【作者】 黄胜平；

【导师】 陈秋南； 姜长清；

【作者基本信息】 湖南科技大学 ， 结构工程， 2008， 硕士

【摘要】 我国高等级公路建设中,在特殊地质及地形条件受限制的地区,为了获得良好的技术经济效果,大量选择了连拱隧道方案。但连拱隧道所处位置地质条件复杂、跨度大、开挖扰动频繁和结构复杂不稳定。在连拱隧道洞口边坡偏斜地段,往往出现一侧无法形成洞室,另一侧可以进行暗洞开挖的现象。为了避免高挖深填,保护自然环境,还需选择特殊的结构形式—半隧半路结构。本文以常吉高速公路殿会坪隧道工程为依托,在偏压连拱隧道典型断面进行了收敛位移、拱顶下沉、围岩内部位移、锚杆轴力、地表沉降等项目测试;对于半隧半路结构,在典型断面进行了收敛位移、围岩内部位移、锚杆轴力、地表沉降、二衬应力和耳墙水平位移及应力测试,获得了围岩位移和支护结构内力分布规律,为现场施工提供指导。基于实测围岩位移数据,应用反分析方法,并结合室内岩石力学试验确定岩体c、φ等力学参数。采用数值模拟方法分析比较了偏压连拱隧道中导洞—台阶法和三导洞—台阶法施工过程中隧道围岩、支护结构和中墙的应力场、位移场的异同,得出三导洞—台阶法是复杂条件下连拱隧道合理的施工方案。首次将地形偏压率引入半隧半路特殊隧道,采用有限元数值模拟方法研究了隧道在不同了偏压率P(分别为7、4和2.5)时,各施工阶段围岩应力场、位移场以及支护结构和耳墙的位移、应力分布规律。重点分析了耳墙应力分布规律,得出耳墙外侧拉应力较大的结论,设计施工时应防止耳墙外侧混凝土发生拉裂破坏。综合考虑半隧半路结构安全和稳定性要求,得出1:1是比较合适的边坡坡度(即P=4)的结论,验证了实际工程的设计合理性。基于偏压连拱隧道水平收敛位移和拱顶下沉现场测试数据,建立神经网络BP预测模型,对围岩位移变化规律进行智能预测,并与实测值进行对比分析,验证了预测结果的正确性。最后,对有限元数值模拟结果和现场量测结果进行比较,进一步论证数值模拟分析结果的正确性,可以用以指导工程设计。更多还原

【Abstract】 With development of economic constructing and highway in china,the type of multi-arch tunnel often is applied in special geologic and topography districts in order to get better technological and economical purpose. But it has some disadvantages including complicated geological conditions, big span, continual disturbing, complicated and unsteady structure. A phenomenon that it can be constructed hidden tunnel on one side of deep depth but can’t on the other side of shallow usually appears in the opening of slope sector. In order to avoid great excavation and protect nature circumstance,the structure of special tunnel with half-tunnel &half-roadbed is an optimum pattern to be selected.Based on the Dianhuiping multi-arch tunnel engineering of Changji highway and it’s need,in-situ monitoring was carrid out for multi-arch tunnel. Basing on the displacement of surrounding rock and indoor test,rock mechanics parameters including c、φare gained by back analysis. The thesis compares construction methods of middle heading bench and three heading bench on displacement field and stress field of surrounding rock , supporting and mid-partition using numerical simulation, three heading bench is commended under unsymmetrical pressure and complex geological condition. By founding analysis calculate model of half-tunnel &half-roadbed key section with FEM, reseaches the stress field and displacement field of the surrounding rock,of the stress field of the supporting structure and the ear wall when the unsymmetrical pressure ratio P is 7,4 or 2.5. Especially analysing the distribution of vertical stress in ear wall and overladen stretching stress on the out side and a advice that it should be prevented riping of the concrete is bringed forward. Considering the security and stabilization of half-tunnel&half-roadbed structure, it comes to a conclution that it is rational when the slope rate is l(P=4),also prove designer of practice engineering reasonable. Base on the datas of in-sute measurement,the displacement result of surrounding rock which is forcasted by using BP model of neural network is compared with test result, and proved accurated. Finally, the the results of numerical simulation that is more confirmed to direct enginreering design is contrasted result of in-site test.更多还原