开挖边坡潜在不稳定范围的预测分析

云南澜沧江小湾水电工程高线公路的开挖，造成6^#山梁高边坡上部岩体失稳，产生塌滑。通过大量野外地质调查，总结分析出塌滑是沿已有结构面组合呈阶梯状的变形破坏方式，根据这一破坏机制和结构面的产出规律，采用类推法大致判定可能失稳的范围。在此基础上采用ANSYS对塌滑前后的坡体进行二维弹塑性有限元分析，并追踪塌滑前后坡体的应力、应变、变形和计算应力集中程度，通过前后比较确定塌滑后边坡的潜在不稳定范围。分析过程中充分利用ANSYS对应力应变逼真的模拟效果这一突出特点，又避免对边坡强度参数进行折减的过程，采用机制分析与数值模拟二者相结合，提供边坡的有效支护范围，结论合理，方法可行。

INSTABLE ZONE ANALYSIS OF HIGH SLOPE AFTER LANDSLIDE

Xiaowan Hydropower Project is located on Lancang River of Yunnan Province in China. The dam is 292 m high, 13 m wide at the top, about 69 m wide at the base and has a maximum capacity of electrical generation of 4 200 MW. The sixth slope is near the dam on the left bank. When digging a road, part of the sixth slope began to slide. For security of the project, countermeasures have to be taken. So it is necessary to find the potential instable zone, which is of the most concern. Through investigation, it is known that landslide happens along original joints and faults, and it is speculated that the next landslide will continue to happen along them. By analyzing the location of joints and faults and the deformation failure mechanism of landslide, the possible unstable zone is deduced. Based on plentiful investigation data and the test results, a numerical model of the sixth slope is built with ANSYS, and the joints and faults are modeled with low strength materials. Results show that the stress and strain of the slope change after landslide. By comparing the tracks and curves of the stress and strain before and after slides, the potential instabe zone of the slope is identified; and countermeasures are designed. The study shows that the identification of the zone by both methods is consistent and this approach is practicable and the result is believable.