碎石土古滑坡的开挖扰动效应及稳定性研究

Excavation effect and stability analysis of ancient debris landslide

在高速公路建设中经常需要开挖边坡,而作为古滑坡在坡体开挖过程中往往会被激活。通过资料搜集整理、现场工程地质勘察和室内外的力学参数试验,采用弹塑性接触有限元强度折减法,以西南某典型碎石土古滑坡的开挖为例,对古滑坡不同开挖工况下的开挖扰动效应及稳定性进行了分析研究。结果表明,开挖对塑性应变分布影响较大,使塑性应变集中区从滑面带前缘转移到了开挖处和滑面带中后部;古滑坡破坏过程中,滑体沿滑面的位移随着距滑面带前缘距离的增大呈非线性增大;滑动面的接触摩擦应力沿滑面分布很不一致。进一步分析可知,开挖深度对安全系数的影响大于开挖角度对安全系数的影响,并对各种工程情况进行了分析对比,提出了合理地处理碎石土古滑坡的建议。

It often needs to excavate slopes in highway construction, and as the ancient landslides, they are easily to be activated during the excavation. Taking a southwest typical ancient debris landslide as example, through the collection, arrangement and analysis of related data, the site investigation of engineering geology, indoor and outdoor mechanical parameters tests, adopting the analytic means of non- separation contact elastoplastic FEM, excavation effect and stability of ancient debris landslide in different excavation conditions have been analyzed and researched. The results show as follows, excavation has a greater impact on the distribution of plastic strain, and the plastic strain concentration zone transferred from the front of slide surface to the excavation division and the rear of slide surface; during the ancient landslide failure process, landslide displacements along the slide surface increased further; the distribution of contact friction stress is very inconsistent. Combined with analysis and comparison of the different engineering situation, we propose reasonable treatment recommendations to control the ancient debris landslide.