| As there have been more and more engineering cases of high-speed railways crossing underneath high-rise buildings in weak and broken surrounding rocks, the fact that surface settlement or uplift occurs in the process of tunnel piercing is now becoming a potential safety hazard to operation of railways. To explore the interaction relationships between existing buildings and the damages they bring about to tunnel construction, this article takes the example of construction of Ren Hechang Tunnel in Lanzhou-Chongqing Railways as the background and focuses on the research of mechanical properties of weak and broken rocks through which shallow-buried tunnels are excavated underneath the high-rise buildings with numerical simulation in order to determine proper construction parameters and methods as well as suitable supporting time for controlling the deformation of surrounding rocks. Primary works of the research that have been done are demonstrated below:Firstly, it performs simulation among different types of excavation schemes from the perspective of statics, thus, main factors that control the deformation of surrounding rocks are obtained. Besides, it works out the optimal matching parameters of surrounding rocks and lining structure in the courses of tunnel excavation by optimizing construction methods and supporting parameters.Secondly, it researches in details on major evaluation indexes of high-rise buildings from the interaction relationships among tunnels, rocks and buildings, and indicates clearly the major indexes:uneven settlement volume, maximum settlement volume and crack width. Optimization analysis is also made to these indexes.Thirdly, it concentrates on the research of mechanics during tunnel construction and conducts computational analysis to evaluation indexes which determine whether buildings belong to high-rise ones or not.Lastly, it carries out monitoring measurement on a job site to peripheral displacement, contact stress of surrounding rocks and axial force of steel arches within an extent of the target section of a tunnel and further tests the construction methods that have been adopted to make sure that supporting parameters are precisely correct so that they shall better guide the construction of tunnels to be much safer. |
