贵州省马达岭滑坡崩滑形成机制及堆积体稳定性分析

Failure Mechanism of Madaling Landslide in Guizhou Province and Stability Analysis of Accumulation Body

马达岭滑坡为典型的平缓反倾斜横向坡,其为"塌陷-拉裂-贯通"破坏模式,自2003年以来发生多期次崩滑,形成目前的崩滑堆积态势,对在建的都匀至香格里拉高速公路造成潜在威胁。在前人研究成果的基础上,通过现场工程地质调查与试验研究,从地层岩性、岩体结构、地下水作用、软弱夹层等方面分析了马达岭HP1滑坡崩滑形成的原因以及马达岭滑坡的形成条件及成灾机理,并采用渗流有限元与极限平衡分析联合求解的方式,模拟计算了在自然状态、降雨状态、地震作用和降雨联合地震作用4种工况条件下马达岭滑坡崩滑堆积体的稳定性,分析了降雨强度、降雨时长和地震作用对滑坡崩滑堆积体稳定性的影响。结果表明:(1)强降雨条件下滑坡崩滑堆积体将处于基本稳定至不稳定状态;(2)随着降雨强度的增加,滑坡的稳定性系数总体呈减小趋势;(3)随着降雨持续时间的增加,滑坡的稳定性系数将持续降低;(4)降雨联合地震作用极端工况下,滑坡的稳定性系数进一步降低,且竖向地震力对滑坡稳定性的影响远小于水平地震力;(5)都匀至香格里拉高速公路选线规避滑坡影响区是合理的。

Madaling landslide is a typically gentle slope which is antidip and lateral,with the failure mechanism which includes collapse,cracking and coalescence.It is a result of accumulation where collapse and slide have happened three times since 2003,which is a potential threat to the highway construction from Duyun to Shangri-La.On the basis of field geology survey and laboratory study,this paper analyzes the forming reason and disaster-causing mechanism about Madaling accumulation HP1 from the aspects of formation lithology,structure of rock,influence of underground water and weak intercalation.Then the paper calculates the stability of accumulation under four conditions of natural state,rainfall,earthquake and the paper also studies the combination of earthquake and rainfall.And the influence of rainfall intensity,rainfall duration and seismic by using the limit equilibrium method and the finite element analysis method.The simulation results indicate that the accumulation will be basically in critical state.With the increase of rainfall intensity,the stability coefficient of accumulation shows a decreasing trend.Besides,with the increase of rainfall duration,the stability coefficient of accumulation will continue to decrease.Under combination of earthquake and rainfall,the stability coefficient is further reduced,and the effect of vertical seismic force on the slope stability is far less than that of the horizontal seismic force.Finally,it is reasonable to avoid the impact zone of the landslide for the route selection of high way from Duyun to Shangri-La.