小规模下伏薄煤层采空区倾角对隧道开挖稳定性的影响研究  

Influence of Small-Scale Underlying Mined-out Areas with Different Dip Angles in Thin Seam on Tunnel Excavation Stability

作　　者：符亚鹏[1] 方勇[2] 崔戈[2] 郭建宁[2] 

机构地区：[1]中铁第一勘察设计院集团有限公司,西安710043 [2]西南交通大学交通隧道工程教育部重点实验室,成都610031

出　　处：《现代隧道技术》2016年第4期70-76,共7页Modern Tunnelling Technology

摘　　要：公路隧道近接下伏采空区施工必定会打破采空区的原始平衡状态,出现应力重分布现象。为研究不同倾角下伏采空区对隧道施工稳定性的影响规律,文章采用有限元软件构建采空区地层隧道计算模型并进行了数值计算,研究了下伏采空区倾角对隧道洞周位移、初期支护内力和塑性区的影响规律。计算结果表明:(1)下伏采空区的存在加大了隧道洞周位移,倾角越小,增幅越大;(2)下伏采空区的存在增强了初期支护内力分布离散性,尤其是对拱顶内力影响幅度较大,主要体现在隧道拱顶轴力降低,倾角越小,降低值越大;(3)下伏采空区的存在增大了围岩塑性区,甚至贯穿到采空区冒落带,倾角越大,塑性区越小。因此,下伏采空区倾角越小,隧道施工风险越高,围岩稳定性越差,结构受力越不利,应采取有效措施提高下伏采空区的处治强度。The original equilibrium state of underlying mined-out area is surely to be broken by the approaching eonslruclion of highway runnels, and it will cause stress redistribution. In order to study the influence law of underlying mined-out areas with ditterent dip angles on tunnel construction stability, it used finite e]emenl software lu buih] a calculation model of tunnel in mined-out layer, carried out a numerical simulation, studied tire influence law of underlying mined-oul area with different clip angles on displaeements around tunnel periphery, inner force of primary support and the plastic zone. The calculations indicate thai the （tisplaeement around lunnel periphery increases with the decrease of dip angles of underlying mined-out areas; the distribution discreteness of inner force of pri- mary support increases due to the mined-out area, the axial force of crown is largely influenced by this and characterized by the decreasing of axial force which has a verse relationship with the dip angle; the plastic zone of surrounding rock enlarges, even penetrates through the caving zone of mined-out area and has a verse relationship with the dip angle. Thus the smaller the angle of underlying mined-out area, the higher the construction risk, the worse the stability of surrounding rock and the more unfavorable regarding force applied on structure, which makes it necessary to lake effective measures to improve tire treatment for underlying mined-out areas.

关 键 词：公路隧道 下伏采空区 倾角 洞周位移 初期支护内力 塑性区 

分 类 号：U452.27[建筑科学—桥梁与隧道工程]