Stability Analysis Of Deep Foundation Pit Support Structure In Kunming Yuehui Shopping Mall

The inner-brace retaining and the underground diaphragm wall are commonly used retaining forms for deep foundation pit engineering.The underground diaphragm wall has stable ensemble,high strength,good water interception and water-resistant effect,and is the top priority chosen form of retaining in foundation pit engineering of high-water level areas.The inner-brace retaining structure has the advantages of simple process,remarkable effect and high utilization rate,and is the most widely used foundation pit support structure.This paper takes the deep foundation pit of Kunming Yuehui Shopping Center as the research object,and analyzes the stability of the interaction between the inner-brace retaining and the underground diaphragm wall support structure.The calculation of the overall stability,anti-overturning stability,anti-lifting stability and fluid-soil stability of the foundation pit was carried out by using the Lizheng foundation pit calculation software.The internal force distribution and displacement of the underground diapthragm wall and the inner-brace retaining structure were analyzed.By using software FRWS 7.2,the embedded depth of underground diaphragm wall was calculated and analyzed;By using the software Midas/GTS and finite element method,we simulated the foundation pit supporting structure.The deformation phenomenon and force characteristics of the supporting structure during the excavation of the foundation pit are studied as well.Finally,the simulation results and the monitoring results are compared and analyzed to evaluate the stability of the foundation pit supporting structure.The research shows that:(1)The calculation and analysis of the deep foundation pit of 14.9meters in Kunming Yuehui Shopping Mall is carried out by using the calculation software of Lizheng deep foundation pit.With the gradual excavation of the foundation pit,the deformation of the supporting structure increases.When the depth reaches to about 10 meters,the deformation of the supporting structure is abrupt,the maximum deformation of the supporting structure is 10.41 mm,which meets the design and specification requirements;(2)When the depth of the underground diaphragm wall is 10.1 m,the overall support structure is stressed.The minimum,the deformation of the supporting structure is the smallest and the most stable.When the depth of the local diaphragm wall is less than or greater than 10.1 meters,the stress and deformation of the supporting structure are increased to different extents.Therefore,the optimal embedded wall is embedded.The solid depth is 10.1 meters.(3)The numerical simulation calculation results show that the second inner-brace retaining is the most stressed and should be reinforced.The maximum bending moment of the underground continuous wall is concentrated in the middle and lower part of the foundation pit;(4)The results of the comparative analysis ofsimulation and monitoring show that the simulated results are slightly larger,and the results are quite consistent from the overall situation.The results of both are less than the warning value of30 mm.The inner-brace retaining and underground diaphragm wall support structure system in the foundation pit support project is obviously different from other composite support forms,and the corresponding force and deformation characteristics are also different.In this paper,theoretical research and numerical simulation are used to study the force and deformation of the inner support and underground continuous wall support structure,and it is also important to promote the support form.