Laboratory Study of the Foaming Agent Used for EPB Shield Tunnels
(1 Shaanxi Engineering Laboratory of High Performance Concrete, Weinan 714000; 2 Department of Road and Bridge Engineering,Shaanxi Railway Institute, Weinan 714000; 3 China Railway First Group Co. Ltd., Xi′an 710054)
Abstract：
In light of the technical requirements of soil mass conditioning for EPB shield tunnel construction, re? search of a new foaming agent formula is conducted. A high-speed mixing method is adopted to choose the proper surface active agent, SDS is determined as the main foaming agent, and SDS is formulated again using AES. The test results indicate that good foam stabilizing effects are obtained if the foam stabilizer dodecanol with a concentration of 0.2 g·L-1 and cationic guar gum with a concentration of 0.04 g·L-1 of high molecular polymer are added when the SDS/AES proportion is 6∶4 and the general concentration is 3 g·L-1. An economical and environment friendly laboratory formula for a foam agent with good foamability and stability is determined, a concentration adjustment is conducted, and the following formula for the finished foam agent is established: 6.82%SDS+4.51%AES+0.57% dodecanol +0.2% cationic guar gum +87.9% water. Compared with other products at home and abroad, this new type of foam agent is an improvement in terms of performance index and economy.
2018, Vol. 55 