【作者】 周能娟；

【导师】 佴磊；

【作者基本信息】 吉林大学 ， 地质工程， 2011， 博士

【摘要】 自然界的岩体中存在着节理、裂隙、断层、泥化夹层等软弱面,这些软弱面对隧道工程钻爆法开挖效果有着很重要的影响,因此研究节理裂隙岩体中隧道在爆炸载荷作用下的动力响应机制,对于合理采用凿岩爆破参数、提高爆炸能量利用率、改善爆破效果等均有其实际意义和理论指导作用。本文在综合分析和研究已有节理岩体爆破理论、试验研究现状及爆破模型发展动态的基础上,以工程项目实体为基础,开展数值模拟研究。选取隧道内RK343+665、RK343+667、RK343+669、RK343+698、RK343+719、RK343+735六个典型断面作为实体,建立节理裂隙岩体隧道爆破模型,重现隧道光面爆破开挖过程。将实际断面模型与完整岩体爆破模型进行对比,分析工程中存在的节理对隧道爆破成型效果的影响,从中分析引起隧道产生超欠挖的原因,继而提出软弱带内部不宜放置炸药的建议,并从能量的角度进行阐述和论证。考虑到节理的物理力学特征,即节理产状、节理宽度、节理间距对隧道成型效果的影响,采用优化拉丁方方法进行DOE试验设计,基于Isight平台做了43组模拟实验,得到了这些影响因素对超挖的影响规律。岩体中的节理是自然形成的,想获得较好的隧道爆破效果主要的方法是调整炸药参数及装药结构。因此本文以减少超欠挖量、提高炸药能量利用率为目标进行了不同炮孔间距、装药密集系数情况下节理岩体的爆破优化分析。更多还原

【Abstract】 Rock mass blasting is one of the most effective technologies for rock mass excavation in tunnel engineering. The numerical modeling of tunnel blasting serves as a link between the theoretical developments and the engineering practice. It simulates the dynamic blasting of the rock mass by employing mathematical physical models approximating the real situation, with a view to revealing the actual transient blasting process and the subsequent effect, and obtaining a better understanding of the rock mass blasting and failure mechanism. At the same time, the credibility of the numerical simulation can be testified by in-situ large-scale experiments. A process consisting of numerical simulation, physical experiment and theoretical investigation has been involved in various mechanical and engineering fields for a systematic and integrated analysis.The dynamic Finite element analysis commercial package ANSYS/LS-DYNA is employed to assist the analysis carried out in this project. The numerical modal for the blasting of the jointed rock mass is efficiently constructed using the ANSYS specified parametric language. The Lagrange algorithm is adopted in the analysis. The unbounded rock mass is modeled by non-reflecting artificial boundary conditions. Relevant materials in this study include rock, joints, air and explosive, with corresponding material types in the numerical model being concrete, rate-independent bilinear kinematic hardening model, high explosive and null-material modals, respectively. Six selected sections of the Gaoling tunnel are examined in this study to explore the failure characteristics and the overbreak/underbreak mechanisms of the jointed rock mass blasting. The DOE technique is adopted to investigate the influence of the geological properties and the blasting parameters on the jointed rock mass blasting. Satisfactory blasting phenomenon is achieved by adjusting the designing blasting parameters according to optimization method.The main conclusions are summarized as follows:1.The influence of joints to the blasting phenomenon is intuitively observed by examining the Six typical sections, i.e., RK343+665, RK343+667, RK343+669, RK343+698, RK343+719 and RK343+735 of the Gaoling tunnel, that is, the closed joints enforce negligible influence on the blasting, whereas the influence from the filled joints mainly depends upon the spacial arrangement of the blastholes:(1)With blastholes being positioned inside the joints, the joint strength decreases dramatically after blasting, secondary stretching faults are resulted from the stress wave reflection between the rocks at the two sides of the joint, leading to severe damages, even to the surrounding rock out of the designing scope.(2)When blastholes are within the vicinity of the joints, the blasting energy can be partially absorbed by the joints, with a correspondingly partial reflection, which may result in massive overbreak.(3)When a couple of or more than two sets of joints are closely located or intersect, a back-and-forth reflection of the stress wave will be created, yielding stretching failure of the rocks in between the joints. This, however, may lead to underbreak if the rocks, on the other side of the joints, are protected without any blasthole arranged.( 4) It is therefore suggested for rock mass blasting with filled joints that Large-diameter blastholes should be designed with little or no explosive. No explosive should be placed inside the joints.2. The characteristics of the joints, i.e., the orientation, width, and the spacing, have different influence on the jointed rock mass blasting, varying from negligible effect to significant overbreak/underbreak, which may unnecessarily increase the blasting cost. Based on the ISIGHT platform, Optimal Latin Hypercube Method is employed in the smooth blasting design of the jointed rock mass. 43 sets of simulations are carried out with the input variables being joint- blasthole center angle, joint width, joint spacing, blasthole spacing, the Intensive factor of peripheral holes and number of explosive, and the output variables being the amount of overbreak or underbreak.(1)Mutil-factor least squared method is utilized to obtain the following conclusions: the weighting ratio of each factor influencing the overbreak/underbreak of the smooth blasting of the joined rock mass is localized within 10%. The first five factors are: the linear affect of the joint- blasthole center angle to the overbreak which takes up to 9.8%; the linear primary effect of the explosive and the interact effect of the joint width JW1 and the joint spacing JD both take up to 7.3%;the second primary effect of Jw2 takes up 6.8% and the interact affect the joint width Jw2 and the joint spacing Jd takes up to 6%.(2)RBF neutral network is adopted in the multi-dimensional spacial approximation of the data constructive modal. a non-linear interact phenomenon is observed with relative complexion.3.Experimental optimization design provides valuable information for acquiring more appropriate blasting parameters. An optimal software platform ISIGHT is used to perform the optimized numerical modeling of the joint rock mass blasting. The optimal blasthole spacing and the Intensive factor of peripheral holes are obtained by inspecting two objective values: the volume of the overbreak/underbreak and the effectiveness of the explosive energy. More variables and objective values can be taken into consideration in this analysis with more practical significance.The main innovation spots in this paper:1.The complex jointed rock mass blasting model is constructed in this study, with a satisfactory simulation of the overbreak and the underbreak of the tunnel blasting. A suggestion that no explosive should be placed inside the filled jointed is provided. Discussions are presented in terms of the energy point of view with empty blasthole.2.The interaction effect between the geological information and blasting parameters are taken into account. The least squared multi-factor formulations are presented. Radial based neutral network is used for the construction of spacial date approximation, which ensures the visualization of the multi-factor interaction effect in multi-dimensions.更多还原