Abstract：Earth pressure balanced(EPB) shield is one of the most important ways in tunneling. While there are still many troubles including disturbing soil liquefaction，quick sand，‘dry cake’ at work-face due to the output difficulty of soil through screw during tunneling in sandy soil with low plasticity，high water content，and large penetration coefficient. The suitable additives (soapy water and foaming agent) are used to improve construction condition when tunnel passes through sandy strata. In-situ tests were conducted to compare shield driving force with different additives blended in sandy strata. Sandy soil mixed with additives is analyzed by laboratory tests. In addition，influences of two different additives on shield driving force in sandy strata for improving characteristic of sandy strata are compared. Based on the tested data，the effects of two additives in improving plasticity-fluid and capability of retaining water of sandy strata as well as the balance mechanics of shield work-face are discussed thoroughly. The research is valuable in improving characteristics of sandy strata to keep shield work normally while reducing construction deformation，controlling ground settlement efficiently，facilitating soil output through screw，decreasing torque and abrasion of cutter head，and decreasing driving force of jack and avoiding geological disaster.
