Study On The Stability Of The Adjacent Structure Induced By Shield Tunnel In Gravel Layer

The construction of metro is an effect way to reduce the traffic jam in big cities. The sector of shield tunnel mostly distributes in the main city zone where the buildings and underground ducts are crowded. Although shield tunnelling construction belongs to one methods of underground excavating, it still can affect soil inevitably and distort soil, causing a series of geotechnical environment problems, such as the buildings inclining, cracking and collapsing and so on. With the fast development of ChendDu metro's construction, the safety of structure induced by metro construction has got more and more attention from people in different kinds of field.In general, the protecting of buildings is not included in the design when starting a subway project, and it depends mainly on the control of ground surface settlement under construction. In China, it can often be able to set a limited settlement for protecting buildings, and the number is always between -30mm to +10mm. If the limit was exceeded, the adjusting of the order of excavation or the correction of initial plan could be done. This processing, however, ignores specific type of buildings and corresponding response to the tunnel excavation for the buildings, then those strengthening measures sometimes seem to be very conservative.The line of ChengDu metro project passes a specific stratum of gravel layer, the shield tunneling construction faces a very difficult situation, and there's no known experience in China. In order to clearly understand the tunneling induced damage and the tunnel ing-adjacent structures interaction in gravel layer, this paper collects damage evaluation details and makes a numerical modeling of the interaction, finding some useful laws and providing guidance for the construction close to buildings.The stability of the buildings induced by the metro construcion attracts more and more attentions from people. Therefore, how to avoid the collapses during construction and how to effectively predict and control the surface settlement caused by construction have already become one of the most important topics that must be addressed during the construction of metros and other urban underground works.This paper has made some analysis and research on the metro construcion adjacent buildings in the special stratum of ChengDu. The main contents are listed as follows.(1) The laws of the ground settlement induced by, tunnel construction and the analysis of the response of the buildings together with tunnelingconstrucion in gravel layer;(2) The practical analysis of the settlement of the shield tunneling constr--uction adjacent the buildings in gravel layer;(3) The appraisal principle and standard of buildings on shield tunneling construction in gravel layer;(4) The appraisal principle of the strcture safety and control measures of the shield tunneling-adjacent structures in ChengDu metro.