天水市罗峪沟古滑坡成因机制及稳定性

基于对古滑坡复活的工程地质要素分析,建立古滑坡复活成因机制评价基本思路。以甘肃罗峪沟古滑坡为例,通过野外地质调查和数值模拟手段,结合滑坡区工程地质条件,分析罗裕沟古滑坡的成因机制,其孕灾模式如下:坡体前缘开挖,形成高陡临空面→后缘拉应力集中,加剧裂隙节理扩张→强降雨水入渗,导致土体自重速增→触发古滑坡失稳。同时,利用雪橇模型对古滑坡的动力学特征进行计算,滑体的运动速度最大达到11. 56 m/s。利用有限元软件FLAC3D对古滑坡的稳定性进行评价,计算得到其在自重+地表荷载和自重+地表荷载+暴雨两种不同状态下的位移图、应力应变等灾害特征,这些研究可为西北地区类似古滑坡的防灾减灾研究提供借鉴。

Study on Genesis Mechanism and Stability of Luoyugou Ancient landslide in Tianshui City

Through the analysis of engineering geological factors of the resurrection of ancient landslides, it is found that the basic idea of evaluating the mechanism of the resurrection of ancient landslides. Taking the Luoyugou ancient landslide in Gansu province as an example, Using the methods of field geological investigation and numerical simulation, combined with the engineering geological conditions in the landslide area, the genetic mechanism of the Luoyugou ancient landslide was analyzed. The disaster model is as follows: Because of the excavation of the front edge of the slope, a high and steep free surface was formed, then the tensile stress concentration of the posterior edge of slope body , which aggravated the crack joint expansion and strongly reduced rain water infiltration, which lead to the instability of the ancient landslide triggered by the rapid increase in the gravity of the soil. At the same time, the dynamic characteristics of the ancient landslide were calculated by using the sleigh model, the results show that the maximum velocity of the sliding body reaches 11.56 m/s. The stability of ancient landslide was evaluated by using finite element software flac3d. The displacement diagram, stress-strain and other disaster characteristics of ancient landslide under two different conditions of gravity surface load and gravity surface load rainstorm are obtained. These provide a reference for the analysis of similar ancient landslides disaster prevention and mitigation in northwest China.