Experimental study on mechanical characteristics of large diameter pipe jacking in moderately weathered siltstone
In order to study the mechanical characteristics of large diameter reinforced concrete pipe jacking during the construction in moderately weathered siltstone,the contact pressure,slurry pressure and strain of the pipes were monitored on site based on the pipe jacking project for utility tunnel in Huanggang Mingzhu road.The variation law and mutual relations of contact pressure,slurry pressure and pipe stress were analyzed.The method for calculating the jacking force by pipe strain was proposed.The results show that the size and change of contact pressure is mainly controlled by the slurry pressure during the pipe jacking process.The axial strain of the pipe is mainly compressive strain,and the axial strain is sensitive to the deflection of the pipe.A small deflection will cause the change of the axial strain and the axial tensile strain will appear when the deflection is large.While the contact pressure and hoop strain will change significantly only when the deflection of pipe is large.Besides,the change of contact pressure caused by grouting pressure has little influence on the hoop strain.The jacking force calculated by multiplying the average axial compressive strain of the pipe by the area of the compression zone is in good agreement with the measured value.
large diameter concrete pipe jackingmechanical characteristic of pipejacking forcesite monitoring
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