循环动载下加筋土地基边界效应及受力特性分析

Analysis of boundary effect and mechanical characteristics of reinforced soil foundation under cyclic dynamic load

为了研究循环动载下加筋土地基的边界效应和承载性能,采用大尺寸模型箱开展室内平板载荷试验,研究了加筋地基的荷载沉降关系、土压力分布、土工格栅受力变形规律及破坏模式,分析了循环动荷载幅值、中心值及循环次数对加筋地基的影响,探讨了加载板宽度B对加筋地基承载力、土体沉降、土工格栅变形的影响。研究表明:随着加载板宽度的增大,加筋地基极限承载力、土体沉降、竖向土压力、格栅变形均随之增大,模型宽度与加载板宽度的比值L/B≥5.33时,边界效应对加筋地基的影响较小;B=200 mm时加筋地基的破坏模式为冲切破坏,B≥300 mm时为整体剪切破坏;动荷载值的改变较循环次数对加筋地基沉降影响更大,荷载幅值的改变对加筋地基沉降的影响更为明显;每级荷载刚开始施加时会出现土压力的衰减现象,竖向土压力埋深越大动土压力的衰减率越小。

In order to study boundary effect and bearing capacity of reinforced foundation under cyclic dynamic loading,the plate load test was carried out using a large-size model box.The load-sediment relationship of reinforced foundation,distribution of soil pressure,deformation law of geogrid and the failure mode are studied.This paper analyses the effects of cyclic dynamic load amplitude,center value and number of cycles on reinforced foundation and discusses the influence of the width of the loading plate on bearing capacity of reinforced foundation,soil settlement and geogrid deformation.The research shows that ultimate bearing capacity of reinforced foundation,soil settlement,vertical earth pressure and geogrid deformation increase with the increase of the width of the loading plate.When L/B≥5.33,the boundary effect has little effect on the reinforced foundation.When B=200 mm,the failure mode of reinforced foundation is punching failure,and when B≥300 mm,it is general shear failure.The dynamic load has more influence on settlement of reinforced foundation than number of cycles.The influence of change of load amplitude on settlement of reinforced foundation is more obvious.The attenuation of earth pressure occurs at the beginning of each stage of load.The greater the depth of vertical earth pressure,the smaller the attenuation rate of earth pressure.