针对刚性挡墙绕基底转动与平动耦合(rotation around the base and translation coupling,简称RBT)模式下砂土非极限主动土压力的分布问题,选取转动中心位置参数n=0.5、1.0、5.0共3组转动中心对其进行离散元模拟研究。结果表明,RBT模式下主动土压力兼具绕基底转动(rotation around base,简称RB)模式下凹型分布和平动(translational,简称T)模式直线分布的特点。在破坏过程中,墙土摩擦角往往先于内摩擦角达到极限值,墙后滑裂面为一曲面,且土体滑裂面处有明显的主应力偏转现象。基于数值模拟结果,根据中间对称圆弧拱得到了层间等效内摩擦角与n的函数关系式,利用水平层分析法,建立了曲边梯形微分单元的受力平衡方程,采用有限差分法求解得到了RBT模式非极限主动土压力数值解。参数分析表明,墙体位移、内摩擦角及转动中心位置参数n对主动土压力具有显著的影响。通过与数值模拟和模型试验的对比,验证了所提理论的合理性和可靠性,研究成果可为刚性挡土墙土压力计算提供参考。
为研究降雨作用下河南省伊川县某滑坡的破坏运动特征分析,利用颗粒离散元软件,采用Ball-Wall法建立1:1数值计算模型并进行模拟计算,得出不同时间步长下的速度与位移云图,并在坡体不同的位置记录坡体运动过程中位移及速度变化的情况。研究结果表明:该滑坡整体破坏特征为:中部剪切–前缘牵引–后缘拉裂。表现为蠕滑–拉裂式破坏。前期坡体处于蠕滑阶段,坡体在位中前部位移速度最大,该位置率先破坏,其次为后缘部位,中前部与后缘因速度差挤压前方颗粒,随着时间推移,前缘部位颗粒开始剪出,后缘出现张拉裂缝,后续速度变化较为稳定,有整体下滑的趋势。In order to study the failure motion characteristics of a landslide in Yichuan County, Henan Province, under the action of rainfall, a 1:1 numerical calculation model was established by using the particle discrete element software and the Ball-Wall method and simulated. The velocity and displacement cloud patterns under different time steps were obtained, and the displacement and velocity changes during the movement of the slope were recorded at different positions of the slope. The research results show that the overall failure characteristics of the landslide are the middle shear-leading edge traction-trailing edge tensile cracking. The performance is a creep-tensile cracking failure. The slope is in the creep stage in the early stage, and the moving speed of the front part of the slope is the largest in the middle, which is the first to be destroyed, followed by the trailing edge. The front and rear parts of the slope are squeezed by the speed difference. As time goes by, the front edge particles begin to cut out, and tensile cracks appear on the trailing edge. The subsequent speed changes are relatively stable, and there is an overall downward trend.
