Experimental Research On Foam Agent In EPB Shield With Soil Conditioning

In the past 30 years, major cities in China’s reform and opening up in the construction of engineering have been got great achievements, but which in recent years have been offset by the rapid growth in traffic demand. With the increasing traffic congestion, the underground railway tunnel has been more and more inevitable in the development of cities. EPBS which represents the main direction of tunnel construction have been gradually in great use of cities’engineering.It may encounter a wide range of issues in EPBS construction. In order to solve these problems, soil conditioning agents are in the need for soil excavation, which may meet the construction requirements. Foamed agents are the best of all the soil agents. Presently, There is no foaming agents in our country and all foaming agents in EPBS are foreign products, so the price is very high. This paper has been developed a new foam agent which can be in use of EPBS soil conditions.In order to get the new foam agent, plenty of experiments have been carried out. The paper select some surfactants that are no pollution to environment and low-cost. Stirring method and Ross-Miles foam meter are used to measure half period and the foaming volume, which can obtain the optimum compound proportion for surfactants. The optimum compound proportion will meet the parameters demand, namely foaming multiple lies between 5～20, half period is more than 5 min. Based on compound proportion, prescription has been studied, which can be applied in EPBS engineering.At last micro-morphology of foam that is generated by surfactants is observed. Form micro-morphology, foam stability mechanism is acquired in theory.