Abstract: The experience of pipe jacking in sand and gravel conditions in Shenyang is limited， especially for pipes with large diameter.So， a numerical method of forecasting the jacking force during construction was put forward based on the initial jacking force， and then jacking forces calculated from numerical simulation were compared with insitu monitored values. Finally， the effect of resistance relieving by using different proportion of thixotropic fluids was numerically analyzed and the jacking forces of seven fluids were contrasted. Simulation results indicate that the numerical method used in this work is feasible in forecasting the jacking force， thus being helpful in reasonably arranging the intermediate jacking stations. It is also shown that the water content in thixotropic fluids has significance influence on the resistance relieving effect of pipe jacking and the optimized proportion of bentonite and water is 1∶9.

Key words: pipe jacking engineering, thixotropic fluids, drag reduction, forecast of jacking force, numerical simulation