韩家岭大跨度公路隧道应力监测分析

ANALYSIS OF STRESS MONITORING OF A LARGE-SPAN HIGHWAY TUNNEL IN HANJIALING MOUNTAIN

韩家岭隧道是沈阳至大连高速公路改扩建关键工程,为目前我国和亚洲最大跨度的公路隧道。隧道为单洞四车道,采用分层台阶法进行开挖,在大跨度隧道施工中是一种新尝试。为了解大跨度公路隧道开挖过程中的力学行为,提供设计和施工依据,对韩家岭隧道进行了稳定性应力监测研究。主要阐述该隧道应力测试方法、喷层与围岩接触应力、锚杆内力随时间变化的量测数据及分析。研究结果表明:(1)韩家岭隧道开挖宽度、高度和空间大,但量测到的围岩与喷层接触应力、锚杆轴力小,说明在初期支护结构中,喷射混凝土和锚杆对围岩变形只起到了协同与辅助的支撑作用,钢拱架和围岩自承起主要支撑作用。(2)依据达到峰值后的喷层接触应力和锚杆轴力数据来看,存在一定波动幅度,尽管不会对隧道的稳定性产生影响,但随开挖进行,围岩对初期支护的作用处在变化状态。(3)同一测试断面,在围岩较完整稳固的一侧,喷层接触应力出现拉应力值,而围岩稳固性差的一侧,喷层接触应力出现压应力值,表明该断面围岩水平位移主要来自围岩稳固性差的一侧。(4)短掘短支、释放地压与控制围岩变形,大跨度公路隧道采用台阶法开挖施工方式是可行的。

Hanjialing Mountain Tunnel is a key engineering in reconstructing the expressway from Shenyang to Dalian, and it is a highway tunnel with the greatest across span of arch in Asia. The tunnel consists of a single tube with four lanes, and was excavated with the layer-step method, which is a new attempt in constructing the tunnel with large across span. In order to clarify the mechanical behavior in the process of digging the large span tunnel and provide the technological data for design and construction, the research ＇of stability stress monitoring for Hanjialing Mountain Tunnel is performed. In this paper, it expresses mainly the method adopted for monitoring the stress of tunnel structure, and analyzes the data of touch stress changing with time between shotcrete lining and surrounding rock, as well as the change of internal force of rock bolt. The research results show. （1） because the width, height and space of digging tunnel is large and the touch stress measured between surrounding rock and shotcrete lining is small, for the initial supporting structure, shotcrete lining and rock bolts only act as cooperationand auxiliary on resisting the deformation of rock, but main support action can be result from the steel arch frame and the beating ability of rock itself. The greatest touch stress is 0.097 MPa, the largest axial force of bolt 4.73 kN. （-2） after reaching the peak value, the touch stress of shotcrete lining and the axial force of bolt are still wavy to a certain extent. Although it will not affect the stability of tunnel with the progress of dig engineering, the loading action on the initial supporting lining from surrounding rock deformation is in a change state. （3） for the measured section of tunnel, on the side in which the surrounding rock is stable, the touch stress is tensile between the surrounding rock and the shotcrete lining, on the other side, the surrounding rock is unsteady. The touch stress is compressive, so it expresses that the horizontal displacement of this across section originate mainly from the side of unsteady rock. （4） the way of layer-step constructing is feasible for large span highway tunnels, by means of short driving and short supporting, so that the ground pressure can be released and the surrounding rock displacement can also be controfled.