秦巴山区典型碎石土抗剪强度变化规律及其在堆积层滑坡机理分析中的应用

Changing law of shear strength of typical gravel soil in Qinba Mountain area and its application in the analysis of landslide mechanism in accumulation layers

秦巴山区堆积层滑坡具有数量多、分布广、密度大和频次高的特点,常造成十分严重的灾害。文章以秦巴山区小岭镇岭丰村三组矿洞滑坡碎石土为研究对象,通过室内大型直剪试验对研究区碎石土进行了深入研究,探讨了不同含水率、不同干密度和不同法向应力下碎石土抗剪强度的变化规律,并基于室内试验成果采用Midas GTS NT有限元数值模拟软件对该滑坡发生前的边坡进行计算分析,模拟分析了该边坡在开挖后及开挖与降雨耦合两种工况下应力、位移和稳定性的变化情况,最后以此为依据总结了典型开挖诱发型堆积层滑坡的发生机理。通过数值模拟计算发现:人类工程活动即开挖坡脚和该地区出现的强降雨是导致滑坡的主要诱发因素;秦巴山区典型开挖诱发型滑坡的变形模式可被归纳为:牵引-蠕滑式。研究成果可为秦巴山区堆积层滑坡的防治提供一定参考。

The mound landslides in the Qinba Mountain area are characterized by their large number,wide distribution,high density,and high frequency occurence,with excavation-induced landslides being particularly severe.This study focuses on the gravel soils from the mine hole landslide in the third group of Lingfeng Village,Xiaoling Town,Qinba Mountain area.Through large-scale direct shear tests conducted in the laboratory,an in-depth investigation of the gravelly soils in the study area was carried out.The variation rules of shear strength under different moisture contents,dry densities,and normal stresses were explored.Based on the results of these indoor tests,the Midas GTS NT finite element numerical simulation software was used to calculate and analyze the slope conditions before the occurrence of the landslide.Simulations were conducted to analyze the changes in stress,displacement,and stability of the slope after excavation and under two working conditions:post-excavation and post-excavation coupled with rainfall.Finally,the mechanism of typical excavation-induced landslides in stockpiles is summarized based on these findings.It was found by numerical simulation:human engineering activities,i.e.,excavation of the toe of slopes and heavy rainfall occurring in the area,are the main triggering factors for landslides:the deformation pattern of typical excavation-induced landslides in the Qinba Mountains can be summarised as:traction-creep-slip type.The research results can provide valuable reference for the prevention and control of excavation-induced landslides in accumulation layers in the Qinba Mountain area.