层状岩质边坡破坏模式及稳定性的数值分析

运用FLAC3D模拟层状岩质边坡的破坏模式,并采用强度折减法分析结构面倾角与稳定性之间的关系。结果表明:①水平层状边坡坡顶变形破坏早于坡面和坡脚,形成拉破坏区。当结构面倾角较小时,顺倾向层状边坡主要发生滑移破坏;当结构面倾角较大时,发生弯折-溃曲破坏。直立层状边坡主要发生弯曲-板间拉裂-塌落破坏。逆倾向层状边坡的破坏形式为对于小倾角为滑移破坏,对于陡倾角为倾倒破坏。②对于顺倾向边坡,整体安全系数随结构面倾角先减小后增大,呈现两头高、中间低的形态,在倾角为30°时安全系数最小;对于逆倾向边坡,曲线呈现增大-减小-增大的态势,并且大部分高于顺倾向边坡曲线,符合实际情况。③所采用的低强度弹塑性单元能够比较真实地模拟软弱结构面的变形。

Numerical analysis of failure modes and stability of stratified rock slopes

The failure modes of stratified rock slopes are simulated by FLAC3D (fast Lagrangian analysis of continua), while the relationship between dip angles of structure planes and stability of slope is analyzed by shear strength reduction method at the same time. Calculation results show that; ① for horizontal layered slope, horizontal deformation failure at the top of slope occurs earlier than that on the surface and toe of slope, which leads to the tensile failure zones. For consequent slope, when dip angle of structure plane is small, the mainly failure mode is slippage; when dip angle is large, the failure is buckling. For vertical layered slope, the failure mode is bending-fissuring-slump. For anti-dip rock slope, the mainly failure mode is slippage for small dip angle of structural plane, and toppling failure for large dip angle of structural plane. ② for consequent slope, the total safety factor F of slope first increases then decreases with structural plane dip angle β; the outline of curve for the relationship between F and β is like shoulder which is higher on both side, and lower at the middle place. When β =30º, F reaches its minimum value. For anti-dip rock slope, the outline of curve for the relationship between F and β shows the trend of increase-decrease-increase. And the most parts of its curve are higher than that of consequent slope, which is in accordance with practical case. ③ the elastoplastic element with lower strength can reasonably simulate the deformation of weakness plane.