) 上海交通大学 船舶海洋与建筑工程学院, 上海 200240
收稿日期:2019-02-01出版日期:2021-09-28发布日期:2021-10-08通讯作者:陈锦剑E-mail:chenjj@sjtu.edu.cn作者简介:熊国军(1985-),男,湖北省黄冈市人,博士生,主要从事岩土工程研究基金资助:国家自然科学基金重点项目(41330633);国家自然科学基金项目(51678360)Stability Analysis and Support Suggestions of Pile Hole Based on Mud Pressure Balance Earth Pressure
XIONG Guojun, WANG Jianhua, CHEN Jinjian() School of Naval Architecture, Ocean and Civil Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
Received:2019-02-01Online:2021-09-28Published:2021-10-08Contact:CHEN Jinjian E-mail:chenjj@sjtu.edu.cn摘要/Abstract
摘要： 基于泥浆压力平衡地压的原理,建立一种分析桩孔稳定的力学模型,分析无支护开挖、泥浆护壁成孔、硬支护成孔3种施工方式的应用条件与使用范围,给出无支护成孔最大深度、护壁泥浆下限容重的确定办法与实用表格.研究结果表明:土体的摩擦角、黏聚力与泥浆容重是维持桩孔稳定的基本要素;当成孔深度小于无支护成孔最大深度时,可采用无支护开挖,否则须采用泥浆护壁辅助成孔,且泥浆重度不得小于场地土要求的护壁泥浆下限容重;当摩擦角大于25°时,可任意选择泥浆重度;当查表计算所得的护壁泥浆下限容重大于规范给定的最大泥浆容重时,则需采用套管等硬支护措施.
关键词: 桩孔稳定, 护壁泥浆, 泥浆重度, 无支护临界深度
Abstract: Based on the principle of mud pressure balance earth pressure, this paper establishes a mechanical model for analyzing the stability of pile hole, and analyzes the applicable conditions and application scopes of the three construction methods, namely, no-support excavation, the hole formation method by mud retaining wall, and the hole formation method by hard support. It also provides reasonable determination methods for maximum depth of pore-creating without support, lower limit value of mud weight of protecting wall, and useful tables. The research results show that the friction angle, the cohesion, and the mud weight of soil are basic factors for maintaining the stability of the pile hole. When the depth of pore-forming is less than the maximum depth of pore-creating without support, no-support excavation can be adopted. Otherwise, hole-forming should be assisted by slurry-support, and mud weight should not be less than the lower limit value of mud weight for the retaining wall determined by the site soil. When the friction angle is greater than 25°, mud weight can be arbitrarily selected. When the lower limit value of mud weight for the retaining wall calculated by look-up table is greater than the maximum mud weight given by specification, casing or other hard support measures should be adopted.
Key words: stability of pile hole, mud of protecting wall, mud weight, critical depth without support
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