吸力对非饱和土抗剪强度的贡献   总被引：7，自引：4，他引：7  

孟黔灵  姚海林  邱伦锋 《岩土力学》2001,22(4):423-426,431

回顾了非饱和土抗剪强度理论，并进行了评价；系统地分析和总结了吸力对抗剪强度的贡献。  相似文献   

气候影响下膨胀土开裂的力学分析   总被引：1，自引：0，他引：1  

郑少河  姚海林  葛修润 《上海国土资源》2007,(2):29-32

采用线弹性断裂力学的方法,针对气候影响下的膨胀土开裂问题,提出了膨胀土开裂深度和裂缝间距的定量表达式,经比较与现场实测结果基本一致。并对开裂深度与泊松比、断裂韧度、基质吸力等土体特性参数的关系进行了详细的论述。  相似文献   

连续降雨作用下非饱和土边坡的稳定性分析   总被引：1，自引：1，他引：1  

崔溦  杨建  刘丽 《水文地质工程地质》2007,34(3):55-58

在边坡稳定性研究中,吸力的影响经常被忽略。基于非饱和土的渗流理论,利用数值分析方法研究了一个由于连续降雨导致的非饱和土边坡失稳的工程实例。研究结果表明:非饱和土的吸力对于维持边坡稳定具有重要影响,而吸力与降雨频率、降雨量、降雨时间、蒸发量等密切相关。对于工程实践而言,吸力的监测对于维持土坡稳定具有重要意义。  相似文献   

真三轴条件下的原状黄土增湿变形特性     

方瑾瑾  冯以鑫  余永强  李震  林志斌 《岩土力学》2020,41(4):1235-1246

为了研究复杂应力条件下原状黄土的增湿变形特性，利用改进的非饱和土湿陷真三轴仪，在测量吸力条件下对原状黄土进行双线法分级浸水增湿试验，探讨力?水耦合作用下吸力的变化特性，研究真三轴浸水试验的增湿变形特性，以及吸力、净围压、中主应力和应力比对增湿变形的影响。研究结果表明：由ei-lgp压缩曲线确定了非饱和土的屈服点，屈服点之前，曲线的斜率近似相等；屈服点之后，曲线的斜率随着初始吸力的减小而减小，且非饱和土与饱和土的交点随着初始吸力的增大呈右下方移动趋势。等向压缩过程中，吸力随着净平均应力的增加近似呈线性减小趋势，初始吸力越小，吸力减小的速度越慢，且吸力变化量越小。均压分级浸水增湿时，吸力s随着浸水量w的增加而减小，增湿体变 随着浸水量w的增加而增大，不同净围压下的 -w关系曲线相互有交叉。交叉区域之前，净围压越大，增湿体变越小，而交叉区域之后，净围压越大，增湿体变越大。在同一净围压条件下，浸水量相同时，初始吸力越大，增湿体变越大。真三轴剪切增湿试验中，应力比k、中主应力参数b值和净围压?3皆对增湿变形有一定的影响。当q/p≤1时，增湿变形曲线前段下凹后段上凹，主要表现为体积增湿变形；当q/p>1时，增湿变形曲线只有下凹部分，主要表现为剪切增湿变形。增湿变形曲线的形态取决于k值和b值的不同组合。  相似文献   

武汉白沙洲长江大桥百米长桩成孔技术与施工实践          下载免费PDF全文

李世京  廖光华 《探矿工程》1998,(3):10-11

介绍了百米长桩的施工方法、施工设备、护孔技术,并就深孔实施泵吸反循环的可行性、主要技术措施以及强风化岩层的糊钻问题进行了分析。  相似文献   

A density‐dependent elastoplastic hydro‐mechanical model for unsaturated compacted soils     

D. A. Sun  D. C. Sheng  H. B. Cui  S. W. Sloan 《国际地质力学数值与分析法杂志》2007,31(11):1257-1279

This paper presents a three‐dimensional elastoplastic constitutive model for predicting the hydraulic and mechanical behaviour of unsaturated soils. It is based on experimental results obtained from a series of controlled‐suction triaxial tests on unsaturated compacted clay with different initial densities. Hydraulic hysteresis in the water‐retention behaviour is modelled as an elastoplastic process, with the elastic part modelled by a series of scanning curves and the elastoplastic part modelled by the main drying and wetting curves. The effect of void ratio on the water‐retention behaviour is studied using data obtained from controlled‐suction wetting–drying cyclic tests on unsaturated compacted clay with different initial densities. The effect of the degree of saturation on the stress–strain‐strength behaviour and the effect of void ratio on the water‐retention behaviour are considered in the model, as is the effect of suction on the hydraulic and mechanical behaviour. The initial density dependency of the compacted soil behaviour is modelled by experimental relationships between the initial density and the corresponding yield stress and, thereby, between the initial density and the normal compression line. The model is generalized to three‐dimensional stress states by assuming that the shapes of the failure and yield surfaces in the deviatoric stress plane are given by the Matsuoka–Nakai criterion. Model predictions of the stress–strain and water‐retention behaviour are compared with those obtained from triaxial tests with different initial densities under isotropic compression, triaxial compression and triaxial extension, with or without variation in suction. The comparisons indicate that the model accurately predicts the hydraulic and mechanical behaviour of unsaturated compacted soils with different initial densities using the same material constant. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

Tapered Suction Caissons： A Numerical Investigation into Their Pull-out Performance   总被引：1，自引：0，他引：1  

M. Zeinoddini  J. Keyvani  M. Nabipour 《中国海洋工程》2009,23(4):695-707

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Streambank dewatering for increased stability     

F. Douglas Shields Jr  Andrew Simon  Seth M. Dabney 《水文研究》2009,23(11):1537-1547

Streambank erosion is often the dominant source of sediment leaving modified watersheds. Mass failure of high, steep banks is one of the most serious forms of streambank erosion. The risk of a given bank experiencing mass failure is a function of bank height, angle, and soil strength, which is governed by soil moisture. Two methods for bank dewatering were tested in adjacent sections of streambank bordering a deeply incised channel in northern Mississippi: a low‐cost pump system and subsurface horizontal drains. Pore water pressures (both positive and negative pressures, or matric suction) were continuously monitored for 2 years at the pumped site, at an adjacent untreated control section, and for 1 year at the site stabilized with horizontal drains. Resulting data were used to calculate a time series of the factor of safety using a computer model. Over the course of two wet seasons, average bank retreats for the control and pumped plots were 0·43 and 0·21 m, respectively. More limited monitoring revealed that the site with passive drains retreated about 0·23 m. At the pumped site pore water pressure was 3–4 kPa lower than at the control site during the most critical periods. Accordingly, computed factors of safety were above the failure threshold at the pumped site, but fell below unity at the control site on 11 occasions over the period of observation. Similarly, the drained site displayed generally lower pore water pressure and higher safety factors except for two events when drains were evidently overwhelmed with the volume of local surface and subsurface flows. These results suggest, but do not prove, that bank dewatering promoted lower rates of bank retreat and higher levels of stability since the three sites had slight differences in soils, geometry and boundary conditions. Initial cost of the dewatering treatments were significantly less than orthodox bank stabilization measures, but operation and maintenance requirements may be greater. Published in 2009 by John Wiley & Sons, Ltd.  相似文献   

压实黄土非饱和渗透系数试验研究   总被引：2，自引：0，他引：2  

赵彦旭  张虎元  吕擎峰  梁晓波 《岩土力学》2010,31(6):1809-1812

压实黄土非饱和渗透特性具有重要的工程意义。对不同干密度的压实黄土试样,采用非饱和导水率测定系统进行非饱和渗透系数量测,得到不同干密度压实黄土的渗透系数与吸力的关系。试验结果表明：渗透系数随吸力的增大而成非线性减小,随干密度的减小而增大;在低吸力时,干密度对渗透系数的影响较大;在较高吸力时,干密度对渗透系数的影响较小。进一步给出了压实黄土的渗透系数模型并进行回归分析,得到各Wind幂函数模型参数与干密度的关系,建立了基于干密度的压实黄土渗透系数的确定方法。  相似文献   

单一松软煤层瓦斯抽采工艺数值模拟     

林萌 《中国煤炭地质》2010,(11):18-21,41

借鉴油气藏数值模拟理论、技术和方法,对单一松软煤层的瓦斯抽采工艺进行了研究分析。根据单一松软煤层特点,提出了单一松软煤层的几何模型技术——单直径球型孔隙模型,在此基础上建立了煤层瓦斯抽采的地质和数理模型,并根据网格差分方法推导出数值解。以实际生产数据对新模型及其数值解进行验证,结果表明该模型可以用于指导单一松软煤层瓦斯抽采工艺的确定。  相似文献