The mechanism of slope instability due to rainfall-induced structural decay of earthquake-damaged loess

Hu Tao, Mengmeng Zhang, Li Gong, Xi Shi, Yijie Wang, Guoqiang Yang, Shaowei Lei
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引用次数: 4

Abstract

Natural loess slopes are characterized by a strong geological structure, which is an important factor in maintaining slope stability. The magnitude and duration of the earthquake may disturb the soil structure at different levels degrees, locally changing the arrangement between soil particles. The process of rainfall humidification weakens the cementation between soil particles, and the disturbance and humidification change the structural state of the soil, which in turn causes sliding of the slope along with the decay of soil mechanical properties. As slope instability is often the result of a series of post-earthquake ripple effects, it is of great scientific significance to study the mechanism of slope instability due to the structural decay of earthquake-damaged loess exacerbated by rainfall. In this paper, the impact of structural decay of loess on slope stability is simulated by GEOSTUDIO software under three conditions: pre-earthquake rainfall, post-earthquake rainfall and earthquake, taking the landslide in Buzi Village, Min County, Gansu Province as an example. The comparative analysis of the calculation results shows that the structural properties of the slope without earthquake disturbance are influenced by infiltration amount. When it is fully saturated, the structural properties are similar to those of saturated soil, and the safety factor is reduced by 12.9%. In addition, the earthquake intensity and duration have different degrees of structural damage to the soil. When the structure is fully damaged, it is similar to that of remodelled soil, and the safety factor is reduced by 45.84%. Notably, the process of the earthquake and the following humidification generates the most serious damage to the loess structure, with a reduction in the safety factor of up to 56.15%. The quantitative analysis above obviously illustrates that the post-earthquake rainfall causes the most severe damage to structural loess slopes, and the resulting landslide hazard should not be underestimated.

地震破坏黄土结构衰减对边坡失稳的影响机制
天然黄土边坡具有强烈的地质构造特征,是保持边坡稳定的重要因素。地震的震级和持续时间会对土壤结构产生不同程度的扰动,局部改变土壤颗粒间的排列。降雨加湿过程削弱了土壤颗粒间的胶结作用,扰动加湿改变了土壤的结构状态,进而引起边坡的滑动和土壤力学性能的衰减。由于边坡失稳往往是一系列震后涟漪效应的结果,因此研究降雨加剧震害黄土结构衰变导致边坡失稳的机理具有重要的科学意义。本文以甘肃省岷县步子村滑坡为例,利用GEOSTUDIO软件模拟了地震前降雨、地震后降雨和地震三种情况下黄土结构衰变对边坡稳定性的影响。计算结果对比分析表明,无地震扰动边坡的结构特性受入渗量的影响。完全饱和时,结构性质与饱和土相似,安全系数降低12.9%。此外,地震烈度和持续时间对土体有不同程度的结构破坏。结构完全破坏时与改造土相似,安全系数降低45.84%。值得注意的是,地震及随后的加湿过程对黄土结构的破坏最为严重,安全系数降低幅度高达56.15%。以上定量分析明显表明,震后降雨对黄土结构性边坡的破坏最为严重,由此产生的滑坡危害不容小觑。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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