【作者】 李勇；

【导师】 佴磊；

【作者基本信息】 吉林大学 ， 岩土工程， 2004， 硕士

【摘要】 随着国民经济迅速发展，公路建设规模日益扩大，对公路快速、舒适、美观也提出了更高的要求。由此带动并促进了公路隧道建设的发展。隧道工程在岩体中开挖，而岩体是经受过变形与破坏的地质体的一部分，是技术学科中最复杂、最难理解的一种材料。因此，地下结构的力学状态是极其复杂的，它具有结构、材料与荷载“三位一体”的特性，传统的“结构－荷载”模型已不再适用，需要用固体力学模型边界条件与力学参数的变化加以描述。70 年代以来在地下工程的结构设计中，将结构与地层视为一体进行稳定性分析的地层结构法有了较大的发展，并已根据围岩和结构材料的本构关系建立了各类计算模型，编制了程序软件，使地下工程的计算理论有了较大的进步。但是，围岩－支护系统的力学机理还不甚清楚；初始地应力场及岩体力学参数的逐点变化；岩体材料破坏准则研究的不完善及多种破坏形式等都表明隧道工程的复杂程度远远高于地面工程。 隧道工程设计，在很大程度上就是设计它的支护系统，隧道支护结构是设计的主要部分，本文利用数值模拟的方法对隧道围岩进行了应力应变分析，按应力集中系数的大小进行分区，并对支护后的锚杆轴力进行计算，根据锚杆轴力与应力集中系数的分区情况设计锚杆长度。最后利用承压拱理论验证修改后支护系统的安全性，表明该锚杆长度的设计是合理的，具体分以下几步： 1、 根据朝阳镇至长白二级公路老岭隧道的区域地质、工程地质条件，结合施工方法，对隧道围岩进行了声波测试、点荷载、回弹以及其它的地质方法（如素描图、展示图等）确定实际围岩类别，将其与勘察设计阶段的围岩类别进行比较。结果表明，由于勘察方法、手段和工具的制约以及地下岩体的复杂性等方面的原因，导致由勘察资料进行的围岩分类与实际的围岩类别存在一定的差异，如果按原设计实施的话，势必造成经济上的浪费或安全上的隐患。 2、由勘察资料提供的物理力学参数，根据实测的围岩类别，用有限单元法对隧道围岩进行应力应变分析，从而确定围岩的应力分布和位移情况。同时，对无衬砌和二次支护后围岩的应力、应变分布情况进行对比。 3、引入“应力集中系数”的概念，“应力集中系数”定义为最大应力或峰值应力σm对基准应力（根据具体情况适当选定）σ0 之比。本文中的σm、σ0 分别对应于各单元体的最大、最小主应力，因为最大、最小主应力不仅反映了应力集中的程度，同时因为它们是 Mohr－Coulomb 破坏准则中的两个重要参数所以也反映了单元体的安全程度。根据应力集硕士毕业论文 58<WP=64>朝阳镇至长白公路老岭隧道围岩应力应变分析中系数在隧道围岩中的分布情况，对其进行了分区，并且对无支护和二次支护后的应力集中系数的分布情况进行对比。4、根据原设计方案的锚杆长度，计算出锚杆轴力分布情况，找出锚杆轴力变化规律，以此确定围岩塑性区或松动区的范围，用围岩内切向应力变化规律验证了此塑性区或松动区确定方法的合理性。5、将按锚杆轴力变化规律确定的围岩塑性或松动区范围与应力集中系数分区情况结合起来，修改原设计中的锚杆长度。6、用承压拱理论计算锚杆长度改变后支护系统的安全性，结果表明，修改后的锚杆长度是合理的。本文的创新之处主要体现在以下几方面：1、最大、最小主应力之比来确定应力集中系数，这一系数既能判断围岩的应力集中程度，同时根据 Mohr－Coulomb 准则，它也能对围岩的潜在破坏趋势进行判定。2、根据硐壁锚杆轴力的两段线性变化特征，确定围岩塑性区或松动区的厚度。3、应力集中系数与锚杆轴力变化规律相结合，设计隧道支护系统中的锚杆长度。更多还原

【Abstract】 With the rapid development of our national economy, the scale ofhighway construction has been expanding day by day, and the properties offast, comfort and beauty have been requested. Therefore, the development ofhighway tunnel construction has been driven and promoted. Tunnel project isexcavated in rock mass, while rock mass, which is one of the mostcomplicated and incomprehensible materials in technological discipline, ispart of geological body that undergo deformation and destruction, thereforethe mechanic state of underground structural is extremely complicated, it hasthe property of trinity of structure, material and load. The traditional“structure - load “model has already been no longer suitable, it needsdescription by solid mechanics model border terms and variety of mechanicparameters. The stratum-structure method, which regards the structure andthe stratum as a whole to perform stability analyses, has receivedconsiderable development in structure design in underground engineeringsince 1970s. Variety of calculation models have been set up according to theconstitutive relationship between surrounding rock and structure materials.Some related programs have been worked out, which promoted thedevelopment of calculation theory in underground engineering. Butsurrounding rock – support systematic mechanics mechanism is not veryclear up to now, the piecemeal change of initial ground stress field and rockmechanic parameters as well as the imperfect research of rocky materialfailure criterion and the variety of failure forms indicate the more seriouscomplexity of tunnel project than ground project. This paper analysis the stress-strain of surrounding rock by numericalsimulation method. According to stress concentration coefficient to divide thetunnel surrounding rock. At the same time, calculate the axial force of theanchor bar. Revised design is implemented in linear structure according to thepartition of stress concentration and the axial force is consideration whencome to the anchor bolt length. At last, using the theory of bearing arch toverify the safety of the new designing support system. The conclusion isreasonable. The analysis processes are as fellows: 1.According to the regional geological and engineering geologicalconditions of Laoling tunnel along Chaoyang Town to Changbai Class IIhighway, the actual surrounding rock classification, with combination ofconstruction method, has been performed using acoustic wave test, point loadexperiment, as well as rebound test and some other geological methods (suchas sketch and extend chart), after comparison with that of survey and designstage which has disadvantages in exploration methods, tools and apparatus,as well as the complexity of underground rocks, certain difference is硕士毕业论文 60<WP=66>朝阳镇至长白公路老岭隧道围岩应力应变分析confirmed , which indicates that implement according to original design willcertainly cause economical waste and latent failure in safety 2. Stress-strain analyses of the tunnel surrounding rock has beenconducted using FEM according to the real rock classification and surveymaterial-provided physical and mechanical parameters to confirm thedistribution of surrounding rock stress, plasticity district and displacement.Meanwhile, comparison has been carried out between non-liner andafter-secondary support on stress and strain distribution 3. The concept of “ stress concentration coefficient " has been induced,which is defined as the ration of maximum stress (or peak stress) σm toreference value σ0 (which should be vary in different conditions). In thispaper, σm and σ0 are correspondent to the maximum or minimumprincipal stress of each element, respectively. Since they not only reflect thedegree that the stress concentrates, but embody the safe condition of eachunit at the same time because they are the two important parameters in M-Cfa更多还原