Numerical analysis of tunnel reinforcing influences on failure process of surrounding rock under explosive stress waves

Based on mesoscopic damage mechanics, numerical code RFPA2D （dynamic edition） was developed to analyze the influence of tunnel reinforcing on failure process of surrounding rock under explosive stress waves. The results show that the propagation phenomenon of stress wave in the surrounding rock of tunnel and the failure process of surrounding rock under explosive stress waves are reproduced realistically by using numerical code RFPA2O; from the failure process of surrounding rock, the place at which surrounding rock fractures is transferred because of tunnel reinforcing, and the rockfall and collapse caused by failure of surrounding rock are restrained by tunnel reinforcing; furthermore, the absolute values of peak values of major principal stress, and the minimal principal stress and shear stress at center point of tunnel roof are reduced because of tunnel reinforcing, and the displacement at center point of runnel roof is reduced as well, consequently the stability of tunnel increases.     

爆炸场可视化

目的将爆炸场可视化并设计一个切实可行的软件工具分析爆炸场. 方法提出一个理想的带防护墙的二维爆炸场模型,该模型用MMIC程序进行数值模拟. 模拟输出的物理数据经过规范化、编码、映射和显示等处理之后转化成DIB位图图像数据. 程序设计采用了面向对象方法. 结果与结论利用该工具,可视化了带防护墙的二维爆炸场,从中可观察到爆炸场的概貌以及冲击波传播的一些细节,如反射、绕流和马赫反射等.     

应力冲击波在结构节点的反射和透射

应用固体冲击波理论，分析杆中一维压应力冲击波，通过结构十字形刚节点时的反射和透射行为，建立估算反射波和透射波波后参数估算公式．     

挡墙形状对二维爆炸场影响的数值模拟研究

研究二维爆炸场中挡墙的形状对冲击波传播的影响 .在整个模拟过程中不考虑外力、外源和热交换的影响 ,采用流体网格得到了可压缩流体的偏微分守恒方程 ;并且通过使用多流体网格方法及运用“和”分裂格式完成了输运步的计算 ;同时对于爆轰产物采用了JWL状态方程 ,并将空气简化成理想气体 .最终获得了挡墙的两侧边缘的形状对冲击波传播影响的具体情况 ,并列出了二者之间的关系 .可以看出靠近爆源一侧的挡墙形状对冲击波传播的影响更明显 .     

Numerical simulation of the parabolic shell surface under blast wave loading

Deformation of parabolic shell surface under explosion shock waves is a complex dynamic problem. Because of reflection and interference of blast wave, it’s hard to analytically delineate the dynamic responds of radar parabolic shell surface on blast wave. To gain the characteristics of thin shell deformation under impulsive loading of blast wave, numerical simulation methods for blast load on the shell structure was studied and analyzed. Euler-Lagrange numerical simulation was implemented by AUTODYN code to simulate the problem. Through analysis on deflection feature of radial position under different explosive mass and detonation height, an equation was founded by fitting the deflection results from numerical simulation results of shockwave loading. Experiments were arranged to confirm the validity of the formula. The results gained by simulation are consistent with experiments, and the formula can be used to delineate the deflection of aluminum alloy parabolic shell under blast loading.     

CE／SE方法在障碍物对爆炸冲击波干扰流场计算中的应用

应用高精度的CE／SE方法对厂房中爆炸冲击波扫过障碍物挡墙形成的流场进行了二维数值模拟，具体分析了障碍物、厂房内壁与冲击波相互作用的规律，得到了能够反映障碍物作用前后波系结构变化的压力等值线图．数值结果显示了冲击波遇障碍物发生反射、绕流等现象，形成复杂波系；通过与尤障碍物存在的爆炸流场对比，分析了相对于爆点不同位置的障碍物对爆炸流场的影响；最后改变爆点个数，对爆炸流场的变化做了进一步分析．数值模拟结果符合相关物理规律．     

Numerical simulation for explosion wave propagation of combustible mixture gas

A two-dimensional multi-material code was indigenously developed to investigate the effects of duct boundary conditions and ignition positions on the propagation law of explosion wave for hydrogen and methane-based combustible mixture gas. In the code,Young’s technique was employed to track the interface between the explosion products and air,and combustible function model was adopted to simulate ignition process. The code was employed to study explosion flow field inside and outside the duct and to obtain peak pressures in different boundary conditions and ignition positions. Numerical results suggest that during the propagation in a duct,for point initiation,the curvature of spherical wave front gradually decreases and evolves into plane wave. Due to the multiple reflections on the duct wall,multi-peak values appear on pressure—time curve,and peak pressure strongly relies on the duct boundary conditions and ignition position. When explosive wave reaches the exit of the duct,explosion products expand outward and forms shock wave in air. Multiple rarefaction waves also occur and propagate upstream along the duct to decrease the pressure in the duct. The results are in agreement with one-dimensional isentropic gas flow theory of the explosion products,and indicate that the ignition model and multi-material interface treatment method are feasible.     

爆炸冲击波的环流效应数值模拟研究

利用任意拉格朗日欧拉（ALE）算法和炸药爆轰产物的JWL状态方程。针对有障碍物阻档时空气冲击波的环流现象进行数值模拟，得到在爆源周围有障碍物时爆炸场初始发展、环流情况及整个传播过程，并分析了空气冲击波的环流规律。研究结果表明，所采用的方法可以很好地描述空气冲击波环流流场参量分布与变化规律。数值模拟结果符合物理规律。     

Air-Decking Technique in Bench Blasting

1 Introduction The air-decking technique (Fig.1) has been ap- plied in mining industry abroad. Melniokov and other experts[1–5]* thought that the existence of the air layer causes the second loading waves and a series of sub- sequent loading waves stirred up in the process of the explosion, and also causes further breakage of the fractured rock mass resulting from the previous pres- sure wave. Although the average pressure on the borehole resulting from the air-decking structure is lower than…     

Characteristics and mechanisms of strain waves generated in rock by cylindrical explosive charges

A superposing principle, by suitably adding the strain waves from a number of concentrated explosive charges to approximate the waves generated by a cylindrical charge based on the strain wave of a point or small spherical explosive charge generated in rock, is used to further study the triggering time of strain gauges installed in radial direction at same distances but different positions surrounding a cylindrical explosive charge in rock. The duration of the first compression phase and peak value of strain wave, and furthermore, their differences are analyzed and some explanations are given. Besides that, the gauge orientation in which the maximum peak value occurs is also discussed. At last, the effect of velocity of detonation(V.O.D.) of a cylindrical explosive charge on the strain waves generated in the surrounding rock is taken as key research and the pattern of peak amplitude of a strain wave varies with the V.O.D. is likely to have been found.     

飞片碰靶产生冲击波的简化模型

提出了一种计算飞片靶产生冲击的增长与衰减规律的简单方法,采用该方法计算了具有密度和速度空间分布的铝飞片碰撞静止铝平面靶驱动的冲击波在靶中的增长与衰减的情况,并与我们在大型计算机上的数值模拟结果进行了比较.     

Numerical simulation of shock wave interaction with a deformable particle based on the pseudo arc-length method

In this paper, we combine the pseudo arc-length numerical method with the mathematical model of multiphase compressible flow for simulating the shock wave interaction with a deformable particle. Firstly, an arc-length parameter is introduced to weaken the discontinuous singularity of governing equations, and an efficient pseudo arc-length numerical method of multiphase compressible flow is proposed. Then the accuracy and adaptive moving mesh property of this algorithm are tested. Finally, the multiphase pseudo arc-length numerical method is applied to the problem of interaction between shock wave and the deformable particle. Through the flow flied change and data analysis of key points, it can be found the complex wave structures are presented after the interactions between the planar incident shock wave and the metal particle, and all these wave interactions lead to the movement and deformation of metal particle, and then the deformed particle will affect the transmitted shock wave back. According to the discussion, the deformation of particle and shock wave propagation in the particle are determined by the shock wave impedance of each medium and shock speed, so the interaction between shock wave and the deformable particle can be studied on the basis of physical properties of explosive mediums.     

结构体对爆炸冲击载荷响应的数值模拟

分析了单自由度弹簧－质体体系对爆炸冲击载荷的特征响应，建立起结构体对爆炸冲击载荷响应的数值模型，并从此模型出发，对爆炸冲击波破坏准则Ｐ－Ｉ准则进行合理性分析，确定其可靠性．     

基于保色散关系的迎风WENO格式的研究

W ENO(W eighted E ssentially N on-O scillatory)格式能够高分辨率地捕捉诸如激波等间断,而保色散关系(D issipation-R elation-P reserv ing,DRP)格式适宜于处理高频波传播问题。计算气动声学(Com putational-A eroacoustics,CAA)领域有大量的既有高频波传播又带有激波的问题,结合W ENO格式和DRP格式的优点基于保色散关系构造出优化的迎风W ENO格式。数值实验中比较该格式捕捉波数的能力和精度,显示处理CAA基本问题具有高精度、高分辨率的特点。     

直角拐弯巷道中瓦斯突出冲击气流传播特征研究

为研究突出冲击气流的传播过程及其特征,以直角拐弯巷道为例,建立了数值计算模型,对突出冲击气流的传播过程和瓦斯气体的输运过程进行了数值模拟,分析了突出冲击气流的传播衰减特征和突出瓦斯气体的输运特征.结果表明：突出能形成高速运动的冲击气流及冲击波,且突出冲击波传播速度能够超过当地音速;突出冲击气流在通过拐弯巷道时,会发生绕射及反射,其强度可能大于拐角前的强度,而在通过拐角之后衰减幅度较大;突出能在巷道内形成高浓度瓦斯区域,且瓦斯对流传质速度小于冲击气流运动速度.通过模型试验研究,初步验证了数值模拟的结论.     

超高应变率下岩石的破坏机理

通过对大理石的轻气炮试验进行三维数值仿真重现,探索了岩石在超高应变率下的破坏机理.大理石试样中两个高速应力计的实测应力信号被用作数值模拟的匹配目标,结果表明,在高速冲击压缩载荷下,细观静水压破坏是大理石的主要破坏机制,而不是通常认为的细观剪切或拉伸破坏.此外,为再现不同冲击速度下大理石的物理实验观测数据,提出了新的考虑...     

煤与瓦斯突出冲击波传播规律研究

应用应力波理论研究了煤与瓦斯突出过程中产生的冲击波在煤体界面上的反射、透射现象,得到了入射、反射和透射超压解析解,根据空气动力学分析了冲击波沿巷道方向传播规律.结果表明：透射超压值为入射超压的两倍,而反射超压值略小于入射超压.冲击波超压与冲击气流、突出的膨胀能量成正比,与通风巷道的截面面积呈反比;当冲击波在单个层状煤体中传播时,它会在其两端自由界面上出现反射,反射波反向卸载,自由面上物体振动速度加倍,又将其撕裂成若干个更薄的层状体;当冲击波传播到构造煤和硬煤岩体的分界面上时,产生了强烈的透射和反射现象,透射波在分界面上叠加,其应力值加倍,煤体受到强烈压缩作用,当其超过软煤强度时,软煤被压裂破坏.     

爆炸荷载作用下部分埋置结构响应的数值模拟方法

为了比较不同的数值模拟方法进行动力响应分析的优缺点,采用爆腔内壁施加经验压力和高爆炸药材料模型(ALE算法)模拟爆炸荷载,分析了部分埋置结构的动力响应.结果表明:爆腔内壁施加经验压力时程模拟爆炸荷载的方法与Lagrangian算法模拟爆炸荷载的方法所得的数值结果相近,但其计算精度低于ALE算法,Lagrangian算法和ALE算法相比,所需计算工作量较少,爆腔内壁施加经验压力模拟爆炸荷载的方法在实用性上具有一定的优势.     

靶场钻地弹爆炸位置的探测

针对靶场钻地弹爆炸位置探测的问题,提出了一种基于变化检测的位置探测方法．首先,利用可重复触发的爆炸源和4个同步地震检波器对靶场地下应力波进行检测,通过比较打弹实验前后应力波的变化扣除地层背景干扰,获得钻地弹爆炸腔的反射信号．然后,根据波程建立以爆炸源和地震检波器为焦点的4个椭球面方程．最后,利用改进的Chan算法估计出椭球模型的交点,亦即钻地弹爆炸腔位置．仿真实验验证了此方法的可行性．该方法对靶场钻地弹实验测试具有一定的指导性．     

非均质炸药冲击起爆的临界判据研究

本文通过分析炸药内部侧向能量分配对热点能量传播的影响，提出了面积效应系数，纠正了以往判据中的不科学性，得到了更合理的透射冲击波起爆判据，并对透射冲击波起爆过程中爆轰界面的关键参数ｐ（ｔ）关系进行了推导