广州地区花岗岩残积土长期累积变形特性研究

Long-Term Cumulative Deformation Characteristics of Granite Residual Soil in Guangzhou

广州地区花岗岩残积土分布广泛,研究循环荷载作用下残积土的累积变形特性对该地区高铁、地铁、公路等地基的长期变形控制至关重要。以广州非饱和花岗岩残积土为研究对象,采用室内GDS动三轴仪,考虑了不同循环荷载幅值和围压两个因素,开展了循环荷载作用下广州花岗岩残积土的累积变形特性和规律的实验研究。结果表明:循环振动荷载幅值和围压对花岗岩残积土的累积变形影响显著,循环荷载幅值与累积变形正相关,而围压与累积变形负相关;在一般交通振动荷载应力幅值下(小于60 kPa),花岗岩残积土的累积塑性变形随循环荷载次数的增加呈现上升趋势,但不会无限增加,而是随着循环次数增加逐渐趋于稳定;广州花岗岩残积土的累积变形随振动次数之间不是简单的指数函数关系,而更符合双曲线函数关系;基于试验数据和已有研究成果,推荐了适合广州地区花岗岩残积土循环累积变形预测模型。研究成果可为广州地区交通荷载作用下花岗岩残积土地基长期变形控制提供一定的参考。

Granite residual soils are widely distributed in Guangzhou,and the study of the cumulative deformation characteristics of residual soils under cyclic loading is essential for the long-term deformation control of foundations of high-speed railways,subways,and highways in the region.In this paper,an experimental study on the cumulative deformation characteristics and laws of granite residual soils in Guangzhou under cyclic loading was carried out by using an indoor GDS dynamic triaxial instrument with two factors,different cyclic load amplitude and surrounding pressure,as the research object.The results show that the cyclic vibrating load amplitude and the surrounding pressure have significant effects on the cumulative deformation of granite residual soil,and the cyclic load amplitude is positively related to the cumulative deformation,while the surrounding pressure is negatively related to the cumulative deformation.Besides,under the general traffic vibration load stress amplitude(less than 60 kPa),the accumulated plastic deformation of granite residual soil shows an increasing trend with the increase of cyclic load,but it will not increase infinitely,it gradually stabilizes with the increase of cyclic load.This indicates that the accumulated deformation of granite residual soil in Guangzhou is not a simple exponential function with the number of vibrations,but more in line with the hyperbolic function.In addition,based on the experimental data and the existing research results,a prediction model for the cyclic cumulative deformation of granite residual soils in Guangzhou is recommended.The research results can provide some reference for the long-term deformation control of granite residual soil foundation under the traffic load in Guangzhou.