| More than 90% of the deep foundation pit accidents in Xiamen area are caused by the instability of foundation pit caused by the failure of groundwater control.Under the influence of granite residual soil,the deep foundation pit project in coastal high water level area is a typical complex project.Combined with the open excavation project of Xinyang Avenue Station of Xiamen Metro Line 2,the three-dimensional geological model of Xinyang Avenue Station is established by using Flac3 D software,and the fluid-solid coupling effect between rock and soil and groundwater is considered during excavation under the condition of high water level of foundation pit.This paper analyzes and compares the horizontal displacement deformation of continuous wall,the settlement of soil around foundation pit,the simulated value of supporting axial force and the actual monitoring value,verifies the reliability of the model,and analyzes the variation law of pore water pressure and seepage velocity during excavation.The actual condition is considering the groundwater situation.After the construction is carried out,the model is established after the model is reasonable and reliable.It will consider the simulation and comparison of the excavation process under the action of groundwater and the action of groundwater,and focus on the horizontal displacement and deformation of the underground continuous wall and the settlement law of soil surrounding the foundation pit.The foundation pit uplift and the variation law of the supporting axis force provide theoretical guidance for the construction of the excavation of the foundation pit in the coastal high water level area and the construction of the water free excavation under the same working condition.This paper analyzes the horizontal displacement of the diaphragm wall at various stages of the foundation pit excavation in the background of the foundation pit project of the Xinyang Avenue station of Xiamen Metro Line 2.The variation law of soil settlement,bottom uplift and supporting axial force around the long side of the surface.Some factors affecting the stability of foundation pit are simply analyzed.The specific conclusions are as follows: 1.According to the engineering geological and hydrogeological conditions of subway station,considering the excavation and supporting scheme of foundation pit,the monitoring scheme of foundation pit engineering is put forward.2,the monitoring data of foundation pit construction are analyzed,and the rule of underground continuous wall,ground settlement,steel support axial force and groundwater level are obtained.3.The 3D geological model of subway station is established by using Flac3 D software.Considering the fluid-solid coupling effect between rock,soil and groundwater under the condition of high water level excavation of foundation pit,the horizontal displacement deformation of continuous wall is obtained by simulation.The variation law of soil settlement and supporting axial force around foundation pit is compared with the actual monitoring value to verify the rationality of the model.The variation law of pore water pressure and seepage velocity during excavation is analyzed.In order to guide anhydrous construction,a comparison of simulation and calculation between ground water action and not considering groundwater action in excavation of foundation pit is carried out in order to guide anhydrous construction. |
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