Abstract: When earth pressure balance(EPB) shield tunneling in argillaceous siltstone strata, muck and water gushing of screw conveyor and poor soil plasticity state are often encountered due to the various development degrees of bedrock fissure water. As a result, soil conditioning should be conducted. A laboratory test is conducted on a shield section of Jinhua station to Shuangxi West Road stastion of JinhuaYiwuDongyang urban rail transit under conditions of normal and large amount of water gushing. Various soil conditioning materials are used to carried out slump test to study the plastic fluidity of improved soil. The results show the following: (1) To reach an ideal soil slump of 10~20 cm, the volume ratio of water added to soil is 40%~46.3% in normal water gushing section, and the soil moisture content is 27.8%~30.6%, which is linearly correlated with the slump. (2) In the section with large amount of water gushing, the ratio of bentonite or quicklime to soil volume is 5.5%~6.8% or 5%~6.9%, respectively. The field test results indicate that after adding bentonite or quicklime in the section with large amount of water gushing, the soil consistency can be effectively improved and the mud and water gushing of screw conveyor can be effectively controlled.

Key words: earth pressure balance shield, soil conditioning, argillaceous siltstone strata, slump test