断层上覆土体破裂的离心试验模型参数设计及应用

Design and application of model parameters for centrifugal test of overlying soil rupture caused by fault

强震发震断层引起的上覆土层变形及地表破裂是工程场地评价中备受关注的问题之一。本文基于土工离心模型试验,通过自行设计的模型试验参数和自行研制的断层错动模拟装置,在100g离心加速度下成功地模拟了逆断层的错动过程,研究了基岩面以上厚度约为40 m、含水量为6%的砂土地表变形演化过程和内部变形特征。试验研究表明,在地表开始产生隆起变形之前有较短暂的整体抬升阶段;土体内部先后产生两条破裂面,向上扩展的同时均向下盘方向弯曲,最终贯通地表的为后产生的第二条破裂面,且第二条破裂面始于底部偏上盘一侧。此外,结合线激光位移传感器获取的高精数据,分析给出地表变形演化规律,地表开始隆起时所需的临界位错量,地表变形影响区域和地表陡坎平移规律。上述研究成果为进一步认识逆断层错动下较厚土层的变形规律提供参考。

The surface rupture and soil deformation caused by strong earthquakes is one of the most con⁃cerned issues in construction projects.In this paper,the geotechnical centrifuge test was used to successful⁃ly simulate the fault process of the reverse fault at 100g through the self-developed device.The surface de⁃formation evolution process and characteristics are obtained with the thickness of 40m and a water content of 6%are studied.The results show that there is a short overall uplift stage before the surface begins to produce uplift deformation with the increase of bedrock dislocation.There are two fracture surfaces in the soil,and both of them bend towards the footwall while expanding upward,finally,it is the second fracture plane that outcropped to the ground surface,and the second fracture plane started at the bottom of the hanging wall.In addition,combining with the high precision data obtained by the linear laser displacement sensor,the evolution law of surface deformation,the critical dislocation when the surface begins to uplift,the affected region of surface deformation and the translational law of surface scarp are analyzed.The above research results can provide some references for further understanding of the deformation law of the thicker soil layer under reverse fault movement.