Calculation And Application Of Active Earth Pressure On Finite Soil Behind Wall

The rapid development of urban construction,the increasing number of high-rise buildings,and the limited area on the ground,the development of underground space has become an effective way to solve urban traffic congestion and shortage of soil resources.However,foundation pit projects often appear next to the foundation or basement of existing buildings or structures.The phenomenon of excavation of foundation pits,some studies have shown that,in such cases,the earth pressure on the supporting structure of the foundation pit can no longer adopt the traditional semi-infinite soil pressure calculation method.Therefore,it is particularly important to study the calculation methods and influencing factors of earth pressure on limited soil.Based on this,the main work of this article has the following four aspects:(1)Based on the existing research on the earth pressure of limited soil,based on the basic mechanical principle of limit equilibrium method,a model for calculating the active earth pressure of finite soil considering the influence of the side wall of the underground structure of the existing building is established,and the finite Calculation formula of active earth pressure for non-cohesive soil and cohesive soil,When the width-to-height ratio of the limited soil satisfies the relationship btan(45°?/2)<H,the earth pressure acting on the supporting structure should be solved according to the calculation method of limited earth pressure.(2)A simplified three-dimensional numerical model of the adjacent existing building was established.By increasing the comparative analysis of the parameters,the four most significant factors affecting the strength of the limited earth pressure were the depth of the excavation,the width of the limited soil,and the shear resistance strength index.And through orthogonal experiments,the mathematical relationship of the comprehensive influence degree of the above four factors on the limited earth pressure strength index is obtained:S=36.4+2.38(?)1+1.18(?)2-0.516(?)3+0.101(?)4.The earth pressure strength of the limited soil is positively related to the excavation depth of the foundation pit,the limited soil width and the cohesive force of the soil,and negatively related to the internal friction angle.(3)When calculating the difference between the effects of different internal friction angles and soil size on the active earth pressure of limited soil,the difference between the active earth pressure limit equilibrium algorithm of cohesive soil and non-cohesive soil is greater than the former.The latter;the limit equilibrium method is greater than the orthogonal experiment fitting formula method when calculating the degree of influence of different cohesive forces on the active earth pressure strength of limited soil.(4)The analysis of the three-dimensional excavation model based on the actual foundation pit engineering shows that the finite earth pressure on the existing building side of the foundation pit has an increasing trend with the increase of the excavation depth.After the earth pressure calculated by the finite earth pressure calculation formula is applied to the envelope structure,the maximum horizontal displacement of the envelope structure is the closest to the actual monitoring value,which is the optimal solution among the three finite earth pressure algorithms.