多层软弱夹层边坡岩体稳定性及加固分析

 野外地质调查发现九顶山边坡岩体内存在3条规模较大的软弱夹层控制着岩体的稳定性。采用数值法对该边坡岩体的变形特征进行研究，发现直接开挖后沿软弱夹层将发生大的相对滑动，岩体最大水平位移位于P2软弱夹层坡面附近，达1.25 cm，相对滑动造成软弱夹层强度降低为残余强度，易造成边坡失稳。P1，P2软弱夹层上剪应力最大值分别为239.0，172.4 kPa，位于滑面中前部。当采用锚喷加固边坡时，锚杆穿过软弱夹层时轴力突然增大，表明3条软弱夹层均发生较大的变形，对边坡稳定较为不利，但锚杆加固效果明显，能较大地提高边坡稳定性，采用强度折减法计算得到加固后边坡稳定性系数为1.65。结果表明，应用数值模拟技术，可以直观形象地反映出边坡变形及应力变化的全过程，从而对工程措施优化、信息化设计和施工起超前预报与辅助决策起到一定的作用。

STABILITY AND STRENGTHENING ANALYSES OF SLOPE ROCK MASS CONTAINING MULTI-WEAK INTERLAYERS

Three weak interlayers were found in the rock mass of Jiudingshan slope by outdoor investigation,which control the stability of the slope. The deformation characteristics of the slope rock mass are studied using numerical simulation. The results indicate that:(1) large relative slide will be induced by the direct excavation,and the maximum horizontal displacement,1.25 cm,happens on the slope surface where the weak interlayer P2 emerges;and (2) the relative deformation makes the strength of the weak interlayers reduce to be the residual one,which makes the slope more instable. The maximum shear stresses at the middle and front of the weak interlayers P_1 and P_2 are 239.0,172.4 kPa respectively. When the slope is strengthened by anchors,the axial force increases rapidly near the weak interlayers,which indicates that the anchors make the stability of the slope be improved. The stability coefficient of the slope after reinforcement calculated by strength reduction method is 1.65. It is shown that the numerical simulation can give the variation process of deformation and stress in the slope,and it is helpful for engineering optimization,informational design and construction.