宁镇地区缓坡滑坡模型试验研究

Study on Model Test of Gentle Slope Landslides in Nanjing-Zhenjiang Area

由于近年来极端强降雨天气增多,宁镇地区发生了多处规模较大的山前缓坡滑坡地质灾害。这些滑坡存在很多相似之处,边坡体地层结构表现为“类二元地层结构”特征,即边坡体表层为透水性弱或不透水的黏性土,下覆为透水性较好的砂砾类土或碎石土。在强降雨条件下,雨水沿后缘基岩中的裂隙入渗,在坡体中下部形成暂时性承压水,受其浮托力作用发生滑坡。为了深入探讨这类滑坡的形成机理,建立概化物理模型进行模拟试验,探究边坡坡度、黏土层厚度与坡体内部孔隙水压力及变形的关系,分析缓坡滑坡的主要控制因素及破坏过程,综合分析给出其破坏模式,以此为宁镇地区这类滑坡的防治及城市建设提供科学依据。

Due to the increase in extreme heavy rainfall weather in recent years,many large-scale geological disasters have occurred in the piedmont gentle slope landslides in Nanjing-Zhenjiang area.These landslides have many similarities,the stratigraphic structure of the slope body is characterized by a“quasi binary stratigraphic structure”,that is,the surface layer of the slope body is cohesive soil with weak or impermeable water permeability,and the underlying layer is sandy gravel soil or gravel soil with good water permeability.Under strong rainfall conditions,rainwater seeps through cracks in the rear edge bedrock,forming temporary confined water in the middle and lower parts of the slope,causing landslides due to its buoyancy.In order to deeply explore the formation mechanism of this type of landslide,a generalized physical model was established to conduct simulation tests to explore the relationship between slope gradient,clay layer thickness,and pore water pressure and deformation within the slope,to analyze the main control factors and failure process of gentle slope landslides,and to comprehensively analyze their failure modes.It provides a scientific basis for the prevention and control of this type of landslide and urban construction in Nanjing-Zhenjiang area.