Model And Effect Evaluation Of Pier-type Reinforcement For Deep Foundation Pit Supporting In Deep Soft Soil

The twenty years since entering the twenty-first century has been the twenty years of China’s economic take-off.During these twenty years,the country has been developing with each passing day.The emergence of large and megacities reflects the continuous improvement of China’s urbanization level.With the development of cities and towns,people’s demands for a better living environment are increasing day by day.Therefore,urban buildings are also developing in a higher and deeper direction,and the construction safety of foundation pit engineering related to civil engineering is also getting more and more attention.Deformation control is the key to all processes from the beginning of foundation pit construction to the completion of main structure construction.Excessive deformation may affect the construction at least,or cause huge safety accidents at worst.In order to improve the safety of foundation pit construction,especially in the case of deep soft homosexual love in this area,the pit reinforcement design is a common engineering measure to control the deformation of deep soft soil foundation pit,and has achieved good results in practical engineering.But since the pit pier reinforcement form is complicated,and some problems such as soil-structure interaction,the current in the field of design calculation and no more perfect theory or method to calculate the reasonable evaluation of the reinforcement effect.Therefore,it is necessary to understand the mechanism and effect of pier-type reinforcement in deep foundation pit with deep soft foundation through theory or practice,so as to perfect the design theory of foundation pit,optimize design and construction,and improve economic benefits.In this paper,based on the actual project,combined with the analysis of site construction and monitoring data,using numerical analysis method,the simulation and comparative analysis of the deep foundation pit in deep soft soil area are carried out,and the effect of the control of foundation pit deformation by the pier reinforcement in the pit is mainly studied systematically.The main work and achievements are as follows:1.The traditional elastic theory method has some limitations in the calculation of pit pier-type reinforcement,which cannot accurately reflect the deformation of the supporting structure and the surrounding soil.The finite element modeling analysis can more reasonably reflect the reinforcement effect of pit pier-type reinforcement.2,Analyzes the pier reinforcement depth,width and intensity of influence factors to control deformation of foundation pit supporting structure and surrounding soil,the influence of by the finite element analysis results: strengthening pier size and strength are important factors influencing foundation pit deformation control effect,but there is a reasonable scope to achieve the best effect of deformation control.3.Based on the research on the influence of five different reinforcement plane arrangement on the deformation of foundation pit,it is found that the use of in-pit reinforcement in deep soft soil foundation pit engineering can well control the overall deformation..According to the deformation control effect,the order is as follows: full reinforcement > grille reinforcement > strip reinforcement > skirt reinforcement > pier type reinforcement.4.For the deep silty soft soil which is common in this area,it is a negative factor for the safety of foundation pit construction.In order to meet the control requirements of foundation pit deformation in this area,a reasonable pit reinforcement mode is selected,which can not only meet the requirements of controlling the deformation of foundation pit,but also reduce the engineering cost.5,Through the comparative analysis with the actual project,it can be seen that the numerical analysis value is not completely consistent with the measured deformation because some construction steps are simplified and some assumptions are made in the numerical analysis,but the trend analysis of the foundation pit deformation between the two is basically the same.It shows that the finite element simulation analysis can be used to evaluate and design the reinforcement effect in deep soft foundation pit.