Study On The Force Characteristics Of The Shaft Wall Of The Circular Caisson Lifting And Controlling The Subsidence

In recent years,caisson construction equipment such as VSM and CJM have adopted the method of raising and controlling the sinking of the shaft wall,which has greatly improved the quality and efficiency of caisson construction.This paper uses this as a background to study the construction force characteristics of the circular caisson shaft wall during the lifting and controlling subsidence process.The main work and research results are as follows:Based on the research of the traditional caisson method,this paper establishes a construction mechanics model for raising and controlling the subsidence of the circular caisson wall under the condition of flooded caisson,and discusses the peak suspension force and the limit sinking depth.The results show that in the theoretical solution of engineering significance,there is a peak in the suspension force,and the magnitude of the peak,the corresponding sinking depth when the peak occurs,and the ultimate sinking depth are closely related to the drag reduction behind the wall;each excavation in the VSM caisson In the sinking cycle,the suspension force increases when excavating the soil,and the suspension force decreases when the soil is sinking.This paper uses finite element analysis software to establish a numerical model of shaft wall raising and controlling subsidence.The model simulates the interaction between shaft wall and soil by setting interface elements and adjusting strength reduction coefficients.Numerical calculation of the wall sinking force is carried out.The study shows that the suspension force change rule in the numerical model is consistent with the theoretical analysis,and the peak value of the suspension force and the appearance depth of the two are similar;the side wall friction data obtained from the numerical calculation and the model test is established The corresponding relationship has a good response.Based on the relationship between the vertical load of the shaft wall established by the theoretical model,this paper designs a circular shaft wall model suspension and sinking test device in the mud.By changing the mud performance method,the suspension force and the side wall friction resistance are studied.law.Data analysis shows that the suspension force first increases and then decreases during the sinking process.The overall trend is in line with the quadratic polynomial change trend,which is slightly different from the linear relationship in the theoretical model;the proportional relationship,peak value and Its appearance depth is consistent with the theoretical calculation result.