【作者】 韩日美；

【导师】 谢永利；

【作者基本信息】 长安大学 ， 道路与铁道工程， 2010， 博士

【摘要】 浅埋土质隧道特性分析及关键技术研究是一个复杂的课题,涉及范围广、难度大,具有重要的学术意义和工程实用价值。本文以黑龙江省哈尔滨市绕城高速公路天恒山隧道为工程背景,综合运用理论分析、数值模拟、现场试验、室内离心模型试验等手段,对浅埋土质隧道施工过程中隧道围岩应力、应变情况及变化规律、施工工法比选及优化、锚杆支护效果及优化等问题进行了深入研究,取得了以下主要成果：1、对于浅埋土质隧道,“微三台阶法”较之“三台阶七步开挖法”施工更加安全、快速和经济,更适合于土质隧道开挖。2、离心模型试验及现场试验均证明,浅埋土质隧道围岩变形为整体变形,从隧顶到地表变形均较大,系统锚杆将会随着土体一起移动,其锚固作用不明显。同时,粘土层中锚杆成孔困难,耗时长。取消系统锚杆,增加拱腰以下锁脚锚管,对隧道安全掘进没有不良影响,且可缩短工期和降低工程造价。3、浅埋土质隧道CRD工法开挖三维数值模拟结果显示,开挖前后离开挖面越近的地方围岩压力越小,随着开挖面不断向前推进逐渐恢复到原始应力水平；围岩主应力方向在开挖过程中不断发生变化,不同开挖方法引起不同的围岩破坏形式；支护结构各个角点处内力都较大,需要加强支护；支护结构的内力在拆除中隔墙和临时仰拱后快速增加,所以拆除临时支护是CRD工法中一个很重要的步骤。4、天恒山隧道监测数据显示,浅埋土质隧道围岩压力分布不均,最大值多出现在墙脚处；喷射混凝土应力分布比较均匀,拱部受力较大；钢架受力主要为压应力,拉应力多出现在拱脚处。钢架所受的应力较大,拱部及外侧墙脚受力最大,说明钢架在隧道初期支护中发挥着重要作用；纵向连接筋多处于受压状态,压应力不大,说明纵向连接筋对加强隧道支护的整体性、稳定性有着一定的作用。二次衬砌接触压力的量测值均小于规范计算值,拱脚和墙脚处接触压力相对较大；拱部混凝土及钢筋多处于受压状态、仰拱大部分处于受拉状态,拉压应力均远小于钢筋的屈服强度。5、浅埋土质隧道CRD工法开挖和微三台阶法开挖二维数值模拟对比试验结果显示,CRD工法由于设置临时仰拱和中隔墙,对限制隧道净空收敛和地层沉降有利。但其开挖步序多、支护结构成环时间长,且在后期需要拆除临时仰拱和中隔墙,天恒山隧道现场监测数据显示CRD工法开挖最终沉降反而较大,因此在设计和施工中应引起重视。6、研究表明浅埋土质隧道采用全土柱法进行围岩压力计算比较合适。土质隧道深浅埋分界标准应结合数值分析手段进行计算。7、土质隧道围岩参数对围岩力学行为影响程度敏感度分析表明,E是影响围岩稳定性和形变位移的敏感性参素,μ是围岩压力的敏感性参数,所以无论是在设计计算中还是在实验测定参数时,都要对这两个参数加强关注。更多还原

【Abstract】 Under the conditions of shallow-buried soil tunnel, the mechanics behavior of soil tunnel is a complicated problem which involved in wide range and greater difficulty. Therefore, the study on the key technique and property of shallow-buried soil tunnel with large-section has the important academic and practical value. Based on the construction of Tian-heng mountain soil tunnel, the paper mainly researched the behavior of mechanics and deformation, the proper and applicable methods of construction and bracing anchor by making use of theoretical analyses, numerical algorithm, prototype modeling, centrifuge modeling and so on. The main achievements are followed:1. The method of "marginal three bench excavation" which is proposed based on "excavation method by three stairs and seven steps" not only successfully deal with the soft stratum of Tian-heng mountain in construction, but also attain the aim of fast, safe and economical construction.2. Focus on the characteristic of the systematic anchor having no effect on the uniform displacement of shallow-buried soil tunnel, thus in order to reduce the cost and time limit of the tunnel engineering, the study recommend the anchor pipe of locking arch foot which could be used the pressed installment stead of the systematic anchor.3. By making use of three-dimensional finite element numerical analysis for Tian-heng mountain tunnel with CRD construction method, results show that the closer the excavating position is, the small rock the pressure is, and the rock pressure maintains the initial stress far from the position of excavation. Furthermore, the direction of principal stress which vary with the excavating process result in the different trend of failure corresponding to the different excavating method. Because the corner force of bracing structure is bigger, the corner of bracing structure needs to be reinforced. In addition, it is the cautious and important step in dismantling process that the force of the moldboard and the inverted arch will increase when they are dismantled.4. Based on the monitor measuring data of Tian-heng mountain soil tunnel construction, the stress distribution of surrounding rock is non-uniform and the maximum is located in the corner of bracing structure, while the stress distribution of excrete is nearly uniform and the maximum is located in vault. Furthermore, the analyses of data also show that the steel truss and longitudinal connecting steel reinforcement have effect on the integrity and stability of the preliminary reinforcement of tunnel. Based on the measuring data of the secondary lining, on the one hand the measured stresses of the secondary lining are smaller than the specified value of standard; on the other hand, both compressive and tensile stresses of steel reinforcement are smaller than the yield strength. Thus, the secondary lining works well done with enough safe reserve.5. By making use of two-dimensional finite element numerical analysis for Tian-heng mountain tunnel with CRD construction method and "marginal three bench excavation", results show that CRD construction method is beter for tunnel deformation and soil settlement because of its horizontaland and vertical temporary support.But, its Multi-step sequence excavation, support structure into the ring for a long time and horizontaland vertical temporary support need to be removed at a later are lead to the larger final settlement, so the design and Construction should be attention.6. Based on the study of the surrounding pressure of Tian-heng mountain soil tunnel, the soil column method was recommended and adopted for the design of shallow-buried soil tunnel. Furthermore, the differentiated standard of the shallow-buried and deep-buried soil tunnel should be determined by theoretical analysis and numerical calculation.7. The soil parameters have much influence on the analysis of mechanical properties of lining structure. According to the incidence of these soil parameters, the sequence which has different role in the application is such as E,μ,ψand C. Thus, the parameters of E andμnot only should be paid close attention to the influence in theoretical analyses and numerical calculation, but also concerned in experimental determination.更多还原