Study On Stability Of Underground Diaphragm Wall And Reinforcement Measures

The diaphragm wall has the advantages of good integrity,high rigidity and good impermeability,but how to ensure the stability of the groove wall of the diaphragm wall under complex environmental conditions is the focus of current engineering research.Based on the rapid reconstruction project of Wuning Road in Shanghai,this paper studies the stability of the trench wall during the construction of the diaphragm wall and the corresponding trench wall reinforcement measures,and analyzes the application effects of the trench wall reinforcement measures.The main research results are as follows:(1)The engineering background,project characteristics and difficulties of the Wuning Road rapid reconstruction project are introduced,and the influence of the channel wall reinforcement on the channel wall deformation and stability of the underground continuous wall is studied by numerical methods.There is a thick sandy silt layer within a depth of 10 meters in the project site,which is prone to collapse of the shallow soil.Numerical calculation results show that the maximum deformation of the groove wall occurs in this layer of soil.The use of groove wall reinforcement measures can effectively reduce the horizontal deformation of the groove wall along the depth direction.In addition,the deeper the groove wall is reinforced,the smaller the horizontal deformation of the groove wall,which indicates the necessity of groove wall reinforcement measures in this project and the effectiveness of the groove wall reinforcement to control the groove wall deformation.(2)The advantages and disadvantages of three common trench wall reinforcement methods and applicable geological conditions were discussed through the comparison and selection of options,and the reinforcement mechanism and construction techniques of these measures were studied,combined with the engineering of the Wuning Road rapid reconstruction project.According to the characteristics of geological conditions,engineering safety level and engineering cost,the three-axis cement-soil mixing pile reinforcement method is determined,and in areas where mixing pile reinforcement is not adopted,jet well point pre-dewatering reinforcement is used.(3)According to the actual measurement results of the project,the application effect of the tank wall reinforcement measures was verified.The filling coefficient analysis,the ultrasonic imaging report analysis and the appearance quality comparison of the tank wall were carried out on the reinforced tank section and the unreinforced tank section.In the groove section of the groove wall reinforcement measures,there are many groove sections with large filling coefficients,and there is the possibility of the groove wall collapsing,and the appearance of the groove wall after the excavation of the foundation pit is found to be uneven,seepage and concrete Sand and mud problems.The filling coefficients of all the groove sections reinforced by the groove wall are within the range of engineering experience,and the appearance quality of the groove wall is good.The ultrasonic imaging report shows that the verticality and uniformity of the reinforced groove wall basically meet the requirements.The effectiveness of the reinforcement measures on the tank wall is proved.