层理位置对近水平软硬互层隧道变形影响研究

江习高速四面山隧道软硬互层围岩为近水平岩层,弹性模量比值为1∶5,黏聚力比值为1∶4,层理效应明显,且层理与隧道相对位置不一,对隧道开挖影响也不同。以砂泥互层V级围岩隧道施工段为工程依托,采用接触分析方法,研究层理与隧道相对位置关系对隧道变形影响,并进行变形预测,得出以下结论:(1)隧道开挖后,其拱顶沉降相对水平收敛变化更大,层理层间滑移相对层间剥离变化更明显。(2)隧道拱顶沉降受隧道上方层理影响最大,水平收敛受穿隧道层理影响最大,底鼓受隧道下方层理影响最大。(3)对于层理本身,隧道开挖对断面以上位置的层理影响更大,对其下方层理影响较小,层理位于隧道上方层理滑移最大,层理穿越隧道断面时层间剥离量最大。研究成果可在类似隧道提出针对性施工工艺设计建议并推广应用。

Stability Analysis and Optimization of Primary Support on Tunnel Excavation with Soft-hard Interbed Rock

Some tunnel sections in Simianshan mountain, Jiangxi highway, are surrounded by interbed of hard and soft rock. The elastic modulus ratio of hard and soft rock is 1:5, cohesive force ratio is 1:4. and bedding effect is remarkable. Bedding and tunnel have different relative position, Its influence on the tunnel excavation is also different . Making use of contact analysis method, To study the relation between bedding and its relative location with tunnel for tunnel deformation effects, to predict the tunnel deformation. Concluded that: 1) After the tunnel excavation, the value of vault sink is larger than the level convergence of the surrounding rock. At the same time, the change of the bedding interlayer sliding is more obvious than the interlayer stripping. 2) The vault sink is largest when the bedding is above the tunnel, while the level convergence is largest when the bedding is cross the tunnel and the tunnel floor heave is largest when the bedding is under the tunnel 3) For bedding itself, it has the largest effect on the above bedding deformation when the tunnel excavated, while it is smaller when the bedding is under the tunnel. Interlayer sliding is the largest when the bedding is above the tunnel, and the interlayer stripping is largest when the bedding cross the tunnel. Research results provides a good model for the similar tunnel construction and put forward construction design suggestions.