e-p curve-based structural parameter for assessing clayey soil structure disturbance

2020 ◽  
Vol 79 (8) ◽  
pp. 4387-4398 ◽  
Author(s):  
Fanyan Meng ◽  
Renpeng Chen ◽  
Xin Kang ◽  
Zhongchao Li
Keyword(s):  
Soil Structure ◽  
Clayey Soil ◽  
Structural Parameter

scholarly journals INFLUENCE OF CLAYEY SOIL STRUCTURE ON ITS MODULUS OF STIFFNESS

1999 ◽  
Vol 5 (2) ◽  
pp. 108-115
Author(s):  
Antanas Alikonis
Keyword(s):  
Soil Structure ◽  
Clayey Soil ◽  
Deformation Modulus ◽  
Natural Soil ◽  
Logarithmic Scale ◽  
Compression Curve ◽  
Engineering Structures ◽  
Compacted Soil ◽  
Deformation Properties ◽  
Compressibility Coefficient

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.

Biochar application alters soil structure but not soil hydraulic conductivity of an expansive clayey soil under field conditions

2020 ◽  
Vol 21 (1) ◽  
pp. 73-82
Author(s):  
Ke Wang ◽  
Xiaoyuan Zhang ◽  
Cengceng Sun ◽  
Kaiqi Yang ◽  
Jiyong Zheng ◽  
...  
Keyword(s):  
Hydraulic Conductivity ◽  
Soil Structure ◽  
Clayey Soil ◽  
Field Conditions ◽  
Soil Hydraulic Conductivity ◽  
Soil Hydraulic

scholarly journals Effect of soil chiseling on soil structure and root growth for a clayey soil under no-tillage

Geoderma ◽  
2015 ◽  
Vol 259-260 ◽  
pp. 149-155 ◽  
Author(s):  
Márcio Renato Nunes ◽  
José Eloir Denardin ◽  
Eloy Antônio Pauletto ◽  
Antônio Faganello ◽  
Luiz Fernando Spinelli Pinto
Keyword(s):  
Root Growth ◽  
Soil Structure ◽  
Clayey Soil ◽  
No Tillage

Study of Soil Structural Parameters Based on the Gunary Model

2014 ◽  
Vol 580-583 ◽  
pp. 185-190
Author(s):  
Xue Feng Huang ◽  
Yang Kong ◽  
Bao Shan Yang ◽  
Ping Fu Zhen
Keyword(s):  
Soil Structure ◽  
Soil Mechanics ◽  
Structural Parameters ◽  
Structural Parameter ◽  
Function Form ◽  
Stress Strain ◽  
Strain Relationship ◽  
Soil Strain ◽  
Relationship Of ◽  
Two Parameter

Structural study of the soil is an important research content of soil mechanics. Based on the previous research results of soil structure, this paper puts forward the Gunary Model as a completely new form to describe the stress-strain relationship of soil, to discuss the method to determine soil strain considering structural parameter under the new model, to give the relevant function of the stress controlling structural parameter with stress. The results show that the Gunary Model is applicable to characterize the stress-strain relationship of soil, the parameter controls the fitting accuracy and decides the curve shape; by using the stress-strain expression of the Gunary Model, this paper finds the calculated value of stress controlling structural parameter and stress meets the two-parameter linear reciprocal function form.

scholarly journals Thermal effects on mechanical behaviour of soil–structure interface

2020 ◽  
Vol 57 (1) ◽  
pp. 32-47 ◽  
Author(s):  
Soheib Maghsoodi ◽  
Olivier Cuisinier ◽  
Farimah Masrouri
Keyword(s):  
Shear Strength ◽  
Mechanical Behaviour ◽  
Soil Structure ◽  
Clayey Soil ◽  
Normal Load ◽  
Shear Characteristics ◽  
Constant Normal Stiffness ◽  
Constant Normal Load ◽  
Dense State ◽  
Interface Behaviour

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.

The Dynamic Effect of Root Exudates on Soil Structure – Characterization by X-ray Tomography

2020 ◽  
Author(s):  
Maoz Dor ◽  
John Koestel ◽  
Simon Emmanuel ◽  
Yael Mishael
Keyword(s):  
Soil Structure ◽  
Clayey Soil ◽  
Loamy Sand ◽  
Clay Loam ◽  
Clay Loam Soil ◽  
Pore Connectivity ◽  
Wetting And Drying ◽  
Sandy Clay Loam ◽  
Sandy Clay ◽  
Loam Soil

<p>Soil mucilage strongly affects soil structural packing and stability. We characterized the effects of mucilage and the subsequent effect of wetting and drying on the microstructure of three agricultural soils: clayey, sandy-clay-loam, and loamy-sand soils. Soil stability measurement trends, assessed by a laser granulometry based aggregate durability index (ADI), varied between the soils. While aggregates stability of the clayey and loamy-sand soils decreased after subjecting soil samples to wetting and drying, stability increased in the case of the sandy-clay-loam soil. This observation can be explained by the high CaCO<sub>3</sub> content in the loamy-sand soils (19.5%) which contributes to the formation of durable aggregates induced by calcite cementation. ADI values of all soils increased following mucilage amendment (0.035 w/w). Mucilage, consisting mainly of polysaccharides and lipids, may affect soil mechanical properties and structure by binding soil particles due to its adhesive properties, thus reinforcing the internal structure of the aggregates. Stability was further analyzed after subjecting the mucilage amended samples to a wetting and drying cycle, and a diverse trend was measured. While stability increased for the clayey and the loamy-sand soils, it decreased for the sandy-clay-loam soil. Mucilage is known to induce surface hydrophobicity, following its dehydration, which may lead to a decrease in the wettability of soil particles and protect aggregates from deterioration by water. However, in the sandy-clay-loam soil, the cumulative effect CaCO<sub>3</sub> and mucilage which increases entropy overpowers the mucilage stabilizing effect.</p><p>The packing of the microstructure as a function of mucilage amendment and wetting and drying was characterized by quantifying morphological and geometrical changes within the pore-network, extracted by X-ray computed tomography (XCT). Pore volume in all soils decreased upon mucilage amendment, correlating with the observed increase in stability. However, while porosity of the clayey soil increased after wetting and drying, it decreased or remained the same in the Loamy-sand and sandy-clay-loam soil, respectively. To evaluate pore connectivity, we calculated the Euler number (c) in which smaller values (negative) indicate better pore-connectivity. Poor connectivity was assessed in the amended clayey (c=1128) and sandy-clay-loam (c=172085) soils, probably due to soil aggregation which is in correlation with porosity assessment. Following wetting and drying, connectivity improved in the clayey soil <br>(c=-17281), while in the sandy-clay-loam it remained poor (c=143119). As expected, pore connectivity (c<0) of the loamy-sand soil remained in all treatments. These observations are in agreement with the stability results. As stability increased in all soils following mucilage amendment, pore-volume, and connectivity decreased. Wetting and drying of the stabilized clayey soil increased porosity and connectivity. However, the decreased stability of the sandy-clay-loam soil, due to the cumulative effect of CaCO3 and mucilage, was expressed by poor connectivity and porosity. These results demonstrate the effect of mucilage amendment and wetting and drying cycle on soil structure. Finally, applying X-ray tomography and laser granulometry measurements to characterize soil structure as a function of soil amendments may shed light on how soil structure controls the storage and fluxes of water, nutrients, and gases.</p>

Effects of Soil Plasticity on Seismic Performance of Mid-Rise Building Frames Resting on Soft Soils

2014 ◽  
Vol 17 (10) ◽  
pp. 1387-1402 ◽  
Author(s):  
Behzad Fatahi ◽  
S. Hamid Reza Tabatabaiefar
Keyword(s):  
Boundary Conditions ◽  
Seismic Response ◽  
Soil Structure ◽  
Clayey Soil ◽  
Soft Soil ◽  
Plasticity Index ◽  
Soil Structure Interaction ◽  
Building Frames ◽  
Structure Interaction ◽  
Soil Deposits

In this study, the effects of Plasticity Index (PI) variation on the seismic response of mid-rise building frames resting on soft soil deposits are investigated. To achieve this goal, three structural models including 5, 10, and 15 storey buildings are simulated in conjunction with a clayey soil representing soil class Ee according to the classification of AS1170.4–2007 (Earthquake actions in Australia) and then varying the Plasticity Index. Structural sections of the selected frames were designed according to AS3600–2009 (Australian Standard for Concrete Structures) after undertaking dynamic analysis under the influence of four different earthquake ground motions. The frame sections are modelled and analysed, employing finite difference method adopting FLAC 2D software under two different boundary conditions: (i) fixed base (no Soil-Structure Interaction), and (ii) flexible base considering soil-structure interaction. Fully nonlinear dynamic analyses under the influence of different earthquake records are conducted and the results in terms of maximum lateral displacements and inter-storey drifts for the above mentioned boundary conditions are obtained, compared, and discussed. Base on the results of the numerical investigations, it becomes apparent that as the Plasticity Index of the subsoil increases, the base shears of mid-rise building frames resting on soft soil deposits increase, while the lateral deflections and corresponding inter-storey drifts decrease. It is concluded that reduction of the Plasticity Index could noticeably amplify the effects of soil-structure interaction on the seismic response of mid-rise building frames.

A New Apparatus for Shear-Seepage Testing at the Clayey Soil-Structure Interface

2021 ◽  
Vol 45 (2) ◽  
pp. 20210126
Author(s):  
Qianhui Liu ◽  
Yuzhen Yu ◽  
Bingyin Zhang ◽  
Xiangnan Wang ◽  
He Lv ◽  
...  
Keyword(s):  
Soil Structure ◽  
Clayey Soil ◽  
New Apparatus

INFLUENCE OF CLAYEY SOIL STRUCTURE ON ITS MODULUS OF STIFFNESS

Statyba ◽  
1999 ◽  
Vol 5 (2) ◽  
pp. 108-115
Author(s):  
A. Alikonis
Keyword(s):  
Soil Structure ◽  
Clayey Soil
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