波浪荷载作用下软土强度软化的加固处理

Consolidation of the Softening of Soft Soil under Wave Loading

摘要:

为加深长江口航道，在上海港附近的海洋软土地基上建造了防波堤。防波堤为重力式结构，采用预制半圆形混凝土沉箱。施工期间一场风暴潮的袭击导致部分已安装好的沉箱失稳破坏。本文对取自现场的原状土样进行了动三轴试验研究，结果表明：堤坝失稳是由基础下方的软土层强度弱化引起的。在此基础上设计了地基加固方案，采用打设竖向排水板联合堆载预压的方法提高地基软土的强度。在随后的强风暴下防波堤保持了较好的稳定性，证明这种地基处理方法是有效的。

Abstract:

A breakwater was constructed near Shanghai Port，China，in order to deepen the navigation channel along the Yangtze Estuary.In some sections of the breakwater a thick layer of soft soils was installed prior to construction.The breakwaters，designed as gravity-retaining structures，are made of prefabricated，semicircular concrete caissons.During construction，the caissons in one section failed during a heavy storm.In this study，the causes of the failure were investigated by running dynamic triaxial tests on undisturbed soil samples taken from the construction site.We found that the dike failure was induced by the weakening of the soft soil layer below the foundation.This paper describes the design of a guide dike and related soil improvement projects.We adopted surcharge preloading and prefabricated vertical drains to improve the soft soils below the caissons.These soil improvement measures were proven to be effective in maintaining the stability of the breakwater in subsequent heavy storms.