Study on Ground Deformation Law of Small Spacing Shield Tunneling in Sand and Rock Composite Stratum

Abstract The construction of shield tunnel often occurs in composite stratum, so it is great significance to study the law surface deformation under working condition stratum order ensure safety construction. Based on actual engineering, ground soil caused by upper sand and lower rock studied using method field measurement. results show that: width coefficient settlement trough basically remains stable with construction, loss rate changes exponentially construction; Affected disturbance previous subsequent no longer top axis, will move process, which greatly affected attitude parameters; Taking into account conditions center movement tunnel, total successive constructions adopts modified Mark-bolt formula make fitting parameters more suitable for reality.