Study Of Ground Surface Settlement Caused By Shied Tunneling In Beijing

Shield tunneling is one of the excavation methods. Compared withother excavation methods, it has many advantages, such as good self-stability and less disturbance to the ground. How to predict andcontrol the ground settlement will be a very important subject whenshield tunneling is adopted to construct underground engineering inurban districts. So based on the experience of the shield tunnelingexperiment in Line 5 Beijing Subways and the study of the groundsettlement under the special geological condition in Beijing area ,we draw some conclusions. As follows:(1)The ground settlement caused by shield tunneling is not onlyrelevant to the condition of the strata , properties of the soil andthe depth of the tunnel and other objective factors , but also to themethod of construction and the level of technique and othersubjective factors. So monitoring and information feedback should beintensified, and the construction scheme should be adjusted timely.(2)Besides the normal pressure leads to the dilation of thestrata, the friction between shell of shield and soil alsocontributes to it, when shield is being pushed ahead.(3)The formula of Peck is valid on condition that settlementtrough is of normal distribution and strict symmetry .But monitordata have showed that the settlement trough caused by shieldtunneling is of approximately normal distribution in Beijing.(4)The process of ground surface settlement caused by shieldtunneling in Beijing can be mainly divided into three phases: beforearrival of the shield machine ,during the shield machine advancing,after pass of the shield machine, and the ground surface settlementin the three different phases accounts for 5~15% of the totalsettlement , 45~50%, and 40~45%, respectively.(5)The predictor formula of the deepest settlement and thesettlement trough were obtained:W max=-1.0969K′exp ( 344. 8h9 /1I...