Research On Optimization Design Method Of Deep Foundation Pit Support Considering Space Effect

In conventional foundation pit design,the supporting structure of foundation pit is often simplified as a plane problem.However,as a three-dimensional space system with long,wide and deep,the foundation pit has spatial effects,and the distribution of soil pressure along the pit wall is not consistent,the conventional foundation pit design method is not reasonable.Due to the space effect,the conventional design methods tend to be conservative and waste of materials.This article through to the cantilever retaining structure,the pile anchor supporting structure and the analysis of the retaining structure with double-row piles,the introduction of the coefficient of earth pressure play,in theory,numerical simulation and actual project the research method of combining conventional design parameters as the first model,numerical simulation top horizontal displacement,in order to calculate earth pressure coefficient,soil pressure and foundation pit the midline position(the most dangerous location)of resistive overturning safety factor,and considering the effect of space resistive overturning safety factor,in foundation pit midline position(the most dangerous location)resistive overturning safety factor is a standard,optimize the foundation pit other location and partition,achieve the goal of economic,time saving and environmental protection.Through the research,it is found that both active and passive earth pressure in the depth range of 1-2 times the foundation pit are affected by the spatial effect,which decreases rapidly and takes the shape of a "bowl" with small size on both sides and large size in the middle,and the change trend remains the same,but the active earth pressure is more obviously affected by the spatial effect.In the calculation of anti-overturning safety coefficient,the overturning moment of active earth pressure decreases faster than that of passive earth pressure,and then,the closer to the position of pit Angle,the larger the anti-overturning safety coefficient of foundation pit is.In this paper,based on the displacement of the slope top,the spatial effect on the soil pressure is calculated in reverse,which can effectively restore the most real stress of the foundation pit.At the same time,an optimization method based on equal anti-overturningsafety coefficient is proposed,which can be used to design and optimize the foundation pit simply and effectively,and provide reference for the optimal design of cantilever,double-row pile and pile-anchor support structure.