Tunneling parameters and comparison of adaptability for compound strata of dual-mode shield machine

Based on the tunnel project between Wuyi Interchange Sation and Xinxiu Park Station of Nanning rail transit line 5, firstly the selection basis of the earth pressure-slurry dual-mode shield is discussed, and then, according to the field excavation test data of the right line and left line slurry shield, changes of excavation parameters and energy consumptions of different geological sections and different mode sections are analyzed. Compared with that of single-mode shield, the adaptability of dual-mode shield in composite strata is analyzed. The results show that the slurry-balanced mode used in the composite stratum consisting of silt, silty fine sand and round gravel in the initial section strictly controls the land subsidence, and the earth pressure-balanced mode effectively avoids the risk of clay formation in the composite stratum consisting of full fault silty mudstone and argillaceous siltstone in the river-crossing section. In terms of the excavation rate, the rate of dual-mode shield is 181.44% higher than that of the slurry shield of the left line. In terms of energy consumption, the oil consumption of the shield tail, water consumption and electricity consumption of the dual-mode shield of the right line are 7.87%, 30.32% and 30.64% lower than those of the left line, respectively. The research results may provide a reference for the study on driving parameters and selection adaptability of double-mode shield in composite strata.