深厚海相软土临河公路扩建地基处理方法探讨

DISCUSSION ON DEEP MARINE CLAY FOUNDATION TREATMENT METHOD OF RIVERBANK HIGHWAY EXTENSION

针对临河段扩建公路,其主要特点是道路拓宽占用了原河道,公路拓宽部分的地基为深厚海相软土以及淤泥层与基岩风化层倾斜相交,需要加固处理。同时,软土地基处理后,对侧河岸需要改移外扩开挖,这会对地基处理效果产生不良影响,因此需要慎重选择地基处理方法。本文借助ABAQUS有限元软件和现场实测数据,对双向粉喷桩和预制方桩的经济性和处理效果进行比较,结果表明:(1)双向粉喷桩联合塑料排水板处理深厚海相软土层优于常规粉喷桩;(2)双向粉喷桩处理淤泥层与基岩风化层倾斜相交时,桩体某深度处将产生明显的滑移剪切面,而预制方桩处理不会出现该情况,因此,当淤泥层与基岩风化层倾斜相交时,应选择预制方桩处理。

The key features for highway extension along river are occupation of the widening road on the original river,deep marine clay,and oblique intersection of deep marine clay with weathered rock layer. Therefore,the foundation is necessary to be reinforced. In addition,the opposite riverbank requires to be expanded and excavated which would have bad influence on the effect of ground improvement. Thus,modification method must be determined carefully. Based on numerical analysis with ABAQUS software and field measurements,the economy and reinforcement effect of the Bidirectional Dry Jet Mixing Method( BDJMM) and Concrete Prefabricated Square Pile are compared.Research results indicate that(1) the reinforcement effect of combination of BDJM and plastic drainage plate is better than that of traditional DJM method.(2) For the oblique intersection of soft clay layer with weathered rock layer,a significant sliding shearing interface at certain depth of the pile body can be formed. Concrete Prefabricated Square Pile would not meet with such kind of problem. So the Concrete Prefabricated Square Pile is the best choice in the ground improvement with the condition of oblique intersection of soft soil layer and rock layer