Field Test Study on Large Diameter Reinforced Concrete Pipe Jacking in Moderately Weathered Siltstone Stratum

In order to study the mechanical properties of large diameter reinforced concrete pipe jacking in moderately weathered siltstone during construction, the contact pressure, mud pressure and strain of the pipe were monitored while microtunneling for the pipe gallery installed on Mingzhu Avenue in Huanggang. The variation law of contact pressure, mud pressure and pipe stress and their relationship were analyzed, and a method for calculating jacking force through pipe strain was proposed. The results show that the size and change of the contact pressure are mainly controlled by the mud pressure during pipe jacking. The axial strain of pipe is mainly compressive strain, and the axial strain is more sensitive to the deflection of pipe. The small deflection will cause the change of axial strain, and the axial pulling strain will appear when the deflection is large. The contact pressure and the annular strain will change significantly when the pipe deflection is large. Meanwhile, the contact pressure change caused by the grouting pressure has less influence on the hoop strain. The jacking force calculated according to the axial strain of the pipe has a good agreement with the measured value, but its calculation accuracy is related to the determination of the compression area. This research provides a new method for the prediction of pipe jacking force and also has guiding significance for the construction of similar projects in the future.