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| Soil conditioning technique of EPB shield in silty clay stratum |
| YANG Hongxi1, HUANG Wei1, WANG Shuying2, LING Fanlin2*, LIU Pengfei2
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1. Communications Engineering Construction Branch of CCCC, the Third Harbor Engineering Co., Ltd., Shanghai 200940, China;
2. School of Civil Engineering, Central South University, Changsha 410075, Hunan, China |
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Abstract In the process of earth pressure balance(EPB)shield tunneling at silty clay stratum, it is easy to occur shield clogging with cutterhead and poor plasticity characteristics of the muck, so it is necessary to carry out soil conditioning to ensure the safe and efficient tunnel-construction of the shield. Taking one construction section of Hangzhou Metro Line 10 as an example, this study conducted liquid and plastic limit tests for soil conditioner selection, and then applied for the improvement of silty clay. The validity of selected conditioner and its parameters was verified through the slump test and compressive strength test of conditioned soil, and field soil conditioning test on the basis of the laboratory test. It was found that foam could significantly reduce the plastic limit of silty clay. Silty clay stratum was more sensitive to the increase of water content(w)and foam injection ratio(FIR). The slump value of conditioned soil increased with the increase of water content and foam injection ratio, and its compressibility also improved with the increase of foam injection. After optimizing the improvement parameters of conditioned soil, the torque of the shield cutter plate was significantly reduced, and the driving parameters of the shield remained stable,which indicated that the optimization and improvement parameters of the stratum were set reasonably, and that the improvement effect of the silty clay stratum using foam agent was significant.
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Published: 04 November 2020
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