Numerical Simulation And Stability Analysis Of Deep Foundation Pit Excavation

The development and utilization of underground space, inevitably to deep excavation. Objective analysis of deep foundation pit in the excavation process all kinds of stress changes, and the resulting changes in the surrounding environment, which has important practical significance and academic value.This paper discusses the design theory of pile anchor structure and supporting mechanism, clear the formation conditions of soil arch between piles and anchor, arch combine arch structure and pile technology, introduced to the deep foundation pit design. Based on the domestic and foreign research results, taking actual project as an example, using three-dimensional fast Lagrange analysis software, the deep excavation, the excavation and precipitation are analyzed by numerical simulation, and discuss the simulation results, analyses the factors affecting the deformation of deep foundation pit. The main conclusions are as follows:Pile anchor retaining structure, soil pressure at the same time to baffle between piles and supporting pile, which acts on the retaining plate a little pressure, mostly by soil arch between piles to bear. The soil arch formation conditions are as follows:the soil between the piles must have anti compression and slip deformation strength enough; the soil between piles is less than or equal to the thrust force generated by the friction pile supporting side; the arch form, the shearing strength is greater than the shear stress. Soil is not uniform deformation during the excavation, the stress with the excavation process adjustment, and to support centralized and the formation of soil arch. The soil arching effect of soil arch, establish mathematical model, through the corresponding mathematical formula, the formula of optimal pile spacing.The analysis of the structure and stability of the foundation software. The results show that, the supporting structure of the internal force and deformation values meet the relevant requirements.In this paper, the geological conditions of rock and soil in the category, select the Mohr Coulomb model for deep foundation pit excavation simulation of soil constitutive model is more appropriate. The results show that, the stability problem of deep foundation pit can be simulated by FLAC3D software, and to determine the pile spacing is reasonable.As the excavation accelerate the diversion, the groundwater level in the neighborhood is relatively low; and deep mixing pile water stop effect, the underground water level is higher than the water curtain. When the hydraulic gradient is formed by underground water level of inside and outside the foundation pit increases to a critical value, seepage in porous soil will be smaller, resulting in a sudden increase of seepage, horizontal displacement, pile heave, ground subsidence equivalent will be significantly changed.