【作者】 王军舰；

【导师】 王小林；

【作者基本信息】 西安科技大学 ， 岩土工程， 2011， 硕士

【摘要】 管棚超前支护技术作为隧道开挖的一种辅助工法,在防止隧道塌方、抑制地层位移、控制地表沉降等方面发挥着重要作用,它能够有效地解决隧道在穿越浅埋大偏压、软弱破碎、流泥等特殊地质条件隧道开挖问题,此外,管棚超前支护技术还具有超前加固距离长、可靠性高、工期短等优点,因此管棚工法正得到越来越多的应用。本论文以管棚超前支护技术为研究对象,运用理论分析、数值模拟等研究手段,主要做了以下工作:(1)在常用围岩压力理论的基础上,综合考虑了隧道埋深、围岩条件、开挖条件以及管棚作为超前支护结构的特点等因素,得出了深、浅埋隧道管棚受力荷载的计算公式,并基于弹性地基梁理论建立了管棚的力学分析模型,采用解析解得到了管棚支护结构的挠度、转角及弯矩方程。(2)应用土拱效应原理得出了管棚环向最大容许间距的计算公式。(3)应用三维有限差分软件(FLAC3D)对管棚超前支护结构进行了数值模拟,对管棚布置型式、支护长度的改变、注浆与否以及注浆厚度的改变对隧道开挖的影响进行了分析,计算结果表明:管棚存在最佳布置型式;管棚支护长度的增大对隧道位移的影响不大;注浆厚度的增大对隧道位移的控制作用并不显著,并存在最佳注浆厚度。以上研究成果对于管棚支护设计理论和施工实践都具有重大的借鉴意义。更多还原

【Abstract】 Pipe roof pre-support technology, as an auxiliary technique in tunnel excavation, has important function on preventing tunnel collapse, restraining ground movement and controlling ground surface settlement. It can solve the tunnel excavating problem effectively when the tunnel is constructed in soft or weak strata, such as shallow buried, crashed soft surrounding rock and abundant underground water. Furthermore, Pipe Roof Method has been widely applied because it has long pre-reinforce distance, high reliability, short construction period and other relative advantages. Taking pipe roof pre-support technology as the object to be investigated, using theory analysis and numerical simulation, a series of results were obtained.(1) Pre-supports and protections mechanism of shed-pipe technology is explored. Considering with the effects of the tunnel cover depth, the geological conditions and manners of excavation on the surrounding rock pressure, the equations for pipe roof reinforcement loading were proposed according to Terzaghi theory. Considering the delay effect of initial lining, an analytical approach based on Winkler elastic foundation beam theory for pipe roof reinforcement was put forward. The analytical solution obtained the deflection of pipe roof supporting structure, corner and bending moment equation.(2) The design parameters of Pipe roof supporting structure are systematically summarized. Application of soil arching effect principle obtains the maximum allowed to pipe roof ring spacing of calculation formula.(3) Taking a tunnel engineering for example, 3-d finite difference numerical simulation software was used to simulate advanced pipe roof supporting structure. Scope of pipe roof length, support arrangement for the change, grouting thickness of tunnel excavation were investigated. The calculation results show that: when using fan-shaped symmetrical arrangement type, when central angle equal to 120 degrees, it is the best arrangement type. Shed-pipe grouting for tunnel displacement control also have more significant effect of the tunnel, up to 45%, the horizontal displacement control also reached to 30%. Don’t shed-pipe grouting for tunnel vertical displacement control also have more significant effect of the tunnel, up to 30%, the horizontal displacement control also reached to 20%. The selection of the length of pipe roof supporting structure need combining geology condition of the strata and the precision of displacement control, then we can achieve economic and security purposes . When grouting thickness changes between 0.3 m to 0.6 m, the change of the tunnel grouting thickness is not significant for the control of the displacement. It shows that there is a value which causes the accuracy of the control of displacement and security and economic to obtain some balance , namely the best grouting thickness.Above research results for pipe roof supporting design theory and construction practice are of great significance.更多还原