再论岩质高边坡稳定性分析方法

Further study of stability analysis methods of high rock slopes

岩质高边坡稳定性分析是岩土工程中经典的研究课题,其假定不同,分析方法就不同。从现有稳定性分析方法中存在的问题入手,指出其存在的优劣性,在刚体极限平衡和有限元等传统边坡稳定性分析方法的基础上,提出了用有限单元法直接求解边坡稳定性。该方法的思路是用潜在滑动面上在开挖、支护完成后尚未发生滑动的所有滑面单元模拟边坡在各工况下的真实应力场和变形场,根据这个真实应力场直接计算边坡安全系数。结合现场即时监测手段和计算机仿真技术可逐步模拟边坡在分步开挖期间的稳定性。算例分析表明,该方法完善了刚体极限平衡法的不足,克服了强度折减法强度参数c、φ值折减比例的难题,弥补了超载法力学方向不明确的缺陷。计算所得的边坡安全系数和稳定状态与工程实际相当接近,表明提出的方法是可靠有效的新方法,为复杂岩质边坡稳定性分析提供了新的思路和途径。

The stability analysis of high rock slopes is a classical research topic in geotechnical engineering. One analysis method based on a certain hypothesis is different from others. This paper is to discuss and compare the advantages and disadvantages of various existing rock slope stability analysis methods. In addition, on the basis of traditional slope stability analysis methods, such as the limited equilibrium method and the finite element method （FEM）, we propose an idea using the FEM to directly solve stability of the slope. The stress field and the deformation field of a slope at all conditions can be well simulated with landslide units which have not yet slid after excavation and support, and thus slope safety factors can be calculated based on the real stress field. Furthermore, the stability analysis of rock slopes is gradually simulated during the step-step excavating process by combining on-site monitoring with computer simulation means. An example of analytical calculation shows that the rigid body limit equilibrium method is complemented and upgraded by this new method. We solve the challenge of determining the strength reduction ratio in the strength reduction method, and deal with the uncertain mechanical direction in the overloading method. The calculated results of the slope safety factor and the stability by using the new method show good agreement with actual field measurements. This paper provides a new thought and approach for the stability analysis of complex rock slope.