Numerical Simulation Of Deep Excavation With Multi-braced Retaining Structure

For the deep excavation, in order to reduce the pressure on the pile and control the deformation of the excavation, usually, multi-braced retaining is used. The strut force must be acted on the struts as soon as it be set, for this can not only ensure that the strut is close enough to the pile and reduce the pile' s lateral displacement, but also improve the condition for bearing the force. Making use of the advantages of FEM, such as strong adaptability and repeatable quality, using a FEM program compiled by myself, this paper analyses that pre-stressed struts how to affect excavation distortion, pile force, strut force and the lateral earth pressure .The main contents can be summarized as follows:1. Through comparing the model of Goodman interface element, Desai thin layer element and element without interface, points out the deficiency of Goodman interface element, and proposes a modified Goodman interface element.2. Calculates and analyses the effect of multi-braced on excavation deformation and pile force, find that the pre-stressed force of struts brings dramatic change of pile force and strut force, points out that the higher demand of stiffness of pile and strut is needed when using pre-stressed force. But the pre-stressed force has little effect on ground surface settlement and uplifts at the pit bottom.3. Analyses the curve of pile' s lateral displacement, gained the relation between lateral displacement and moment of pile, compares and analyses the different calculating result which got by changing the pre-stressed force, sums up the interaction among the struts and the effect on pile moment which caused by changing of strut pre-stressed force.4. Summarizes the common law about the distributing of the lateral earth stress acting on remaining wall, lists stress level and principal stress orientation of soil around pile, Analyses the reason of deviation between Rankine theory of earth pressure and calculated data, gets the fitting formula of active earth pressure and the law about the distributing of passive earth pressure.