In the preliminary investigation, the longitudinal FRP bars in these beams were designed without optic fibers to focus on the mechanical behavior. The beams were tested under four-point load and measured using the digital sensor technique, digital image correlation (DIC). The test results showed that introducing a new ECC layer on the tensile side improves the cracking control and flexural behavior (load capacity and deformability) of a FRP-reinforced sea sand and seawater concrete (SSC) beam, especially in the serviceability limit state. We demonstrate the new composite beam can steadily and fully improve the tensile capacity of FRP bars, which is the basis of using FRP bars as sensors.
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Schnaid, F., L. Passini, F. Stracke, and S. Mezzomo. "On the response of fluidized piles from laboratory model tests in granular soils." Journal of Geo-Engineering Sciences 1, no. 2 (2014): 69–81. http://dx.doi.org/10.3233/jgs-140024.
Full textAbstract:
Design guidelines of foundation anchors and piles embedded in fluidized sand comprises understanding of installation processes, defining constitutive parameters and establishing analysis techniques. These fundamental aspects have been investigated by a series of laboratory model tests designed to evaluate the mechanism taking place during pile installation through the influence of downwardly-directed vertical water jets in the geometry of fluidized cavities in saturated sands. Measurements indicate fluidization geometry to be controlled by combined effects of jet velocity and the ratio of particle and jet diameters which can be conveniently expressed by the Froude number of particles. Characteristics of the fluidized zone geometry prior and after fluidization indicate considerable reduction of relative density of fluidized samples. Limit equilibrium analysis using geotechnical parameters approaching critical state provided indicative horizontal stress levels to estimate the uplift skin friction of model steel piles.
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Shirazi, Sharif Moniruzzaman, Md Ibrahim Adham, Noorul Hassan Zardari, Zubaidah Ismail, Hosen Md Imran, and Munir Ahmed Mangrio. "Groundwater quality and hydrogeological characteristics of Malacca state in Malaysia." Journal of Water and Land Development 24, no. 1 (March 1, 2015): 11–19. http://dx.doi.org/10.1515/jwld-2015-0002.
Full textAbstract:
Abstract Groundwater quality and aquifer productivity of Malacca catchment in Peninsular Malaysia are presented in this article. Pumping test data were collected from 210 shallow and 17 deep boreholes to get well inventory information. Data analysis confirmed that the aquifers consisting of schist, sand, limestone and volcanic rocks were the most productive aquifers for groundwater in Malacca state. GIS-based aquifer productivity map was generated based on bedrock and discharge capacity of the aquifers. Aquifer productivity map is classified into three classes, namely high, moderate and low based on discharge capacity. Groundwater potential of the study area is 35, 57 and 8% of low, moderate and high class respectively. Fifty two shallow and 14 deep aquifer groundwater samples were analyzed for water quality. In some cases, groundwater quality analysis indicated that the turbidity, total dissolved solids, iron, chloride and cadmium concentrations exceeded the limit of drinking water quality standards.
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Tang, Chong, and Kok-Kwang Phoon. "Statistical evaluation of model factors in reliability calibration of high-displacement helical piles under axial loading." Canadian Geotechnical Journal 57, no. 2 (February 2020): 246–62. http://dx.doi.org/10.1139/cgj-2018-0754.
Full textAbstract:
An industry survey suggests an increasing application of high-displacement helical piles with greater shaft and helix diameters to support various structures. In this paper, a database of 84 static load tests is compiled and analyzed to evaluate the disturbance effect and characterize the model factors that can be used for reliability-based limit state design. The measured capacity is defined as the load at a pile head settlement equal to 5% of helix diameter. For similar helix configurations tested at the same site, the ratio of uplift to compression capacity indicates a low degree of disturbance for very stiff clay (0.8–1) and a medium degree of disturbance for dense sand (0.6–0.8). At the ultimate limit state, the model factor is defined as the ratio between measured and calculated capacity, where three design guidelines are considered. A hyperbolic model with two parameters is used to fit the load–displacement curves. At the serviceability limit state, the model factor can be defined with the hyperbolic parameters. Based on the database, probabilistic distributions of the capacity model factor and hyperbolic parameters are established. Finally, the capacity model statistics are applied to calculate the resistance factor in the load and resistance factor design.
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Tang, Chong, and Kok-Kwang Phoon. "Statistics of model factors in reliability-based design of axially loaded driven piles in sand." Canadian Geotechnical Journal 55, no. 11 (November 2018): 1592–610. http://dx.doi.org/10.1139/cgj-2017-0542.
Full textAbstract:
This paper compiles 162 reliable field load tests for axially loaded driven piles in sand from previous studies. The L1–L2 method is adopted to interpret the measured resistance from the load–settlement data. The accuracy of resistance calculations with the ICP-05 and UWA-05 methods based on cone penetration test profile is evaluated by the ratio (bias or model factor) of the measured resistance to the calculated resistance. A hyperbolic model with two parameters, where the load component is normalized by the measured resistance, is utilized to fit the measured load–settlement curves. The means, coefficients of variation, and probability distributions for the resistance model factor and the hyperbolic parameters are established from the database. Copula theory is employed to characterize the correlation structure within the hyperbolic parameters. The statistical properties of the model factors are applied to calibrate the resistance factors in simplified reliability-based designs of closed-end piles driven into sand at the ultimate and serviceability limit state by Monte-Carlo simulations. A simple example is provided to illustrate the application of the proposed resistance factors to estimate the allowable load for an allowable settlement at the desired serviceability limit probability.
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Okoyeh, Elizabeth I., Anthony E. Akpan, B. C. E. Egboka, and H. I. Okeke. "An Assessment of the Influences of Surface and Subsurface Water Level Dynamics in the Development of Gullies in Anambra State, Southeastern Nigeria." Earth Interactions 18, no. 4 (January 1, 2014): 1–24. http://dx.doi.org/10.1175/2012ei000488.1.
Full textAbstract:
Abstract Gully erosion–induced problems have been challenging the people and government of Anambra State in southeastern Nigeria for a long time. In spite of the numerous geoscientific and engineering studies so far conducted in the area, the underlying causes of these problems still remain poorly understood. In an attempt to contribute to the understanding of the underlying processes responsible for the persistent gully erosion problems in Anambra State, an integrated study utilizing hydrological, geomorphological, and geophysical data was undertaken. Results of the analyses show that bulk density, pH, and organic matter content of the soil range from 1610 to 1740 kg m−3, 5.10 to 5.30, and 0.32% to 0.46%, respectively. Particle size analyses results show that the soils are dominated by coarse sand materials (50%–68%). Variations in the Atterberg limit parameters (liquid limit, plastic limit, and plasticity index) also point to the dominance of coarse materials in the shallow subsurface. Vertical electrical sounding results capture the shallow surface as being dominated by resistive sandy materials that are underlain by lowly resistive clayey materials. Thus, the area is dominated by porous, friable, and poorly cemented coarse materials that are located on a long and steeply sloping terrain of the tectonically elevated Awka–Orlu cuesta. Both overland and subsurface flow processes are responsible for the gully erosion problems confronting the area. Human activities (e.g., deforestation, uncontrolled urbanization, and absence of requisite legislation to protect the environment) and the high elevation of the Awka–Orlu cuesta have aggravated the severity of the problems. An aggressive reforestation program particularly with native trees, promulgation of necessary legislation to protect the environment, and setting up and empowering an enforcement agency should be vigorously pursued. Also, necessary enlightenment campaigns on best agricultural practices that can reduce surface runoff in soil and water conservation may also be helpful in changing the mindset of people.
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Uchaipichat, Anuchit, and Ekachai Man-Koksung. "Simulations of Bearing Capacity of Foundation on Unsaturated Granular Soils." Applied Mechanics and Materials 52-54 (March 2011): 1400–1405. http://dx.doi.org/10.4028/www.scientific.net/amm.52-54.1400.
Full textAbstract:
Typically a shallow foundation is chosen to support several types of common structure. Several equations for the ultimate bearing capacity of shallow foundation have been proposed with assumption of fully saturated or completely dry conditions. In fact, almost 40 percent of natural soils on the earth surface are in an unsaturated state. Therefore, the ultimate bearing capacity of shallow strip foundation on unsaturated granular soils is developed in this paper using limit equilibrium concept. The simulations from the developed equation for a laboratory-compacted-sand are performed. The results are carefully presented and discussed.
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Nguyen, Anh Thuc Thi, Huan Ngoc Tran, Huong Thi Vu, and Trinh Manh Nguyen. "Applying MIKE 21 FM (HD + ST) model to evaluate the ability to regenerate sand and gravel for efficient management of river exploitation and protection, (A case study at Red River crossing Phuc Tho District, Hanoi)." Journal of Mining and Earth Sciences 61, no. 4 (August 31, 2020): 86–94. http://dx.doi.org/10.46326/jmes.2020.61(4).09.
Full textAbstract:
Sand and gravel in River bed are common construction materials indispensable in urban development, infrastructure, and wharves ... due to the shortage of supply, throughout the rivers in Vietnam. Determination of the volume of regenerated sand annually or according to a certain cycle can use the MIKE 21 FM (HF + ST) hydraulic model given by Danish Institute of Water and Environmental Engineering. Calculation results of the experimental model for the river section across the Phuc Tho district, Hanoi city show that the Vinh Khang sand mine was more simulated during period from 2010 to 2019 and still lower regenaration in the comming years. These results will be significal basis for Mining lisener to orient mine development, adjust capacity and limit exploitation in sediment-deficient areas, avoid locations where there are high erosion trend. The simulation results from the model also are scientific basis for the state management to make master plane, locate sand and gravel material potential areas. But in completing a model it takes time, synthesized data of fields such as geology, hydrometeorology, surveying, geophysics,… it is essential that the functional ministries would make coordinate to bring benefits for organizations and individuals to use lifting data to get high reliability for model results.
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Xu, Honglu, Xiaoguang Cai, Haiyun Wang, Sihan Li, Xin Huang, and Shaoqiu Zhang. "Analysis of the Working Response Mechanism of Wrapped Face Reinforced Soil Retaining Wall under Strong Vibration." Sustainability 14, no. 15 (August 8, 2022): 9741. http://dx.doi.org/10.3390/su14159741.
Full textAbstract:
A series of shaking table tests were carried out to explore the dynamic characteristics and working mechanisms of wrapped-face reinforced soil-retaining walls under strong vibration. Under the 0.1–1.0 g horizontal peak ground acceleration (HPGA), the damping ratio of sand shows a downward trend as a whole, so the acceleration amplification coefficient decreases with the increase of HPGA. However, when HPGA reaches 1.0 g, the acceleration amplification coefficient increases; the range of acceleration amplification coefficient at the top of the wall is 1.69–1.36. When HPGA is 1.0 g, the maximum cumulative residual displacement of the panel is 2.96% H, and the maximum uneven settlement of the sand is 3.57% H, both of which have exceeded the limit of the specification. With the increase of HPGA, the ratio of the dynamic earth force increment to the total dynamic earth force gradually approaches 50%. Since the reinforcement effect of geogrid is not considered, the predicted value of traditional earth pressure theory is different from the measured value. According to the Washington State Department of Transportation displacement index, the deformation range of wrapped-face reinforced soil-retaining walls is divided into three stages: the quasi-elastic stage, the plastic stage, and the failure stage.
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Hu, Weidong, Xinnian Zhu, Tao Hu, Weiwei Wang, and Guozhi Lin. "Non-limit passive earth pressure against cantilever flexible retaining wall in foundation pit considering the displacement." PLOS ONE 17, no. 3 (March 11, 2022): e0264690. http://dx.doi.org/10.1371/journal.pone.0264690.
Full textAbstract:
A series of model tests are carried out on flexible retaining walls such as cantilevered piles, continuous walls, and sheet pile walls in the foundation pit to study the deformation, failure surface, and earth pressure distribution of soils in a passive zone. The shape, displacement, and shear strain of slip failure surface of sand in a passive area are analyzed by Particle Image Velocimetry. The slip failure surface is a broken line, the upper end slides out from the top of the soil, and the lower end is close to the zero displacements of the retaining wall. With the increase of the flexural deformation and horizontal displacement of the wall, the shear strain of the soil increases, and the shear fracture zone in the upper part of the sliding surface is more prominent. Based on the broken line rupture surface in the test results, the passive area can be divided into two zones, the limit state zone and the non-limit state zone. Then the mechanical models are set up respectively. Considering soil displacement, the upper and lower soil layer’s internal friction angle and wall-soil interface friction angle mobilize differently. The relationship between mechanical parameters along the retaining wall and horizontal displacement is estimated. Finally, the earth pressure distribution is obtained by using the horizontal differential layer method. The calculation results of this paper are consistent with the existing research results and the model test results in terms of earth pressure distribution. With the increase of depth, the unit earth pressure increases in the limit state zone. Still, after entering the non-limit state zone, the unit earth pressure rises to a certain extent and decreases rapidly.
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Ugoji, Kelechi Uchenna, Abba Ibim Green, Ruth Ngozi Nmoye, and Ndukam Billy Igbere. "A Partial Environmental Engineering Management Study of Open Dump Site and Its Impact on Land and Water." European Journal of Engineering Research and Science 5, no. 10 (October 15, 2020): 1247–34. http://dx.doi.org/10.24018/ejers.2020.5.10.2120.
Full textAbstract:
This research appraises in partial the environmental engineering effects of open dumpsite with peripheral study of the dumpsite at km 3 Aba-Enugu Expressway in Abia State southeast of Nigeria. The investigation includes visual assessment, interviews / questionnaires results, and analysis. The study reveals that the waste dump serves as a sink to many parts of Aba metropolis being one of the biggest dumpsites in Abia state. The sand value of 47.7% obtained from the study agrees with existing literature/hydrogeology of the area. Results proved that the ground water is safe as samples display quality, which are below the Nigerian standards for drinking water quality limit. These values also fall below the World Health Organization (WHO) water quality limit so the residents around do not stand any health risk at the moment. However, increasing concentration of pollutants indicates that the Soil and probably the potential drinking water source may be contaminated with time, supporting existing study. Therefore, this research recommends a well-engineered waste management plan alongside Extended Producer Responsibility (EPR) cradle-to-grave approach to management of open dumpsite.
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Ugoji, Kelechi Uchenna, Abba Ibim Green, Ruth Ngozi Nmoye, and Ndukam Billy Igbere. "A Partial Environmental Engineering Management Study of Open Dump Site and Its Impact on Land and Water." European Journal of Engineering and Technology Research 5, no. 10 (October 15, 2020): 1247–34. http://dx.doi.org/10.24018/ejeng.2020.5.10.2120.
Full textAbstract:
This research appraises in partial the environmental engineering effects of open dumpsite with peripheral study of the dumpsite at km 3 Aba-Enugu Expressway in Abia State southeast of Nigeria. The investigation includes visual assessment, interviews / questionnaires results, and analysis. The study reveals that the waste dump serves as a sink to many parts of Aba metropolis being one of the biggest dumpsites in Abia state. The sand value of 47.7% obtained from the study agrees with existing literature/hydrogeology of the area. Results proved that the ground water is safe as samples display quality, which are below the Nigerian standards for drinking water quality limit. These values also fall below the World Health Organization (WHO) water quality limit so the residents around do not stand any health risk at the moment. However, increasing concentration of pollutants indicates that the Soil and probably the potential drinking water source may be contaminated with time, supporting existing study. Therefore, this research recommends a well-engineered waste management plan alongside Extended Producer Responsibility (EPR) cradle-to-grave approach to management of open dumpsite.
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Sawicki, Andrzej, Marek Kulczykowski, and Robert Jankowski. "Estimation of Stresses in a Dry Sand Layer Tested on Shaking Table." Archives of Hydro-Engineering and Environmental Mechanics 59, no. 3-4 (December 1, 2012): 101–12. http://dx.doi.org/10.2478/heem-2013-0002.
Full textAbstract:
Abstract Theoretical analysis of shaking table experiments, simulating earthquake response of a dry sand layer, is presented. The aim of such experiments is to study seismic-induced compaction of soil and resulting settlements. In order to determine the soil compaction, the cyclic stresses and strains should be calculated first. These stresses are caused by the cyclic horizontal acceleration at the base of soil layer, so it is important to determine the stress field as function of the base acceleration. It is particularly important for a proper interpretation of shaking table tests, where the base acceleration is controlled but the stresses are hard to measure, and they can only be deduced. Preliminary experiments have shown that small accelerations do not lead to essential settlements, whilst large accelerations cause some phenomena typical for limit states, including a visible appearance of slip lines. All these problems should be well understood for rational planning of experiments. The analysis of these problems is presented in this paper. First, some heuristic considerations about the dynamics of experimental system are presented. Then, the analysis of boundary conditions, expressed as resultants of respective stresses is shown. A particular form of boundary conditions has been chosen, which satisfies the macroscopic boundary conditions and the equilibrium equations. Then, some considerations are presented in order to obtain statically admissible stress field, which does not exceed the Coulomb-Mohr yield conditions. Such an approach leads to determination of the limit base accelerations, which do not cause the plastic state in soil. It was shown that larger accelerations lead to increase of the lateral stresses, and the respective method, which may replace complex plasticity analyses, is proposed. It is shown that it is the lateral stress coefficient K0 that controls the statically admissible stress field during the shaking table experiments.
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Aka, Mfoniso U., Christopher I. Effiong, Okechukwu E. Agbasi, and Dianabasi N. Akpan. "GEOTECHNICAL INVESTIGATION OF BORROW PIT AS A SUBGRADE MATERIAL FOR ROAD CONSTRUCTION AT VICTOR ATTAH INTERNATIONAL AIRPORT, UYO, NIGERIA." Structure and Environment 14, no. 2 (June 30, 2022): 44–54. http://dx.doi.org/10.30540/sae-2022-006.
Full textAbstract:
One of the mass prompt practices of soils is for engineering projects such as the construction of roads, buildings, dams, and so on. Therefore, suitability of index and mechanical properties needs to be investigated. This study aims to determine the essential quality material required for road construction, thereby poses détente prospect for the disposal of ineffectual atrophy generated on sites. Such materials are classified into index and mechanical properties. Six subgrade samples were taken at the depth to bottom ranging from (1.0-5.0) m and tested. The sample was subdued to the laboratory tests, such as Sieve Analysis, Atterberg limits, compaction, California Bearing Ratio (CBR), and Specific Gravity (SG) respectively. The mechanical analysis which involved particle size distribution revealed that the subgrade was finely grated with a limit of ≤35% for subgrade passing sieve No. 200 (0.075 mm) with 29.1%, with an average Natural Moist Content (NMC) of 13.9%. The Maximum Dry Density (MDD) and Optimum Moisture Content (OMC) were 1.83 mg/m3 and 11.5%. The index analysis involved the liquid and plastic limits determination of Liquid Limit (LL) of 35.8%, Plastic Limit (PL) of 24.0%, and a Plasticity Index (PI) of 12%. California Bearing Ratio (CBR) results were 20.3% (soaked). The SG test results ranged from (2.68-2.94) kg/m3, employing the American Association of State Highway and Transport Officials (AASHTO) system of soil classification. The AASHTO grouped the materials into A-1, subgroups A-1-b and A-2-4 constituting 50% and 29.1%, with significant materials composed of stone fragments and sand rating the subgrade samples as excellent to good materials suitable for road construction.
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Syahdi, Syahdi, and Muhammad Suhaimi. "Pengaruh Penggunaan Pasir Putih Sebagai Bahan Tambah Untuk Stabilisasi Tanah Desa Bangkuang Kabupaten Barito Selatan." Jurnal Gradasi Teknik Sipil 3, no. 2 (December 2, 2019): 1–7. http://dx.doi.org/10.31961/gradasi.v3i2.749.
Full textAbstract:
Tanah merupakan salah satu dari sekian banyak material yang bervariasi (heterogen) antara satu lokasi dengan lokasi yang lain., maka dalam penelitian ini melakukan penambahan material pasir putih yang kemudian dicampurkan dengan tanah asli yang berasal dari desa Bangkuang Kecapamatan Karau Kuala Kabupaten Barito selatan.
Kegiatan penelitian dilakukan di laboratorium Geoteknik dan Transportasi Politeknik Negeri Banjarmasin meliputi beberapa metode pungujian dilakukan sesuai dengan standar penelitian yaitu: SNI 03-1965-2008, SNI 03-1964-2008, SNI 03-1967-2008, SNI 03-1965-2008,SNI 03-1743-2008 SNI 03-1738-2011, dan SNI 2828:2011.
Hasil penelitian, dengan penambahan pasir putih sangat berpengaruh terhadap perbaikan sifat – sifat tanah yang akan digunakan untuk bahan stabilisasi subgredre, maka didapat nilai sifat-sifat tanah diberi bahan pasir putih (0%) meliputi; kadar air (W) 23,87%, berat jenis (Gs) 2,59, batas cair (LL) 33,9%, batas plastis (PL) 20,11%, plastisitas indeks (PI) 13,79%, kadar air optimum (OMC) 18,6%, kepadatan kering maksimum (dMax) 1,61 Gr/Cm3 dan CBR desain 5%. Nilai sifat-sifat tanah diberi bahan tambah pasir putih. Nilai sifat-sifat tanah diberi bahan tambah pasir putih (15%) meliputi; berat jenis gabungan (Gs) 2,62, batas cair (LL) 29,6%, batas plastis (PL) 19,52%, plastisitas indeks (PI) 10,08%, kadar air optimum (Omc) 81,5%, kepadatan kering maksimum (dMax)) 1,54 Gr/Cm3 dan CBR desain 6,1%, berat isi kering (d) 1,538 gr/cm³.
Abstract
Land is one of the many varied material (heterogeneous) between one site and another location., then in this research performs addition material of white sand is then blended with the native soil that comes from the village of Karau Kuala Kecapamatan District Bangkuang Barito South.
Research activities carried out in the laboratory of Geotechnical and transportation State Polytechnic Banjarmasin includes several methods of pungujian conducted in accordance with the standards of research, namely: in accordance with the SNI 03-1965-2008, SNI 03-1964-2008, SNI 03-1967-2008, SNI 03-1965-2008, SNI 03-1743-2008, SNI 03-1738-2011, and SNI 2828:2011.
Results of the study, with the addition of white sand is very influential towards the improvement of the nature – nature of the land to be used for subgredre stabilization materials, then obtained the value soil properties are given materials white sand (0%) include; moisture content (W) 23.87%, heavy types (Gs) 2.59, liquid limit (LL) 33.9%, limits plastis (PL) 20.11%, plasticity index (PI) 13.79%, optimum moisture content (OMC) 18.6%, maximum dry density (/dMax) 1.61 Gr/Cm3 and CBR design 5%. The value soil properties are given the added ingredient of white sand. The value soil properties are given the added ingredient of white sand (15%) include; the weight of the combined type (Gs) 2.62, liquid limit (LL) 29.6%, limits plastis (PL) 19.52%, plasticity index (PI) 10.08%, optimum moisture content (Omc) 81.5%, maximum dry density (/dMax)) 1.54 Gr/Cm3 and CBR design 6.1%, weight dry (/d) 1.538 gr/cm ³.
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Tang, Chong, and Kok-Kwang Phoon. "Evaluation of model uncertainties in reliability-based design of steel H-piles in axial compression." Canadian Geotechnical Journal 55, no. 11 (November 2018): 1513–32. http://dx.doi.org/10.1139/cgj-2017-0170.
Full textAbstract:
To account for uncertainties of load and resistance in a more rational way, reliability-based design (RBD) concepts have been increasingly applied to design bridge foundations. One of critical elements in the geotechnical RBD process is the characterization of model uncertainties. This paper compiles 126 and 23 reliable static load tests for steel H-piles in axial compression from two databases: Pile-Load Tests (PILOT) and Deep Foundation Load Test Database (DFLTD), respectively. The Davisson offset limit is adopted to define the measured resistance in clay, sand, and layered soil, which is verified with the L1–L2 method developed for drilled shafts. A hyperbolic model with two parameters is chosen to fit the measured load–settlement curves. The uncertainties in resistance calculations and the load–settlement curves are captured by a ratio (or model factor) of measured to calculated resistance and the hyperbolic parameters. The mean values, coefficients of variation, and the probability distributions of the model factors are established from 149 load tests. The statistics of the resistance model factor are applied to calibrate the resistance factors (for the ultimate limit state) in load and resistance factor design of steel H-piles in axial compression. In future, the statistics of the hyperbolic parameters can be incorporated into the development of RBD of steel H-piles at the serviceability limit state.
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Yao, Ying, Wei Cui, Wen Wang, Fu-Min Ma, and Ben-Yue Chen. "Impacts of dam construction on river channel evolution: a case of Minjiang River in Southeastern China." Proceedings of the International Association of Hydrological Sciences 383 (September 16, 2020): 341–46. http://dx.doi.org/10.5194/piahs-383-341-2020.
Full textAbstract:
Abstract. The Minjiang River is the largest river in Fujian Province. In 1993, the Shuikou Reservoir, which has an effective storage capacity of 700 million m3, was built at about 161 km above the estuary. The completion of the Shuikou Dam trapped most of the upstream sediment in the reservoir area, resulting in a drastic decrease in sediment in the lower reaches of the Minjiang River. The average annual sand load at the Zhuqi Station (about 45 km below the dam) was reduced about 2∕3 after the construction of the reservoir, from 7.42 to 2.55 million t by average, resulting in severe river bed downward cutting. At the same time, the demand for the sand in Minjiang River channel is increasing year by year. The amount of mined river sand is greater than the incoming sediment deposited in the river, which intensified the downcutting of the river bed. The downcutting leads to a continuous upward movement of the tide limit in the river channel especially in the low-flow season. Meanwhile, river embankments and river-related structures are damaged, and the navigation capacity of the Minjiang River is reduced. At present, the river bed of the lower Minjiang River is not yet stable, and the river regime is in a state of constant adjustment.
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George, Jofin, and Arun Menon. "A mechanism-based assessment framework for masonry arch bridges under scour-induced support rotation." Advances in Structural Engineering 24, no. 12 (April 16, 2021): 2637–51. http://dx.doi.org/10.1177/13694332211009325.
Full textAbstract:
Increase in the frequency of flash floods owed to climate change, excessive sand mining, and urbanisation of watersheds has accelerated the need to quantify the structural effect of scour-induced structural damages in masonry arch bridges. The structural effects of scour-induced rotation are unaddressed in literature. In this context, a mechanism-based framework based on limit state principles is developed for masonry arch bridges subjected to scour-induced rotation. Critical collapse mechanisms caused by scour-induced rotation are identified, and analysis framework is developed using rigid-body kinematics. The spectrum of bridges under consideration is classified into subsets, and an assessment scheme is developed using fragility curves as a function of scouring location as well as bridge typology.
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O.K, Iheme, Okoye V.U., Chinwuko A.I., Usman A.O., Ejeke C.F., and Osele C.E. "Evaluation of geotechnical properties of gully erosion materials in ORLU and its environs, IMO state, Nigeria." International Journal of Advanced Geosciences 4, no. 1 (April 26, 2016): 8. http://dx.doi.org/10.14419/ijag.v4i1.5991.
Full textAbstract:
The evaluation of geotechnical properties of rock materials is used to ascertain the environmental factor that necessitated gully erosion in Orlu and its environs, Imo State, Nigeria. The study is aimed at geotechnically defining the characteristics, causes and formation of the gully erosion with particular emphasis on the current land degradation in the study area. Data used in the study were derived from field measurements, and laboratory analysis. Gully variables such as length, depth and widths were also determined. The result of the geological mapping revealed that there are three geologic formations encountered in the study area namely; Ameki, Ogwashi Asaba, and Benin Formations. The result of the field studies shows that 27% of the gullies observed occur in Ameki Formation while no gully was discovered in Ogwashi Asaba formation. The grain size distribution curves interpretation revealed that 80% (by weight) of the soils are medium to coarse grained sand and fine gravels, while the remaining 18% and 2% are for fine grained sand and coarse grained silt. The Atterberg Limit Test interpretation shows that the plasticity index of the formations ranges from 24.83% to 48.42%. Based on the results of the geotechnical properties of rock materials in the study area, the factors responsible for gullies occurrence in the study area were identified as topography, rainfall, geology, and anthropogenic factors. The devastating effects of gully erosion in the study area were observed to include loss of about 22km2 of arable lands; 2 major and 6 minor road failures; loss of many houses and other infrastructures; pollution of surface and underground water. Finally, it is recommended that the appropriate authorities, individuals and all stakeholders in the environmental protection agency should develop ideas in environment watch towards gully erosion control.
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Racault, Y., and C. Boutin. "Waste stabilisation ponds in France: state of the art and recent trends." Water Science and Technology 51, no. 12 (June 1, 2005): 1–9. http://dx.doi.org/10.2166/wst.2005.0413.
Full textAbstract:
Waste stabilisation ponds represent 20% of the total number of wastewater treatment plants in France. Practical expertise acquired during these last 20 years has led to modification in the design of the first facultative basin of WSP systems. Its active surface area is now dimensioned at 6 m2(p.e.)−1 in order to limit the risk of malfunctioning. The cumulated surface of the 2nd and 3rd basin is maintained at 5 m2(p.e.)−1. Another practical point is also that WSPs must receive mainly diluted influents. Globally, the plants are on average far from their nominal loadings, which explains why the first sludge removals took place on average 13 years after being put in operation. Based on a representative sample of plants, i.e. 15% of the French WSPs, it has been possible to estimate the time, material means and cost needed for sludge removal as well as the amount of sludge accumulated. The sludge removed at the 1st yields on average 110 L (p.e.)−1 which represents 12 kg DM (p.e.)−1. The current trend of increasing the quality levels necessary for discharge into sensitive receiving bodies has led to adaptive solutions of polishing treatments by intermittent sand filter systems with or without the plantation of reeds.
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Ajetunmobi, A. E., S. K. Alausa, J. O. Coker, T. W. David, and A. T. Talabi. "Measurement of ambient dose rates in tantalite mining sites in Oke ̶ Ogun, southwest, Nigeria." Scientia Africana 20, no. 2 (September 7, 2021): 1–12. http://dx.doi.org/10.4314/sa.v20i2.1.
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The work scenarios involved in the mining of tantalite a radioactive material expose the miners to ionizing radiation from the ore and the surrounding environment. The dose level in the mine air may be higher than the safe limit due to various contributory sources of ionizing radiation such as radionuclides from rocks, effluents, sand, and radon gas that emanates from caves and this can be of health detriment to the miners. Measurements of ambient dose rates in four selected mining sites have been investigated. Gamma absorbed dose rates were measured in air onsite at Komu, Sepenteri, Gbedu, and Eluku mining sites in Oke-Ogun areas of Oyo State, Nigeria using GammaRAE II dosimeter. Radiation dose to risk software was used to estimate the cancer risk for the period the miners spent onsite. The measured mean dose rate at the sites falls within the range of (19-240) nSv/y and the estimated annual dose rate, cumulative dose, and cancer risk fall within the range of (37-314) μSv/y, (4.0 ̶ 11.1) mSv and (0.5 ̶ 4.5) E-04 respectively. The upper limits of the range for the radiological parameters are all above the safe limit. The health implication of that is that increased work activities at these mining sites may over the years have a negative health effect on the miners. The exposure time of workers can be reduced through proper planning of working shifts for the miners.
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Jendzelovsky, Norbert, and Katarina Tvrda. "Probabilistic Analysis of a Hospital Building Slab Foundation." Applied Sciences 10, no. 21 (November 6, 2020): 7887. http://dx.doi.org/10.3390/app10217887.
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This paper deals with the design of a five-storey hospital building, in which we focus on the deterministic and probabilistic analysis of its slab foundation. The hospital building bearing structure was modeled as a reinforced concrete skeleton. The Boussinesque model was selected for the subsoil under the plate foundation, which was a model of the elastic half-space, where properties of individual layers of the subsoil were entered according to the geological survey. The geological topology consisted of clay gravel and also included a layer of clay sand. In the stochastic solution, the variance of values was considered for individual mechanical properties of different types of soil. We analyzed the influence of the variance of input values on the resulting deflections, strain, and stress state of the plate foundation. Two variants of the solution were considered on the given numerical example. Probability calculations confirmed the probability of failure, which was allowed for the second limit state.
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Abalouch, Ibtissam, Siham Sakami, Fatima-Ezzahra Elabbassi, and Lahcen Boukhattem. "Effects of Recycled Fine Glass Aggregates on Alkali Silica Reaction and Thermo-Mechanical Behavior of Modified Concrete." Applied Sciences 11, no. 19 (September 28, 2021): 9045. http://dx.doi.org/10.3390/app11199045.
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The objective of this work is to develop a new composite material by substituting sand with recycled waste glass (RWG). Different volume percentages of RWG varying from 0 to 50% were incorporated into concrete, with maximum size that did not exceed 1.25 mm. The microscopic characterization by scanning electron microscopy SEM-EDS and optical microscopic test, as well as the durability against alkali silica reaction (ASR) test, were performed respectively to visualize the morphology and assess the damage caused by ASR. Furthermore, the mechanical and thermophysical properties measurements were carried out. The results of microscopic characterization showed the presence of cracks inside a minority of glass particles due to ASR, and ASR test indicated that expansion activity remained well below the limit expansion value of 0.15%. The obtained results also showed that, at 28 and 90 days of curing, compressive strength increased respectively by up to 1.63% and 29% for 20% of the incorporated RWG volume rate in concrete; however, beyond this rate it diminished receptively by 30% and 3.2%. This improvement with curing age was attributed to pozzolanic reaction. Regarding density, it reduced by around 5%. Furthermore, thermal conductivity and thermal effusivity decreased respectively by 36% and 8.06% at dry state and they dropped respectively by 44% and 21.28% at saturated state, related to reference concrete RC. It is therefore feasible to substitute high amount of natural sand with RWG to obtain new composite that may be successfully used as structural material in construction building.
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Zhang, J. J., C. S. Rai, and C. H. Sondergeld. "Mechanical Strength of Reservoir Materials: Key Information for Sand Prediction." SPE Reservoir Evaluation & Engineering 3, no. 02 (April 1, 2000): 127–31. http://dx.doi.org/10.2118/62499-pa.
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Summary The mechanical strength of a reservoir formation is the most crucial information required for predicting sand production and recommending sand control completion. So far, the only reliable technique to obtain the formation strength quantitatively is to perform laboratory tests on core samples. The laboratory tests require substantial volumes of cores, which in most cases are not available. In this study, we present a new method to avoid this restriction. The significance of this approach is in its simplicity and efficiency in constructing a reliable mechanical failure envelope. The key results of this study, based on measurements on a variety of sandstones, are the following.A single normalized failure envelope characterizes sandstone formations. This universal curve makes it possible to construct the failure envelope for a sandstone formation from the knowledge of critical pressure.There exists a correlation between the critical pressure and the compressional wave velocity (at equivalent depths of burial).The failure envelope for a sandstone formation can then be constructed simply from compressional wave velocities. These velocities are generally accessible from conventional logging data. Introduction A major problem encountered during hydrocarbon production is the influx of sand, or sand production.1 It can cause severe damage to both production equipment and the producing formation. Furthermore, remediation processes after sanding are extremely difficult, costly or often impossible. Although significant research has been conducted on sand production, we are still at an embryonic stage in predicting sand influx. Several factors determine sand production. The most critical factors are (1) formation strength; (2) in-situ stress; and (3) production rate. The hydrocarbon production process is associated with reservoir depletion, which results in a decrease of reservoir pore pressure. Consequently, the effective overburden pressure, defined as total overburden pressure minus pore pressure, increases. Formation collapse is most likely if the effective stress exceeds the formation strength. In addition, production rate increase, which is associated with large fluid pressure gradients near the borehole, tends to draw the sand into the wellbore. Generally, one can estimate the in-situ stress. For example, the horizontal minimum stress can be measured from hydraulic fracture testing,2-4 and the overburden pressure from overburden density data. The production rate is a controllable parameter. The parameter of concern is the formation strength, which is the focus of this study. The most reliable technique for obtaining mechanical strength data is triaxial testing of core samples in the laboratory. With appropriate arrangements of applied stresses one can determine a failure envelope in stress space. Such a failure envelope quantifies the stress conditions under which the material fails. Although the laboratory test can provide dependable mechanical strength data, it is not followed routinely simply because it is time-consuming and costly. Moreover, in most cases, a sufficient amount of core is not available. Traditionally the mechanical strength, or Mohr-Coulomb failure criterion, is estimated from P- and S-wave velocities and density log data5-8 based on the correlation of Deere and Miller.9 This approach estimates uniaxial compressive strength, and assumes a constant frictional angle. In this study, we seek an alternative method of estimating overall nonlinear mechanical strength in a three-dimensional stress space. Basic Concept of Failure Envelope Formation collapse is an indication that the in-situ stress is beyond the failure limit of the formation material. This failure stress limit is a quantitative parameter that defines the formation mechanical strength. For a one-dimensional state of stress, the mechanical strength can be simply quantified with a single parameter: the uniaxial compressive strength. However, because the in-situ formation stress is three dimensional and anisotropic, a more complicated mathematical expression involving all the stresses is required to quantify the mechanical strength. This quantitative expression of mechanical strength is known as the failure envelope or failure criterion.
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Shahrooz, Bahram M., Arnol J. Gillum, Jeremiah Cole, and Ahmet Turer. "Bond Characteristics of Overlays Placed over Bridge Decks Sealed with High-Molecular-Weight Methacrylate." Transportation Research Record: Journal of the Transportation Research Board 1697, no. 1 (January 2000): 24–30. http://dx.doi.org/10.3141/1697-05.
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The bond strength between portland cement overlays and bridge decks treated with high-molecular-weight methacrylate sealers is examined. The data universally suggest that sealers reduce the available bond strength. However, extra surface preparation techniques, such as light sandblasting of the sealed surface or broadcasting sand over the surface immediately after sealing [at approximately 1 kg/m2 (20 lb/100 ft2)], restore the strengths to 80 or 85 percent, respectively, of the unsealed surface. Service-level fatigue testing and loading well beyond the serviceability limit state do not adversely affect the bond strength so long as the sealed surface is treated before the application of the overlay. Therefore, to seal the existing cracks, bridge decks may be sealed if either of the recommended secondary surface preparation techniques is followed.
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Naser, Naser Al, Annette Grilli, Stephan Grilli, Christopher Baxter, Aaron Bradshaw, and Brian Maggi. "LAND USE AND MITIGATION EFFECTS ON BARRIER BEACH EROSION IN STORMS: CASE STUDY IN RHODE ISLAND." Coastal Engineering Proceedings, no. 36 (December 30, 2018): 108. http://dx.doi.org/10.9753/icce.v36.papers.108.
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Sea Level Rise (SLR) and storm intensification lead to re-evaluating inundation assessments along the North Atlantic US shoreline. A particular effort is devoted to assessing coastal community risk to “100-year storm†events in Rhode Island, US, using a chain of state-of-the-art storm surge, wave propagation, and coastal erosion 2D models. Damage risks imposed on infrastructures and services incited US federal and state agencies to come up with innovative engineering solutions to improve coastal resiliency while preserving natural coastal and marine environments. This study critically evaluates available design tools used to assess the performance of two types of Natural and Natural Based Features (NNBFs) for coastal protection: natural vegetated barrier islands and dunes reinforced with Geotextile Sand-filled Containers (GSCs), on urbanized barrier islands. Comparative analyses with field data identifies the capabilities and limitations of phase averaging and phase resolving hydro-morphodynamic models used for simulating bed level changes in dissipative beaches, during 3 Sallenger storm regimes. Recommendations are provided on modeling approaches for simulating effects of vegetation and using GSCs to limit coastal erosion.
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Jasiński. "Research on the Influence of Bed Joint Reinforcement on Strength and Deformability of Masonry Shear Walls." Materials 12, no. 16 (August 9, 2019): 2543. http://dx.doi.org/10.3390/ma12162543.
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The areas of Central and Eastern Europe and, thus, Poland are not exposed to the effects of seismic actions. Any possible tremors can be caused by coal or copper mining. Wind, rheological effects, the impact of other objects, or a nonuniform substrate are the predominant types of loading included in the calculations for stiffening walls. The majority of buildings in Poland, as in most other European countries, are low, medium-high brick buildings. Some traditional materials, like solid brick (> 10% of construction materials market) are still used, but autoclaved aerated concrete (AAC) and cement-sand calcium-silicate (Ca-Si) elements with thin joints are prevailing (> 70% of the market) on the Polish market. Adding reinforcement only to bed joints in a wall is a satisfactory solution (in addition to confining) for seismic actions occurring in Poland that improves ULS (ultimate limit state) and SLS (serviceability limit state). This paper presents results from our own tests on testing horizontal shear walls without reinforcement and with different types of reinforcement. This discussion includes 51 walls made of solid brick (CB) reinforced with steel bars and steel trusses and results from tests on 15 walls made of calcium-silicate (Ca-Si) and AAC masonry units reinforced with steel trusses and plastic meshes. Taking into account our own tests and those conducted by other authors, empirical relationships were determined on the basis of more than 90 walls. They are applicable to the design and construction phases to determine the likely effect of reinforcements on cracking stress that damage shear deformation and wall stiffness.