Study On The Overall Mechanical Properties Of The Working Well Structure Of Large Section Pipe Jacking

Due to the small excavation quantity and convenience of pipe jacking, it has good economic benefits and its application is more and more widely. Pipe jacking construction is generally performed in wells and the working wells need to withstand all kinds of horizontal jacking force. Therefore, the integrity of the well body by force performance of jacking can be the key to success. Nowadays, due to the needs of urban development, the diameter and length of pipe jacking gradually increased, and the required horizontal jacking force increases. Therefore, the overall stress of the working well body becomes more complex. If the stress and strain of the well body is too large, well body will crack, and even lead to well body overturning.This paper focuses on the stability of circular working shaft in a large section of pipe jacking engineering in Foshan city. In on the basis of theory and practice of the existing pipe jacking work well research, and through theoretical analysis, numerical simulation, real-time monitoring data and other means, this paper deeply analyses the stress deformation and stability of the well body during pipe jacking construction process and explore stress and deformation characteristics of the surrounding soil in the excavation and the jacking state. This research based on the following specific:1. Combined with the actual characteristics of the pipe jacking construction, the thesis analyses the stress characteristics of different kinds of working wells and surrounding soil and explore jacking force calculation method and influence factor in theoretical perspective, and then calculate the control jacking force of the actual engineering and the calculation of related parameters.2. Using the finite element software, the working well for pipe jacking in excavation and jacking stage is numerically simulated with the parameters of the actual construction. And the numerical simulation results are analyzed and studied deeply.3 According to the actual pipe jacking engineering and the purpose of this research, a set of feasible monitoring scheme will be worked out. Through monitoring the circular caisson working well of pipe jacking project in Foshan City and collecting relevant working well stress and strain data, the corresponding curve will be made. And the monitoring results will be compared with the results of three-dimensional simulation.4. Finally, on the basis of the above work, the mechanical properties of the whole working well and the characteristics of the stress and deformation of the soil mass in the excavation and the jacking process will be summed up. And according to this conclusion, some feasible design principles of pipe jacking well will be putting forward.Simulation results show that the stress and deformation of the well body affected by well depth and jacking influence distance, soil stress and deformation have certain space effect, the well body bottom plate and the rear backrest plays an important role in the jacking process, the optimization design of the bottom plate and the rear backrest is feasible to improve the integrity of the well body stress properties. The field monitoring data are in agreement with the simulation results, which verify the accuracy of the numerical model.