Abstract: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.
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