【作者】 张国华；

【导师】 刘明贵；

【作者基本信息】 中国科学院研究生院（武汉岩土力学研究所） ， 工程力学， 2010， 博士

【摘要】 爆破以其经济、高效、快捷的特点广泛应用于地下岩体工程的开挖中,然而岩体中爆炸在造成爆区岩体破碎、剥离的同时,不可避免的也造成近区岩体的扰动、损伤,中远区岩体的振动等危害。岩体的损伤效应在多次频繁爆破作业的情况下更为突出,如大断面隧洞双侧壁导坑法开挖时围岩发生的累积损伤。损伤岩体的力学性能劣化,强度降低、完整性变差,从而对岩体的安全稳定造成威胁。因此,多次爆炸动荷载作用下岩体的累积损伤特征进而采取合理的控制方式是工程中关注的中心问题之一,在国内外爆破和岩石力学领域受到越来越多的关注。本文依托大帽山大断面小净距隧道群,开展爆破振动、声波波速和围岩内部围岩的现场监控量测工作。研究表明：推进式往复爆破作业的双侧壁导坑法开挖的隧道必然导致围岩产生一定程度的损伤、破坏,尤其是小净距隧道间的中夹岩岩墙。任一固定断面上,在整个推进式往复的爆破过程中与爆源越近,损伤度和位移量越大,越远越小。双侧壁导坑法开挖的大断面隧道,控制岩体的损伤程度和损伤范围是相互矛盾的。所以工程实践中,应根据实际工程的特点和围岩的特性,开展相关的研究工作来确定最优的施工方案。双侧壁导坑法开挖的大断面隧道,任一固定断面上围岩的累积损伤是爆炸损伤和在此基础上叠加的振动损伤两部分组成。其演化过程是,在Ⅰ导洞逐渐接近断面时围岩发生爆炸损伤,并且与断面齐平的单次爆破导致的损伤增量远大于其它几次的损伤增量,围岩的累积损伤范围由与其齐平的单次爆破决定。振动损伤又包括变形损伤和岩体的疲劳损伤,变形损伤在开挖轮廓线附近的围岩中占主导地位。通过DYNA、UDEC软件实现的爆炸动荷载、各向异性岩体爆炸损伤模型,可以较好地模拟推进式往复爆炸动荷载作用下围岩的累积损伤范围。根据此计算模型,综合考虑既有隧道的安全状况、新建隧道施工、支护参数和成本等因素,提出优化后的单循环开挖进尺是1.2m。从围岩位移和结构应力的现场监测结果可以看出,大帽山隧道优化后的1.2m单循环开挖进尺开挖时,现有的施工工艺和支护参数是可行的,围岩变形可控,基本稳定,支护结构受力普遍较小,尽管施工工序复杂,但可以确保围岩的稳定。更多还原

【Abstract】 Zhang Guohua (Engineering Mechanics) Directed by Prof. Liu MingguiBlasting, as an economical efficient shortcut method in rock mass engeneering excavation, has been widely used more and more. Yet blasting construction of Small clear distance tunnel not only causes rock mass crashed and peeled in blasting area, but also inevitably causes damage to nearby rock mass and vibration in moderate or remote areas as well. It is more outstanding to damage effect of rock mass in repeated frequently blasting operations. For example, accumulative damage of surrounding rock is significant in tunnel with large section excavating with two side-wall pilot tunnel method. damaged rock mass will threaten the security and stability of the rock mass due to inferior mechanics function, weaker rock strength and worse integrality. Character of rock mass accumulative damage in repeated blasting dynamic load and the control damage have always been one of the key techniques during construction, and is also a great concernin blasting and rock mechanics at home and abroad.Damaoshan tunnel with large section and small clear-distance is relied on in this paper, the on-site supervision measure of internal displacements of surrounding rock, blasting vibration velocity, acoustic wave velocity of rock mass are carried out. It was shown that the surrounding rock of the tunnel constructed by double side-wall heading excavation method would unavoidably be damaged in a certain degree because of repeating blasting, especially the interlaid rock wall in tunnel groups with closely-spaced. The more near the explosion source, the more big the extent of the damage degree and the displacement amount of the surrounding rocks, the more far the explosion source, the more small in advancing to-and-fro blasting load operations for any one of section.In construction of large cross-section tunnel with double side-wall heading excavation method, it is contradictory to control both damage extent and damage scope. The most optimization of construction method should be researched in engeneering practice, based on the character of surrounding rock and engeneering. In construction of large cross-section tunnel with double side-wall heading excavation method, accumulative damage scope of surrounding rock in any one of section is made up of blasting damage and vibration damage that develops from blasting damage. The evolvement of accumulative damage scope of surrounding rock that blasting damage happed when the excavating face of pilot tunnel I gradually is close to section. The damage increment, that caused by sigle blasting is the most close to section, is bigger than the sum of damage increments before blasting operations. The accumulative damage scope of surrounding rock is mainly determined by the blasting of excavating face of pilot tunnel I which is parallel to it. Vibration damage consist of distortion damage and fatigue damage of surrouding rock. Vibration damage is dominant for near excavating outline rock.The blasting dynamic load and anisotropic damage model of rock realized by software DYNA and UDEC can better simulate the accumulative damage range of surrounding rock in advancing to-and-fro blasting load operations. Based on the exciting tunnel save condition, construction of new tunnel, support parameters and cost et al factor, the result of numerical method is that the optimized sigle repeated excavating length is 1.2m.When sigle repeated excavating length of Damaoshan tunnel is 1.2m, the supervision results of internal displacements of surrounding rock and structure stress indicate the existing construction techonolog and support parameter is feasible, because of controllable surrounding rock distortion, stable surrounding rock, small operation force of support structure. Despite the construction technology is complexitical, the surrounding rock is stable.更多还原