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Journal of Rock Mechanics and Geotechnical Engineering 2018年第4期10卷 653-660页

作者： Libin Gong Ana Heitor Buddhima Indraratna School of Civil Mining and Environmental Engineering University of Wollongong

Rock joints infilled with sediments can strongly influence the strength of rock mass. As infilled joints often exist under unsaturated condition, this study investigated the influence of matric suction of infill on the overall joint shear strength. A novel technique that allows direct measurement of matric suction of infill using high capacity tensiometers(HCTs) during direct shear of infilled joints under constant normal stiffness(CNS) is described. The CNS apparatus was modified to accommodate the HCT and the procedure is explained in detail. Joint specimens were simulated by gypsum plaster using threedimensional(3D) printed surface moulds, and filled with kaolin and sand mixture prepared at different water contents. Shear behaviours of both planar infilled joints and rough joints having joint roughness coefficients(JRCs) of 8-10 and 18-20 with the ratios of infill thickness to asperity height(t/a)equal to 0.5 were investigated. matric suction shows predominantly unimodal behaviour during shearing of both planar and rough joints, which is closely associated with the variation of unloading rate and volumetric changes of the infill material. As expected, two-peak behaviour was observed for the rough joints and both peaks increased with the increase of infill matric suction. The results suggest that the contribution of matric suction of infill on the joint peak normalised shear stress is relatively independent of the joint roughness.

关键词： Infilled rock joints matric suction High capacity tensiometer (HCT) Three-dimensional (3D) printing Normalised shear stress Unloading rate

Study of swelling-shrinkage regularity of montmorillonite crystal and its relation with matric suction

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Science China Earth Sciences 2001年第6期44卷 498-507页

作者：谭罗荣孔令伟 LRSM Laboratory Institute of Rock and Soil Mechanics Chinese Academy of Sciences Wuhan 430071 China

The swell-shrinking mineral of saturated and unsaturated expansive soil has important effect on engineering mechanical behavior. Based on the swelling-shrinkage change regularity of montmorillonite crystal in this paper, the actions between various interlayers of montmorillonite crystal are generally summarized as two kinds of action potentials-shrinkage potential and swelling potential. Moreover, through the experimental research and analysis, the expression formula for variations of the swelling potential and shrinkage potential with interlayer distance is presented, and the regularity of matric suction variations with interlayer distance is also obtained for unsaturated expansive soil. It may provide a new theoretical basis and research path for further research on the swelling-shrinkage mechanism of expansive soil and matric suction potential of unsaturated soil.

关键词： montmorillonite crystal interlayer distance swelling-shrinkage potential osmotic pressure comprehensive action potential matric suction

Seismic stability of expansive soil slopes reinforced by anchor cables using a modified horizontal slice method

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Earthquake Engineering and Engineering Vibration 2024年第2期23卷 377-387页

作者： Wang Long Chen Guoxing Hu Wei Zhou Enquan Feng Jianxue Huang Anping School of Mechnical Engineering Jiangnan UniversityWuxi 214122China Institute of Geotechnical Engineering Nanjing Tech UniversityNanjing 211816China State Key Laboratory of Geohazard Prevention and Geoenvironmental Protection Chengdu University of TechnologyChengdu 610059China Faculty of Civil Engineering and Mechanics Jiangsu UniversityZhenjiang 212013China Architectural Engineering College Guizhou Minzu UniversityGuiyang 550025China School of Civil Engineering Lanzhou University of TechnologyLanzhou 730050China

Earthquake-induced slope failures are common occurrences in engineering practice and pre-stressed anchor cables are an effective technique in maintaining slope stability,especially in areas that are prone to ***,the soil at typical engineering sites also exhibit unsaturated *** considerations of these factors in slope stability estimations are crucial in producing accurate *** this study,the seismic responses of expansive soil slopes stabilized by anchor cables is studied in the realm of kinematic limit analysis.A modified horizontal slice method is proposed to semi-analytically formulate the energy balance *** illustrative slope is studied to demonstrate the influences of suction,seismic excitations and anchor cables on the slope *** results indicate that the stabilizing effect of soil suction relates strongly to the seismic excitation and presents a sine shape as the seismic wave *** higher and steeper slopes,the stabilizing effect of suction is more *** critical slip surface tends to be much more shallow as the seismic wave approaches the peak and vice versa.

关键词： limit analysis expansive soil slope matric suction anchor cable pseudo-dynamic analysis

Effect of degree of saturation on stresses and pore water pressure in the subgrade layer caused by railway track loading

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Railway Sciences 2024年第4期3卷 413-436页

作者： Mohammed Y.Fattah Qutaiba G.Majeed Hassan H.Joni Department of Civil Engineering UOTBaghdadIraq Department of Civil Engineering Diyala UniversityDiyalaIraq

Purpose-The experiments of this study investigated the effect of the subgrade degree of saturation on the value of the stresses generated on the surface and the middle(vertical and lateral stresses).The objectives of this study can be identified by studying the effect of subgrade layer degree of saturation variation,load amplitude and load frequency on the transmitted stresses through the ballast layer to the subgrade layer and the stress distribution inside it and investigating the excess pore water pressure development in the clay layer in the case of a fully saturated subgrade layer and the change in matric suction in the case of an unsaturated subgrade ***/methodology/approach-Thirty-six laboratory experiments were conducted using approximately half-scale replicas of real railways,with an iron box measuring 1.5×1.031.0 *** the box,a 0.5 m thick layer of clay soil representing the base layer was *** it is a 0.2 m thick ballast layer made of crushed stone,and on top of that is a 0.8 m long rail line supported by three 0.9 m(0.1×0.1 m)slipper *** subgrade layer has been built at the following various saturation levels:100,80,70 and 60%.Experiments were conducted with various frequencies of 1,2 and 4 Hz with load amplitudes of 15,25 and 35 ***-The results of the study demonstrated that as the subgrade degree of saturation decreased from 100 to 60%,the ratio of stress in the lateral direction to stress in the vertical direction generated in the middle of the subgrade layer decreased as *** average,this ratio changed from approximately 0.75 to approximately ***/value-The study discovered that as the test proceeded and the number of cycles increased,the value of negative water pressure(matric suction)in the case of unsaturated subgrade soils *** frequency of loads had no bearing on the ratio of decline in matric suction values,which was greater under a larger load amplitude than a lower *** the test progr

关键词： Subgrade clay Unsaturated Track matric suction Stresses

Seismic bearing capacity of strip footing on partially saturated soil using modal response analysis

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Earthquake Engineering and Engineering Vibration 2022年第3期21卷 641-662页

作者： Abhijit Anand Rajib Sarkar Department of Civil Engineering IIT(ISM)DhanbadDhanbad 826004India

The present study proposes a novel and simplified methodology to assess the seismic bearing capacity(SBC) of a shallow strip footing by incorporating strength non-linearity arising due to partial saturation of a soil matrix. Furthermore, developed methodology incorporates the modal response analysis of soil layers to assess SBC. A constant matric suction distribution profile has been considered throughout the depth of the soil. The Van Genuchten equation and corresponding fitting parameters have been considered to quantify matric suction in the analysis. SBC has been obtained for three different geomaterials;viz. sand, fly ash and clay, based on their predominant grain size and diverse soil water characteristics curve(SWCC) attributes. Variation of SBC with different modes of vibration and damping ratio are reported for ranges of matric suction pertinent to the geomaterials considered in the study. The relative significance of matric suction on SBC has been reported for suction values within the transition zone of each geomaterial. It is observed that the SBC of sand is drastically reduced, with matric suction reaching beyond the residual suction value. The SBC of fly ash remains constant beyond the residual suction value, whereas the SBC of clay shows an increasing trend toward the practical range of matric suction values.

关键词： seismic bearing capacity modal analysis matric suction

Influence of rainfall infiltration on the stability of unsaturated coal gangue accumulated slope

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Journal of Mountain Science 2021年第6期18卷 1696-1709页

作者： Kaleem Ullah Jan KHAN WANG Chang-ming Muhammad Wasim Jan KHAN LIANG Zhu LI Shuo LI Bai-long College of Construction Engineering Jilin UniversityChangchun 130021China Department of Management Sciences University College of Zhob(Sub-Campus BUITEMS)Balochistan 85200Pakistan

The slope instability is associated with increasing rate of rainfall infiltration which cause shear strength reduction and suction loss and the slope tend to failure. The influences of rainfall infiltration on the stability of clayey and sandy slopes have been analyzed but the effect of rainfall infiltration on the stability of unsaturated coal gangue accumulated slope was needed to study. Therefore, a coal gangue accumulated slope prone to failure in Fuxin area of Northeast China was considered to evaluate its failure mechanism under different rainfall events. The effects after five different rainfall events on slope stability were physically analyzed, numerically investigated and the results from both uncoupled(hydraulic) and coupled(hydromechanical) responses were compared using finite element analysis. It was observed that the decisive soaking and leaching under different rainfall conditions caused maximum deformation at the crest of slope due to maximum value of permeability coefficient of coal gangue. The critical duration of moderate intensity(147 mm/day) of rainfall for the instability of coal gangue accumulated slope is declared as five days. The results from finite element analysis in this paper further clarifies that increase in duration of rainfall infiltration process cause hysteretic change in positive pore-water pressure causing decrease in factor of safety and increase in deformation. It is concluded that the stability of unsaturated coal gangue accumulated slope is greatly influence by the coupled effect of stress and porewater pressure in comparison of uncoupled(hydraulic) analysis as the obtained factor of safety values after five days of rainfall infiltration were 0.9 and 1.1 respectively.

关键词： Hydro mechanical coupling Factor of safety Ground water table Rainfall infiltration matric suction Coal gangue

Experimental investigation on cohesionless sandy bank failure resulting from water level rising

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International Journal of Sediment Research 2018年第1期33卷 47-56页

作者： Ryosuke Arai Kazuyuki Ota Takahiro Sato Yasushi Toyoda Fluid Dynamics Sector Central Research Institute of Electric Power Industry

In the last decade, sediment replenishment forming cohesionless sandy banks below dams has become an increasingly common practice in Japan to compensate for sediment deficits downstream. The erosion process of the placed cohesionless sediment is a combination of lateral toe-erosion and the following mass failure. To explore cohesionless bank failure mechanisms, a series of experiments was done in a soil tank using a compacted sandy soil mass exposed to an increasing water level. Two types of uniform sand(D50= 0.40 mm and 0.17 mm) and two bank heights（50 cm and 25 cm） were used under the condition of a constant bank slope of 75°. The three dimensional（3D） geometry of the bank after failure was measured using a handheld 3D scanner. The motion of bank failure was captured using the particle image velocimetry（PIV） technique, and the matric suction was measured by tensiometers. The compacted sandy soil was eroded by loss of matric suction accompanying the rise in water level which subsequently caused rotational slide and cantilever toppling failure due to destabilization of the bank. The effect of erosion protection resulting from the slumped blocks after these failures is discussed in the light of different failure mechanisms. Tensile strength is analyzed by inverse calculation of cantilever toppling failure events. The tensile strength had non-linear relation with degree of saturation and showed a *** findings of the study show that it is important to incorporate the non-linear relation of tensile strength into stability analysis of cantilever toppling failure and prediction of tension crack depth within unsaturated cohesionless banks.

关键词： Riverbank erosion matric suction Cohesionless bank Tensile strength

Surficial Stability Analysis of Unsaturated Loess Slopes Subjected to Rainfall Infiltration Effects

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Wuhan University Journal of Natural Sciences 2006年第4期11卷 825-828页

作者： LI Xinpo WANG Chenghua XU Jun Institute of Mountain Hazards and Environment Chinese Academy of Sciences Chengdu 610041 SichuanChina Graduate University of Chinese Academy of Sciences Beijing 100049 China College of Architecture and Storage Engineering China University of Petroleum Dongying 257061 ShandongChina

According to theory of unsaturated soil strength and Green-Ampt model, an analysis method based on limit equilibrium theory is introduced to consider rainfall infiltration effects in loess slope stability analysis. The relationships between wetting band depth and surficial stability of slopes are analyzed. It is found that the infiltration adds to the weight of the soil and at the same time reduces the shear strength provided by matric suction of the soil. The wetting band depth plays a key role in the stability of slopes. The minimum rainfall intensity and the minimum rainfall duration needed to infiltrate to the wetting front depth are calculated based on the Green-Ampt model. The method in this paper will contribute to the predication of slope stability considering rainfall characteristics.

关键词： slope stability unsaturated soils infiltration matric suction

Creep model for unsaturated soils in sliding zone of Qianjiangping landslide

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Journal of Rock Mechanics and Geotechnical Engineering 2013年第2期5卷 162-167页

作者： Liangchao Zou Shimei Wang Xiaoling Lai Key Laboratory of Geological Hazards of Three Gorges Reservoir Area of Ministry of Education China Three Gorges University Department of Geotechnical Engineering College of Civil Engineering Tongji University

The mechanical behavior of sliding zone soils plays a significant role in landslide. In general, the sliding zone soils are basically in unsaturated state due to rainfall infiltration and reservoir water level fluctuation. Meanwhile, a large number of examples show that the deformation processes of landslides always take a long period of time, indicating that landslides exhibit a time-dependent property. Therefore, the deforma- tion of unsaturated soils of landslide involves creep behaviors. In this paper, the Burgers creep model for unsaturated soils under triaxial stress state is considered based on the unsaturated soil mechanics. Then, by curve fitting using the least squares method, creep parameters in different matric suction states are obtained based on the creep test data of unsaturated soils in the sliding zones of Qianjiangping landslide. Results show that the predicted results are in good agreement with the experimental data, Finally, to fur- ther explore the creep characteristics of the unsaturated soils in sliding zones, the relationships between parameters of the model and matric suction are analyzed and a revised Burgers creep model is developed correspondingly. Simulations on another group of test data are performed by using the modified Burgers creep model and reasonable results are observed,

关键词： Sliding zone Unsaturated soils matric suction Creep behavior Burgers model

Unsaturated creep tests and empirical models for sliding zone soils of Qianjiangping landslide in the Three Gorges

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Journal of Rock Mechanics and Geotechnical Engineering 2010年第2期2卷 149-154页

作者： Xiaoling Lai Shimei Wang Hongbin Qin Xianfeng Liu Key Laboratory of Geological Hazards in Three Gorges Reservoir Area Ministry of EducationChina Three Gorges UniversityYichang443002China

Creep of sliding zone soils may cause significant displacement in large-scale landslides in the Three Gorges reservoir *** investigate the effects of water on the soil creep behavior of the Qianjiangping landslide,a series of unsaturated triaxial creep tests on the sliding zone soils were *** on the analyses of testing results,a new stress intensity incorporating matric suction was defined and an unsaturated Singh-Mitchell creep model was *** results are in good agreement with the experimental results,which indicates that the established unsaturated model can reasonably simulate the effects of water on the soil creep behavior of the ***,relationships between matric suction and the parameters of the model were *** study provides a calculation model and parameters for the evaluation of long-term stability of landslides under the influence of water.

关键词： Qianjiangping landslide matric suction creep Singh-Mitchell creep model