水闸翼墙地基处理设计研究

Study on Design of Subgrade Treatment for Sluice Wing Wall

某工程水闸翼墙底板位于淤泥质粉质粘土层,经计算挡墙地基承载力、整体稳定安全系数和基底应力比不满足规范要求,对水泥土搅拌桩、预制桩、钻孔灌注桩三种地基处理方案进行比选,查阅规范表明:现行国标和浙江省地标尚未明确给出水泥土搅拌桩处理后复合地基抗剪强度指标计算方法,因此依据相关资料取水泥土黏聚力c=100kPa,内摩擦角φ=20°进行计算。选用水泥土搅拌桩方案可提高地基土质,使地基承载力和整体稳定性满足要求,但挡墙基底应力比问题无法得到实质性解决。经结构比选,采用预制桩和钻孔灌注桩方案,从工期、造价和施工质量等多方面综合考虑,挡墙采用前板桩后方桩的预制桩处理方案,可供类似工程设计参考。

The baseplate of sluice wing wall for a project is located in the mucky silty clay layer. After calculation, the bearing capacity of subgrade for retaining wall, the overall stability safety coefficient and the base stress ratio do not meet the standard requirements. Three subgrade treatment schemes of cement-soil mixing pile, precast pile and cast-in-place pile are compared. The referenced standard shows that the current national standard and the local standard of Zhejiang Province have not explicitly given the calculation method of shear strength indexes of the composite subgrade after the treatment of cement-soil mixing pile. Therefore, based on the related data, the cement-soil sticky cohesion 100 kPa and the internal friction angle 200 are taken for calculation. The selection of cement-soil mixing pile scheme can improve the subgrade soil quality and can make the subgrade bearing capacity and integral stability meet the requirements. But the base stress ratio of retaining wall could not be substantially solved. After the comparison of structures, the selection of precast pile and cast-in-place pile schemes are all feasible. According to the comprehensive consideration from the construction time, cost and construction quality, the front sheet pile and rear square pile treatment scheme of precast pile is adopted for the retaining wall, which can be referred for the design of the similar projects.