Research On Simulation Calculation Of Jacking Force In The Process Of Jacking Pipe

The pipe jacking method trenchless pipe laying construction technology has the advantages of not excavating the pavement during the construction process,high efficiency,and good economic benefits.It is widely favored in the current urban municipal pipeline laying and the construction of comprehensive pipe corridors.The reasonable configuration of jacking force is very important in the construction of the pipe jacking method.Excessive or too small jacking force may lead to project failure.Therefore,the estimation of jacking force is of great significance to actual construction.In this paper,by combining the actual construction conditions,the theoretical analysis and numerical simulation of soil mechanics,a simulation study of the jacking force calculation in the construction of the pipe jacking method is carried out.The specific content is as follows:1.Summarize the related research on jacking force calculation by past research scholars,and conclude that the current jacking force calculation formula is mostly applicable to circular jacking and relying on empirical coefficients;discusses the influence of jacking method on jacking Engineering and geological factors of force estimation,including pipeline depth,cohesion in soil and friction angle in soil are the key factors for calculating jacking force.2.Calculate the earth pressure on the pipe wall with soil column theory,Terzaghi theory,and general theory respectively,and get the corresponding jacking force calculation formula and applicable conditions.Analyzed the flaws in the calculation of earth pressure by Terzaghi and the general method under the condition of deep burial.Based on the general method,a modified general method suitable for the condition that the crossing soil is cohesive soil and the pipe jacking is deeply buried is obtained.Theory,and derived the corresponding jacking force calculation formula.3.Based on the FLAC3 D software,the construction process of the pipe jacking method under three actual working conditions is simulated,and the stress on the pipe circumference in the pipe jacking method construction is analyzed,and compared with the actual engineering data and the earth pressure calculated by different theories.It is concluded that if the cohesion of the pipe jacking through the soil layer is small,the soil pillar theory should be used for shallow burial conditions,and the general theory and modified general theory should be used for deep burial;virtual working conditions are created by increasing the soil cohesion as a control The simulation shows that when the pipe jacking through the soil layer is cohesive soil and shallow buried conditions,Terzaghi theory should be selected.4.Assuming a rectangular pipe jacking construction project buried deep in the cohesive soil layer as a comparative simulation,it is concluded that the stress simulation data is more consistent with the modified model,which proves that it makes up for the fact that the general theory does not consider the cohesion of the soil and the Terzaghi theory The calculation accuracy is improved for the defects of soil disturbance extending to the ground surface;by analyzing the pipe wall stress cloud diagram,it is found that there is stress concentration at the right corners of the rectangular pipe section when it is jacked;the rectangular section is replaced with an imitation rectangle,and the imitation rectangle is obtained.The arc of the pipe section can effectively alleviate the stress concentration,but there will still be greater stress in the fillet and where the fillet meets the cross section of the pipe section.