隧道等效弹性振动边界的建立及精确爆破振动分析

发布时间：2018-01-16 01:03

本文关键词：隧道等效弹性振动边界的建立及精确爆破振动分析　出处：《北京科技大学》2015年博士论文　论文类型：学位论文

【摘要】：隧道及地下工程等岩体的掘进开挖多采用爆破的方法。在爆破过程中,部分能量转化为爆破地震波并在岩上介质中传播,当其强度超过一定限度时,就会对围岩体及既有地表建(构)筑物的内部结构产生影响,此影响可能表现为内部介质的损伤或破坏。本文围绕爆破振动的产生方式、传播规律及其对围岩体和建(构)筑物的作用机理展开了较为系统的分析。 (1)通过分析爆破孔内爆破气体压力变化、炮孔体积扩张、围岩裂隙发展和爆破气体运动规律等,应用查普曼-柔格模型、气体状态方程以及气体动力学方程,深入研究了爆破过程中能量的耗散机理,推导了不同爆破阶段的载荷计算形式,建立了爆破动力载荷的时程模型,考虑了尺度效应,分析了不同炮孔截面上的载荷变化及爆轰波在孔内的反射叠加作用,建立了爆破动力载荷随时间和炮孔尺寸变化的拟三维载荷模型。 (2)将爆破孔划分为掏槽孔及存在二次临空面的工作孔,应用动力梯度理论推导了爆破粉碎区和爆破碎裂区的能量衰减程度及其作用范围。基于此分析,将爆破孔、爆破粉碎区及爆破碎裂区等效为产生弹性振动的爆破载荷作用边界(等效弹性振动边界),并通过声发射监测的现场爆破相似模拟实验和掏槽爆破及其它工作孔爆破的数值模拟分析,对等效爆破载荷作用边界的范围及其作用方式进行了界定和验证。 (3)爆破能量分为炸药爆炸过程中因化学损耗和气体喷出所消耗的耗散能、用于隧道围岩体开挖的有效机械功能及产生爆破振动的振动效应能。本文中考虑了化学损耗及气体喷出原理,建立了拟三维动力载荷模型,并分析了爆轰压力下围岩的粉碎及碎裂机制,界定了等效振动载荷的作用边界,分别实现了对耗散能和有效机械功能的剔除。 (4)通过砂岩及砾岩的室内常规试验和分离式霍布金森冲击试验,初步确定了不同应变率下的冲击硬化因数,结合PFC3D模拟展现了岩石在不同应变率下的破坏过程,并补充了高应变率下的冲击硬化因数。之后,基于冲击硬化因数对岩石的弹性模量进行了修正,解决了动力分析过程中的冲击硬化问题。 (5)现场声发射及爆破振速的监测给出了隧道围岩体的振动波波长,由此确定了模拟过程中满足分析精度的最大单元体尺寸。在实际爆破中,受围岩体非均质及振动相互叠加等因素影响,由等效载荷作用边界方式得出的结果存在一定偏差,文章基于BP神经网络法的爆破振动场反演,提出了载荷过度系数,对结果进行了有效修正。最后,结合大量的现场爆破振动速度的监测曲线,采用数值模拟的方式反演出了弹性振动区的局部载荷阻尼系数。 (6)在上述分析的基础上,本文以烧锅隧道工程爆破为实例,建立了道爆破开挖及建(构)筑物响应分析模型。通过模拟分析,提取了距爆源不同位置处的振动速度曲线及有效拉应力曲线,建立了弹性振动场,对隧道围岩体的动力响应特性和振动场内既有建(构)筑物的安全稳定性进行了分析。
[Abstract]:The use of blasting excavation method of tunnel and underground engineering rock mass excavation. In the blasting process, part of the energy into the blasting seismic wave propagation in the medium and on the rock, when its strength exceeds a certain limit, will be on the surrounding rock body and both the surface construction (structure) affect the internal structure of the building. Effects may be manifested as injury or damage the internal medium. This paper around the blasting vibration, propagation and the rock body and built (structure) mechanism of building out a more systematic analysis.
(1) through the analysis of changes of blasting gas pressure blasting hole, hole volume expansion, rock fracture development and blasting gas movement law, the application of Chapman soft lattice model, gas state equation and gas dynamics equations, in-depth study of the energy dissipation mechanism of blasting process calculation, deduced the different blasting load stage. A process model of blasting dynamic load, considering the scale effect, analyzes the variation of the load of different hole sections of the detonation wave superposition and reflection in the hole, three-dimensional load model of blasting dynamic load with time and hole size change is established.
(2) will be divided into cuthole blasting holes and has two free face working hole, application of dynamic gradient theory is deduced and the blasting blasting crushing zone fragmentation region energy attenuation degree and scope. Based on this analysis, the blasting hole blasting, crushing zone and blasting fragmentation region is equivalent to the boundary blasting load produce elastic vibration (the equivalent elastic vibration boundary), and through numerical simulation and analysis of acoustic emission monitoring of Blasting simulation and blasting hole blasting and other work, the definition and verification of the equivalent blasting load boundary and its mode of action.
(3) the blasting energy dissipation into the explosive process due to the chemical loss and gas discharge energy consumed, for the vibration effect of surrounding rock of tunnel excavation and the effective mechanical function of blasting vibration can be generated. This paper considers the chemical loss and gas discharge principle, a quasi three-dimensional dynamic load model, and analyzes the explosion under the pressure of the surrounding rock crushing and detonation fragmentation mechanism, defines the boundary of equivalent vibration loads, are implemented to remove the energy dissipation and effective mechanical function.
(4) the sandstone and conglomerate laboratory and separation type hob Higginson impact test, impact hardening factor under different strain rates have been determined, with PFC3D simulation show the failure process of rock under different strain rate, and the high strain rate impact hardening factor. Then, elastic modulus the impact factor of rock hardening based on modified to solve the problem of dynamic analysis of impact hardening process.
(5) monitoring the acoustic emission and the velocity of blasting vibration in tunnel surrounding rock wave length, the maximum cell size analysis meet the accuracy of the simulation process. In practical blasting, confining rock heterogeneity and vibration superimposed factors, obtained by the equivalent load boundary mode results there is a certain deviation, the inversion of blasting vibration field based on BP neural network method is proposed, the load over coefficient, the results were corrected effectively. Finally, combining with the blasting vibration velocity monitoring curve of the numerical simulation method of local load damping coefficient of elastic vibration of the performance counter.
(6) on the basis of the above analysis, this paper takes pot tunnel blasting example, established the road of blasting excavation and construction (structure) building response analysis model. Through simulation analysis, extraction of vibration velocity curves at different positions away from the explosion source and the effective tensile stress curve, established the elastic vibration field. The characteristics of vibration and dynamic response of the surrounding rock of the tunnel floor is built (structure) safety and stability of structures are analyzed.

【学位授予单位】：北京科技大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：U455.6

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