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Field testing of irrigation effects on the stability of a cliff edge in loess,North-west China

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Field testing of irrigation effects on the stability of a cl...

中国科学院地质与地球物理研究所第11届（2011年度）学术年会

作者： l.g.tham Department of Civil Engineering The University of Hong Kong

As it is not uncommon that irrigation has triggered landslides in the Chinese loess Plateau,a full-scale field testing in a typical cracked plateau in Heifangtai,Cansu Province of China to simulate such phenomenon was *** the study,piezometers were installed to measure the groundwater,and crackmeters as well as inclinometers were used to measure the slope *** was pumped from the nearby source daily to simulate the irrigation *** was a sharp increase of pore pressure in the undisturbed loess below the crack when the inclinometer registered considerable movement due to the inflow of water via the *** increase in pore pressure also dissipated ***,the irrigation water daylighted at the major cracks from the face of the plateau leading to local *** results show that cracks have significant effects on the flow of the irrigation water into the *** rapid rise in the local pore water pressure had reduced the stability of the slope.

关键词： Field testing Irrigation Crack landslide loess plateau

landslide susceptibility mapping based on Support Vector Machine:A case study on natural slopes of Hong Kong,China

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Landslide susceptibility mapping based on Support Vector Mac...

中国科学院地质与地球物理研究所2008学术年会

作者： l.g.tham Department of Civil Engineering The University of Hong Kong

The Support Vector Machine(SVM) is an increasingly popular learning procedure based on statistical learning theory,and involves a training phase in which the model is trained by a training dataset of associated input and target output *** trained model is then used to evaluate a separate set of testing *** are two main ideas underlying the SVM for discriminant-type *** first is an optimum linear separating hyperplane that separates the data *** second is the use of kernel functions to convert the original non-linear data patterns into the format that is linearly separable in a high-dimensional feature *** this paper,an overview of the SVM,both one-class and two-class SVM methods,is first presented followed by its use in landslide susceptibility mapping.A study area was selected from the natural terrain of Hong Kong,and slope angle,slope aspect,elevation,profile curvature of slope,lithology,vegetation cover and topographic wetness index(TWI) were used as environmental parameters which influence the occurrence of ***-class and two-class SVM models were trained and then used to map landslide susceptibility *** resulting susceptibility maps obtained by the methods were compared to that obtained by the logistic regression(lR) *** is concluded that two-class SVM possesses better prediction efficiency than logistic regression and one-class ***,one-class SVM,which only requires failed cases,has an advantage over the other two methods as only"failed"case information is usually available in landslide susceptibility mapping.

关键词： landslide susceptibility mapping Support Vector Machine(SVM) One-class sample Two-class sample logistic regression method Hong Kong

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不同孔隙配比人工岩芯试件水力学试验研究

东北大学学报（自然科学版） 2007年第2期28卷 258-261页

作者：于庆磊杨天鸿唐春安 l.g.tham 东北大学资源与土木工程学院辽宁沈阳110004 香港大学土木工程系香港999077

应用电液伺服岩石力学试验系统,研究了不同孔隙配比的人工岩芯试件的应力应变渗流特性,比较系统地分析了孔隙分布配级、孔隙度、渗流作用对强度、刚度的影响.试验得到了孔隙配比、孔隙度与初始渗透性的关系,建立了水压和孔隙度对试件强... 详细信息

应用电液伺服岩石力学试验系统,研究了不同孔隙配比的人工岩芯试件的应力应变渗流特性,比较系统地分析了孔隙分布配级、孔隙度、渗流作用对强度、刚度的影响.试验得到了孔隙配比、孔隙度与初始渗透性的关系,建立了水压和孔隙度对试件强度弱化的关系方程,对于定量描述孔隙结构与渗流率、试样强度的关系,具有一定的参考价值.试验结果表明,粗颗粒比例和大孔径孔隙对孔隙度和渗透性影响较大,随着孔隙度增加,水对试件的强度弱化程度更加显著.

关键词：试验研究人工试件孔隙配比孔隙结构渗透率

Stress Solution of Multiple Elliptic Hole Problem in Plane Elasticity

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Stress Solution of Multiple Elliptic Hole Problem in Plane E...

中国科学院地质与地球物理研究所2003学术年会

作者： C.F.lee l.g.tham Dept.of Civil Engineering The Univ.of Hong Kong

Using Schwarz’s alternating method and Muskhelishvili’s complex variable function techniques,this paper presents an iterative algorithm method for the effective and accurate calculation of the stresses in an elastic solid of infinite extent containing multiple elliptic holes and subject to external loading at the *** elliptic holes can have different dimensions and locate at any points while their axis orientations must be *** proposed iterative algorithm method is based on the approximation of the resultant force vector on each elliptic hole boundary as a series of complex *** a result,exact closed-form analytical stress solutions can then be obtained for the solid with a single elliptic hole whose boundary is subject to the reverse resultant force vector in the forms of complex *** numerical results presented in the paper show that the iterative solution converges quickly and *** proposed convergent criterion ensures the satisfaction of the required accuracy of the stress *** stress concentration at elliptic holes can then be evaluated with high accuracy.

关键词： Elasticity Holes Stress analysis Stress concentration Computation

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分层土中的群桩分析法

同济大学学报（自然科学版） 1993年第2期21卷 211-218页

作者：杨敏 l.g.tham Y.K.Cheung 同济大学地下建筑与工程系香港大学土木与结构工程系

本文将文献[1]中提出的分层土中的单桩分析方法推广应用于群桩问题,并将计算结果与已有的精确法结果进行了比较。就筏—桩—土基础体系编制了共同作用分析计算程序,并对群桩分析中一些常见的问题进行了计算讨论。

关键词：群桩共同作用分层土计算

Irrigation-induced loess flow failure in Heifangtai Platform,North-West China

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Irrigation-induced loess flow failure in Heifangtai Platform...

中国科学院地质与地球物理研究所2012年度（第12届）学术年会

作者： l.Xu F.C.Dai Q.M.gong l.g.tham H.Min Institute of geology and geophysics Chinese Academy of Sciences Beijing University of Technology Department of Civil Engineering The University of Hong Kong Institute of Rock and Soil Mechanics Chinese Academy of Sciences

Because the construction of dams and hydroelectric power stations of liujiaxia and Yanguoxia across the Yellow River in West gansu Province,North-West China,inhabitants in the reservoir areas were resettled in Heifangtai loess *** thus started in 1968. Perched water table was significantly raised and resulted in many loess flow failures in the past 30 *** type of landslide was often featured by long runout distance,high speed and *** tests along ICU and CSD stress paths were *** is shown that the loess has a strong strain-softening behavior and instability can occur in drained condition before undrained *** failure mechanism of loess flow can be interpreted as the following process:with increasing perched water table, collapse in loess was first triggered in drained condition and led to undrained loading to adjacent soil in the lower saturated part of me loess *** gravity loading applied by upper dry loess,undrained flow failure mobilized, eventually.

关键词： loess flow loess platform Agricultural irrigation laboratory test

Investigating landslide-related cracks along the edge of two loess platforms in northwest China

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Investigating landslide-related cracks along the edge of two...

中国科学院地质与地球物理研究所2012年度（第12届）学术年会

作者： l.Xu F.C.Dai l.g.tham Y.F.Zhou C.X.Wu Division of Tibetan Plateau Research Institute of Geology and GeophysicsChinese Academy of Sciences Institute of geology and geophysics Chinese Academy of Sciences Department of Civil Engineering The University of Hong Kong

Cracks are widely developed along the edge of loess platforms in northwest *** surveys reveal that these cracks can be grouped into shallow and deeply penetrating *** former occur at a small distance from the platform edge,normally penetrate into the top unsaturated loess with the penetration depth being controlled by the joints in *** latter penetrate deeper into the saturated loess farther away from the platform *** cracks control the inflow and drainage of irrigation *** shallow penetrating crack can fail as a slide or fall with a volume of up to hundreds of cubic *** deeply penetrating crack can fail as a flow-like landslide with a volume of thousands of cubic meters or more.A full-scale field test simulating irrigation on the platform surface was *** two types of crack can be interconnected so that the water applied in the test finally flowed into the deep crack and was discharged from the *** of soil stress states and the results of field test show that the deeply-penetrating cracks could have both positive as well as negative effects on slope *** the one hand,water can flow more freely in the cracks, and the loess could be saturated and trigger a *** the other hand,the water can drain more easily along the crack and slope stability could be enhanced as the groundwater level is ***? 2012 |ohn Wiley & Sons,ltd.

关键词： cracks landslide loess plateau slope stability

沟道流域坡面与沟谷侵蚀演化关系——以晋西王家沟小流域为例

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地理研究 2004年第3期23卷 329-338页

作者：陈浩 Y.Tsui 蔡强国 l.g.tham 胡文生 Z.Q.Yue 黄建国中国科学院地理科学与资源研究所北京100101 香港大学土木工程系西南农业大学资源环境学院重庆400716

以往坡、沟侵蚀关系研究主要限于水沙关系的探讨 ,有关原型尺度小流域坡、沟地貌侵蚀演化关系的定量研究甚少 ,尤其是坡、沟地貌特征对流域切割程度的综合影响与交互作用的定量研究尚属空白。本文在 3S技术支持下 ,根据晋西王家沟小流域... 详细信息

以往坡、沟侵蚀关系研究主要限于水沙关系的探讨 ,有关原型尺度小流域坡、沟地貌侵蚀演化关系的定量研究甚少 ,尤其是坡、沟地貌特征对流域切割程度的综合影响与交互作用的定量研究尚属空白。本文在 3S技术支持下 ,根据晋西王家沟小流域 196 7年 1∶5 0 0 0正摄影像图 (DOM )、高程数字化模型 (DEM )和同期、同比例尺地形图 ,利用正交多项式回归分析方法 ,定量分析了坡、沟地貌特征对流域切割程度的影响与交互作用。研究表明 ,沟谷地在流域地貌演化及地表切割程度中起主导作用 ,在沟间地面积相同时 ,沟谷地面积约为0 1km2 是影响流域切割裂度侵蚀演化强度最大的区域 ,流域面积愈小影响流域地表破碎的程度最大。其沟道流域坡、沟地貌演化机制可用坡。

关键词：坡面与沟谷侵蚀小流域黄土高原

Occurrence of landsliding on slopes where flowsliding had previously occurred:An investigation in a loess platform,North-west China

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Occurrence of landsliding on slopes where flowsliding had pr...

中国科学院地质与地球物理研究所2013年度（第13届）学术年会

作者： l.Xu F.C.Dai X.B.Tu I.Javed M.J.Woodard Y.l.Jin l.g.tham Institute of geology and geophysics Chinese Academy of Sciences Department of Earth Sciences COMSATS Institute of Information Technology

loess slides in South Jingyang platform,Shaanxi Province,usually occur on slopes where loess flowslides had previously occurred,Numerical modeling shows that flowslide occurrence causes conditions that increase shear stress and water content in the subsequent slopes,Both of these factors move the soil stress states towards its theoretical failure line,Under these conditions only small increases in water content can cause soil collapse,This leads to the backscarps of former flowslides being much more prone to landsliding,Wetting test results show that the loess can collapse suddenly as the water content gradually ***, the wetting process induced by continued irrigation may result in the subsequent *** constant water content tests of the loess material soil shear strength increases with the development of specimen deformation, Therefore,slide mobilization,which may be a relatively slow process,is dependent on whether the wetting conditions exist,Finally,a slope evolution model for loess platforms is proposed in this study,

关键词： landslides Numerical modeling Wetting test Constant water content test Slope evolution loess Plateau