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Analysis of Ground Responses to Shield Shutdowns in Soft Clay
(1 College of Civil Engineering and Architecture, Zhejiang University, Hangzhou 310058; 2 Research Center of Coastal and Urban Geotechnical Engineering, Zhejiang University, Hangzhou 310058; 3 College of Civil, Construction and Environmental Engineering, Ningbo University, Ningbo 315211; 4 Key Laboratory for Geotechnical and Underground Engineering of Ministry of Education, Tongji University, Shanghai 200092; 5 The Institute of Info-Physics and Geoscience Engineering, Central South University, Changsha 410083; 6 Shool of Civil Engineering and Architecture, Zhejiang Sci-Tech University, Hangzhou 310018)
Abstract Based on two shutdowns of the EPB shield during construction of a Hangzhou metro running tunnel in soft ground, the law of ground deformation during the stoppage is investigated. The results indicate that: the affected settlement scope is more than 5 times the shield diameter and much higher than 3 times under normal driving conditions; settlement of the soil mass in front of the shield develops as a whole, and its settlement trough does not fit the Peck normal distribution formula; the total thrust of jacks increases sharply when the shield driving restarts as compared to normal driving. It is thought that disturbed structural clay recovers its strength during the shutdown time, and this results in a substantial increase of friction between the shield skin and soil mass.
Abstract：
Based on two shutdowns of the EPB shield during construction of a Hangzhou metro running tunnel in soft ground, the law of ground deformation during the stoppage is investigated. The results indicate that: the affected settlement scope is more than 5 times the shield diameter and much higher than 3 times under normal driving conditions; settlement of the soil mass in front of the shield develops as a whole, and its settlement trough does not fit the Peck normal distribution formula; the total thrust of jacks increases sharply when the shield driving restarts as compared to normal driving. It is thought that disturbed structural clay recovers its strength during the shutdown time, and this results in a substantial increase of friction between the shield skin and soil mass.
2015, Vol. 52 