浅埋双连拱隧道围岩—边坡体系变形机理及稳定性分析

DEFORMATION MECHANISM AND STABILITY STUDY ON SYSTEM OF SURROUNDING ROCK AND SLOPE OF SHALLOW DOUBLE-ARCH TUNNEL

双连拱隧道是一种新的隧道形式,由于其整体跨度大、结构复杂、施工工序繁琐,在地形偏压、地质条件复杂的情况下修建双连拱隧道难度较高,尤其在洞口段容易出现衬砌开裂、边坡变形等一系列工程问题。结合安徽铜黄高速公路汤屯段富溪隧道进口段工程,采用地质条件研究与数值模拟分析相结合的研究手段,对复杂地质条件下偏压双连拱隧道围岩—边坡体系在施工过程中应力应变发展过程进行了研究。综合分析表明,富溪隧道进口段处于F5断层影响带内,岩体呈碎裂结构,同时,受到地形偏压影响,隧道开挖后衬砌和围岩表现为沉降变形和侧向变形,进口边坡在隧道围岩变形的诱导下,表现为"蠕滑-拉裂"变形破裂。根据以上研究成果,提出了富溪隧道变形治理应以控制进口段隧道拱顶的变形为主。

Double - arch tunnel is a kind of new tunnel form. It has a large span, complicated structure and cock- amamie working procedure. Therefore, it is difficult to be constructed under unsymmetrical pressure and complex geological conditions. Especially, a series of engineering problems, such as lining cracking and tunnel slope deformation, often occur in the entrance portal region. This paper is based on the project of Fuxi tunnel and uses both geological analysis and numerical simulation method. The stress - strain processes of lining and rock mass are examined systematically during the construction of the double - arch tunnel under unsymmetrical pressure and complex geological conditions. The comprehensive analysis shows that owing to the influence of the F5 fault, fragmental structure rock mass was encountered in the portal region. Due to poor rock mass and unsymmetrical pressure, lining and surrounding rock occurred settlement and lateral deformation after tunnel excavation. The slope deformation mode was ＂creep sliding - fracturing＂ which was is a result from surrounding rock deformation. Based on the above analysis, a conclusion was drawn that control of the tunnel vault deformation is a key step to control the whole deformation of the entrance region.