(1. Key Laboratory of Transportation Tunnel Engineering，Ministry of Education，Southwest Jiaotong University，Chengdu，Sichuan 610031，China；2. School of Civil Engineering，Southwest Jiaotong University，Chengdu，Sichuan 610031，China)
Abstract：Sandy stratum with poor plasticity and large permeability can easily be disturbed when the earth- pressure-balance(EPB) shield machine passes through；the induced ground surface settlement is difficult to control；and the earth pressure acting on the segment lining structures changes. It is particularly important to employ an analysis method，which could represent the whole dynamic process of shield tunnelling，to study the soil disturbance caused by shield tunnelling in sandy stratum. The 800 mm EPB shield model machine was developed and manufactured on the basis of the EPB shield machine used in the city metro tunnel projects. The EPB model shield machine consists mainly of a jacking system，a cutting system and a slag discharge system. It can achieve some main function such as shield machine originating，cutter head cutting，muck discharging，segment assembling，etc. Ground settlements caused by shield tunnelling and earth pressure acting on the lining structure were monitored in the laboratory test to find out the settlement features and earth pressure distribution rule；and then the results were compared with the theoretical and numerical results and field test. Results show that，soil characteristics and shield tail grouting have significant influence on the ground settlement；and the ground loss is still the main reason of ground settlement. The surface settlement values caused by the tail void are more than 60% of the final settlement values without grouting；and a 20% to 30% proportion due to that without grouting. The settlement time-history curves show periodic and timeliness. The width parameter of surface settlement trough is consistent with the field test values. The distribution of the earth pressure acting on the lining structure is like an oval，which upper and lower side is the semimajor，left and right side is semiminor. The tested earth pressures are smaller than the theoretical values.
MELIS M，MEDINA L，RODRIGUEZ J M. Prediction and analysis of subsidence induced by shield tunnelling in the Madrid Metro extension[J]. Canadian Geotechnical Journal，2002，39(6)：1 273-1 287.
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2013, Vol. 32 
