Study on soil conditioning technology for an EPB shield in an argillaceous siltstone formation

Since the ground in the Najing area consists of an argillaceous siltstone formation with high contents of clay minerals, soil conditioning tests were carried out based on the shield tunnelling of Najing Metro Line 1, and a correction factor of FIR was determined by the contrastive analysis of laboratory soil tests and field soil tests. The results show that the moisture content of the soil shall be controlled within 16%~30%, and 20%~35% for the FIR value when the foaming agent is used to improve the argillaceous siltstone, and there are differences between the calculated FIR value and the actual FIR value of the soil in the earth chamber, therefore the theoretical FIR value of the soil shall be corrected with the correction factor of 0.59~0.76. ©, 2015, Editorial Office of Modern Tunnelling Technology. All right reserved.