Geophysical modeling of fissuring sets in geomaterials

Experimental investigation into sets of fissures is conducted in brittle layer under uniform biaxial tension and in model of a mine working at contraction of points of a circle in radial direction.__________Translated from Fiziko-Tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 5, pp. 26–35, September–October, 2004.     

Physical modeling of the grain size influence on acoustic emission in the heated geomaterials

Physical modeling of deformation of a hardening composite sample with a filler made of quartz sand with different grain sizes has established a relation between the acoustic emission parameters in the heated geomaterial, its grain size and strength. Anomalous acoustic emission has been revealed within definite heating temperature ranges, correlating the geomaterial strength in the first case and with the geomaterial grain size in the second case. The resultant experimental relation between the strength and grain size of agrees with the Hall-Petch relation.     

脆性孔洞煤样承载过程破坏模式及能量阶段蓄积释放规律分析

能量蓄积和释放是煤岩变形破坏的本质属性,含孔煤岩破坏模式及能量蓄积释放规律的认识对裂纹发育演化、巷道硐室围岩稳定性以及动力学灾害防控至关重要.为了得到脆性孔洞煤样承载过程破坏模式及能量阶段蓄积释放规律,通过开展单轴压缩试验,运用高速摄像机和声发射监测系统分别对承载煤样的破坏过程及内部损伤演化信息进行监测,并对煤样力学特...     

分层开采煤矿的矿震能量释放模型与能量释放谱

以下行分层开采的我国东北某大型煤矿为工程背景,通过现场微震观测和工程数据分析,探索矿震能量释放的时空分布规律及其工程应用价值.发现在没有显著的外部长周期调制动力流入的矿区,各相同地应力强度环境持续开采引发的矿震能量累积释放的时域分布均符合3参数的S形Logistic阻滞增长模型;不同地应力强度环境间,该模型的3个参数是地应力强度的自相似函数.通过最大主应力建立起不同地应力强度环境开采进程的典型矿震能量释放谱,定量揭示了开采活动与矿震能量释放间的内在联系及力学机理.     

开挖卸荷条件下煤岩变形破坏与能量释放的数值分析

煤岩原始存在着大量不规则无序分布的节理/裂隙和软弱夹层等断续结构,这些断续结构的几何形态、尺寸、分布、接触以及填充物性质决定着煤岩的物理力学性能与变形破坏行为。现有的数学或力学方法尚不足以从理论上准确刻画断续结构及其对煤岩变形破坏的控制作用。本文采用高精度CT成像和三维重构方法,构建了体现不连续节理/裂隙的不规则几何形态、接触与切割状态以及网络结构特征的断续煤岩三维数值模型,引入单元生死算法定量分析和直观显示了不同开挖卸载模式下断续煤岩变形破坏的应力场、破坏区域及空间分布、能量耗散与能量释放特征,揭示了卸载模式、断续节理/裂隙对煤岩力学性质及破坏机制的影响,为认识和掌握开挖卸荷对断续煤岩变形破坏的控制作用提供了方法和途径。     

基于Steiner最小树相似模拟裂纹扩展与能量传播的机理

采矿工程中上覆岩层裂纹扩展及其分布规律一直是研究的难点,直接影响井下工作高效开展及安全,对于高瓦斯矿井还涉及到瓦斯抽采效率提高问题。基于Steiner最小树模型建立裂纹拓展与能量传播的关系,指出裂纹的贯通拓展是沿着耗能最小而最快释放能量的路径。并建立相似模型试验中的真实裂隙与数学裂隙模型,将问题定义为约束型的Steiner树问题。覆岩破坏形式遵循基于四点以离层裂隙为主导的模型。进一步开展室内三轴加载试验,表明理论和真实破裂角与赋存深度的关系并不明显。从力学机理上分析,局部岩石的破坏面可以由摩尔库仑准则解释,而从能量角度分析,众多不同岩性破裂面组合而成的路径也是最优路径。最后揭示了岩层移动角公式参数的内在涵义,指出修正公式是煤炭地下开采上覆不同部分岩层裂隙拓展的有机统一,是Steiner最小树原理的直接体现。     

Numerical modeling of rock failure

Numerical calculations for the magnitudes of stresses at the instant of failure and angles at which it occurs are presented on the basis of stiff- and elastoplastic body models for plane and axially symmetric strain. Institute of Mining, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia. Translated from Fiziko-Tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 2, pp. 36–44, March–April, 2000.     

Numerical modeling of hydraulic fracture initiation and development

Studying initiation and propagation of hydraulic fractures is carried out based on the hypersingular boundary element method. __________ Translated from Fiziko-Tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 1, pp. 45–63, January–February, 2007.     

Geomechanical conditions for quasi-resonances in geomaterials and block media

Conclusions  Based on voluminous information about relations between the dimensions of the central zones of crustal earthquakes and various energy classes of underground explosions, as well as mine shocks and man-induced tremors, therefore, the hypothesis that we had previously advanced relative to the quasi-resonant mechanism of their manifestation is confirmed. Here, the geomechanical conditions for the development of quasi-resonances associated with the inducement of pendulum waves are characterized by the dimensionless energy criterion k:

Utilization of elastic energy of rock mass as a source of renewable energy

The authors investigate modes and parameters of mining operations with a view to create conditions for transmission of geotechnologically produced kinetic energy of rocks to electric generators. The features of application of energy-harvesting equipment in underground mining of hard minerals are discussed. The low-frequency energy trap designed to entrap elastic energy of rock mass oscillations operates in a wide range of amplitudes and frequencies of rock mass vibration, and is composed of three nonlinear oscillators having preset mass and elastic characteristics.     

Numerical modeling of deformation and failure of sandstone specimens

The author has simulated behavior of geomaterials based on the modified models of Drucker-Prager-Nikolaevski and Rudnicki. It is shown how fractures extend under stresses applied on a section of a specimen surface. The characteristic patterns are obtained for deformation localization in low porosity and high porosity sandstone under biaxial compression, and the stress-to-strain curves are plotted. __________ Translated from Fiziko-Tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 1, pp. 69–79, January–February, 2008.     

Variations of temperature in specimens of rocks and geomaterials under failure

Loading causes stress concentration around defects in rocks, which induces initiation and propagation of cracks. Physically, external loading shows itself in rocks as acoustic and electromagnetic emission, included infrared radiation. Experimentally, it is found that in specimens of geomaterials under uniaxial tension, temperature is minimum; under uniaxial compression, temperature grows; under triaxial stress, temperature is maximum. It has been succeeded to derive equations for temperature prediction in a material in the zone of main crack as function of failure load. The method to estimate stress state based on the data on infrared radiation in materials is developed.     

岩石加荷破坏弹性能和耗散能演化特性

开展大理岩、灰岩和砂岩的常规三轴试验,研究岩石变形过程的能量非线性演化特征。结果表明:岩样屈服前外力功大部分转化为弹性应变能存储于岩样内部,耗散能增加的很少,屈服点后耗散能快速增加,弹性能增速变缓。岩石的极限存储能具有围压效应,随着围压增加,岩石破坏时的极限存储能逐渐增加。极限存储能还与岩石本身的性质有关,岩石的强度越高,脆性越强,极限存储能愈大。灰岩极限存储能最大,大理岩极限存储能次之,砂岩极限存储能最小。根据弹性能和耗散能的演化规律,构建了岩石变形破坏过程中弹性应变能的非线性演化模型,理论模型与3种岩石的试验结果吻合较好。     

油气悬挂缸数学模型和仿真分析

根据油气悬挂缸的结构和工作原理 ,建立了数学模型 ,模型仿真结果和试验结果的一致性 ,证明了该模型的正确性。通过对油气悬挂缸进行计算机仿真和试验研究 ,分析了气腔初始充气压力和温度对悬挂缸性能的影响     

Numerical modeling of overburden rehandling with draglines

The numerical modeling techniques are exposed and some mathematical problems are formulated to determine final spatial positions of the technology components included in open cutting with direct dumping, such as a disintegration of broken rocks, a rock pile and a dragline. The discussed formulations were integrated in algorithms and programs designed for automated composition of operating procedures for blasted overburden rehandling by draglines.     

Numerical modeling of hydrofracturing in a multilayer coal seam

The mathematical model of the process for hydrodynamic fracturing in a multilayer coal seam is proposed. The model is based on the equation of continuity and Darcy’s law. The filtration — temperature analogy allows solving the obtained non-linear, non-stationary problem in an axisymmetric statement for the pressure function as the heat-conductivity problem, by the finite-element method. The calculation results yield estimation of the radius of degassing borehole influence zone. __________ Translated from Fiziko-Tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 1, pp. 61–70, January–February, 2006.     

Numerical modeling of the coal-and-gas outburst gasdynamics

The article discusses the problem of coal outbursts into mined-out space based on the nonstationary and nonequilibrium velocity and temperature approach of the mechanics of inhomogeneous media, presents the math models with and without taking account of intergranular pressure of solid particles, and compares the new assessment with the available calculation and experimental references. Based on the analysis of the mixture flow behavior, the authors have found some rules in the relationships of depression waves, shock waves, initial concentration and diameter of particles in coal-and-gas mixtures.     

Numerical modeling of wavefields of microseismic events in underground mining

The article describes modeling procedure and calculation of wave fields in microseismicity monitoring in anisotropic medium. The research findings are intended for testing of processing algorithms for data of seismic observations in underground mining.     

Numerical modeling of localized shear deformation in a convergent channel

The paper discusses mathematical modeling of localized shearing in a convergent channel, where displacement discontinuities occur along slip lines, and it is assumed that material behaves plastically at them and elastically outside them. Based on the finite element method, algorithms and numerical solutions for boundary value problems involving arbitrary number of slip lines are developed, as well as fields of stresses and displacements are built.