【作者】 王克东；

【导师】 朱俊高；

【作者基本信息】 河海大学 ， 岩土工程， 2006， 硕士

【摘要】 以往的土坡稳定分析基本上都是基于粘性土边坡展开的,研究较多。对于粗粒土,由于在强度与变形特性方面与粘性土存在差异,其土坡失稳时的变形破坏规律和滑面形态与粘性土坡有一定不同,在这方面少有人进行专门研究,值得深入研究。 土坡在发生整体破坏之前,往往伴随着相当大的垂直沉降和侧向变形,刚体极限平衡法因没有考虑边坡的变形不能准确反映边坡的稳定性,其计算结果是有误差的;有限元强度折减法是一种很有前景的边坡稳定分析方法,该法的关键问题是临界破坏状态的确定,即如何定义失稳判据,而现有的各种失稳判据存在一些应用上的缺陷。 基于以上分析,本文进行了室内粗粒土边坡的模型试验,研究了粗粒土边坡变形失稳规律及其失稳时的滑裂面形态特征;同时利用非线性弹性有限元法模拟了模型土坡极限状态时的变形特征和失稳时的滑面形态;采用有限元法研究了变形对土坡稳定性的影响;最后,对有限元强度折减法在粗粒土边坡中的应用进行了研究。 具体研究成果如下: （1） 利用模型试验设备进行了不同坡比和加压板宽的6组粗粒土边坡模型试验,研究了模型土坡坡面特征点的位移规律、边坡内的位移场分布和发生失稳破坏后滑裂面的形态特征; （2） 采用传统极限平衡条分法计算了各模型土坡极限状态时坡顶的极限荷载,用非线性弹性有限元法模拟了极限荷载作用下各模型土坡的变形、破坏特征和滑裂面形态,并与模型试验得到的结果进行对比,验证了有限元法的可靠性; （3） 利用平面应变有限元法计算土坡的应力场,再利用圆弧搜索法对土坡在不同变形条件下稳定性的变化规律进行研究,揭示了变形对土坡稳定性影响的规律; （4） 强度折减有限元方法分析边坡的关键问题是临界破坏状态的确定。基于模型试验粗粒土边坡的变形破坏特点,并结合一简单粗粒土边坡算例,进行了线性强度指标和非线性强度指标下的强度折减计算,分析了强度折减过程中最大等效剪应变e_qmax等五个变量随折减系数F_sr的变化规律,提出以F_sr～e_qmax曲线发生“突变”作为土坡失稳的判据,通过与传统方法计算结果的比较验证了判据的可靠性。更多还原

【Abstract】 A lot of studies have been carried out to analysis the slope stability of clay slope. As we know that there are differences in strength and deformation behaviour between coarse grained soil and clay, and failure law and slip surface shape of coarse grained soil slope are different from clay slope to some extent when slope failure. So far few people studied on this field in the past, and it is worth to pay more attention on this issue.Slope has given birth to a large vertical settlement and lateral deformation before failure occurred. Limit equilibrium method can’t exactly analysis slope stability and its result is inaccurate because without taking into account doformation;As a kind of promising stability analysis method, the key of strength reduction method is how to define the failure of slope, that is to say how to define criterion of slope failure. But several criteria proposed are unreasonable in practical application.Based on the former analyses, firstly, indoor model tests of coarse grained soil slope are carried out to study its failure law and slip surface shape;Secondly, deformation behaviour and shape of slip surface of model slopes when failure are simulated using non-linear elastic FEM;Thirdly, the influence of deformation on the slope stability is investigated using FEM;Finally, how to use strength reduction method to analysis stability of coarse grained soil slope is studied.The study results of this paper are as follows:（1） 6 model tests of coarse grained soil slope with various slope ratio and width of holder are carried out using model testing devices to study on the deformation law of certain nodes, the distribution of displacement field within the slope and shape of slip surfaces after slope failure.（2） Limit load of model slopes at limit state is calculated by limit equilibrium method. Deformation, failure law and slip surface shape of model slopes under limit load are simulated using non-linear elastic FEM. The dependability of FEM is proved by comparing the results of FEM and model tests.（3） Using plane-strain FEM, the stress field of the soil slope is found. The influence of deformation on the slope stability is investigated using FEM with arch searching. The law of deformation influencing slope stability is discovered.（4） The key of strength reduction method is how to define the critical failure state of slope. Based on deformation behaviour of model slopes and analysis for a simple coarse grained soil slope, change characteristics of five variables (such as maximum equivalent shear strain e_qmax) with reduction coefficient F_sr during strength reduction are studied using linear shear strength and nonlinear shear strength. A new criterion is put forward by F_sr^e_qmax curve. By comparing its results with other methods, its dependability is proved.更多还原