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The deformation and permeability of Yanji mudstone under cyclic loading and unloading

Journal of Mountain Science 2019年第12期16卷 2907-2919页

作者： ZENG Zhi-xiong kong ling-wei WANG Jun-tao State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan 430071China University of Chinese Academy of Sciences Beijing 100049China Ecole des Ponts ParisTech U.R.Navier/CERMES6 et 8 av.Blaise PascalCite DescartesChamps-sur-Mame77455 Mame-la-Vallee cedex 2France

During the constructions of motorways and high-speed railway lines in the Yanji Basin,large amounts of excess mudstones due to the enormous tunnel excavations and slope cuts would be deposited as *** the deformation and permeability of Yanji mudstone became important for the design,construction and operation of the *** paper presents an experimental study on the deformation and permeability of Yanji mudstone by carrying out a series of oedometer tests with loading/unloading *** results show that the sample with a lower initial water content exhibited greater swelling deformation after inundation,a lower yield stress,greater deformation and a higher hydraulic conductivity during the loading/unloading *** the number of loading/unloading cycles increased,the yield stress and accumulated plastic deformation increased,while the compression index,rebound index and hydraulic conductivity *** samples became stiffer and their hydromechanical behaviour tended to be stable after three *** compression curves could be divided into pre-yield and post-yield *** post-yield zones of compression curves and the rebound curves could be normalized into a unique line,and the pre-yield zones of the compression curves could be described as *** equations were developed to predict mudstone deformation under cyclic loading and ***,an empirical relationship between the hydraulic conductivity and void ratio was also *** ability of the proposed methods was verified by the overall good agreement between the experimental results and predicted values.

关键词： Mudstone Swelling Cyclic loading and unloading Deformation Permeability

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Evolution of macro-meso properties of intact loess under long-term seepage and its influence on irrigation-induced loess flowslides

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Journal of Mountain Science 2022年第10期19卷 2935-2951页

作者： JIAN Tao kong ling-wei BAI wei LIU Bing-heng SUN Zhi-liang State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan 430071China University of Chinese Academy of Sciences Beijing 100049China

The loess tableland provides an excellent site for people to live and ***,flowslides occur frequently on the slope of loess tablelands due to agriculture irrigation,resulting in serious economic losses and *** structure degradation effect of irrigation water seepage on intact loess leads to a weakening of its mechanical properties,which may be responsible for the recurrent occurrence of flowslides in irrigated loess *** this paper,seepage tests and triaxial tests were carried out to investigate the evolution of the microstructure and undrained shear properties of intact loess during *** results show that water seepage leads to a significant decrease in pore water ion concentration and migration of fine particles with water flow,but no noticeably change in mineral *** seepage,the metastable structure of intact loess collapses,the fine particles disperse around the skeleton particle to fill the pores,and the total porosity *** permeability coefficient gradually decreases with seepage time and then tends to a *** saturated intact loess shows strongly contractive behavior during undrained shear and has considerable liquefaction *** seepage,the intact loess is characterized by more rapid build-up of pore water pressure and more intense strain-softening during shearing and has lower shear strength(including peak strength and steady-state strength).In irrigated loess tablelands,long-term seepage could weaken the shear strength of intact loess and increases its liquefaction potential,which contributes to the initiation of loess flowslide failure and the movement with high-speeds and long run-outs.

关键词： Intact loess Long-term seepage Undrained shear behavior Static liquefaction Flowslides

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Effect of drying environment on engineering properties of an expansive soil and its microstructure

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Journal of Mountain Science 2017年第6期14卷 1194-1201页

作者： kong ling-wei WANG Min GUO Ai-guo WANG Yong State Key Laboratory of G-eomechanics and G-eotechnical Engineering Institute of Rock and Soil Mechanics Chinese Academy of Sciences Wuhan 430071 China Rockfield Software Limited Swansea Wales SA1 8AS UK

This paper investigates the effect of drying environment, i.e. temperature and relative humidity, on the engineering properties and microscopic pore size distribution of an expansive soil. The shrinkage tests under different drying temperatures and relative humidity are carried out in a constant climate chamber. Then, the undisturbed samples, prepared in different drying environment, are used for the triaxial tests and mercury intrusion tests. It is found that the drying environment has noticeable influence on the engineering properties of expansive soils and it can be characterized by the drying rate. The linear shrinkage and strength increase with the decrease of the drying rate. The non-uniform deformation tends to happen in the high drying rate, which subsequently furthers the development of cracks. In addition, during the drying process, the variation of pores mainly focuses on the inter-aggregate pores and inter-particle pores. The lower drying rate leads to larger variation of pore size distribution.

关键词： Expansive soils Drying environment Shrinkage Strength Pore size distribution Triaxial test

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The lateral pressure coefficient at rest of expansive soils in landfill at various vertical stresses and moisture contents

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Journal of Mountain Science 2023年第4期20卷 1102-1117页

作者： ZHOU Zhen-hua kong ling-wei SUN Zhi-liang LI Tian-guo YAN Jun-biao State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan430071China University of Chinese Academy of Sciences Beijing100049China

When expansive soils in the original location are artificially transferred to landfill in different seasons,and subject to engineering activities afterwards,the corresponding deformation and stability of retaining structures become *** necessitates the determination of lateral pressure coefficient at rest(k_(0) value)for expansive soils in *** compaction,excavation of expansive soils,as well as construction of landfill in different seasons,series of stepwise loading and unloading consolidation tests at various moisture contents were carried out in this work to explore the evolution characteristics of k_(0) value and assess the dependence of k_(0) value on vertical stress and moisture ***,scanning electron microscope(SEM)was used to track the change in microstructural features with vertical *** results indicated that the k_(0) value of expansive soil shows a pronounced nonlinearity and is inextricably linked with vertical stress and moisture content,based on which a prediction formula to estimate the variation in k_(0) value with vertical stress during loading stage was proposed;there is a significant exponential increase in k_(0) value with overconsolidation ratio(OCR)during unloading stage,and OCR dominates the release of horizontal stress of expansive soil;SEM results revealed that with an increase in vertical stress,the anisotropy of expansive soil microstructure increases dramatically,causing a significant directional readjustment,which is macroscopically manifested as an initially rapid increase in k_(0) value;but when vertical stress increases to a critical value,the anisotropy of microstructure increases marginally,indicating a stable orientation occurring in the soil microstructure,which causes the k_(0) value to maintain a relatively stable value.

关键词： Expansive soil k_(0)value Landfill Vertical stress Moisture content

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Mesoscopic measurement of damage and shear bands of granite residual soil using Micro-CT and digital volume correlation

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Journal of Mountain Science 2023年第11期20卷 3423-3436页

作者： LI Cheng-sheng ZHANG Bing-xin LIU Zhi-jun kong ling-wei SHU Rong-jun Department of Civil and Environmental Engineering Shantou UniversityShantou 515000China State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicsChineseAcademy of SciencesWuhan 430000China College of Civil and Architecture Engineering Chuzhou UniversityChuzhou 239000China

The mesomechanics of geotechnical materials are closely related to the macromechanical properties,especially the mesoscale evolution of shear bands,which is helpful for understanding the failure mechanism of geotechnical ***,there is lack of effective quantitative analysis method for the complex evolution mechanism of threedimensional shear *** this work,we used X-ray computed tomography(CT)to reconstruct volume images and used the digital volume correlation(DVC)method to calculate the three-dimensional strain fields of granite residual soil samples at different loading *** trend of the failure surface of the shear bands was obtained by the planar fitting method,and the connectivity index was constructed according to the projection characteristics of the shear bands on the failure trend *** results support the following findings:the connectivity index of the shear band increases rapidly and then slowly with increasing axial strain,which is characterized by a near'S'*** the stress reaches the peak value,the connectivity index of the shear bands almost exceeds *** contribution of the new shear band volume to the connectivity of the shear bands becomes increasingly small with increasing axial *** by quartz grains and stress at the initial stage,the dip angle gradually and finally approaches the included angle of the maximum shear stress from the discrete state with increasing axial *** tendency and dip angle of the resulting shear bands are dynamic,and the tendency slightly deflects with increasing loading.

关键词： Damage Shear band Digital volume correlation Micro-CT Granite residual soil

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Modeling of ratcheting accumulation of secondary deformation due to stress-controlled high-cyclic loading in granular soils

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Journal of Central South University 2015年第6期22卷 2306-2315页

作者：贾鹏飞孔令伟 State Key Laboratory of Continental Dynamics (Northwest University) State Key Laboratory of Geomechanics and Geotechnical Engineering (Institute of Rock and Soil Mechanics Chinese Academy of Sciences)

An objective of this work is to develop a validated computational model that can be used to estimate ratcheting accumulation behavior of granular soils due to high-cyclic loading. An accumulation model was proposed to describe only the envelope of the maximum plastic deformations generated during the cyclic loading process, which can calculate the accumulated deformation by means of relatively large load cycle increments. The concept of volumetric hardening was incorporated into the model and a so-called overstress formulation was employed to describe the evolution of the accumulated volumetric deformation as a state parameter. The model accounted for ratcheting shakedown and accumulation such as a pseudo-yield surface(a shakedown surface) associated with loading inside the current virgin yield surface which was implemented into the well-known modified Cam-clay model. Finally, the model was calibrated using data from the stress-controlled drained cyclic triaxial tests on homogeneous fine grained sands. It is seen that the model can successfully represent important features of the ratcheting accumulation of both volumetric and deviatoric deformation caused by repeated drained loading over a large number of cycles.

关键词： ratcheting accumulation secondary deformation response envelope high-cyclic loading granular soils

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连续桩键结构的抗滑机制及加固效果研究

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岩土力学 2014年第9期35卷 2616-2622页

作者：郑轩孔令伟长江勘测规划设计研究院武汉430010 中国科学院武汉岩土力学研究所岩土力学与工程国家重点试验室武汉430071

连续桩键是一种新型抗滑结构,结合了阻滑键和抗滑桩结构型式的综合功能。采用二维FLAC程序对连续桩键结构与滑坡的作用效应进行了数值模拟。分析表明,结构的内在抗滑机制主要体现于有效减小滑带区域的剪切变形量、降低塑性区的发展程度... 详细信息

连续桩键是一种新型抗滑结构,结合了阻滑键和抗滑桩结构型式的综合功能。采用二维FLAC程序对连续桩键结构与滑坡的作用效应进行了数值模拟。分析表明,结构的内在抗滑机制主要体现于有效减小滑带区域的剪切变形量、降低塑性区的发展程度、阻滞滑坡体的整体位移、调动滑体区域的岩土体抗力等方面,而其外在抗滑机制则对应于结构能有效加固设置区域岩土体和充分发挥整体抗滑支挡这两种作用。总体上结构处于剪切、弯曲和拉压的复杂受力状态,内力变形连续分布且均衡,相当于整体协调受力的连续刚架体系,其抗滑效果更加明显,并表现出良好的工作状态。连续桩键结构克服了单体结构的应用局限问题,而更充分发挥了对滑坡体的加固阻滑效果,显著提高了滑坡体的整体稳定安全裕度,对滑坡治理工程有更广泛的适用性,已被成功应用于三峡库区最复杂的地质灾害治理项目——猴子石滑坡治理工程,取得了良好的治理效果。

关键词：连续桩键结构抗滑机制加固效果滑坡治理三峡库区

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利用扫描电镜、压汞法、氮气吸附法评价近海黏土孔隙特征

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岩土力学 2013年第S2期34卷 134-142页

作者：张先伟孔令伟中国科学院武汉岩土力学研究所岩土力学与工程国家重点实验室武汉430071

近海地区黏土的微观结构单元——黏土畴中含有大量的粒内孔隙,其孔径小至纳米级,这部分孔隙对黏土的物理指标、水稳性、膨胀性、收缩性等具有重要影响,一般方法很难准确地描述其孔隙特征。试验利用扫描电镜、压汞法、氮气吸附法对湛江... 详细信息

近海地区黏土的微观结构单元——黏土畴中含有大量的粒内孔隙,其孔径小至纳米级,这部分孔隙对黏土的物理指标、水稳性、膨胀性、收缩性等具有重要影响,一般方法很难准确地描述其孔隙特征。试验利用扫描电镜、压汞法、氮气吸附法对湛江黏土的微观孔隙特征及其孔隙发育的控制因素分析,建立微观结构与物理指标、力学行为的相互关系与灵敏性分析。结果表明,湛江黏土具有不良物理性质和良好力学特性指标的异常组合,是一种高灵敏性的强胶结结构性黏性土,其机制主要是:湛江黏土的微观结构为带有胶质联结特性的、定向性无序的开放式絮凝结构,孔隙结构为具有较高的强度和空间稳定性的边-面-角联结的空间网架系统。由于特殊的孔隙网架结构以及"墨水瓶"型孔隙的存在,导致退汞过程出现滞留现象及产生吸附回线。研究表明,联合扫描电镜、压汞法、氮气吸附法能够准确、完整地对近海地区黏土孔隙体系特征进行定性与定量的评价。

关键词：湛江黏土扫描电子显微镜(SEM) 压汞(MIP) 氮气吸附(NA) 微观孔隙孔隙分布

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First principles calculation of the electronic-optical properties of Cu2MgSn(SxSe1-x)4

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Optoelectronics Letters 2020年第1期16卷 29-33页

作者： SUN Ding DING Yan-yan kong ling-wei WANG ling-qun DING Bai-xiu ZHANG Yu-hong wei Li-ming ZHANG Li ZHANG Li-xin School of Physics Nankai UniversityTianjin 300071China School of Electrical and Computer Engineering Jilin Jianzhu UniversityChangchun130118China School of Materials Science and Engineering Jilin Jianzhu UniversityChangchun 130118China Institute of Photo Electronics Thin Film Devices and Technology Nankai UniversityTianjin 300071China

Based on the density functional theory with hybrid functional approach,we calculated the structural,electronic,and the optical properties of Cu2MgSn(S1-xSex)4(CMTSSe),an potential photovoltaic material for thin film solar *** calculation reveals a phase transition from kesterite to stannite structure when Zn atoms are substituted by Mg *** particular,the S-to-Se ratio can determine the energy splitting between the electronic states at the top of the valence *** band gaps of CMTSSe can be tuned in the ranges of 1.01-1.58 *** optical properties and tunable band gaps make them beneficial for achieving band-gap-graded solar cells.

关键词： electronic calculation substituted

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从新发现的藏文文献看藏传佛教在土尔扈特东归中的历史作用

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中国藏学 2019年第1期 125-136页

作者：孔令伟日本京都大学大学院

近年新疆伊犁特克斯县发现两篇完整的藏文文书,原收藏于当地藏传佛教寺院,经笔者考证,为1771年自伏尔加河流域东归的土尔扈特人所携回。作为遗留性史料的这两件藏文文书,为史家探索17—18世纪土尔扈特、西藏地方以及清廷三者间的交往,... 详细信息

近年新疆伊犁特克斯县发现两篇完整的藏文文书,原收藏于当地藏传佛教寺院,经笔者考证,为1771年自伏尔加河流域东归的土尔扈特人所携回。作为遗留性史料的这两件藏文文书,为史家探索17—18世纪土尔扈特、西藏地方以及清廷三者间的交往,开启了一扇大门。结合藏文档案、托忒文史籍与清朝官方文献,可知咱雅班第达圆寂后,其弟子所组成的卫拉特大库伦于1676年由额尔齐斯河中游远徙至今日俄国伏尔加河流域一带,并与土尔扈特人建立联系,自此成为土尔扈特联系西藏地方与清朝的重要桥梁。由现存藏文档案可以确知,17世纪以来,土尔扈特人即便受到地理的隔绝与沙俄的阻挠,仍然通过卫拉特大库伦与西藏地方政府保持密切联系,更促成土尔扈特数度绕道北京前往西藏进行朝圣之旅。文章最后讨论18世纪后期随土尔扈特东归的卫拉特大库伦如何被纳入清朝的边疆秩序中,及其最终淡出历史舞台的过程。

关键词：土尔扈特清朝卫拉特大库伦西藏甘丹颇章咱雅班第达

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