Calculation Of Active Earth Pressure Of Limited Soil And Deformation Research Of Foundation Pit Near The River

With the development of the times,the available land in cities has been decreasing year by year.A lot of buildings have to be built adjacent to the river,which has caused many problems.In order to study the active earth pressure of the limited soil in the foundation pit near the river,the limited soil between the river and the foundation pit is selected as the research object.The calculation expressions of active earth pressure of single-layer soil and multi-layer soil are obtained by establishing the equilibrium equation.In order to explore the deformation law of the foundation pit near the river in the process of excavation,the influence of stacking load and time-space effect is considered in the process of numerical simulation,so that the finite element model which is more in line with the actual situation is established.Finally,with the help of theoretical derivation,numerical simulation,on-site monitoring and other technical means,the corresponding research work has been completed.The main work and conclusions of this paper are as follows:(1)The finite clayey soil is selected as the research object,and the corresponding active earth pressure calculation expressions are obtained by considering the stress conditions of single-layer soil and layered soil respectively.It is found that the calculation formula of active earth pressure is greatly influenced by soil properties,space size of the foundation pit,fracture angle,surface load of the soil,distance along the river,water level along the river and embedded depth.The values change greatly with the above factors,rather than a single variable.(2)With the help of the finite element software PLAXIS 3D,the overall simulation of the excavation process of the foundation pit under river conditions is carried out.Through the analysis of the soil deformation of the foundation pit and the axial force of the internal support,it is found that the maximum value of the horizontal displacement of the pile top is obtained near the midpoint of the foundation pit,and the horizontal displacement curve of the pile top is approximately normally distributed.The horizontal displacement of the pile body is obviously affected by the spatial effect.The value is different in different directions and different points of the foundation pit.The vertical displacement of the ground surface around the pile becomes smaller as the distance from the foundation pit gets farther.The maximum vertical settlement is obtained at the supporting pile.The axial force of the internal support is more prominently affected by the working conditions.With the increase of the excavation depth of the foundation pit,the axial force continues to increase,and finally tends to be stable.It can be seen that the foundation pit near the river is more prominently affected by the time-space effect,and relevant excavation foundation pits should be prepared in advance and preventive measures should be taken.(3)The impact of stacking on the deformation of the foundation pit varies significantly with the distance from the stacking center.At the same time,due to the coupling of time-space effect,the impact of the pile load at different excavation stages on the deformation of the foundation pit is different.(4)Comparing the simulation results of the excavation of foundation pit near the river with the actual measurement results,it is found that the changes of the two are basically the same,which shows the rationality of the built model.