Research On Technology Of Replacing Cutting Tool With Pressure Of EPB Shield In Water-Rich And Pebbly Sand Stratum

In the construction of urban underground railway, shield construction method, with its many advantages, has become the main method of subway construction. Shield construction experience shows that cutting-tool wear of shield machine is easy to become severe worn, needing regular maintenance and replacement operation, so choosing economic and feasible way for replacing tool is imperative. Taking Chengdu subway engineering background, this article study the feasibility and technology of replacing cutting-tool in pressure of EPB shield in water-rich and pebbly sand stratum.The contents in this paper enumerated as follows:1,Comparative analysis of replacing tool modeAccording to the different way of replacing tool wear, contrasting and analyzing relative merits of these ways, the suitable way for replacing tool of shield construction in water-rich and pebbly sand stratum is definited.2,The principle and basic research of replacing cutting-tool with pressureAccording to the mechanism of shield excavation, replacing cutting-tool with pressure is analyzed. To direct at the water-rich and pebbly sand stratum of Chengdu, using the method of separating soil and water, empirical formulas of the pressure value of replacing cutting-tool with pressure is drew.3,key technology of replacing cutting-tool with pressurekey technology of replacing cutting-tool with pressure mainly including: bentonite proportioning and preparation,control technology of building and maintaining pressure,pressure value and parameter setting of shield in replacing tools,measure of pressure adjusting in special circumstances, finally the entire technics process of replacing tool with pressure is concluded.4,Risk management technique of replacing cutting-tool with pressureThe application of risk management idea, risk assessment and countermeasure is researched for process of building pressure, keeping pressure, replacing cutting-tool with pressure and recovering tunneling technology. In the process of replacing cutting-tool with pressure, there exists security risk and risk of health. Many successful experience of replacing cutting-tool with pressure shows that, replacing cutting-tool in pressure of EPB shield in water-rich and pebbly sand stratum is safe and feasible.