A calculation model for the head-on resistance of rock pipe jacking based on the rock breaking characteristics of the disc cutter

Abstract

Jacking force is one of the most important parameters in the design and construction of pipe jacking. The accuracy of the jacking force will directly affect the success or failure of the pipe jacking project. Pipe jacking is increasingly applied to rock formations, but there are few calculation models for the jacking force in rock formations. To calculate the head-on resistance in the rock formation more accurately, a new calculation formula of the construction face resistance during pipe jacking is derived. The pipe jacking face is assumed to be stable; the rock pipe jacking force is analyzed by consideration of the rock breaking mechanism, force model and influence law of the rock pipe jacking machine cutter head hob. The results show that in rock pipe jacking, the compressive and shear strengths of the rock and the depth of the pipe jacking hob cut into the rock directly determine the value of the head-on resistance; after determining the appropriate hob spacing, the number of tools is not blindly increased; otherwise, the rock breaking effect of each hob will be affected. Moreover, the measured head-on resistance in engineering practice is consistent with the predicted value of the formula, which proves its applicability.

Keywords

• pipe jacking in rock
• jacking force
• head-on resistance
• disc cutter