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蠕变对河流侧蚀型黄土滑坡影响的数值模拟

2020-10-12张吉宏段钊唐皓

人民黄河 2020年2期

张吉宏 段钊 唐皓

摘 要:为了解蠕变对黄土斜坡变形破坏的影响,给河流侧蚀型黄土滑坡治理提供技术参考,对泾河下游舒唐王村一带塬边黄土进行蠕变试验,建立适用于该区黄土的自定义蠕变模型并进行数值模拟,分析蠕变效应对河流侧蚀型黄土滑坡变形破坏的影响,结果表明:蠕变对黄土滑坡变形破坏过程具有显著的促滑效应,蠕变效应显著加速了滑坡土体塑性区的发展及贯通,明显加剧了滑坡土体剪应变增量的放大与集中、增大了滑坡的水平位移。

关键词:黄土滑坡;蠕变效应;本构模型;河流侧蚀;数值模拟

中图分类号:S157.1;P642.22 文献标志码:A

doi:10.3969/j.issn.1000-1379.2020.02.030

Abstract:In order to understand the effect of creep on the deformation and failure of loess slope, and to provide technical reference for the treatment of loess landslide caused by river erosion, the creep test of loess in the loess plateau area of the downstream region of Jinghe River was carried out. A self-defined creep model suitable for the loess in this area was established and simulated with numerical method in this paper. It is concluded that the creep effect on the deformation and failure process of loess landslides is obvious, which accelerates the development and penetration of the plastic zone, and intensifies the enlargement and concentration of the shear strain increment in the soil, and the horizontal displacement of landslide is obviously increased.

Key words: loess landslide; creep effect; constitutive model; river erosion; numerical simulation

我國滑坡灾害以西部地区最为严重[1]。近年来黄土滑坡灾害的发生次数有逐年增加的趋势,对社会生产及群众生活构成了严重威胁,甚至引发重大灾难性后果[2],因此对黄土滑坡及其变形破坏规律的研究已成为一个热点。河流侧蚀型黄土滑坡具有厚度大、滑面深、潜伏期长、不易预警等特点,国内外众多学者[2-7]对其诱发机理、破坏模式等进行了研究,但研究中对蠕变的影响因素考虑较少。许多学者[8-14]将蠕变理论用于研究滑坡产生原因、变形规律等,并提出不同土的蠕变经验模型,但在黄土滑坡研究中的应用较少,黄土的蠕变特性对河流侧蚀黄土滑坡变形破坏规律的影响研究尚不够深入。陕西省泾河下游沿河分布有30多千米长的黄土台塬,受地貌影响及泾河不断侧蚀,在泾河南岸诱发了大量滑坡,笔者以目前该区仍在侵蚀过程中的舒唐王村一带塬边典型滑坡为例,分析其基于蠕变效应的变形破坏规律,以期为该类黄土滑坡治理提供技术参考。……

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