含剪切带单元模型及其在边坡渐进破坏分析中的应用

提出了含剪切带单元模型。根据最小势能原理,确定了由剪切带横截而产生的新节点位移同单元周边节点位移之间的关系,求出该单元的等效刚度矩阵和等效载荷向量,然后和其他普通单元一起形成总刚度矩阵和总载荷向量求解。应用含剪切带单元模型和破坏面自动寻踪技术,模拟了边坡的渐进破坏过程,分析了粘聚力、内摩擦角和残余系数对滑动面形迹和安全系数的影响。计算结果表明,考虑渐进破坏所得到的滑动面类似于悬链线而非圆弧,这与实际观察和理论分析所得的结果一致。进一步的研究表明,滑动面形迹不仅与边坡中的应力与强度有关,而且还与前一段的破坏历史有关。强度参数对滑动面形迹的影响较小,但对安全系数的影响较大。

ELEMENT MODEL WITH SHEAR BAND AND ITS APPLICATION TO PROGRESSIVE FAILURE ANALYSIS OF SLOPES

An element model in which a shear band crosses through the element is presented.By way of the minimum potential energy principle in the element,the displacements of the new internal nodes which are produced by the shear band crossing the element boundary are related with the peripheral nodes of the element;thereby the equivalent stiffness matrix and equivalent load vector are obtained.And then put the shear band elements together with the other common elements to assemble the total stiffness matrix and total load vector.The progressive failure process is simulated by using the shear band element model and the automatic tracking procedure.The effects of the cohesionf,riction angle and residual strength coefficients on the slide track and safety factor of slope are analyzed.The computing results show that the slide track obtained by considering the progressive failure is similar to the catenary but not to the circular arc,which is accordant with the results obtained from practical observation and theoretical analysis.The further studies show that the slide track is not only related to the stress and strength in the slope,but also related to the history of failure.The strength parameters have slight effects on the slide track,but have relative strong effects on the safety factor of slope.