内排压脚与边坡稳定性的关系

Study on the relationship between the slope stability and the pressing foot by using the internal dumping

为了研究边坡角及边坡形状与边坡稳定性的关系,采用有限元软件ANSYS模拟了不同边坡角对应的稳定系数,以及不同平盘宽度和压脚高度所形成的等储备强度边坡的稳定系数。模拟中假设材料符合相关联的理想弹塑性本构关系,强度准则符合Drucker-Prager准则,用计算收敛性作为边坡稳定性的准则,用强度折减法得出边坡的稳定系数。为了形成等储备强度边坡,由下到上分步骤进行压脚。先在平面边坡最下台阶压脚,这样提高了边坡稳定系数,在边坡进入临界状态时,最下两台阶的塑性状态相同,则压脚停止;再在最下两台阶同时压脚,在边坡进入临界状态时,最下3个台阶的塑性状态相同,则压脚停止;以此类推,在最下边n个台阶同时压脚,在边坡进入临界状态时,压到与第n+1个台阶的塑性状态相同为止。结果表明,边坡总是从坡脚开始形成塑性区,在重力加载过程中,塑性区以弧形条带向坡顶扩展,形成滑带。最有效的内排压脚是从最下台阶开始形成等储备强度边坡的压脚。

The paper is dedicated to a study of the relationship be- tween the slope stability and the slope shape and angle. For this pur- pose, we havemade a simulated study of the factors of slopes ＂affect- ing the stability due to the difference of the slope angles and the fac- tors of the slopes with the reserved uniform strength by using the finite element method （FEM） via a software named ANSYS. Tile so-called uniformed strength reserve slope is referred to as those of the uniform strength margin in all the bench toes in them, which can be formed by adjusting the bench width and the height of the pressing foot. In the process of preparing the simulation model, the slope shape has to be made in conformity with an associated ideal elastic plastic constitu- tive relation. In addition, the strength criterion should be the Druck- er-Prager criterion with the convergence of calculation being taken as the slope stability one. The stability factors of the slope have to be calculated by the strength reduction method, In order to form the uni- form strength reserved slope, it is necessary to press the foot step by step from bottom to top. First of all, we have to press the foot at the lowest step of the plane slope so as to increase the stability factors of the slope. If the lowest two ste^s get into the same plastic state when the slope goes into the critical slip, it can stop its own pressing foot, Secondly, it is necessary to press the lowest two steps of the slope, in case it is necessary to make the lowest three steps get into the same plastic state when the slope gets into critical slip state. In the same way, it can also be possible to press the lowest n steps of slope. If the lowest n ＋ 1 steps gets into the same plastic state when they are getting into the critical slip state by pressing its stop foot. Thus, the study shows that the plastic zone can always appear at the bottom bench toe of the slope and the plastic zone extends to the slope top in the arc band shape, thus forming the slip zone eventually. The most effective pressing foot by internal dumping is the pressing foot starting from the bottom bench toe and forming the uniform strength reserved slope.