碎石土滑坡的发育机制分析及防治对策研究

Analysis of the Development Mechanism and Prevention Measures of Gravel Soil Landslides

[目的]以甘肃礼县夹关沟滑坡为例,计算其在降水和地震作用下的稳定性系数,对其发育机制进行分析,并针对不同情况下碎石土滑坡的发育提供防治对策。[方法]选取强度折减法,利用的本构模型为莫尔-库伦模型,同时利用Midas有限元软件对夹关沟滑坡进行数值模拟。[结果]碎石土边坡天然条件下的稳定性系数为1.271 9,处于基本稳定;降雨条件下稳定性系数为1.125,处于不稳定状态;地震条件下稳定性系数为1.006 8,处于不稳定状态。[结论]在降水作用时,滑坡内部岩体受到入渗水的侵蚀,在坡面松散堆积物和下伏基岩层顶部的位置逐渐形成饱水带,成为滑坡失稳滑动的潜在滑移面;在地震作用时,滑坡体松散堆积物的抗滑力逐渐减小,直到小于其自重时,滑坡发生失稳滑动,再加上河道侵蚀冲刷的影响,滑坡前缘处不断受到河水的侵蚀冲刷,形成不合理的切坡,导致滑坡内部的应力发生重分布,在外力作用下,滑坡容易发生失稳滑动。

[Purposes]Taking Jiaguangou landslide in Lixian County,Gansu Province as an example,the stability coefficient under the action of precipitation and earthquake is calculated,the development mechanism is analyzed,and the prevention and control countermeasures are provided for the develop-ment of gravel soil landslide under different conditions.[Methods]The strength reduction method is se-lected as the calculation method in this article,and the constitutive model used is the Mohr Coulomb model.At the same time,Midas finite element software is used to numerically simulate the Jiaguangou landslide.[Findings]The stability coefficient of the gravel soil slope under natural conditions is 1.2719,which is basically stable;Under rainfall conditions,the stability is 1.125 and it is in an unstable state;The stability coefficient under earthquake conditions is 1.0068,indicating an unstable state.[Conclu-sions]During precipitation,the internal rock mass of the landslide is eroded by infiltration water,gradu-ally forming a saturated zone at the top of the loose accumulation and underlying bedrock layer on the slope surface,becoming a potential sliding surface for landslide instability and sliding;During an earth-quake,the anti slip force of loose deposits in the landslide body will gradually decrease until it is less than its own weight,and the landslide will experience unstable sliding.In addition,under the influence of river erosion and erosion,the front edge of the landslide is constantly eroded and eroded by river wa-ter,forming an unreasonable cut slope,leading to the redistribution of stress inside the landslide.Under external forces,the landslide is prone to unstable sliding.