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1
Usmanov, Rustam, Ivan Mrdak, Nikolay Vatin i Vera Murgul. "Reinforced Soil Beds on Weak Soils". Applied Mechanics and Materials 633-634 (wrzesień 2014): 932–35. http://dx.doi.org/10.4028/www.scientific.net/amm.633-634.932.
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Changing a layer of weak soil in deformed foundation with a compacted soil bed consisted of various strong materials (sand, gravel, pebble-gravel, production waste materials). Existing calculation methods and techniques to build compacted soil beds based on weak highly compressive soils do not meet up-to-date requirements. Calculation methods used the dimensions of compacted beds quite often appear to be overestimated, and this results in increase in costs and working hours needed to build artificial foundation. The paper presents the possibility of using reinforced soil beds as an efficient method to build artificial foundation based on weak soils.
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Zaitsev, A. A., i V. G. Ofrikhter. "THE RESULTS OF FIELD TESTS OF WEAK SOILS". Construction and Geotechnics 10, nr 2 (15.12.2019): 56–65. http://dx.doi.org/10.15593/2224-9826/2019.2.05.
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Organization of construction on sites built of weak soils is associated with certain problems, one of which is the construction of temporary roads and foundations for building mechanisms (pile drivers, cranes, etc.). Temporary roads necessary attributes of any construction, ensuring the availability of facilities and linear structures. One of the features of the temporary roads is their erection in accordance with the staged scheme of the organization of construction. Physico-mechanical characteristics of the soils are necessary for the design of such passages using which it is possible to perform calculations using approved soil models. During civil engineering processes on weak soils, it is also important to preserve geological diversity, which is possible with a comprehensive assessment of soil properties. Work on weak soils, even at the survey stage, is associated with accessibility problems due to their low bearing capacity. Usually travel by transport on such soils in warm season is impossible. Evaluation of the physico-mechanical properties of weak soils is possible using lightweight portable devices that can be delivered to the testing sites manually. This paper presents the results of the evaluation of the mechanical characteristics of weak soil using lightweight portable devices such as probe penetrometer, vane shear meter, and dynamic density meters. Soil properties obtained during field tests can be used as input parameters for design models, the use of which allows to perform immediate out calculations temporary road construction or the base for the construction mechanism. Works performed according to the proposed method are of low laboriousness, low cost and high efficiency, do not require the use of mechanisms and can be performed by one person.
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Akulova, Yu N., I. I. Sakharov i V. V. Lushnikov. "Strengthening of weak foundation soils with crushed stone piles". Вестник гражданских инженеров 17, nr 6 (2020): 126–31. http://dx.doi.org/10.23968/1999-5571-2020-17-6-126-131.
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The article presents an innovative technique of deep vibration compaction for soft saturated soils with crushed stone piles. The methods for calculating the strength and deformation characteristics of reinforced soil mass proposed by H. J. Priebe and A. Z. Ter-Martirosyan are presented. An example of the road embankment base in the Plaxis 3D software package is given, taking into account the improvement of the soil mass with crushed stone piles.
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Alsharef, Jamal M. A., Mohd Raihan Taha, Ali Akbar Firoozi i Panbarasi Govindasamy. "Potential of Using Nanocarbons to Stabilize Weak Soils". Applied and Environmental Soil Science 2016 (2016): 1–9. http://dx.doi.org/10.1155/2016/5060531.
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Soil stabilization, using a variety of stabilizers, is a common method used by engineers and designers to enhance the properties of soil. The use of nanomaterials for soil stabilization is one of the most active research areas that also encompass a number of disciplines, including civil engineering and construction materials. Soils improved by nanomaterials could provide a novel, smart, and eco- and environment-friendly construction material for sustainability. In this case, carbon nanomaterials (CNMs) have become candidates for numerous applications in civil engineering. The main objective of this paper is to explore improvements in the physical properties of UKM residual soil using small amounts (0.05, 0.075, 0.1, and 0.2%) of nanocarbons, that is, carbon nanotube (multiwall carbon nanotube (MWCNTs)) and carbon nanofibers (CNFs). The parameters investigated in this study include Atterberg’s limits, optimum water content, maximum dry density, specific gravity, pH, and hydraulic conductivity. Nanocarbons increased the pH values from 3.93 to 4.16. Furthermore, the hydraulic conductivity values of the stabilized fine-grained soil samples containing MWCNTs decreased from 2.16E-09 m/s to 9.46E-10 m/s and, in the reinforcement sample by CNFs, the hydraulic conductivity value decreased to 7.44E-10 m/s. Small amount of nanocarbons (MWCNTs and CNFs) decreased the optimum moisture content, increased maximum dry density, reduced the plasticity index, and also had a significant effect on its hydraulic conductivity.
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Lawrence, David M., i Julia M. Slingo. "Weak Land–Atmosphere Coupling Strength in HadAM3: The Role of Soil Moisture Variability". Journal of Hydrometeorology 6, nr 5 (1.10.2005): 670–80. http://dx.doi.org/10.1175/jhm445.1.
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Abstract A recent model intercomparison, the Global Land–Atmosphere Coupling Experiment (GLACE), showed that there is a wide range of land–atmosphere coupling strengths, or the degree that soil moisture affects the generation of precipitation, amongst current atmospheric general circulation models (AGCMs). Coupling strength in the Hadley Centre atmosphere model (HadAM3) is among the weakest of all AGCMs considered in GLACE. Reasons for the weak HadAM3 coupling strength are sought here. In particular, the impact of pervasive saturated soil conditions and low soil moisture variability on coupling strength is assessed. It is found that when the soil model is modified to reduce the occurrence of soil moisture saturation and to encourage soil moisture variability, the soil moisture–precipitation feedback remains weak, even though the relationship between soil moisture and evaporation is strengthened. Composites of the diurnal cycle, constructed relative to soil moisture, indicate that the model can simulate key differences in boundary layer development over wet versus dry soils. In particular, the influence of wet or dry soil on the diurnal cycles of Bowen ratio, boundary layer height, and total heat flux are largely consistent with the observed influence of soil moisture on these properties. However, despite what appears to be successful simulation of these key aspects of the indirect soil moisture–precipitation feedback, the model does not capture observed differences for wet and dry soils in the daily accumulation of boundary layer moist static energy, a crucial feature of the feedback mechanism.
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Kopiika, Nadiia, i Yuriy Petrenko. "Analysis of the Weak Soil Behavior, Modified Through Cementation". Advanced Journal of Graduate Research 7, nr 1 (20.10.2019): 27–36. http://dx.doi.org/10.21467/ajgr.7.1.27-36.
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The purpose of the study is to conduct thorough theoretical research and literature overview regarding possible ways of soil stabilization on the basis of this practice increasing demand. In particular an emphasis is made on the chemical technique for weak soils strengthening, due to its prevalence and various practical and economic advantages. Great amount of promiscuous data was analyzed and organized; in addition on its basis an attempt is made to provide convincing calculation technique for further usage in engineering soils` stabilization practice. Besides, various factors which could influence on the results` accuracy are identified with corresponding recommendations for further possible research on this issue.
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Eisa, M. S., M. E. Basiouny, A. Mohamady i M. Mira. "Improving Weak Subgrade Soil Using Different Additives". Materials 15, nr 13 (24.06.2022): 4462. http://dx.doi.org/10.3390/ma15134462.
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Weak subgrade is the main problem facing most highway projects. Therefore, this study focuses on trying to improve the properties and increase the strength of weak, clayey, swelling soil for use as a subgrade for pavement structural sections. This trial was developed using a mix of granular and chemical stabilization for the soil. Granular stabilization was applied firstly by mixing natural sand at different percentages of 20%, 35%, and 50% of the total weight of clayey, swelling soil samples to find the minimum percentage that could be added to improve it to sandy, clayey soil, which is acceptable as a subgrade according to the Egyptian highway specification code. Secondly, chemical stabilization was applied to enhanced sandy, clayey soil to increase its strength properties. This was performed by adding chemical additives (lime, cement kiln dust (CKD), fiberglass, Addicrete 11, and gypsum) at different ratios of 2%, 4%, and 6% of the total weight of the samples of enhanced sandy, clayey soil. An experimental program was conducted consisting of characteristics and consistency tests, the California bearing ratio (CBR) test, a proctor test, and a consolidated-drained (C-D) tri-axial shear test. The results showed that 50% sand was the minimum percentage that could be mixed with swelling, clayey soil for granular stabilization to be enhanced and become sandy, clayey soil, which is accepted as a subgrade layer according to the Egyptian highway specification code. In addition, using a mix of granular and chemical stabilization increased the compressive strength of this enhanced subgrade by adding 6% lime or cement kiln dust (CKD) of the total sample weight. They enhanced the strength of the soil and reduced its plasticity. Adding 6% fiberglass and polymers could slightly enhance the desired properties; however, it is not recommended to use them due to their slight effect and economic cost. In addition, it is not recommended to use gypsum at more than 4% due to its negative effect on CBR.
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Jayasree, Parameswaran K., i Musthafakunju Ansar. "Use of novel materials for reinforced soil walls on weak soils". Proceedings of the Institution of Civil Engineers - Construction Materials 165, nr 6 (grudzień 2012): 345–53. http://dx.doi.org/10.1680/coma.10.00038.
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Yadav, B. Manoj. "Improvement of weak soil by DSM method". International Journal of Civil Engineering 4, nr 6 (25.06.2017): 42. http://dx.doi.org/10.14445/23488352/ijce-v4i6p107.
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Lin, Chunxiu, Chang Xia, Zhen Liu i Cuiying Zhou. "A Comprehensive Correlation Study of Structured Soils in Coastal Area of South China about Structural Characteristics". Journal of Marine Science and Engineering 10, nr 4 (6.04.2022): 508. http://dx.doi.org/10.3390/jmse10040508.
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Granite residual soil is a common engineering material, and its mechanical properties are of great importance to engineering safety. This kind of soil presents obvious structural characteristics, and many researchers have emphasized the significance of its structural features. According to previous experiments, from a macroscopic perspective, many researchers have investigated the structural relationship between undisturbed and remolded soils, but few studies have considered it in the mesoscopic aspect. Adopting DEM (a mesomechanical simulation method), we can study how the structure affects the mechanical process between undisturbed and remolded soil. Therefore, this paper combines DEM with laboratory tests to study the structural characteristic correlation between undisturbed and remolded soil. The results indicate that a weak cohesion effect exists in undisturbed soil, and the damage of weak cohesion elements accompanies the failure process. Weak cohesion elements in undisturbed soil cause inhomogeneities in deformation, stress state, and damage accumulation, which ultimately causes differences in strength curves. This paper explains the mechanism of the structural effect on mechanical evolution from a mesomechanical perspective. The DEM simulation method proposed in this paper can be applied to structured soils and better guide engineering practice.
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TIUTKIN, O. L., V. P. KUPRII i S. I. BIELIKOVA. "COMPARATIVE ANALYSIS OF NATM CONSTRUCTION TECHNOLOGIES OF DNIPRO METRO ESCALATOR TUNNEL". Bridges and tunnels: Theory, Research, Practice, nr 20 (1.12.2021): 86–91. http://dx.doi.org/10.15802/bttrp2021/245600.
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Purpose. On the basis of the comparative analysis to carry out a substantiation of the most expedient and rational way of strengthening of a weak massif during a construction of Dnipro metro escalator tunnels by NATM. Methodology. To achieve this goal, an analysis of construction technologies in weak soils was conducted. The most used technologies are Forepoling Umbrella System (FUS), artificial ground freezing and chemical cementation. The peculiarities of carrying out each of the technologies for the conditions of inclined production were analyzed. It is determined how each of the technologies is applied to escalator tunnels and implements the strengthening of weak soil. Findings. The advantages and disadvantages of three technologies for fixing weak soil around the escalator tunnel are identified. Based on comparative analysis, it was found that the only technology that provides increased strength parameters of loamy soils, characteristic for the upper part of the escalator tunnel of the Dnipro metro, is the technology of chemical strengthening (cementation). In some cases, if necessary, short sections of sloping course, characterized by particularly weak soil, can be supported by several pipes, without creating a continuous leading mount. The results of the analysis are the basis for further substantiation of cementation, which creates a multilayer system "reinforced soil massif – temporary fastening – permanent lining". Originality. Based on the results of comparative analysis of three technologies for escalator tunnel construction by NATM, it is proved that the use of cementation not only increases the strength of the soil during drilling, but also further in operation serves as an additional element of the multilayer system "reinforced soil massif – temporary fastening – permanent lining". Practical value. In the course of research, the substantiation of cementation as the most rational and effective technology of strengthening of the surrounding weak massif at construction of the Dnipro metro was carried out.
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Nijjer, Somereet, William E. Rogers i Evan Siemann. "Negative plant–soil feedbacks may limit persistence of an invasive tree due to rapid accumulation of soil pathogens". Proceedings of the Royal Society B: Biological Sciences 274, nr 1625 (21.08.2007): 2621–27. http://dx.doi.org/10.1098/rspb.2007.0804.
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Soil organisms influence plant species coexistence and invasion potential. Plant–soil feedbacks occur when plants change soil community composition such that interactions with that soil community in turn may positively or negatively affect the performance of conspecifics. Theories predict and studies show that invasions may be promoted by stronger negative soil feedbacks for native compared with exotic species. We present a counter-example of a successful invader with strong negative soil feedbacks apparently caused by host-specific, pathogenic soil fungi. Using a feedback experiment in pots, we investigated whether the relative strength of plant–soil feedbacks experienced by a non-native woody invader, Sapium sebiferum , differed from several native tree species by examining their performance in soils collected near conspecifics (‘home soils’) or heterospecifics (‘away soils’) in the introduced range. Sapium seedlings, but no native seedlings, had lower survival and biomass in its home soils compared with soils of other species (‘negative feedback’). To investigate biotic agents potentially responsible for the observed negative feedbacks, we conducted two additional experiments designed to eliminate different soil taxa (‘rescue experiments’). We found that soil sterilization (pot experiment) or soil fungicide applications (pot and field experiments) restored Sapium performance in home soil thereby eliminating the negative feedbacks we observed in the original experiment. Such negative feedbacks apparently mediated by soil fungi could have important effects on persistence of this invader by limiting Sapium seedling success in Sapium dominated forests (home soils) though their weak effects in heterospecific (away) soils suggest a weak role in limiting initial establishment.
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Kornienko, Mykola, Veronika Zhuk, Samar Abed i Igor Chegodaev. "EXPERIENCE OF FIXING A WEAK BASE FOUNDATION BY VERTICAL SOIL-CEMENT ELEMENTS USING DRILL-MIXING TECHNOLOGY". TECHNICAL SCIENCES AND TECHNOLOG IES, nr 2 (12) (2018): 290–96. http://dx.doi.org/10.25140/2411-5363-2018-2(12)-290-296.
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Urgency of the research. Most construction sites in Ukraine have soil conditions area created by weak soils. Permanent pursuit of economical of engineering solutions require the use of new design solutions in the construction on weak soils. Target setting. In the last years new ways to fixing base of foundations using drill-mixing technology are gaining popular-ity. In the process of drilling a special wing bit is a destruction of natural soil and mixing with cement solution. As a result of solidification mixture formed is solid soil-cement element. Actual scientific researches and issues analysis. It has been previously performed in the laboratory study of strength soil-cement vertical elements depending on the amount of cement composition "soil-cement"¸ water-cement ratio in the mixture clay-cement additives properties. In order to a preliminary assessment of effectiveness fixing foundation using drill-mixing technology numerical simulation was performed. Uninvestigated parts of general matters defining. Using the weak soils as the basis for foundations of buildings and structures is seen in view of the possible destruction of their structure and the development of non-uniform deformation. The research objective. Perform evaluation of the effectiveness of fixing the building foundations on the example of a real construction site. The statement of basic materials.. In practice fixing foundations was performed using drill-mixing technology at the con-struction site in the city of Kiev. The article presents data about the experience fixing of weak base foundation, composed bulk soils with the contents of construction and domestic garbage. Fixing performed by soil-cement vertical elements using drill-mixing technology. Conclusions. The choice of a rational scheme of «basis - the foundation - over ground part of the building» should be based on an objective assessment of the mechanical properties of soil, and bearing structures of the building. Applying the basics fixing technology has allowed to reduce the cost of foundation structures up to 20 %.
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Musielok, Łukasz, Marek Drewnik, Wojciech Szymański i Mateusz Stolarczyk. "Classification of mountain soils in a subalpine zone – a case study from the Bieszczady Mountains (SE Poland)". Soil Science Annual 70, nr 2 (1.06.2019): 170–77. http://dx.doi.org/10.2478/ssa-2019-0015.
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Abstract The aim of the study was to test the suitability of the 6th edition of Polish Soil Classification (SGP6) in reflecting the typical features of subalpine Bieszczady Mts. soils in comparison with the 5th edition of Polish Soil Classification (SGP5) and the newest version of World Reference Base for Soil Resources (WRB). Five soil profiles located in differentiated in terms of the parent material, topography and vegetation conditions of the natural environment were investigated. On the basis of described morphology and determined properties soils were classified according to different soil classifications. All soils under study were featured by presence of thick A horizons and high content of soil organic carbon accumulated even very deep in the profiles. Some of the mineral topsoil layers were classified as umbric/umbrik horizons. Moreover cambic/kambik horizons were present and in some cases also weak redoximorphic features occurred. The SGP6 enabled to distinguish soils with a thick, organic carbon-rich A horizons as umbrisols, a newly created subtype of grey soils. Furthermore, the soil taxonomic position according to SGP6 was more detailed in relation to the soil trophic status (in case of brown soils) and occurrence of weak redoximorphic features. That was reflected in number of subtypes to which analyzed soils were classified – 4 in SGP6 vs 2 in SGP5.
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Al-Obaidi, Ahmed, i Pinar Mahmood. "Ultimate capacity of piles penetrating in weak soil layers". MATEC Web of Conferences 162 (2018): 01025. http://dx.doi.org/10.1051/matecconf/201816201025.
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A pile foundation is one of the most popular forms of deep foundations. They are routinely employed to transfer axial structure loads through the soft soil to stronger bearing strata. Piles generally used to increase the load carrying capacity of the foundation and reduce the settlement of the foundation. On the other hand, many cases in practice where piles pass through different layers of soil that contain weak layers located at different depths and extension, also some time cavities with a different shape, size, and depth are found. In this study, a total of 96 cases is considered and simulated in PLAXIS 2D program aiming to understand the influence of weak soil on the ultimate pile capacity. The piles embedded in the dense sand with a layer of weak soil at different extension and location. The cross section of the geometry used in this study was designed as an axisymmetric model with the 15-node element; the boundary condition recommended at least 5D in the horizontal direction, and (L+5D) in the vertical direction where D and L are the diameter and length of pile, respectively. The soil is modeled as Mohr-Coulomb, with five input parameters and the behavior of pile material represented by the linear elastic model. The results of the above cases are compared with the results found in a pile embedded in dense soil without weak layers or cavities. The results indicated that the existence of weak soil layer within the surrounding soil around the pile decreases the ultimate capacity. Furthermore, it has been found that increase in the weak soil width (extension) leads to reduction in the ultimate capacity of the pile. This phenomenon is applicable to all depth of weak soil. The influence of weak layer extension on the ultimate capacity is less when it is presentin the upper soil layers.
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Eckertová, Terézia, Karol Holý, Monika Müllerová, Ivan Sýkora i Jozef Masarik. "EMANATION OF RADON-222 FROM DIFFERENT SOIL TYPES AND SOIL GROUPS". Radiation Protection Dosimetry 198, nr 9-11 (sierpień 2022): 771–77. http://dx.doi.org/10.1093/rpd/ncac132.
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Abstract In this paper, we deal with measurement of 222Rn emanation coefficient (Ke) of soils using an accumulation method. We created a database of Ke values of dried soils for various soil types and soil groups, classified by the size of soil particles. For 18 different soil samples we obtained the Ke values in range 0.083–0.234. The analysis of radon emanation dependence on moisture for seven of these samples shows two different trends which were related to soil texture (clays or sands). Soils with predominant sandy particles prove weak dependence on moisture and Ke values from minimum value (at zero moisture) do not increase much (max 15% increase on every 5% of moisture), for soils with majority of clayey particles the moisture can affect the Ke more significantly (increase up to 60%).
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Degtyar, A. A., i A. M. Burgonutdinov. "REINFORCEMENT OF SUBGRADE DOUBLE-CONE PILES". Russian Journal of Building Construction and Architecture, nr 2(50) (21.05.2021): 62–73. http://dx.doi.org/10.36622/vstu.2021.50.2.005.
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Statement of the problem. The problem of designing the reinforcement method of weak seasonally freezing soils in subgrade base by using double-cone hollow piles and geotechnical materials for roads in the northern regions of the Russian Federation is investigated. Results. As a result of the study, the construction of the subgrade in the form of pile strip foundation of double-cone piles reinforced by geotechnical materials on weak heaving soils taking into account traffic loads and weight of subgrade is considered. A method has been developed of calculating the road base in the form of pile strip foundation of double-cone piles reinforced by geotechnical materials on weak heaving soils taking into account traffic loads and weight of subgrade is considered. The developed method of calculation is based on the formation of soil compaction zones in the near-pile space as a result of pile driving into the ground, which leads to an increase in the structural strength of the weak soil, and also takes the arch effect that occurs in the soil between adjacent pile heads. Conclusions. The obtained research results allow us to conclude that the developed subgrade design and its calculation method are of great interest both to scientists and design engineers, and can be used in construction practice.
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Swami, Akhileshwar, Pushpendra Kumar Kushwaha i Mohit Gangwar. "Studies on Effect of Different Environmental Conditions on CBR of Black Cotton Soil Reinforced with Coir Fibre". Asian Journal of Engineering and Applied Technology 7, nr 1 (5.05.2018): 20–28. http://dx.doi.org/10.51983/ajeat-2018.7.1.982.
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Expansive soil covers nearly 20 percent of the land mass in India. These soils are known to possess weak properties due to the presence of clay minerals known as “Montmorillonite”. Typical behaviour of soil results in the failure of structures, in form of settlements, cracks etc. Thus it is important to remove the existing weak soil and replace it with non-expansive soil or to improve the properties of weak soil by stabilization. Soil reinforcement is a technique that can be used to improve the engineering characteristics of expansive soils. Use of natural fibres to reinforce soil is an old and ancient idea. Randomly distributed fibre reinforced soil have recently attracted growing attention in geotechnical engineering. The present dissertation aims to study the effect of different environmental conditions on performance of coir fibres included in black cotton soil to enhance its strength and reduce the swelling behaviour. Coir fibre is known as a biodegradable material that tends to decay under extreme environmental conditions such as in contaminated and polluted water, in getting contact with the leachate, in alternate cycles of wetting and drying, also in alternate cycles of freezing and thawing and so on. In general, life of coir fibre in soil is expected to 8-10 years. Therefore under different environmental condition it may degrade fast. The gain in soil strength or decrease in swelling might be lost. This aspect is not studied so far. Hence in this work this is attempted. The work in the project is experiment based, California bearing ratio of soil is an important soil strength parameter used in design of pavements. Effect of some different possible environmental conditions on CBR of expansive soil improved by coir fibre reinforcement will be studied experimentally in the present work.
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PETRENKO, V. D., V. S. ANDRIEIEV i V. V. KHARCHENKO. "COMPARATIVE ANALYSIS OF TECHNOLOGIES OF MICROPILES ARRANGEMENT DURING STRENGTHENING OF WEAK SOIL BASES". Bridges and tunnels: Theory, Research, Practice, nr 19 (27.07.2021): 69–77. http://dx.doi.org/10.15802/bttrp2021/233978.
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Purpose. Perform a comparative analysis of drill and injection (jet-grouting) and drill and mixing technologies of micropiles arrangement of weak soil bases with the identification of technological features that significantly effect on the design and calculation of weak soil bases strengthening. Methodology. To solve this problem, was conducted of the detailed analysis of the most effective methods of micropiles arrangement during the strengthening of weak soil bases (physical immersion, bored and packing of concrete, drill and injection of ground, drill and mixing soils and application of special effects). Peculiarities of technological parameters of jet-grouting and drill and mixing technologies are considered in detail. The advantages and disadvantages of each of the technologies are revealed. It is proved that the drill and mixing technology has a greater degree of prediction of the stress-strain state change of the inhomogeneous base. To determine the influence of deformation characteristics, a spatial finite-element model based on a flat prototype was created, which was built using automatic triangulation of the professional calculation complex SCAD. Findings. A significant reduction of the deformed state at an almost constant stress state is obtained. When the deformation characteristic increases by 3 times (the ratio of the modulus of elasticity of the soil cement pile and the weak soil), the vertical displacements of the foundation decrease by 1.23 times. Originality. It consists in obtaining the dependence of the change of vertical displacements and stresses on the modulus of elasticity of the soil cement micropile, created on the basis of drill and mixing technology. Practical value. It consists in the obtained results of comparative analysis of substantiation of micropile installation drill and mixing technology during strengthening of weak soil bases with definition of technological features and choice of drill and mixing as the most effective variant from the point of view of technology realization.
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Zotsenko, Mykola, Yuriyvynnykov . i Maksym Kharchenko. "Experience of Weak Soil Reinforcement by Soil-Cement Elements Manufactured by Deep Soil Mixing Technology". International Journal of Engineering & Technology 7, nr 3.2 (20.06.2018): 486. http://dx.doi.org/10.14419/ijet.v7i3.2.14577.
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Problematic issues of construction and operation in complex geotechnical conditions are systematized (subsiding and peaty soil, silt, filled, man-made soil, saturated, land sliding and seismically hazardous territories, densely developed areas) by the means of reinforcing soil massif by vertical soil-cement elements (SCE) using deep soil mixing (DSM) technology. The practical solution experience of highly efficient “man-made soil-cement base – foundation – structure” systems is shown by the example of complex geotechnical conditions under static and dynamic influences (including earthquakes and critical failure man-made loads), and excavation using SCE. A decreasing in a settlement of soil-cement bases of buildings by 2 – 4 times compared to natural soil massif and increasing in soil-cement mechanical features by 2.5 times has been established. The options of decreasing the seismic hazard (increasing the seismic stability of soil) for securing the emergency-free operation of oil storage vertical steel tank in case of the varying intensity earthquakes utilizing the man-made soil-cement base has been justified.
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Ou, Ou, Xin Gui Zhang i Nian Ping Yi. "The Experimental Study on Strength of Subgrade Soil Treated with Liquid Stabilizer". Advanced Materials Research 194-196 (luty 2011): 985–88. http://dx.doi.org/10.4028/www.scientific.net/amr.194-196.985.
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The liquid soil stabilizer technology is a chemically modified method that can stabilize or reinforce those soils with weak engineering properties. In this paper, two typical high liquid limit soils ，which can not be directly used as subgrade materials，were treated with a new soil stabilizer and it were processed that serials of comparison test on the main engineer properties of soil that pre-and post-treated with soil stabilizer. Then the results show that the soil liquid stabilizer is effective to improve strength and moisture susceptibility for two selected soils. The liquid soil stabilizer technology opened up a new approach for soil improvement and ground treatment.
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Affam, M., R. Ewusi Wilson i D. Asenso-Gjambibi. "Effect of Graded Oil Palm Kernel Shells on Compaction of Weak o Problematic Sub-Grade Soils". Ghana Mining Journal 19, nr 2 (22.12.2019): 17–25. http://dx.doi.org/10.4314/gm.v19i2.3.
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AbstractSub-grade is the ultimate load bearer of vehicular traffic load in a pavement structure. A weak sub-grade or problematic soils require some improvements like soil stabilisation, soil reinforcement and/or capping of the sub-grade layer. These sub-grade improvement methods increase the total project cost because non-local materials such as cement, geosynthetics and hydrated lime are commonly used. The use of graded oil palm kernel shells (OPKS) which are local, cheaper and readily available as a soil improvement material was assessed in this research. This assessment was done by mixing sub-grade material with 2.8 mm, 5 mm and 10 mm graded OPKS. 10 %, 20 % and 30 % of each graded OPKS was added separately to the soil to form nine composite materials. These composite materials including the natural soil were tested for their California Bearing Ratio (CBR) values. The investigation proved that the composite made of 20 % 2.8 mm graded OPKS yielded a soaked CBR of 23.5 % which is a 197.47 % increase in soaked CBR compared to that of the natural soil. The soaked CBR samples of the graded OPKS composite materials absorbed lesser amounts of water in comparison to that of the natural soil. This behaviour implies that some capillary force created at un-soaked condition in the composite materials was preserved; therefore, the composite materials generally have higher CBR values than the natural soil. Keywords: Oil Palm Kernel Shells (OPKS), Problematic Soils, Lightweight Aggregate (LWA)
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Md Nujid, Masyitah, i Mohd Raihan Taha. "Assessment on Bearing Capacity of Two Clay Layers Soil Using COMSOL". Applied Mechanics and Materials 567 (czerwiec 2014): 675–80. http://dx.doi.org/10.4028/www.scientific.net/amm.567.675.
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Natural soils are often deposited in layers and homogeneous soils which are very rarely found in nature. Thus, bearing capacity of layered soil cannot be treated anymore as single soil since the soil strength and stiffness parameters are different and increase their linearly with depth. There are two cases which can be consider as inhomogeneous layer soil where strong clay overlaying weak clay layers or weak clay overlaying strong clay layers. A parametric study was conducted to assess the ultimate bearing capacity of a smooth strip footing subjected to vertical load resting on two undrained clays layered soil. A two dimensional (2D) plane strain model incorporated in COMSOL Multiphysics (version 4.3a) which a finite element software was adopted with two physical branches that have been chosen. Two clays layered soil were assumed as linear elastic incompressible material which failed in the Mohr-Coulomb criterion. The finite element results were presented in terms of a modified bearing capacity factor for different ratios of top layer thickness, strength and stiffness ratio of two clay layers. The computation results were then compared to published studies. The numerical analysis showed that strong clay overlaying weak clay layers with c1/c2 >1 resulted in increase of Nc* as h/B ratio increase. In contrast, for a case where weak clay overlaying strong clay layers with c1/c2 <1 showed decrease of Nc* as h/B ratio increase. In comparing results of bearing capacity factor, Nc* indicated a similar trend from previous studies. Stiffness parameters did not affect the solutions as long as remain constant for all cases within suitable ranges of parameters.
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Alshami, Abeer W., Bashar H. Ismael, Mohammed F. Aswad, Ali Majdi, Murtatha Alshijlawi, Mustafa Mohammed Aljumaily, Mohamed Khalid AlOmar, Ibraheem A. Aidan i Mohammed Majeed Hameed. "Compaction Curves and Strength of Clayey Soil Modified with Micro and Nano Silica". Materials 15, nr 20 (14.10.2022): 7148. http://dx.doi.org/10.3390/ma15207148.
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Some Clayey soils are generally categorized as weak soils, and structures lying on such soils have been exposed to severe damage. Therefore, the central thesis of this paper is the impact of a waste material known as a silica fume as nano and micro material on soil’s behaviour. To evaluate the effects of those additives on Atterberg limits, compaction characteristics and unconfined compressive strength, clayey soil samples have been transformed using micro and nano silica fume (by-product materials). In the current investigation, silica fume is used at four different percentages: 0, 2, 4, and 7%. The results show that the plasticity index of soil decreases with the addition of micro silica and increases with the addition of nano-silica. Increasing nano silica percentage improves the dry density of the compacted soil and reduces the optimum moisture content. An opposite behavior is observed with adding micro silica to compacted soil. Finally, 4% of silica fume is found to be the optimum dosage to improve the unconfined compressive strength of the treated soil with both additives. As a result, treating the weak clay soil with micro and/or nano-silica fume has the potential to be impactful.
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Кукина, О. Б., В. П. Волокитин, В. В. Волков, М. С. Ким i А. С. Чунихина. "METHODOLOGY AND EXPERIMENTS ON THE DESIGN OF GROUND PADS ON THE BASIS OF WEAK SOILS". Stroitelʹnaâ mehanika i konstrukcii, nr 4(35) (19.12.2022): 82–91. http://dx.doi.org/10.36622/vstu.2022.35.4.009.
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В статье рассматриваются новые методологические подходы к решению задачи улучшения свойств глинистых грунтов с одновременной утилизацией строительных материалов, образовавшихся в результате демонтажа зданий и сооружений. Показан пример получения метаморфизированного глинистого грунта с использованием вторичного пенобетона, который сформирован по безобжиговой бесцементной технологии получения строительного композита. В работе представлены механизмы модификации и образования метаморфизированных уплотненных глинистых грунтов; определены механические показатели образцов глинистых грунтов, модифицированных диспергированным пенобетоном и гашеной известью; создана расчетная схема грунтовой подушки, выполненной из глинистого грунта, модифицированного диспергированным пенобетоном и гашеной известью; установлены оптимальные геометрические параметры грунтовой подушки для строительства зданий и сооружений; определено напряженно-деформированное состояние слабого основания, усиленного грунтовой подушкой, выполненной из модифицированного глинистого грунта. The article discusses new methodological approaches to solving the problem of improving the properties of clay soils with the simultaneous disposal of building materials resulting from the dismantling of buildings and structures. An example of obtaining a metamorphosed clay soil using recycled foam concrete, which is formed according to a non-firing cementless technology for obtaining a building composite, is shown. The paper presents the mechanisms of modification and formation of metamorphosed compacted clay soils; the mechanical properties of clay soil samples modified with dispersed foam concrete and slaked lime were determined; a design scheme for a soil pad made of clay soil modified with dispersed foam concrete and slaked lime was created; the optimal geometric parameters of the soil cushion for the construction of buildings and structures have been established; the stress-strain state of a weak base reinforced with a soil cushion made of modified clay soil was determined.
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Ter-Martirosyan, Zaven G., Armen Z. Ter-Martirosyan i Aleksandr S. Akuleckij. "Stress-strein state of weak and filled soils reinforced with reinforced concrete and soil piles, respectively". Vestnik MGSU, nr 9 (wrzesień 2021): 1182–90. http://dx.doi.org/10.22227/1997-0935.2021.9.1182-1190.
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Introduction. The overwhelming majority of construction areas are characterized by difficult engineering and geological conditions, represented by the presence of weak soils at the base. There are construction sites on which a large thickness of fill soil is observed. In these conditions, designers apply: soil consolidation, soil reinforcement, significant deepening of the underground part of buildings, etc. This article presents the formulation and solution of the problems of interaction of reinforced concrete piles with weak soils, as well as the interaction of soil piles with bulk soils as part of a pile-slab foundation, which allow one to determine the reduced deformation modulus and the bedding value.
Materials and methods. To describe the change in shear stresses depending on depth, a law was adopted in the form τ(z)=τ0е–αz. The solution is presented by analytical and numerical methods. The results obtained were compared by the analytical solution of the problem with the results obtained in the PLAXIS 3D software package.
Results. Regularities of the distribution of the total load on the pile-slab foundation between the pile field and the grillage have been obtained. The analytical solutions in the article are supported by the graphical part, performed using the Mathcad program. Numerical simulation of the problem was carried out in the PLAXIS 3D software package. The dependence of the settlement on the load, calculated by analytical and numerical methods, is shown. An expression is obtained for defining the stresses in different sections of the pile shaft and under the grillage slab. The theoretical and practical aspects of the construction of crushed stone piles are considered. The theoretical substantiation of compaction of bulk soils with crushed stone piles using a special technology is given. A dependence is obtained for determining the reduced modulus of deformation for bulk soil mass reinforced with soil piles.
Conclusions. Comparative evaluation of the results of solutions obtained by analytical and numerical methods showed good convergence. The solutions obtained can be used to preliminary determination of the settlement of piles as part of a pile-slab foundation. Selection of the optimal ratio of the pile length and its diameter allows the most effective use of the bearing capacity of the pile. For bulk soils, reinforced with soil piles, it is possible to select the optimal reduced modulus of deformation by varying the pitch of the soil piles.
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MacDougall, Andrew S., Matthias C. Rillig i John N. Klironomos. "Weak conspecific feedbacks and exotic dominance in a species-rich savannah". Proceedings of the Royal Society B: Biological Sciences 278, nr 1720 (16.02.2011): 2939–45. http://dx.doi.org/10.1098/rspb.2010.2730.
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Whether dominance drives species loss can depend on the power of conspecific self-limitation as dominant populations expand; these limitations can stabilize competitive imbalances that might otherwise cause displacement. We quantify the relative strength of conspecific and heterospecific soil feedbacks in an exotic-dominated savannah, using greenhouse trials and field surveys to test whether dominants are less self-suppressed, highly suppressive of others or both. Soil feedbacks can impact plant abundance, including invasion, but their implications for coexistence in invader-dominated systems are unclear. We found that conspecific feedbacks were significantly more negative than heterospecific ones for all species including the dominant invaders; even the rarest natives performed significantly better in the soils of other species. The strength of these negative feedbacks, however, was approximately 50 per cent stronger for natives and matched their field abundance—the most self-limited natives were rare and narrowly distributed. These results suggest that exotics dominate by interacting with natives carrying heavier conspecific feedback burdens, without cultivating either negative heterospecific effects that suppress natives or positive ones that accelerate their own expansion. These feedbacks, however, could contribute to coexistence because all species were self-limited in their own soils. Although the net impact of this feedback stabilization will probably interact with other factors (e.g. herbivory), soil feedbacks may thus contribute to invader dominance without necessarily being detrimental to species richness.
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Hiller, E., M. Khun, L. Zemanová, Ľ. Jurkovič i M. Bartaľ. "Laboratory study of retention and release of weak acid herbicide MCPA by soils and sediments and leaching potential of MCPA". Plant, Soil and Environment 52, No. 12 (19.11.2011): 550–58. http://dx.doi.org/10.17221/3546-pse.
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MCPA sorption and desorption in five surface soils (denoted as A1-5), three bottom sediments (S1-3), two river sediments (L1-2) and one subsurface soil (SS) at two initial concentrations in aqueous solution – C<sub>0</sub> = 0.5 and 10 mg/l were studied. No significant effect of the initial concentration on MCPA equilibrium distribution between soil/sediment and aqueous solution was observed. The difference between distribution coefficient K<sub>D</sub> at C<sub>0</sub> = 0.5 mg/l and K<sub>D</sub> at C<sub>0</sub> = 10 mg/l was found only in the case of one bottom sediment (S2). A simple regression analysis between K<sub>D</sub> at C<sub>0</sub> = 0.5 and 10 mg/l and soil/sediment properties indicated that the most important property which determined the variation in MCPA sorption is organic carbon (r = 0.886*** and r = 0.926***, respectively). Similarly, desorption of MCPA was inversely proportional to organic carbon content of the soils and sediments used (r = –0.862* and r = –0.842**). These observations showed that MCPA sorption and desorption in soils and sediments were primarily controlled by organic components of the geosorbents used. Overall, the percentage of MCPA sorption in soils and sediments was low (P<sub>sorp</sub> ≈ 3–53%; K<sub>D</sub> = 0.077–2.827 l/kg) and the percentage of MCPA desorbed was relatively high (P<sub>des</sub> ≈ 11–70%), especially in the soils and sediments with lower organic carbon content. The experimental results and calculated values of groundwater ubiquity score GUS and relative leaching potential index RLPI imply that MCPA is very mobile in all the surface soils and has a potential to contaminate groundwater.
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Lattupeirissa, Anggi Asafita, Marcus Luhukay i Robby G. Risamasu. "Karakteristik Fisik, Kimia dan Mineral Tanah Di Lokasi Kampus IAIN- Ambon Kecamatan Sirimau Kota Ambon". JURNAL PERTANIAN KEPULAUAN 6, nr 2 (26.10.2022): 82–92. http://dx.doi.org/10.30598/jpk.2022.6.2.82.
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The aims of this study was to identify morphological characteristics, clay mineral composition and soil similarity index between two soil profiles at the IAIN campus. The results showed that soil color characteristics of soil layers of both soils are different. Both soil profiles have deep solums with loam to sandy loam texture distribution. The increasing of clay content in the B horizon of both soil profiles is still weak as indicated by the present of a Bw (kambik) horizon. Soil structure is a subangular blocky with fine to coarse sizes and weak to strong structural development. Soil consistency is slightly sticky to sticky. Cation exchange capacity is very low as indicated by low Ca dan Na, medium to high Mg and high Na soil exchangeable cations. The dominant clay mineral in both soil profiles is kaolonit, which is formed by unwell-consolidated weathering materials mixed with weathering-resistant quartz. The silt/clay ratio and CEC values shows similarity between layers between both profiles, however, the Ca/Mg ratio shows dissimilarity. The soil type in both soil profiles is district Kambisol (Typic distrudepts) categorized as a developed soil
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Ehizemhen C, Igibah, Agashua Lucia O i Sadiq Abubakar A. "Influence of hydrated lime and bitumen on different lateritic soil samples: case study of Sheda-Abuja, Nigeria". International Journal of Engineering & Technology 9, nr 1 (18.02.2020): 218. http://dx.doi.org/10.14419/ijet.v9i1.30054.
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This research was performed so as to appraise strength and properties of lateritic soils enriched with hydrated lime and bitumen as construction materials. Soil samplings S1, S2, S3, S4, and S5 was collected from Dualization of Sheda - Abaji, Abuja, F.C.T, Ni-geria and augment with 0, 3, 6, 9, and 12% of hydrated lime and bitumen. Laboratory tests like Consistency (Atterberg limit), California Bearing Ratio (C.B.R), compaction and sieve scrutiny were done on the soil sampling. The study exposed that construc-tive effects were gotten via the addition of hydrated lime and bitumen in order to augment the strength of weak soils. All the 5 samplings have C.B.R values of 48.0% with hydrated lime as additives, whereas bitumen additive is 40.60%. Introduction of addi-tives enriched the soil samplings from weak materials to an excellent base material with C.B.R values above 40%. Hence, aug-mentation of lateritic soil samplings from the studied locality could be perform efficiently by using lime.
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Demsie, Tarekegn Shumetie, Markos Tsegaye Beyene, Abuye Boja Lemma i Esayas Alemayehu. "NSF (Nylon Synthetic Fiber) Effectiveness in Stabilizing Weak Subgrade Soil: An Experimental Investigation". Advances in Civil Engineering 2023 (30.05.2023): 1–13. http://dx.doi.org/10.1155/2023/3085842.
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Improvement in subgrade soil has always been an area of concern for highway and geotechnical engineers. Weak subgrade soil results in a greater thickness of the pavement layer, which increases the cost of pavement construction. It further leads to large deformations, which in turn cause continuous deterioration of the paved surface. To solve this problem, various engineering solutions and soil improvement mechanisms were previously proposed. This study was designed to investigate the stabilization of weak subgrade soil with nylon synthetic fiber (NSF) in a compromising combination. Previously, some investigations used a lower fiber content with a higher fiber length, whereas others used a lower fiber length with a higher fiber content. However, this investigation was uniquely designed to stabilize weak subgrade soil with the consideration of appropriate fiber length (10 mm and 20 mm) and content (0.5%, 1%, 1.5%, and 2.5%). The engineering properties of the soil, the effect of NSF on weak subgrade soil, various fiber content and aspect ratios, and the optimum content and critical fiber aspect ratio were investigated in a laboratory. The effect of fibers on compaction, CBR values, and CBR swell values has also been studied. Laboratory results on the modified compaction tests showed that maximum dry density (MDD) was increased with the increment of fiber content, whereas optimum moisture content (OMC) remained constant. The soaked CBR and CBR swell values of natural soil were 1.80% and 8.95%, respectively. Due to reinforcement, the percentage increase in soaked CBR value at the optimum NSF content is 265.3, 310.0, 282.8, and 342.2 for aspect ratios of 33.33, 66.67, 25, and 50, respectively, with reference to natural soil. Also, the percentage decrease in swelling is 34.7, 52.75, 43.55, and 36.9, respectively. Moreover, the CBR value increases with the increase in aspect ratio by keeping the diameter constant and decreases with the increase in aspect ratio by keeping the length constant. It was also observed that increasing the length and diameter of NSF further increased the CBR value of reinforced soil. This increment was substantial at a fiber content of 1.5% for an aspect ratio of 50 (length = 20 mm, diameter = 0.4 mm). There was also a decrease in the CBR swelling value with an increase in fiber content. Finally, this investigation concluded that the use of NSF is a solution to weak soils with regard to moisture and performance problems.
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Bandara, Nishantha, Hiroshan Hettiarachchi, Elin Jensen i Tarik H. Binoy. "Upcycling Potential of Industrial Waste in Soil Stabilization: Use of Kiln Dust and Fly Ash to Improve Weak Pavement Subgrades Encountered in Michigan, USA". Sustainability 12, nr 17 (3.09.2020): 7226. http://dx.doi.org/10.3390/su12177226.
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The State of Michigan in the United States often encounters weak soil subgrades during its road construction and maintenance activities. Undercutting has been the usual solution, while a very few attempts of in-situ soil stabilization with cement or lime have been made. Compared to the large volume of weak soils that require improvement and the cost incurred on an annual basis, some locally available industrial byproducts present the potential to become effective soil subgrade stabilizers and a better solution from the sustainability perspective as well. The candidate industrial byproducts are Cement Kiln Dust (CKD), Lime Kiln Dust (LKD), and Fly Ash (FA), out of which only a fraction is currently used for any other secondary purposes while the rest is disposed of in Michigan landfills. This manuscript describes a laboratory investigation conducted on above industrial byproducts and/or their combinations to assess their suitability to be used as soil subgrade stabilizers in three selected weak soil types often found in Michigan. Results reveal that CKD or a combination of FA/LKD can be recommended for the long-term soil subgrade stabilization of all three soil types tested, while FA and LKD can be used in some soil types as a short-term soil stabilizer (for construction facilitation). A brief discussion is also presented at the end on the potential positive impact that can be made by the upcycling of CKD/LKD/FA on sustainability.
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Hullur, Uma G., Dr S. Krishnaiah i Dr K. B. Prakash. "Stabilization of Black Cotton Soil Using Rice Husk Ash for Flexible Pavement Construction". International Journal for Research in Applied Science and Engineering Technology 10, nr 8 (31.08.2022): 1870–74. http://dx.doi.org/10.22214/ijraset.2022.46535.
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Abstract: In India there are different types of soils, and the most likely present soil is clay. The flexible pavement consists of different layers such as embankment, subgrade, GSB, WMM, DBM and BC. Sub grade is the layer which acts as the foundation for pavement. In order to use the cut and fill principle, available nearby lands are selected as the borrow area for making sub grade. In this situation, the soil may not be suitable for subgrade construction. Keeping this in view stabilization of weak soil in situ may be done with suitable stabilizers to save the construction cost considerably. In the present investigation agricultural waste materials like Rice Husk Ash (RHA) which is mixed with soil to study improvement of weak sub grade in terms of compaction and strength characteristics.
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Abu-Hasan, Mahmud, Valentina Solov'eva i Antonina Saharova. "Methods for Stabilizing and Strengthening Yoldian Clays and Weak Clay Soils When Creating a Subgrade in the Far North Regions". Proceedings of Petersburg Transport University 19, nr 3 (25.09.2022): 444–54. http://dx.doi.org/10.20295/1815-588x-2022-3-444-454.
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Purpose: Definition of the most effective methods and components for strengthening weak Yoldian clays used in the creation of transport routes in the North regions. Methods: The definition of the main physical-mechanical characteristics of clay soil was carried out in accordance with the requirements: of GOST (Russia State Standard) 12536—2014 “Soils. Methods for laboratory determination of granulometric (grain) and microaggregate composition”; GOST 25584—2016 “Methods for laboratory determination of the filtration coefficient”; GOST 22733—2016 “Soils. Method for laboratory determination of maximum density”; GOST 5180—2015 “Soils. Methods of laboratory determination of physical characteristics”; GOST 25100—2020 “Soils. Classification”. It is shown that the effective strengthening of weak clay soil is achieved as a result of its preliminary stabilization with the help of granulated blast-furnace slag or natural limestone of ≈2.5 mm fraction. The rational amount of granulated blast-furnace slag or limestone is 15 wt.% of the soil mass and at the same time, clay soil has the highest strength value — (2.25–2.45) MPa. The difference in strength indicators in favor of limestone constitutes 9.0%. It has been experimentally established that in order to increase reinforced clay soil strength it is effective to use granulated blast-furnace slag in combination with finely ground blast-furnace slag which rational amount of is 10 wt.% of soil mass which achieved strength of corresponds to M20–M25 grade. It has been defined that for comprehensive improvement of the indicators as strength, density, and frost resistance it is necessary to introduce additionally to clay soil, reinforced with blast-furnace metallurgical slag as reactive components which it’s effective to use Portland cement in amount of not more than 5 wt.% of soil mass in combination with dry complex chemical additive “PRA” which rational amount of constitutes 2.0 wt.% by weight of (Portland cement + finely ground blast-furnace slag). Practical significance: Stabilized and comprehensively strengthened weak clayey soil is characterized by the following actual indicators: M50 F35 K10 — 0.026 m/day which can be used as a base at construction of transport routes of local importance in the regions of the North.
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Abdul-Razzaq, Khattab. "DISTRIBUTION OF SHEAR STRESSES IN ISOLATED SQUARE CONCRETE FOUNDATION HAVING SPOTS OF VERY WEAK SOILS". Diyala Journal of Engineering Sciences 5, nr 2 (1.12.2012): 137–61. http://dx.doi.org/10.24237/djes.2012.05211.
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In the usual methodology for soil investigation, boreholes locations are selected in site, machinery extract, with due care, soil samples (or specimens) and tested, and then soil strength parameters for site are calculated. The soil report may contain some of the field tests, the SPT for instance, as well. The procedure is to pass this information to the structural engineer who, in turn, may design the structure. In soil investigation principle, the small soil specimen extracted from the soil strata have complete representation of the soil body underneath the footing. In soil mechanics theory the soil is well known to be nonhomogeneous and nonisotropic. This, eventually, means that soil properties and strength parameters change not due to location only but due to change of direction as well. This situation imposes the fact that the principle of representing the whole body of soil with a small sample is practically incorrect. The principle is assumed correct only as much as the soil is more and more isotropic and homogeneous. Therefore, it is in reality not uncommon for cavities to be present in soils body due to many reasons. If those cavities are detected before footing construction, then it is assumed that there is no serious problem. On the other hand, if it is not detected, the situation imposes a serious problem to the footing and structure depending on size and location of cavity.
This study deals with cavity presence directly underneath a single separated footing of proposed multi-storey building. Location and size of cavity are changed and a finite element (FE) analysis is run for each individual case. The subgrade soil is assumed medium-dense sand with a modulus of subgrade reaction 35000 kN/cu.m. Other than cavity location, the subgrade is assumed to be homogeneous and isotropic, i.e. have same material and strength properties. Suitable graphs are used to illustrate the stresses in footing. The study, however, take into account the shear stresses in 3D only (a shear-care study) in concrete. The foundation concrete is assumed to have low compressive strength such as 20 MPa. Other properties of concrete are assumed program’s default.
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Lv, Mengfan, Yonghui Li i Yuancheng Guo. "Water Retention Characteristics and Soil-Water Characteristic Curve Model of Weak Expansive Soil". Soil Mechanics and Foundation Engineering 58, nr 2 (maj 2021): 123–29. http://dx.doi.org/10.1007/s11204-021-09716-0.
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Kamenchukov, Aleksey, Ilya Ukrainskiy i Gamilia Nikolaeva. "Improving the stability of high embankment slopes on weak foundations". E3S Web of Conferences 244 (2021): 05018. http://dx.doi.org/10.1051/e3sconf/202124405018.
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The article considers the issues of assessing the stability of non-standard soil-geological systems in difficult conditions. An analytical review of modern methods and tools for assessing the stability of embankment slopes is carried out. The features of the work of the embankment in the areas of the spread of permafrost are considered. The features of the design of embankments on permafrost soils with the preservation or partial thawing of frozen soils have been studied. Two versions of the calculated static schemes of sliding surfaces are presented: base - subgrade and base - subgrade - pavement. Based on the results of field studies, the physical and mechanical characteristics of the soils of the embankment and the base of the subgrade were determined, which became the basis for mathematical modeling and assessment of the stability of the embankment slopes. In software packages GeoStab and Geo5, based on the finite element method and the results of field studies, digital models of embankments were built on a weak foundation. The calculation of the stability of the system “base - subgrade” under the action of a standard uniformly distributed load has been performed. Two models of the system and the base - subgrade - road surface are considered: without cracks on the rolling strip and with cracks. It was found that coating defects affect the stability of the system only in the presence of an earthquake of medium strength and more. Recommendations for strengthening the slopes of embankments operating in difficult soil-geological conditions are given.
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Tafasca, Salma, Agnès Ducharne i Christian Valentin. "Weak sensitivity of the terrestrial water budget to global soil texture maps in the ORCHIDEE land surface model". Hydrology and Earth System Sciences 24, nr 7 (24.07.2020): 3753–74. http://dx.doi.org/10.5194/hess-24-3753-2020.
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Abstract. Soil physical properties play an important role in estimating soil water and energy fluxes. Many hydrological and land surface models (LSMs) use soil texture maps to infer these properties. Here, we investigate the impact of soil texture on soil water fluxes and storage at different scales using the ORCHIDEE (ORganizing Carbon and Hydrology in Dynamic EcosystEms) LSM, forced by several complex or globally uniform soil texture maps. At the point scale, the model shows a realistic sensitivity of runoff processes and soil moisture to soil texture and reveals that loamy textures give the highest evapotranspiration and lowest total runoff rates. The three tested complex soil texture maps result in similar water budgets at all scales, compared to the uncertainties of observation-based products and meteorological forcing datasets, although important differences can be found at the regional scale, particularly in areas where the different maps disagree on the prevalence of clay soils. The three tested soil texture maps are also found to be similar by construction, with a shared prevalence of loamy textures, and have a spatial overlap over 40 % between each pair of maps, which explains the overall weak impact of soil texture map change. A useful outcome is that the choice of the input soil texture map is not crucial for large-scale modelling, but the added value of more detailed soil information (horizontal and vertical resolution, soil composition) deserves further studies.
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Zhadanovsky, Boris, Liliya Pakhomova i Valentin Gorbachevskii. "Organization and technology of the construction on the weak and water-saturated soils". E3S Web of Conferences 91 (2019): 07007. http://dx.doi.org/10.1051/e3sconf/20199107007.
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Organizational and technological solutions have been developed for the production of the underground part of a capital construction facility on weak and aquiferous soils in extremely cramped conditions. The main technological operations for the arrangement of protective measures are considered. The following tasks were formulated and solved: - rational anti-landslide activities were defined; - ways to preserve the performance properties of existing buildings and structures were defined; - technological solutions to strengthen the soil array of foundations and foundations of closely located buildings and structures are proposed; - a rational way to develop the soil in the pit is proposed.
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Lagerev, Igor, Alexander Lagerev i Vadim Tarichko. "Modeling the swing of mobile loader cranes with anchor outriggers when operating on weak soils". E3S Web of Conferences 326 (2021): 00011. http://dx.doi.org/10.1051/e3sconf/202132600011.
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The paper presents a dynamic model illustrating the swing of a mobile machine on a wheeled chassis equipped with a loader crane and anchor outriggers during loading and unloading operations. The model regards the interaction effect of the outrigger anchoring device with weak soil within the system “load – loader crane – chassis – outriggers – anchor devices – soil”. Possible variants of single and multiple step soil compaction and changes in its deformation characteristics in the area of the outrigger anchor device implementation are considered. The impact of the gaps formed during soil compaction on the swing parameters of a mobile machine during the swing of the boom of the loader crane is demonstrated as applied to a full-scale crane-manipulator. The rate of chassis tilt angle and swing period of the mobile machine increase during the loader crane operation with an increase in the gaps in the ground. The swing parameters during the initial stage of crane operation gradually increase for soils characterized by multiple compaction until these parameters reach some steady-state values determined by soil stiffness. Awareness of the steady-state value of the crane tilt angle amplitude achieved at the end of the process of weak soil compaction enables to reasonably assess the risk of a mobile machine overturning.
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Gao, Lei, Yi Luo, Yingeng Kang, Mingjun Gao i Omar Abdulhafidh. "Experimental Study on Physical Mechanical Properties and Microstructure of Diatomite Soil in Zhejiang Province, China". Applied Sciences 12, nr 1 (31.12.2021): 387. http://dx.doi.org/10.3390/app12010387.
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Diatomite soil is a kind of bio-siliceous soil with complex composition and special structure, the physical and mechanical properties of diatomite soil are very important for the engineering project. In this paper, the physical properties, mechanical properties, and microstructure of diatomite soil in Zhejiang Province are studied by geotechnical tests and microscopic tests from the macroscopic and microscopic perspective. The results show that: (1) The diatomite soil has special properties different from other soils, including small particle size, low specific gravity value, high liquid-plastic limit, and low compressibility, and the strength indexes c and φ of diatomite soil will decrease with an increase in soil water content; (2) in the triaxial test, when the dry density of diatomite soil increases from 1.30 g/cm3 to 1.50 g/cm3, the effective internal friction angle of diatomite soil increases from 5.6° to 14.5° and the effective cohesion increases from 30.9 kPa to 49.6 kPa. The stress–strain curve of diatomite soil changes from weak softening type to weak hardening type when the confining pressure is above 200 kPa; (3) the diatomite soil has high porosity due to its unique microstructure; it is rich in aluminum oxides and minerals, which will greatly reduce the engineering performance of diatomite soil.
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Singh, Avinash, Nikhil Vishwakarma, Manish Kr Maurya, Chandan Singh i Somnath Singh. "Stabilization of Soil in Road Construction Using Lime and Fly Ash". International Journal for Research in Applied Science and Engineering Technology 11, nr 5 (31.05.2023): 2571–77. http://dx.doi.org/10.22214/ijraset.2023.52163.
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Abstract: Currently, inefficient soil properties are a crucial concern in engineering projects. In some cases, enhancing the characteristics of unsuitable soil is a necessary step to facilitate construction. Pavement structures built on weak soil sub grades exhibit premature distress, which leads to the early failure of the pavement. Silty soil often exhibits undesirable engineering behaviour, such as low bearing capacity, and high moisture susceptibility. Therefore, stabilizing these soils is a common practice to improve their strength.
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Mangushev, R. A., i R. A. Usmanov. "Ways of improving the efficiency of using compacted soil beds on weak soils". Вестник гражданских инженеров 16, nr 2 (2019): 62–70. http://dx.doi.org/10.23968/1999-5571-2019-16-2-62-70.
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Madhavi Latha, G., i K. Rajagopal. "Parametric finite element analyses of geocell-supported embankments". Canadian Geotechnical Journal 44, nr 8 (sierpień 2007): 917–27. http://dx.doi.org/10.1139/t07-039.
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This paper presents the results from parametric finite element analyses of geocell-supported embankments constructed on weak foundation soils. A composite model is used to numerically simulate the improvement in the strength and stiffness of the soil as a result of geocell confinement. The shear strength of the geocell-encased soil is obtained as a function of the additional confining pressure due to the geocell encasement considering it as a thin cylinder subjected to internal pressure. The stiffness of the geocell-encased soil is obtained from the stiffness of the unreinforced soil and the tensile modulus of the geocell material using an empirical equation. The validity of the model is verified by simulating the laboratory experiments on model geocell-supported embankments. Parametric finite element analyses of the geocell-supported embankments are carried out by varying the dimensions of the geocell layer, the tensile strength of the material used for fabricating the geocell layer, the properties of the infill soil, and the depth of the foundation layer. Some important guidelines for selecting the geocell reinforcement to support embankments on weak foundation soils are established through these numerical studies.
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Akhmedova, A. "Evaluation of Water-Stability Indicators of Light Gray Brown (Chestnut) Soils in the Condition of Mountain Shirvan". Bulletin of Science and Practice, nr 7 (15.07.2023): 168–78. http://dx.doi.org/10.33619/2414-2948/92/24.
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In article, the influence of tillage methods (conventional, minimal, zero), predecessor (wheat, barley, fallow) and mineral fertilizer on the water-stability indicators of the soil of rain-fed condition Mountain Shirvan is explained. In 2014-2017 years, the results of the research conducted in the agrocenosis of cereal crops in light gray brown (chestnut) soils show that the water-stability indicators of the soil exhibit intra-vegetation dynamics depending on factors such as the predecessor, tillage methods, growth stages of cereal. Furthermore, these indicators vary in the plow and sub-plough layers. According to the research results, the water-stability of light mountain gray brown soils in the conditions of Mountain Shirvan can be evaluated as ‘weak’ and ‘moderate’ based on the values of >0.25 mm water-stable aggregates and as ‘very weak’ and ‘weak’ based on the values of the mean weight diameter of water-stable aggregates, using the provided classifications.
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Wick, Lukas Y., Friederike Buchholz, Ingo Fetzer, Sabine Kleinsteuber, Claus Härtig, Lei Shi, Anja Miltner, Hauke Harms i Graciela N. Pucci. "Responses of soil microbial communities to weak electric fields". Science of The Total Environment 408, nr 20 (wrzesień 2010): 4886–93. http://dx.doi.org/10.1016/j.scitotenv.2010.06.048.
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Monnet, J., I. Galera i M. Mommessin. "Some theoretical approaches about reinforced embankments on weak soil". Computers and Geotechnics 7, nr 1-2 (styczeń 1989): 37–52. http://dx.doi.org/10.1016/0266-352x(89)90005-0.
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Mann, A. W. "Strong versus weak digestions: ligand-based soil extraction geochemistry". Geochemistry: Exploration, Environment, Analysis 10, nr 1 (luty 2010): 17–26. http://dx.doi.org/10.1144/1467-7873/09-216.
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Abuzaid, Ahmed S., Mostafa S. El-Komy, Mohamed S. Shokr, Ahmed A. El Baroudy, Elsayed Said Mohamed, Nazih Y. Rebouh i Mohamed S. Abdel-Hai. "Predicting Dynamics of Soil Salinity and Sodicity Using Remote Sensing Techniques: A Landscape-Scale Assessment in the Northeastern Egypt". Sustainability 15, nr 12 (12.06.2023): 9440. http://dx.doi.org/10.3390/su15129440.
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Traditional mapping of salt affected soils (SAS) is very costly and cannot precisely depict the space–time dynamics of soil salts over landscapes. Therefore, we tested the capacity of Landsat 8 Operational Land Imager (OLI) data to retrieve soil salinity and sodicity during the wet and dry seasons in an arid landscape. Seventy geo-referenced soil samples (0–30 cm) were collected during March (wet period) and September to be analyzed for pH, electrical conductivity (EC), and exchangeable sodium percentage (ESP). Using 70% of soil and band reflectance data, stepwise linear regression models were constructed to estimate soil pH, EC, and ESP. The models were validated using the remaining 30% in terms of the determination coefficient (R2) and residual prediction deviation (RPD). Results revealed the weak variability of soil pH, while EC and ESP had large variabilities. The three indicators (pH, EC, and ESP) increased from the wet to dry period. During the two seasons, the OLI bands had weak associations with soil pH, while the near-infrared (NIR) band could effectively discriminate soil salinity and sodicity levels. The EC and ESP predictive models in the wet period were developed with the NIR band, achieving adequate outcomes (an R2 of 0.65 and 0.61 and an RPD of 1.44 and 1.43, respectively). In the dry period, the best-fitted models were constructed with deep blue and NIR bands, yielding an R2 of 0.59 and 0.60 and an RPD of 1.49 and 1.50, respectively. The SAS covered 50% of the study area during the wet period, of which 14 and 36% were saline and saline-sodic soils, respectively. The extent increased up to 59% during the dry period, including saline soils (12%) and saline-sodic soils (47%). Our findings would facilitate precise, rapid, and cost-effective monitoring of soil salinity and sodicity over large areas.
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Darragh, Robert B., i Anthony F. Shakal. "The site response of two rock and soil station pairs to strong and weak ground motion". Bulletin of the Seismological Society of America 81, nr 5 (1.10.1991): 1885–99. http://dx.doi.org/10.1785/bssa0810051885.
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Abstract The site response to strong and weak ground motion depends largely on the subsurface conditions at the soil site for the two rock-soil station pairs studied. The first station pair consists of a soft-soil site (Treasure Island) and a sandstone and shale site (Yerba Buena Island). These stations recorded strong ground shaking from the Loma Prieta mainshock and weak ground motion from four aftershocks. The range of peak ground acceleration is from approximately 0.00006 to 0.07 g at the rock site. Compared to the rock site, the strong ground motion at the soft-soil site is amplified by a factor of about 3 over a frequency range from 0.5 to 2.0 Hz. The amplification is much higher for weak motion and suggests a dependence on signal amplitude. For example, near 1 Hz, the site response shows an increasing amplification as magnitude (and the peak velocity at the rock site) decreases. For events of local magnitude 7.0, 4.3, 4.1, 3.5, and 3.3, the maximum soil-site amplifications are 4, 12, 17, 19, and 25, respectively. A second station pair consisting of a stiff-soil site (Gilroy #2) and a sandstone site (Gilroy #1) was also studied with contrasting results. These two stations recorded strong ground shaking from the 1979 Coyote Lake, 1984 Morgan Hill, and 1989 Loma Prieta mainshocks. Weak ground motion was recorded at these stations after the Loma Prieta mainshock. The range of peak ground acceleration is from 0.006 to 0.43 g at the rock site. Unlike the results for the soft-soil study above, the estimated stiff-soil site responses are not significantly different for strong and weak motion from 0.5 to 2.0 Hz. Near 0.7 Hz, the stiff-soil site responses range from 2.5 to 4.5 for strong ground shaking from three mainshocks and from 1.5 to 4.0 for weak ground shaking from thirteen aftershocks.