Model Test And Numerical Simulation Of Heave Stability Of Large And Deep Excavation Near River

With the rapid development of social economy,excavation near rivers or lakes becomes more and more,such excavations are often affected by groundwater seepage and asymmetric loads.The change of river water level will inevitably affect the deformation and stability of the excavation,in the present engineering practice,the traditional method of resisting heave stability of foundation pit has not considered the influence of water level change on it.In this paper,an intuitive laboratory model is used to study the effect of river level on the stress and deformation stability of the excavation.Then,the finite element numerical analysis model is established to analyze the anti-uplift stability under the influence of various parameters.The research of the thesis includes the following aspects:Based on the engineering background of Xianfeng Island in Yancheng City,the indoor model test of river level change of excavation near river is carried out.The change of river water level is simulated by controlling the water level change of the model box to monitor the change of the bending moment and horizontal displacement of the wall and to analyze its change law.The results show that the rise of river water level will increase the bending moment and deformation of the retaining wall.The finite element numerical model of the actual size is established at the same time.It is found that the bending moment and the deformation of the wall are increasing with the rise of the river level.The conclusion of the numerical simulation is consistent with model test results,which shows the rationality of the numerical analysis.Based on the same engineering background,the finite element numerical model of excavation near river under different parameters is established through Plaxis.The influence of river level,over-river distance,retaining wall insertion ratio and excavation width on the stress,deformation and anti-heave stability of the retaining structure of excavation are studied.It is found that the magnitude of over-river distance has a certain influence on the deformation and stability of the excavation,but the influence is not unlimited.In a certain range of over-river distance the bending moment and horizontal displacement of wall will increase with the increase of the distance.The bending moment and horizontal displacement of the retaining structure increase with the increase of the excavation width of the foundation pit,and the anti-heave stability o is reduced.The increase in the insertion ratio of the retaining wall will reduce the horizontal displacement of the foundation pit and improve the anti-heave stability,but it is not an unrestricted improvement and it has a reasonable range.All of the above changes near the river side of the changes are more obvious than the back side of the river.A numerical analysis model of finite element method is established for an example of foundation pit engineering.The simulation results are compared with the data obtained from field monitoring.The result shows a certain deviation,but is within reasonable range,the finite element numerical simulation can be used to analyze the excavation process.