隐伏地裂缝破裂扩展物理模型试验边界效应

Boundary Effect of Physical Model Tests on Rupture Propagation of Buried Ground Fissures

物理模型试验是研究地质灾害变形破裂特征、动力学过程和成因机制的有效手段,受制于模型箱尺寸,试验过程中边界效应问题显著,如何减弱边界效应影响一直是研究者所关注的焦点问题.本文以隐伏地裂缝破裂扩展物理模型试验为研究对象,通过物理模型试验现象分析以及数值模拟验证等手段,对物理模型箱体边界效应进行了系统分析.结果表明,模型箱体边界效应的主要控制因素为箱体边壁阻尼与箱体尺寸比,其中:边壁阻尼与边界效应幅值呈正相关,边壁摩擦角小于土体内摩擦角时,黏聚力是边界效应影响的主要因素,边壁摩擦角大于土体内摩擦角时,摩擦力是边界效应影响的主要因素;箱体尺寸比影响边界效应幅值,长宽比与边界效应幅值呈正相关,并确定试验模型箱设计最优尺寸比为5∶3∶2.2.箱体边界效应对隐伏地裂缝破裂扩展物理模型试验结果存在显著影响.

Physical model test is an effective means to study the deformation and fracture characteristics,dynamic process,and genetic mechanism of geological disasters.Limited by the size of model box,the boundary effect is significant in the test process,so how to reduce the influence of boundary effect has always been the focus of researchers.In this study,the physical model test of the rupture propagation of buried ground fissures was taken as the research object,and the boundary effect of physical model box was systematically analyzed by means of phenomenal analysis of the physical model tests and numerical simulation verification.The results show that the main controlling factor of the boundary effect of the model box is the ratio of sidewall damping to box size.The sidewall damping is positively correlated with the amplitude of the boundary effect.When the sidewall friction angle is smaller than the internal friction angle of the soil,the cohesion is the main factor affecting the boundary effect.When the friction angle of the sidewall is larger than the friction angle of the soil,the friction is the main factor affecting the boundary effect.The box size ratio affects the amplitude of boundary effect,and the aspect ratio is positively correlated with the amplitude of boundary effect.The box boundary effect has a significant influence on the results of the physical model test on the fracture propagation of buried ground fissures.The optimal size ratio of the experimental model box is determined to be 5∶3∶2.2.