软土地基沉箱防波堤失稳模式及稳定性分析方法  

Research on the failure mode and stability analysis method of caisson breakwater on soft foundation

作　　者：孙百顺[1,2] 王元战[1] 孙熙平[2] 尹纪龙[2] 张华庆[2] 

机构地区：[1]天津大学建筑工程学院天津市港口与海岸工程重点实验室,天津300072 [2]交通运输部天津水运工程科学研究所港口水工建筑技术国家工程实验室水工构造物检测诊断与加固技术交通行业重点实验室,天津300456

出　　处：《海洋工程》2016年第3期72-79,共8页The Ocean Engineering

基　　金：国家自然科学基金项目(51409134);交通运输部建设科技项目(2014328224040)

摘　　要：针对现阶段深水软黏土地基防波堤建设的设计理论和稳定性分析方法尚不成熟,结合实际工程,采用三维弹塑性有限元数值分析方法,研究在水平或竖直单一方向荷载以及复合加载条件下软黏土地基上沉箱防波堤的失稳模式,提出破坏包络线的稳定性判别方法。在波浪水平荷载作用下,深水软基上沉箱防波堤发生倾覆失稳破坏,失稳转动点为沉箱底面以下中轴线偏右的某点,不同于规范中规定的岩石或砂质地基沉箱倾覆转动点为其后踵点;在重力等竖向荷载作用下,沉箱的失稳模式为结构整体下陷,抛石基床及地基形成连贯的塑性区域,呈现较明显地冲剪破坏形式;在水平、竖向复合荷载作用下,软基上沉箱防波堤的破坏包络线由结构倾覆破坏线和地基承载力破坏线组成,包络线将荷载组合区分成稳定区、仅发生水平承载力不足倾覆破坏区、仅发生地基竖向承载力不足破坏区、同时发生水平承载力和地基竖向承载力不足破坏区4个区域。研究成果为深水软基沉箱防波堤建设提供参考和借鉴。The design theories and stability analysis methods for the caisson breakwater built on soft clay foundation are still not mature at present. In this paper,based on a practical engineering project,by using a three-dimensional mathematical model,the failure style and the stability analysis method of the caisson breakwater built on soft foundation are studied. Under single direction load（ such as horizontal load or vertical load） or these two direction loads at the same time. The failure mode of the caisson breakwater by horizontal wave loads is overturning,but the overturning point is not the caisson heel which is recommended by the standard method; the overturning point is on the right of the caisson bottom axis according to the calculation results; the caisson breakwater subsids under vertical load,and the rubble bed and foundation have a coherent plastic region,which shows an obvious punching shear failure form;the overturning and foundation bearing capacity failure lines of the caisson breakwater under combined loads（ horizontal load and vertical load） divide the whole V-H loads space into four regions,namely the stable region,the overturn-only failure region,the region where only foundation bearing capacity failure happens,and the region where both overturning failure and foundation bearing capacity failure happen. This research will provide a good reference for the design and construction of breakwaters.

关 键 词：软黏土地基 沉箱式防波堤 复合荷载 失稳模式 稳定性分析 包络线 

分 类 号：U656.2[交通运输工程—港口、海岸及近海工程]