Journal articles on the topic 'Soil structure'
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1
Cotching, W. E., and K. C. Belbin. "Assessment of the influence of soil structure on soil strength/soil wetness relationships on Red Ferrosols in north-west Tasmania." Soil Research 45, no. 2 (2007): 147. http://dx.doi.org/10.1071/sr06113.
Abstract:
The relationship of soil wetness to soil strength in Red Ferrosols was compared between fields of well structured to degraded soil structure. Soil structure was assessed using a visual rating. Soil resistance measurements were taken over a range of soil wetness, using a recording penetrometer. Readings were taken as the soil dried by evapotranspiration after both irrigation and rainfall events. The influence of soil wetness on penetration resistance was greater on fields with degraded structure than on well-structured fields. In fields with degraded structure, the wetter the soil, the smaller were the penetration resistance values. Field soil structure score was negatively correlated with the slope of the line relating soil wetness and penetration resistance at 150–300 mm depth. The structurally degraded fields had a highly significant relationship between penetration resistance and soil wetness at 150–300 mm depth. In well-structured fields, variations in soil wetness had less effect on penetration resistance. These results indicate that visual assessment can be used with confidence to assess Ferrosol structure. The implications for soil management are that fields with degraded soil structure have greater resistance to root growth at drier moisture contents than well-structured fields. Consequently, farmers need to keep degraded soils wetter with more frequent irrigation than well-structured soils, to ensure optimum plant growth.
2
Rengasamy, P., and KA Olsson. "Sodicity and soil structure." Soil Research 29, no. 6 (1991): 935. http://dx.doi.org/10.1071/sr9910935.
Abstract:
Sodic soils are widespread in Australia reflecting the predominance of sodium chloride in groundwaters and soil solutions. Sodic soils are subject to severe structural degradation and restrict plant performance through poor soil-water and soil-air relations. Sodicity is shown to be a latent problem in saline-sodic soils where deleterious effects are evident only after leaching profiles free of salts. A classification of sodic soils based on sodium adsorption ratio, pH and electrolyte conductivity is outlined. Current understanding of the processes and the component mechanisms of sodic soil behaviour are integrated to form the necessary bases for practical solutions in the long term and to define areas for research. The principles of organic and biological amelioration of sodicity, as alternatives to costly inorganic amendments, are discussed.
3
JavidSharifi, Behtash, and Sedigheh Gheisari. "EFFECTS OF STRUCTURE HEIGHT ON SEISMIC DEMAND OF MOMENT-RESISTING REINFORCED CONCRETE FRAMES CONSIDERING SOIL-STRUCTURE INTERACTION." NED University Journal of Research XVIII, no. 1 (January 1, 2021): 15–32. http://dx.doi.org/10.35453/nedjr-stmech-2020-0006.
Abstract:
Forces and displacements induced in a building due to structural responses to earthquake excitation are called seismic demands which depend upon the input motion, structural characteristics, site effects and the interaction of structure with soil. Structural response of three laterally non-controlled moment-resisting reinforced concrete frame structures with three different soil conditions are have been investigated in this paper. The soil conditions include loose soil, medium soil and rigid ground. The soil-structure interaction of low-, mid- and high-rise frame structures with the above mentioned soil types was analysed by performing nonlinear response history analyses. A set of eleven earthquake motions was employed in the analyses and maximum structural seismic demands for the frame structures were calculated. It was found that pressure-independent relatively loose sandy soils are not very critical for low-rise structures. On the other hand, pressure-independent relatively loose sandy soils and pressure-independent medium sandy soils are highly critical for mid-rise and high-rise structures, respectively. Categorisation of the soils is performed based on the value ranges of a series of constitutive parameters. Further, fixity of the base is most effective in controlling storey displacements until approximately one-third of the structure height. Medium soil leads to highest maximum base shears in low-rise structures while fixed-base and medium cases, and fixed base state control the behaviours of mid-rise and high-rise structures, respectively.
4
Cheng, C., D. Zhao, D. Lv, S. Li, and G. Du. "Comparative study on microbial community structure across orchard soil, cropland soil, and unused soil." Soil and Water Research 12, No. 4 (October 9, 2017): 237–45. http://dx.doi.org/10.17221/177/2016-swr.
Abstract:
We examined the effects of three different soil conditions (orchard soil, cropland soil, unused soil) on the functional diversity of soil microbial communities. The results first showed that orchard and cropland land use significantly changed the distribution and diversity of soil microbes, particularly at surface soil layers. The richness index (S) and Shannon diversity index (H) of orchard soil microbes were significantly higher than the indices of the cropland and unused soil treatments in the 0–10 cm soil layer, while the S and H indices of cropland soil microbes were the highest in 10–20 cm soil layers. Additionally, the Simpson dominance index of cropland soil microbial communities was the highest across all soil layers. Next, we found that carbon source differences in soil layers under the three land use conditions can mainly be attributed to their carbohydrate and polymer composition, indicating that they are the primary cause of the functional differences in microbial communities under different land uses. In conclusion, orchard and cropland soil probably affected microbial distribution and functional diversity due to differences in vegetation cover, cultivation, and management measures.
5
Bezih, Kamel, Alaa Chateauneuf, and Rafik Demagh. "Effect of Long-Term Soil Deformations on RC Structures Including Soil-Structure Interaction." Civil Engineering Journal 6, no. 12 (November 30, 2020): 2290–311. http://dx.doi.org/10.28991/cej-2020-03091618.
Abstract:
Lifetime service of Reinforced Concrete (RC) structures is of major interest. It depends on the action of the superstructure and the response of soil contact at the same time. Therefore, it is necessary to consider the soil-structure interaction in the safety analysis of the RC structures to ensure reliable and economical design. In this paper, a finite element model of soil-structure interaction is developed. This model addresses the effect of long-term soil deformations on the structural safety of RC structures. It is also applied to real RC structures where soil-structure interaction is considered in the function of time. The modeling of the mechanical analysis of the soil-structure system is implemented as a one-dimensional model of a spring element to simulate a real case of RC continuous beams. The finite element method is used in this model to address the nonlinear time behavior of the soil and to calculate the consolidation settlement at the support-sections and the bending moment of RC structures girders. Numerical simulation tests with different loading services were performed on three types of soft soils with several compressibility parameters. This is done for homogeneous and heterogeneous soils. The finite element model of soil-structure interaction provides a practical approach to show and to quantify; (1) the importance of the variability of the compressibility parameters, and (2) the heterogeneity soil behavior in the safety RC structures assessment. It also shows a significant impact of soil-structure interaction, especially with nonlinear soil behavior versus the time on the design rules of redundant RC structures. Doi: 10.28991/cej-2020-03091618 Full Text: PDF
6
Kolaki, Aravind I., and Basavaraj M. Gudadappanavar. "Performance Based Analysis of Framed Structure Considering Soil Structure Interaction." Bonfring International Journal of Man Machine Interface 4, Special Issue (July 30, 2016): 106–11. http://dx.doi.org/10.9756/bijmmi.8165.
7
Aliboeva, M. A. "Morphological Structure Of Mountain Soils." American Journal of Agriculture and Biomedical Engineering 03, no. 12 (December 30, 2021): 33–37. http://dx.doi.org/10.37547/tajabe/volume03issue12-08.
Abstract:
This article discusses morphological structure of mountain soils. The mountainous regions of the Republic of Uzbekistan are located mainly in Tashkent, Surkhandarya, Samarkand, Jizzakh, Syrdarya, Fergana Valley and Navoi regions, and differ from each other in their greenery, charm and structure. Mountain soils are distributed sequentially according to the law of vertical zoning, depending on the altitude above sea level. The soil cover in these regions is characterized by their development (evolution), genesis, agrochemical, agrophysical properties and, most importantly, morphological structure. Each region has its own natural factors, which directly affect the development and morphological structure of the soil cover.
8
Zhai, Zhanghui, Yaguo Zhang, Shuxiong Xiao, and Tonglu Li. "Undrained Elastoplastic Solution for Cylindrical Cavity Expansion in Structured Cam Clay Soil Considering the Destructuration Effects." Applied Sciences 12, no. 1 (January 3, 2022): 440. http://dx.doi.org/10.3390/app12010440.
Abstract:
Soil structure has significant influences on the mechanical behaviors of natural soils, although it is rarely considered in previous cavity expansion analyses. This paper presents an undrained elastoplastic solution for cylindrical cavity expansion in structured soils, considering the destructuration effects. Firstly, a structural ratio was defined to denote the degree of the initial structure, and the Structured Cam Clay (SCC) model was employed to describe the subsequent stress-induced destructuration, including the structure degradation and crushing. Secondly, combined with the large strain theory, the considered problem was formulated as a system of first-order differential equations, which can be solved in a simplified procedure with the introduced auxiliary variable. Finally, the significance and efficiency of the present solution was demonstrated by comparing with the previous solutions, and parametric studies were also conducted to investigate the effects of soil structure and destructuration on the cavity expansion process. The results show that the soil structure has pronounced effects on the mechanical behavior of structured soils around the cavity. For structured soils, a cavity pressure that is larger than the corresponding reconstituted soils when the cavity expands to the same radius is required, and the effective stresses first increase to a peak value before decreasing rapidly with soil structure degradation and crushing. The same final critical state is reached for soils with different degrees of the initial structure, which indicates that the soil structure is completely destroyed during the cavity expansion. With the increase of the destructuring index, the soil structure was destroyed more rapidly, and the stress release during the plastic deformation became more significant. Moreover, the present solution was applied in the jacking of a casing during the sand compact pile installation and in situ self-boring pressuremeter (SBPM) tests, which indicates that the present solution provides an effective theoretical tool for predicting the behavior of natural structured soils around the cavity.
9
Patil, K. S., and Ajit K. Kakade. "Seismic Response of R.C. Structures With Different Steel Bracing Systems Considering Soil - Structure Interaction." Journal of Advances and Scholarly Researches in Allied Education 15, no. 2 (April 1, 2018): 411–13. http://dx.doi.org/10.29070/15/56856.
10
Liu, M. D., and J. P. Carter. "A structured Cam Clay model." Canadian Geotechnical Journal 39, no. 6 (December 1, 2002): 1313–32. http://dx.doi.org/10.1139/t02-069.
Abstract:
A theoretical study of the behaviour of structured soil is presented. A new model, referred to as the Structured Cam Clay model, is formulated by introducing the influence of soil structure into the Modified Cam Clay model. The proposed model is hierarchical, i.e., it is identical to the Modified Cam Clay soil model if a soil has no structure or if its structure is removed by loading. Three new parameters describing the effects of soil structure are introduced, and the results of a parametric study are also presented. The proposed model has been used to predict the behaviour of structured soils in both compression and shearing tests. By making comparisons of predictions with experimental data and by conducting the parametric study it is demonstrated that the new model provides satisfactory qualitative and quantitative modelling of many important features of the behaviour of structured soils.Key words: calcareous soils, clays, fabric, structure, constitutive relations, plasticity.
11
Lee, KE, and RC Foster. "Soil fauna and soil structure." Soil Research 29, no. 6 (1991): 745. http://dx.doi.org/10.1071/sr9910745.
Abstract:
Significant effects of soil fauna on soil structure are achieved mainly by a few groups among the larger soil invertebrates that are widely distributed and generally present in large numbers. Of these groups the most important are earthworms, termites and ants. The review deals mainly with earthworms, which are distributed throughout all but the coldest and the driest regions of the world. The effects of termites and ants on soil structure are also discussed. These groups of soil animals are also widely distributed, but are most common and most effective in influencing soil structure in tropical and warm temperate regions. A brief section deals with the influence of microarthropods, which are commonly found in large numbers, but because of their small size are unable to make large burrows in the mineral soil horizons, and are largely confined to pre-existing voids in litter and surface soil horizons. Their faecal pellets are granular and largely organic, with little included mineral soil material, and they sometimes make up the major proportion of forest litter layers. Quantitative assessment of the influence of earthworms on soil structure is available, but information on other groups is largely qualitative. The burrows of earthworms contribute to macroporosity and so influence water infiltration and aeration. Anecic species, that live in semi-permanent burrows opening to the soil surface and feed at the surface, provide more or less vertical channels for water infiltration and gas exchange. Endogeic species, that burrow continuously in search of food within the soil, provide more horizontally oriented, frequently extensive and intersecting networks of macropores that promote water movement and gas diffusion. Burrows that penetrate soil surface crusts are particularly important for water entry to the soil. Water movement through pores of the dimensions of earthworm burrows is important only when rainfall or irrigation supplies water at rates that exceed the capacity of the soil surface for capillary uptake. The combination of increase in surface area available for capillary uptake through the burrow walls and of hydraulic pressure resulting from the column of water in a water-filled burrow increases infiltration. Occupied burrows of anecic species may be sealed with soil or plant litter by the resident earthworm when water is ponded on the soil surface, or blocked by the earthworm's body, so as to be ineffective for water infiltration. When burrows are air-filled they provide surfaces that penetrate below ground and facilitate gas exchange.
12
Xu, Bin Bin. "Influence of Soil Structure on the Mechanical Response of Soft Soil." E3S Web of Conferences 38 (2018): 03027. http://dx.doi.org/10.1051/e3sconf/20183803027.
Abstract:
Usually the natural sedimentary soils possess structure more or less, which makes their mechanical response much different from the fully remolded soils. In this paper, the influence of soil structure on the mechanical response such as compressibility, shear, permeability is literately reviewed. It is found that the compressibility and consolidation behavior of structured and remolded soils can be divided clearly before or after the structural yield stress. The stress-strain relationship can be divided into two segments before and after the structural yield stress. Before the yield stress, the curve is elevating and after the yield stress the curve is decreasing. The increasing rate of pore water pressure increases after the soil reached yield stress.
13
Trombetta, Nicholas W., H. Benjamin Mason, Tara C. Hutchinson, Joshua D. Zupan, Jonathan D. Bray, and Bruce L. Kutter. "Nonlinear Soil–Foundation–Structure and Structure–Soil–Structure Interaction: Engineering Demands." Journal of Structural Engineering 141, no. 7 (July 2015): 04014177. http://dx.doi.org/10.1061/(asce)st.1943-541x.0001127.
14
Timofeeva, Yulia, Elena Sukhacheva, Boris Aparin, Vitaly Terleev, Aleksandr Nikonorov, and Luka Akimov. "Soil structure of sand quarries territory." E3S Web of Conferences 157 (2020): 02017. http://dx.doi.org/10.1051/e3sconf/202015702017.
Abstract:
Anthropogenic activities are one of the leading factors of soil differentiation. Significant changes in the soil cover occur as a result of the construction of quarries. The mining industry causes the complete degradation of soils in large areas, the change of the natural soil cover and elevation around the quarries, the destruction of vegetation, disturbs biodiversity of the territory and the death of ecosystems. Soil cover structures of mining quarries have been considered on the example of the Leningrad region such as a natural conditions and environmental peculiarities typical for the whole Russian North-West area. Decoding and diagnostic signs of anthropogenic transformed soils were determined. The type and degree of transformation of the component composition, the contrast and heterogeneity of the soil cover, intercomponent connections, the shape and figure of the internal organization of the of soil cover structures have been identified. The complexity of the anthropogenic transformed soils cover is illustrated by “key site”.
15
Zhang, Miao Xin, Bao Dong Liu, Peng Fei Li, and Zhi Mao Feng. "Structure-Soil Interaction of Buried Corrugated Steel Arch Bridge." Advanced Materials Research 163-167 (December 2010): 2112–17. http://dx.doi.org/10.4028/www.scientific.net/amr.163-167.2112.
Abstract:
Corrugated steel plate and surrounding soils are working together to share the load in buried corrugated steel structures. It is complicated to consider the structure-soil interaction, so the finite element method has already become the chief means of complicated structure analysis. Based on a practical project, considering structure-soil interaction, by using the finite element program of ANSYS, the paper set up a 2-D FE model and analyzed the soil pressure, the structural deformation and the internal force under different load conditions in detail. The analysis shows that structure-soil interaction has brought about stresses redistribution of surrounding soils, and adverse effects of soil pressure and displacement were limited. The variation range of soil pressure on the crown of arch increases with the load increases and the peak value of soil pressure approach to the code value and a rebound appears in the vehicle load range. The tendencies of vertical soil displacement are nearly the same to different load conditions, and the peak value of moments has an obvious change and can be influenced greatly by deflective load.
16
Collis-George, N. "Drainage and soil structure - a review." Soil Research 29, no. 6 (1991): 923. http://dx.doi.org/10.1071/sr9910923.
Abstract:
Definitions of soil structure and drainage are proposed that would allow a more useful interaction between the two areas of interest that appear to have developed independently. Drainage phenomena in three structural systems are quantitatively described. Firstly a simple uniform profile is described; then wormholes and stones are added to the upper layer of this soil; finally the upper layer is given a 23% stable macropore space and its depth is proportionately increased by biotic activity. Numerical solutions of these geometries (supported by experimental work) show that if the structure enhancements are confined to the upper horizons, the drainage behaviour of the matrix is unaffected and only the early stages of the drainage hydrograph are affected. More complex structures are considered qualitatively. The influence of entrapped and encapsulated air within the soil pore space is outlined. It is concluded that a major problem in correlating drainage phenomena with soil structure is that the structural description of wet soils is rarely attempted. In particular, the descriptions of structures, naturally occurring and those enhanced by cultivation, which change with time and with wetting and drying, are presently only described by soil surveyors in qualitative terms.
17
Leuther, Frederic, and Steffen Schlüter. "Impact of freeze–thaw cycles on soil structure and soil hydraulic properties." SOIL 7, no. 1 (June 11, 2021): 179–91. http://dx.doi.org/10.5194/soil-7-179-2021.
Abstract:
Abstract. The ploughing of soils in autumn drastically loosens the soil structure and, at the same time, reduces its stability against external stresses. A fragmentation of these artificially produced soil clods during wintertime is often observed in areas with air temperatures fluctuating around the freezing point. From the pore perspective, it is still unclear (i) under which conditions frost action has a measurable effect on soil structure, (ii) what the impact on soil hydraulic properties is, and (iii) how many freeze–thaw cycles (FTCs) are necessary to induce soil structure changes. The aim of this study was to analyse the cumulative effects of multiple FTC on soil structure and soil hydraulic properties for two different textures and two different initial structures. A silt clay with a substantial amount of swelling clay minerals and a silty loam with fewer swell/shrink dynamics were either kept intact in undisturbed soil cores taken from the topsoil from a grassland or repacked with soil clods taken from a ploughed field nearby. FTCs were simulated under controlled conditions and changes in pore structure ≥ 48 µm were regularly recorded using X-ray µCT. After 19 FTCs, the impact on hydraulic properties were measured, and the resolution of structural characteristics were enhanced towards narrow macropores with subsamples scanned at 10 µm. The impact of FTC on soil structure was dependent on the initial structure, soil texture, and the number of FTCs. Frost action induced a consolidation of repacked soil clods, resulting in a systematic reduction in pore sizes and macropore connectivity. In contrast, the macropore systems of the undisturbed soils were only slightly affected. Independent of the initial structure, a fragmentation of soil clods and macro-aggregates larger than 0.8 to 1.2 mm increased the connectivity of pores smaller than 0.5 to 0.8 mm. The fragmentation increased the unsaturated hydraulic conductivity of all treatments by a factor of 3 in by a factor of 3 in a matrix potential range of −100 to −350 hPa, while water retention was only slightly affected for the silt clay soil. Already 2 to 5 FTCs enforced a well-connected pore system of narrow macropores in all treatments, but it was steadily improved by further FTCs. The implications of fewer FTCs during milder winters caused by global warming are twofold. In ploughed soils, the beneficial seedbed consolidation will be less intense. In grassland soils, which have reached a soil structure in dynamic equilibrium that has experienced many FTCs in the making, there is still a beneficial increase in water supply through increasing unsaturated hydraulic conductivity by continued FTCs that might also be less efficient in the future.
18
Granados, Jaime, and Bernardo Caicedo. "Physical and numerical modelling of soil-atmosphere-structure interaction." E3S Web of Conferences 382 (2023): 06002. http://dx.doi.org/10.1051/e3sconf/202338206002.
Abstract:
Extreme, extended wet and dry seasons increase the adverse effects that soil wetting and drying cycles have on the response of shallow geotechnical structures. In expansive soils, volumetric changes due to water content variations may result in the incompatibility of deformations at the soil-structure interface. This study proposes a physical approach and a numerical model to address the soil-atmosphere-structure interactions during soil saturation and desiccation. Experimental desiccation tests were performed on relatively thin, compacted kaolin clay samples that represent the soil-atmosphere boundary. A climatic chamber was used to impose atmospheric conditions of air relative humidity, temperature, wind velocity, and irradiance on the soil surface. Empirical mathematical expressions were obtained to estimate soil desiccation rates as a function of basic atmospheric parameters and soil properties. The experimental desiccation approach was complemented with a coupled thermo-hydro-mechanical (THM) numerical model for unsaturated soils. The coupled THM model calculates water and thermal fluxes, soil volumetric changes, vertical stresses, and the compatibility of soil-structure movements during swelling and shrinking. An example of the capabilities of the numerical model is presented for a full-scale geotechnical problem.
19
SA, Wemedo. "Impact Assessment of Gas Flaring on Soil Bacterial Community Structure and Physicochemical Property in Nigeria." Open Access Journal of Microbiology & Biotechnology 5, no. 2 (2020): 1–9. http://dx.doi.org/10.23880/oajmb-16000165.
Abstract:
Gas flaring is the wasteful emission of hydrocarbon gases into the atmosphere; it is routinely used to dispose flammable gas that either is assumed unusable or uneconomical to recover. The burning of the wasteful gas has been shown to have significant environmental consequences. Therefore, this study was designed to determine the impact of gas flaring on soil bacterial spectrum and its physicochemical property. Soil microbiological quality was investigated using culture techniques while physicochemical property of the soil was analyzed using standard analytical procedures. Results obtained showed that pH and Av. phosphorus decreased from 5.80 and 8.86mg/kg in control soil to 5.40 and 6.50mg/kg in flared soil respectively. Electrical conductivity and total organic carbon increased from 100μS/cm and 0.20% in control soil to 160μS/cm and 0.63% in flared soil respectively. Total nitrogen slightly increased from 0.01% in control soil to 0.02% in flared soil. Soil textural class was sandy-clay-loam for both control and flared soils. Mean counts of bacteria increased from 4x10 3 cfu/g in SD50m to 2.0x10 4 cfu/g in SD100m, 3.1x10 4 cfu/g in SD200m, 4.5x10 4 in SD300m to 4.8x10 5 cfu/g in control soil. All the bacterial species were isolated from control and SD300m soils except Acinetobacter and Microbacteriun species which did not occur in SD300m soil. Six (6) organisms: Bacillus, Corynebacterium , Pseudomonas , Paenibacillus, Pusillimonas and Salinicoccus species were isolated from SD50m soil. The number of bacterial genera isolated increased to eleven (11) in SD100m soil with Cronobacter , Enterobacter , Escherichia coli , Kluyvera , and Microbacterium species added to those of SD50m soil. Fifteen (15) organisms occurred in SD200m soil as Acinetobacter , Arthrobacter , Brevibacterium , Klebsiella , Rathayibacter and Staphylococcus species were added. This study revealed that gas flaring decreased bacterial population in soil in close proximity to the flare point; the effect being reduced as the sampling distance from the flare point increased. Some physicochemical parameters decreased in flared soils and others increased when compared with control soils. Gas flaring selectively inhibited soil bacteria with more species occurring in soils farther away from the flare and soil closest to the flare point having less numbers of bacteria. In conclusion, gas flaring had negative impact on soil bacteria and varied effect on physicochemical properties of the soil; in this way soil fertility could have been hampered. Oil and gas companies as well as government agency need to adopt measures that would curb unnecessary gas flaring in Nigeria by putting the flared gas into economic use.
20
Trombetta, Nicholas W., H. Benjamin Mason, Tara C. Hutchinson, Joshua D. Zupan, Jonathan D. Bray, and Bruce L. Kutter. "Nonlinear Soil–Foundation–Structure and Structure–Soil–Structure Interaction: Centrifuge Test Observations." Journal of Geotechnical and Geoenvironmental Engineering 140, no. 5 (May 2014): 04013057. http://dx.doi.org/10.1061/(asce)gt.1943-5606.0001074.
21
Al Qadad, A., I. Shahrour, and M. Rouainia. "Influence of the soil-atmosphere exchange on the hydric profile induced in soil-structure system." Natural Hazards and Earth System Sciences 12, no. 6 (June 26, 2012): 2039–49. http://dx.doi.org/10.5194/nhess-12-2039-2012.
Abstract:
Abstract. Soil-atmosphere exchange leads to a moisture change in the soil. This can cause major damage to engineering structures due to the soil expansion and shrinkage. The soil-atmosphere exchange is related to several parameters, in particular the soil characteristics and climate conditions. The presence of an engineering structure causes a variation of the hydraulic profile in the soil, which can lead to heterogeneous soil movement and consequently to structural damage. This paper presents a coupled numerical model based on the consideration of both water flow in unsaturated soils and soil-atmosphere exchange. After the validation of the model, the paper presents its use for the analysis of the influence of the presence of structures on moisture change induced under climatic conditions recorded in a semi-arid region. Analysis shows that the presence of the structure leads to important change in the moisture distribution, in particular in the vicinity of the structure.
22
Maghsoodi, Soheib, Olivier Cuisinier, and Farimah Masrouri. "Thermo-mechanical behaviour of clay-structure interface." E3S Web of Conferences 92 (2019): 10002. http://dx.doi.org/10.1051/e3sconf/20199210002.
Abstract:
The mechanical behaviour of the soil-structure interface plays a major role in the shear characteristics and bearing capacity of foundations. In thermo-active structures, due to non-isothermal conditions, the interface behaviour becomes more complex. The objective of this study is to investigate the effects of temperature variations on the mechanical behaviour of soils and soil-structure interface. Constant normal load (CNL) and constant normal stiffness (CNS) tests were performed on soil and soil-structure interface in a direct shear device at temperatures of 5, 22 and 60 °C. Kaolin clay was used as proxy for clayey soils. The results showed that, in clay samples the temperature increase, increased the cohesion and consequently the shear strength, due to thermal contraction during heating. The temperature rise had less impact on the shear strength in the case of the clay-structure interface than in the clay samples. The adhesion of the clay-structure interface, is less than the cohesion of the clay samples.
23
Maghsoodi, Soheib, Olivier Cuisinier, and Farimah Masrouri. "Thermal effects on mechanical behaviour of soil–structure interface." Canadian Geotechnical Journal 57, no. 1 (January 2020): 32–47. http://dx.doi.org/10.1139/cgj-2018-0583.
Abstract:
Mechanical behaviour of the soil–structure interface plays a major role in the shear characteristics and bearing capacity of foundations. In thermoactive structures, due to nonisothermal conditions, the interface behaviour becomes more complex. The objective of this study is to investigate the effects of temperature variations on the mechanical behaviour of soils and the soil–structure interface. Constant normal load (CNL) and constant normal stiffness (CNS) tests were performed on the soil and soil–structure interface in a direct shear device at temperatures of 5, 22, and 60 °C. Fontainebleau sand and kaolin clay were used as proxies for sandy and clayey soils. The sandy soil was prepared in a dense state and the clayey soil was prepared in a normally consolidated state. Results show that the applied thermal variations have a negligible effect on the shear strength of the sand and sand–structure interface under CNL and CNS conditions, and the soil and soil–structure interface behaviour could be considered thermally independent. In clay samples, an increase in the temperature increased the cohesion and consequently the shear strength, due to thermal contraction during heating. The temperature rise had less impact on the shear strength in the case of the clay–structure interface than in the clay samples. The adhesion of the clay–structure interface is less than the cohesion of the clay samples.
24
Behnamfar, Farhad, Seyyed Mohammad Mirhosseini, and Hossein Alibabaei. "Seismic behavior of structures considering uplift and soil–structure interaction." Advances in Structural Engineering 20, no. 11 (April 17, 2017): 1712–26. http://dx.doi.org/10.1177/1369433217693628.
Abstract:
A common assumption when analyzing a structure for earthquake forces is that the building is positively attached to a rigid ground so that it can sustain possible tensile forces without being detached, or uplifted, from its bearing points. Considering the facts that almost no tension can be transferred between a surface foundation and soil and soft soils interact with the supported structure during earthquakes, in this research, the effects of uplift and soil–structure interaction on nonlinear seismic response of structures are evaluated. Several reinforced concrete and steel structures under different suits of consistent ground motions are considered. The base of the buildings is modeled with vertical no-tension springs being nonlinear in compression. The total soil–structure interaction system is modeled within OpenSees, and the seismic behavior is evaluated using a nonlinear dynamic analysis. The nonlinear responses of buildings are determined and compared between three cases: fixed base, flexible base without uplift, and flexible base with uplift. The cases for which uplift in conjunction with soil–structure interaction should be considered are identified.
25
Proffitt, APB, RJ Jarvis, and S. Bendotti. "The impact of sheep trampling and stocking rate on the physical properties of a red duplex soil with two initially different structures." Australian Journal of Agricultural Research 46, no. 4 (1995): 733. http://dx.doi.org/10.1071/ar9950733.
Abstract:
The effect of sheep trampling and stocking rate on the physical properties of a red duplex soil with two initially different structures was examined over an 8 week period when the soil was wet following winter rains. The experimental site was located at Merredin in Western Australia where the average annual rainfall is 307 mm. A previous long-term tillage and gypsum trial at the experimental site had resulted in the development of contrasting topsoil structures. Three grazing treatments were imposed at the trial site: grazing at the normal high stocking rate (8 DSE ha-1), grazing at half the normal stocking rate (4 DSE ha-1), and no grazing (where pasture was mown to simulate grazing without trampling). Topsoil structure was assesed by measuring water-stable aggregation (> 2 mm diameter aggregates), the relative contribution of dispersion and slaking to structural instability (measured as soil strength on < 2 mm fine earth soil fractions), steady-state infiltration rates (at 10 mm tension), and in situ soil strength characteristics (measured as penetration resistance). At the end of the grazing period, all structure attributes measured showed that topsoil structure had been damaged as a result of sheep trampling. The magnitude of such structure damage was affected by the initial physical condition of the soil and stocking rate. When compared with ungrazed pasture, there was a greater decline in structural condition as a consequence of grazing on less well-structured soil than on better-structured soil. Halving the normal stocking rate reduced the degree of structure damage on both soils. Within-season variability in soil hydraulic properties was large. The temporal changes in infiltration rates were attributed to changes in drainage pore volume brought about by the growth and decay of pasture roots, the formation and disruption of a surface crust, and the processes of soil compaction and remoulding resulting from animal trampling (no direct measurements were made). The variability in hydraulic behaviour found in this study emphasizes the need to maintain consistent sampling dates and soil water contents at sampling in long-term studies on soil structure changes.
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Cacciola, Pierfrancesco, Maria Garcia Espinosa, and Alessandro Tombari. "Vibration control of piled-structures through structure-soil-structure-interaction." Soil Dynamics and Earthquake Engineering 77 (October 2015): 47–57. http://dx.doi.org/10.1016/j.soildyn.2015.04.006.
27
Roy, Christine, Said Bolourchi, and Daniel Eggers. "Significance of structure–soil–structure interaction for closely spaced structures." Nuclear Engineering and Design 295 (December 2015): 680–87. http://dx.doi.org/10.1016/j.nucengdes.2015.07.067.
28
ECK, HAROLD V. "Soil Structure Assessment." Soil Science 145, no. 1 (January 1988): 77. http://dx.doi.org/10.1097/00010694-198801000-00012.
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Dongol, Nasala, Prachand Man Pradhan, and Suman Manandhar. "Study of Pushover Analysis on RC Framed Structure with Underground Structure Considering the Effects of Soil Structure Interaction." Journal of Science and Engineering 8 (November 12, 2020): 22–29. http://dx.doi.org/10.3126/jsce.v8i0.32859.
Abstract:
This study states that the effects of soil structure interaction on the Reinforced Concrete (RC) framed structures is directly influenced by the soil properties of the site. Here, one preexisting structure is taken for the study. The building is a hospital building with two underground basements. Taking into account the actual soil condition of building site, this study provides idea on the soil structure interaction on the structure The properties of springs are calculated from different standard penetration test (SPT) values, Poisson’s ratio and elasticity of soil along the depth of the soil. Entire soil-foundation-structure system is modelled and analyzed using spring approach. Static analysis, response spectrum analysis and pushover analysis (PA) are done in order to find the variations in natural periods, base shears and deflections of the structures by incorporating soil flexibility as compared to structures with conventional fixed base. Pushover analysis is done to evaluate the performance of the structure when modelled in fixed base and spring base system.
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Cresswell, HP, DE Smiles, and J. Williams. "Soil structure, soil hydraulic properties and the soil water balance." Soil Research 30, no. 3 (1992): 265. http://dx.doi.org/10.1071/sr9920265.
Abstract:
We review the influence of soil structural change on the fundamental soil hydraulic properties (unsaturated hydraulic conductivity and the soil moisture characteristic) and utilize deterministic modelling to assess subsequent effects on the soil water balance. Soil structure is reflected in the 0 to -100 kPa matric potential section of the soil moisture characteristic with marked changes often occurring in light to medium textured soils' (sands, sandy-loam, loams and clay-loams). The effect of long-term tillage on soil structure may decrease hydraulic conductivity within this matric potential range. The 'SWIM' (Soil Water Infiltration and Movement) simulation model was used to illustrate the effects of long-term conventional tillage and direct drilling systems on the water balance. The effects of plough pans, surface crusts and decreasing surface detention were also investigated. Significant structural deterioration, as evidenced by substantially reduced hydraulic conductivity, is necessary before significant runoff is generated in the low intensity rainfall regime of the Southern Tablelands (6 min rainfall intensity <45 mm h-1). A 10 mm thick plough pan (at a depth of 100 mm) in the A-horizon of a long-term conventionally tilled soil required a saturated hydraulic conductivity (K,) of less than 2.5 mm h-1 before runoff exceeded 10% of incident rainfall in this rainfall regime. Similarly, a crust K, of less than 2.5 mm h-1 was necessary before runoff exceeded 10% of incident rainfall (provided that surface detention was 2 or more). As the crust K, approached the rainfall rate, small decreases in Ks resulted in large increases in runoff. An increase in surface detention of 1 to 3 mm resulted in a large reduction in runoff where crust K, was less than 2-5 mm h-1. Deterministic simulation models incorporating well established physical laws are effective tools in the study of soil structural effects on the field water regime. Their application, however, is constrained by insufficient knowledge of the fundamental hydraulic properties of Australian soils and how they are changing in response to our land management.
31
Pattanashetti, Prateek, and M. S. Bhandiwad. "Seismic Performance of Regular and Irregular Flat Slab Structure with Soil Structure Interaction." Bonfring International Journal of Man Machine Interface 4, Special Issue (July 30, 2016): 215–19. http://dx.doi.org/10.9756/bijmmi.8186.
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Sadek, Marwan, Fadi Hage Chehade, Bassem Ali, and Ahmed Arab. "Seismic Soil Structure interaction for Shear wall structures." MATEC Web of Conferences 281 (2019): 02006. http://dx.doi.org/10.1051/matecconf/201928102006.
Abstract:
For soft soil subjected to earthquake loading, the soil non linearity could significantly amplify the ground motion. This paper presents a 3D numerical study on the influence of soil non linearity on the seismic soil structure interaction for shear wall structures. Numerical simulations are conducted for both elastic and elastoplastic behaviour for the soil. Real ground motions records are used in the study. The analysis is focused on the seismic induced response of the soil and the structure in terms of displacement and velocity. The results show that considering elastic model for the soil behaviour is not sufficient and could significantly affect the seismic induced response of the system.
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Masia, Mark J., Peter W. Kleeman, and Robert E. Melchers. "Modeling Soil/Structure Interaction for Masonry Structures." Journal of Structural Engineering 130, no. 4 (April 2004): 641–49. http://dx.doi.org/10.1061/(asce)0733-9445(2004)130:4(641).
34
KAWAKAMI, HIDEJI. "SOIL-STRUCTURE INTERACTION OF RIGID STRUCTURES CONSIDERING THROUGH-SOIL COUPLING BETWEEN ADJACENT STRUCTURES." Journal of Structural and Construction Engineering (Transactions of AIJ) 388 (1988): 121–30. http://dx.doi.org/10.3130/aijsx.388.0_121.
35
Kozlovskii, V. E., E. V. Gorodnova, and S. S. Kolmogorova. "STRUCTURE SETTING ON COMPOSITE-BASED SOILS." Vestnik Tomskogo gosudarstvennogo arkhitekturno-stroitel'nogo universiteta. JOURNAL of Construction and Architecture 22, no. 1 (February 27, 2020): 164–70. http://dx.doi.org/10.31675/1607-1859-2020-22-1-164-170.
Abstract:
The paper studies the interaction between the building construction and composite-based soil with a view to determine its elastic properties affecting the structure deformation and internal forces. The soil model is assumed to be elastic, according to the Winkler coefficient calculated from the Kolosov stress decay function. The Galerkin numerical method used in calculations utilizes basic functions corresponding to the type of fixing the discontinuous and continuous structures. Unknown coefficients in linear combinations of basic functions are obtained via linear algebra methods, solving the system of equations. The force functions of the structure are found by derivation of the deflection function. Geological parameters are accepted to be real and matching the construction conditions of a large industrial warehouse of agricultural designation in the Pskov region, Russia. The soil effect on the flexural strength, shearing forces, and bearing reaction is estimated under the discontinuous and continuous structures at the available geological soil parameters. The structure setting on composite-based soils under the operating load is predicted herein.
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Li, Wugang, Wenhua Liu, Zhijia Xue, and Xiuli Sun. "A Constitutive Model for Overconsolidated Structured Soils Using Structural Variable." Shock and Vibration 2021 (August 9, 2021): 1–14. http://dx.doi.org/10.1155/2021/5530038.
Abstract:
Due to the influence of soil structure, structured soils exhibit significantly different mechanical behavior compared to the reconstituted soils having the same material. In this work, a theoretical analysis focusing on the mechanical behavior of structured soils is presented. Based on the mechanical behavior of the structured soil, a newly defined variable structural index was used as a measurement of the integrity of soil structure based on the concept of intrinsic compression line of intact structured soils. Furthermore, a novel correlation for the variation in volume of structured soils is established using effective stress and newly defined structural index as the constitutive variables. The novel correlation provided interpretation about the mechanism of compression behavior of the structured soils. Afterwards, the proposed correlation for the variation in volume was extended to triaxial stress state in the framework of subloading surface to include the effect of overconsolidation. Comparisons between the predictions and experimental results validated the proposed constitutive model for structured soils.
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Passioura, JB. "Soil structure and plant growth." Soil Research 29, no. 6 (1991): 717. http://dx.doi.org/10.1071/sr9910717.
Abstract:
Soil structure affects plant growth in many ways. Roots grow most rapidly in very friable soil, but their uptake of water and nutrients may be limited by inadequate contact with the solid and liquid phases of the soil. This contact is much more intimate in hard soil, but then the growth of the roots is strongly inhibited, so that their foraging ability is poor, and the plant may eventually become short of water or nutrients. However, many soils, even if hard, contain continuous macropores that provide niches for the roots to grow in. The presence of such macropores increases the extent of the root system, but because the roots are clumped within them, the rate at which the roots can extract water and nutrients from the soil between the macropores is considerably slowed. These macropores also provide niches for microorganisms, both symbiotic and pathogenic, so that the response of roots to different tillage treatments may differ markedly on this account alone. Soil structure not only affects the ability of roots to grow and to supply the leaves with water and nutrients; if adverse, it also induces them to send hormonal signals that slow the growth of the shoot, even if they are currently able to take up adequate water and nutrients.
38
Gao, Yang, Xiuwei Wang, Zijun Mao, Liu Yang, Zhiyan Jiang, Xiangwei Chen, and Doug P. Aubrey. "Changes in Soil Microbial Community Structure Following Different Tree Species Functional Traits Afforestation." Forests 12, no. 8 (July 30, 2021): 1018. http://dx.doi.org/10.3390/f12081018.
Abstract:
The soil microbial community structure is critical to the cycling of carbon and nitrogen in forest soils. As afforestation practices increasingly promote different functional traits of tree species, it has become critical to understand how they influence soil microbial community structures, which directly influence soil biogeochemical processes. We used fungi ITS and bacteria 16S rDNA to investigate soil microbial community structures in three monoculture plantations consisting of a non-native evergreen conifer (Pinus sibirica), a native deciduous conifer (Larix gmelinii), and a native deciduous angiosperm (Betula platyphylla) and compared them with two 1:1 mixed-species plantations (P. sibirica and L. gmelinii, P. sibirica and B. platyphylla). The fungal community structure of the conifer–angiosperm mixed plantation was similar to that of the non-native evergreen conifer, and the bacterial community structure was similar to that of the angiosperm monoculture plantation. Fungal communities were strongly related to tree species, but bacterial communities were strongly related to soil nitrogen. The co-occurrence networks were more robust in the mixed plantations, and the microbial structures associated with soil carbon and nitrogen were significantly increased. Our results provide a comparative study of the soil microbial ecology in response to afforestation of species with different functional traits and enhance the understanding of factors controlling the soil microbial community structure.
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Alikonis, Antanas. "INFLUENCE OF CLAYEY SOIL STRUCTURE ON ITS MODULUS OF STIFFNESS." JOURNAL OF CIVIL ENGINEERING AND MANAGEMENT 5, no. 2 (April 30, 1999): 108–15. http://dx.doi.org/10.3846/13921525.1999.10531444.
Abstract:
Disturbance of soil structure influences its density, strength and deformation properties. Among other cases soil structure could be disturbed by compacting it. It is possible to increase deformation properties of sand or gravel by compacting them. However, for clay soils deformation properties may increase if they are compacted. Differences of settlements of a building depends on the different deformation properties of the artificially placed and compacted soils beneath the foundations. Different values of stiffness modulus are used for the structural design of the buildings which are constructed on the soils with different compressibility. Coefficient of changeability of soil compression (1) was used. It may be calculated as a ratio of maximum and minimum values of deformation modulus, or according to the maximum and minimum values of coefficient of relative compressibility (3). Coefficient of the relative compressibility of soil can be calculated depending on the maximum and minimum values of tip resistence from CPT test (5). According to the coefficient of the relative compressibility we could estimate whether the soil is uniform, nonuniform or extremely non-uniform. It is important for the design of civil engineering structures. Mechanical properties of soils may be back-calculated using theoretical values of settlements and loads. Most frequently within the building layout area soils are natural and artificially compacted. For a compacted soil it is possible to draw compression curve in semi-logarithmic scale using compression curve of the same natural soil and the void ratio of the artificially placed and compacted soil. Thus we can determine compressibility of the soil with disturbed or undisturbed structure. Using parameters of soil compressibility, we can determine the coefficient of the relative compressibility, maximum and minimum values of settlement and modulus of stiffness.
40
GUÉGUEN, PHILIPPE, and PIERRE-YVES BARD. "SOIL-STRUCTURE AND SOIL-STRUCTURE-SOIL INTERACTION: EXPERIMENTAL EVIDENCE AT THE VOLVI TEST SITE." Journal of Earthquake Engineering 9, no. 5 (September 2005): 657–93. http://dx.doi.org/10.1080/13632460509350561.
41
Bengough, A. Glyn, Roy Neilson, Bryan Griffiths, and David Trudgill. "The extent to which nematode communities are affected by soil factors-a pot experiment." Nematology 4, no. 8 (2002): 943–52. http://dx.doi.org/10.1163/156854102321122566.
Abstract:
AbstractFour similar, agricultural soils with distinct nematode communities were used to determine the extent to which soil and inoculum factors affected nematode community structure. The soils all had a sandy loam texture from the same geographical area and had been in pasture or arable rotation for the last 10 years. Treatments were established in pots containing a middle layer of frozen defaunated soil, sandwiched between an inoculum that was either fresh soil from the same site ('self') or a mixture of soils to give a more diverse inoculum ('mixed'). Principal component analysis indicated that a single soil type given different inocula developed different community structures (i.e., the community under 'self' differed from that under 'mixed') suggesting an inoculum effect. It was also true that different soil types under a single inoculum soil also developed different community structures (i.e., community under 'mixed' differed with soil type), suggesting a soil effect. It is likely that the nematode community structure is influenced by a combination of antecedent land use, soil factors, species introductions and inter-species competition, which should be considered in any interpretation of nematode communities as a biotic indicator.
42
Yerro, Alba, and Francesca Ceccato. "Soil–Water–Structure Interactions." Geotechnics 3, no. 2 (May 5, 2023): 301–5. http://dx.doi.org/10.3390/geotechnics3020017.
Abstract:
Interactions between soil, fluids (e.g., water), and structures are intrinsic to most geotechnical problems. However, these can be extremely complex and further understanding is needed in this field. Soil–water–structure interactions can be studied on many different scales (micro to macro) and perspectives (experimental, numerical, and theoretical). In any case, the consequences of these interactions control soil behaviour, the stability of civil infrastructure, and, ultimately, the safety of our communities. This Special Issue consists of five papers (three research papers and two literature reviews) that highlight the importance of soil–water–structure interactions in a broad range of different applications. The topics addressed in the research contributions include (a) the performance of shallow footings under oblique loads, (b) the assessment of nonlinear base-isolated building systems under dynamic loading, and (c) the applicability of lightweight materials as fill for retaining wall systems. The other innovative papers, on the other hand, provide comprehensive reviews on (d) the role of the clay content in the interface characteristics between sand–clay mixtures and structures and (e) the latest developments in the understanding and measurements of the Atterberg limits.
43
Holland, J. E., R. E. White, and R. Edis. "The relation between soil structure and solute transport under raised bed cropping and conventional cultivation in south-western Victoria." Soil Research 45, no. 8 (2007): 577. http://dx.doi.org/10.1071/sr07068.
Abstract:
This study examined the relationship between soil structure and solute transport in a texture contrast soil under 2 different tillage treatments—raised beds and conventional cultivation—in south-western Victoria. Undisturbed soil samples were collected for resin-impregnation and image analysis. This enabled several descriptive parameters of macropore structure to be calculated. Large, undisturbed soil samples were also collected for a solute transport experiment using a KCl solution. A convective log-normal transfer function was used to model Cl– movement. The assessment of soil structure showed that the raised beds contained a better connected pore network than the conventionally cultivated soil. Solute transport was faster through the raised bed soil when close to saturation (at –5 mm tension). Under these conditions, the solute transport parameters showed a smaller ratio of transport volume to soil water volume in the raised bed than the conventionally cultivated soil. Together, these data strongly indicate that the raised beds had greater pore connectivity and were able to transmit solute faster and more efficiently than the conventionally cultivated soil. It is concluded that raised bed soils are better structured and provide less risk from waterlogging than conventionally cultivated soils. However, there is greater potential for preferential flow of pesticides and solutes in raised bed soils.
44
Lou, Menglin, Huaifeng Wang, Xi Chen, and Yongmei Zhai. "Structure–soil–structure interaction: Literature review." Soil Dynamics and Earthquake Engineering 31, no. 12 (December 2011): 1724–31. http://dx.doi.org/10.1016/j.soildyn.2011.07.008.
45
Bocuti, Edwaldo D., Ricardo S. S. Amorim, Kaynara F. L. Kavasaki, Marcelo R. V. Prado, Carlos L. R. Santos, and Luis A. Di L. Di Raimo. "Soil structure and its relationship with soybean yield." Revista Brasileira de Engenharia Agrícola e Ambiental 25, no. 3 (March 2021): 168–73. http://dx.doi.org/10.1590/1807-1929/agriambi.v25n3p168-173.
Abstract:
ABSTRACT Soil structure conditions the interaction between the physical-hydraulic, chemical, and biological attributes and determines the potential of soil productivity. Therefore, the objective of this study was to evaluate the structure of soils of areas subjected to soybean production and the impacts of soil structure on crop yield. In total, 28 soybean production areas were selected in the State of Mato Grosso, Brazil, and analyzed for particle size, soil organic carbon and aggregates. Data of soil attributes were subjected to descriptive analysis, Pearson’s correlation and Kruskal-Wallis test at p ≤ 0.05. In general, considering the non-irrigated soybean production areas, it was found that soils with mean sand content between 100.00 and 800.10 g kg-1 and clay content between 120.00 and 627.80 g kg-1 showed average soybean yield of 3,536.36 kg ha-1. Soils that had aggregates with mean weight diameter and mean geometric diameter above 1.50 mm showed soybean yield equal to or greater than 3,370.67 kg ha-1. Soils of similar textural groups can define different levels of soybean yield, depending on characteristics such as the type of management adopted and production technology applied in the soybean production area.
46
Yu, Zhi, Kunnan Liang, Guihua Huang, Xianbang Wang, Mingping Lin, Yinglong Chen, and Zaizhi Zhou. "Soil Bacterial Community Shifts Are Driven by Soil Nutrient Availability along a Teak Plantation Chronosequence in Tropical Forests in China." Biology 10, no. 12 (December 15, 2021): 1329. http://dx.doi.org/10.3390/biology10121329.
Abstract:
Soil bacterial communities play crucial roles in ecosystem functions and biogeochemical cycles of fundamental elements and are sensitive to environmental changes. However, the response of soil bacterial communities to chronosequence in tropical ecosystems is still poorly understood. This study characterized the structures and co-occurrence patterns of soil bacterial communities in rhizosphere and bulk soils along a chronosequence of teak plantations and adjacent native grassland as control. Stand ages significantly shifted the structure of soil bacterial communities but had no significant impact on bacterial community diversity. Bacterial community diversity in bulk soils was significantly higher than that in rhizosphere soils. The number of nodes and edges in the bacterial co-occurrence network first increased and then decreased with the chronosequence. The number of strongly positive correlations per network was much higher than negative correlations. Available potassium, total potassium, and available phosphorus were significant factors influencing the structure of the bacterial community in bulk soils. In contrast, urease, total potassium, pH, and total phosphorus were significant factors affecting the structure of the bacterial community in the rhizosphere soils. These results indicate that available nutrients in the soil are the main drivers regulating soil bacterial community variation along a teak plantation chronosequence.
47
Zou, Lihua, Leiqing Fang, Kai Huang, and Liyuan Wang. "Vibration control of soil-structure systems and Pile-Soil-Structure systems." KSCE Journal of Civil Engineering 16, no. 5 (June 29, 2012): 794–802. http://dx.doi.org/10.1007/s12205-012-1358-2.
48
Sun, H. Y., S. P. Deng, and W. R. Raun. "Bacterial Community Structure and Diversity in a Century-Old Manure-Treated Agroecosystem." Applied and Environmental Microbiology 70, no. 10 (October 2004): 5868–74. http://dx.doi.org/10.1128/aem.70.10.5868-5874.2004.
Abstract:
ABSTRACT Changes in soil microbial community structure and diversity may reflect environmental impact. We examined 16S rRNA gene fingerprints of bacterial communities in six agroecosystems by PCR amplification and denaturing gradient gel electrophoresis (PCR-DGGE) separation. These soils were treated with manure for over a century or different fertilizers for over 70 years. Bacterial community structure and diversity were affected by soil management practices, as evidenced by changes in the PCR-DGGE banding patterns. Bacterial community structure in the manure-treated soil was more closely related to the structure in the untreated soil than that in soils treated with inorganic fertilizers. Lime treatment had little effect on bacterial community structure. Soils treated with P and N-P had bacterial community structures more closely related to each other than to those of soils given other treatments. Among the soils tested, a significantly higher number of bacterial ribotypes and a more even distribution of the bacterial community existed in the manure-treated soil. Of the 99 clones obtained from the soil treated with manure for over a century, two (both Pseudomonas spp.) exhibited 100% similarity to sequences in the GenBank database. Two of the clones were possible chimeras. Based on similarity matching, the remaining 97 clones formed six major clusters. Fifty-six out of 97 were assigned taxonomic units which grouped into five major taxa: α-, β-, and γ-Proteobacteria (36 clones), Acidobacteria (16 clones), Bacteroidetes (2 clones), Nitrospirae (1 clone), and Firmicutes (1 clone). Forty-one clones remained unclassified. Results from this study suggested that bacterial community structure was closely related to agroecosystem management practices conducted for over 70 years.
49
Makino, M., T. Takeyama, and M. Kitazume. "The influence of soil disturbance on material properties and micro-structure of cement-treated soil." Lowland Technology International 17, no. 3 (2015): 139–46. http://dx.doi.org/10.14247/lti.17.3_139.
50
KUNDU, T., R. P. MATHUR, and C. S. DESAI. "THREE DIMENSIONAL SOIL‐STRUCTURE INTERACTION ANALYSIS: DEFORMABLE STRUCTURES IN MULTILAYERED SOIL MASS." Engineering Computations 8, no. 2 (February 1991): 153–80. http://dx.doi.org/10.1108/eb023831.