研究目的: 地下连续墙槽壁失稳分为整体失稳和局部失稳,当地下连续墙跨越软弱夹层时极易出现局部失稳。为研究地下连续墙跨软弱夹层时槽壁局部失稳机理,利用槽壁最小主应力迹线,确定成槽施工的扰动范围,构建槽壁局部失稳计算模型,基于塑性极限破坏理论,推导槽壁局部稳定安全系数表达式。
研究结论: (1)本文获得的地下连续墙局部稳定安全系数理论解答与现场超声波检测结果一致,可用于定量分析地下连续墙槽壁局部稳定性;(2)土拱长度可近似取槽段长度,土拱高度与槽段长度和土的内摩擦角呈正相关;(3)槽壁局部稳定性与软弱夹层的厚度、黏聚力、内摩擦角呈正比关系,与槽段长度、地表荷载、地下水位呈反比关系;(4)本研究成果对跨软弱夹层地下连续墙设计及施工具有指导意义。

Research purposes: The instability of trench wall of diaphragm wall can be divided into overall instability and local instability. The construction of diaphragm wall through the weak interlayer is easy to induce the local instability. In order to study the local instability mechanism of trench wall during trench construction of diaphragm wall crossing weak interlayer, the disturbance range of trench construction is determined by using the trace of minimum principal stress of trench wall, the calculation model of local instability of trench wall is constructed, and the expression of local stability safety coefficient of trench wall is deduced based on plastic limit failure theory.
Research conclusions: (1)The theoretical solution of the local safety factor of diaphragm wall obtained in this paper is consistent with the field ultrasonic detection results, which can be used to quantitatively analyze the local stability of the trench wall of diaphragm wall; (2) The length of soil arch can be approximately taken as the length of trench section, and the height of soil arch is positively correlated with the length of trench section and the internal friction angle of soil; (3) The local stability of the trench wall is directly proportional to the thickness, cohesion, and internal friction angle of the weak interlayer, and inversely proportional to the length of the trench, surface load and underground water level; (4) The research results have important guiding significance for the design and construction of diaphragm wall across weak interlayer.