煤岩力电耦合模型及其参数计算

电磁辐射技术已经在矿山煤岩动力灾害预报中得到了应用，根据煤岩强度的统计理论和损伤力学理论，建立了受载煤岩的力电耦合模型，推导得到了该模型中参数的确定方法，并结合实验结果对其中的参数进行了计算．结果表明：煤岩材料的破坏是内部代表性体元微损伤累积的结果，电磁辐射可以反映煤岩体的损伤程度，力电耦合模型能够较好地描述煤岩变形破裂过程的电磁辐射规律，参数的拟合相关系数较大说明该方法合理可行．     

基于有限元模型修正技术的结构损伤检测

结构损伤检测已成为工程领域中的前沿性课题之一.由于联合静动法模型修正技术包含了结构的众多信息,因此利用联合静动法模型修正技术进行结构损伤检测时能够得到较好的结果.在传统的联合静动法基础上,提出了一种基于有限元模型修正技术的新式联合静动法.结合一个简支梁的算例,讨论研究了该方法实现过程.仿真计算结果表明了该新式联合静动法模型修正技术的有效性.     

动静耦合加载下受载钻孔试件力学特性及破坏特征研究

钻孔卸压是防治冲击地压的主要手段,卸压孔径是重要的卸压参数.研究动静组合作用下受载试件钻孔卸压单轴压缩力学性质和破坏特征,对钻孔卸压参数优化及保持钻孔卸压后围岩的稳定性具有重要意义.采用三维动静载多场耦合试验系统、DS5-8B声发射采集分析系统和XTDIC三维全场变形测量及分析系统,开展了受载试样钻孔卸压后动载扰动的单轴压缩试验,探究了预静载水平、动载幅值、钻孔直径对试件单轴力学特性和破坏特征的影响.试验结果表明:动静载荷之和小于73%无侧限抗压强度(σuc)时动静组合作用对试件单轴压缩强度起增强作用.扰动后试件的弹性模量明显增大,钻孔对试件强度起削弱作用,且呈正相关,钻孔直径越大,削弱效果越明显.钻孔和动静载荷影响疲劳应变,随着钻孔孔径和动载幅值增大疲劳应变呈线性增大,预静载影响疲劳应变,试件处于压密阶段时,动载扰动会使试样内部原生裂隙压密,疲劳应变较大;试件处于弹性阶段时,裂隙发育很少,疲劳应变减小;试件处于塑性阶段时,出现不可逆的塑性变形,疲劳应变增加.钻孔直径的增加会使试件声发射事件(振铃计数、能量)减少,损伤阈值降低;动载扰动会使试件压密,增加声发射事件,提高试件的损伤阈值,且破坏时瞬间释放的能量变大,试件表现出更强的脆性.钻孔直径的增大改变了试件裂隙发育特征,钻孔直径从0增大到12 mm,试件从拉伸破坏转变为X状共轭斜面剪切破坏,且部分试件表面出现了片状剥落.该研究为钻孔卸压围岩破坏机理的揭示提供理论基础,对钻孔卸压参数优化具有重要参考作用.     

基于统计损伤本构模型和能量演化机理的含瓦斯煤岩脆性评价方法（英文）

脆性是评估岩石力学性能的重要指标,准确评估脆性对钻井和水力压裂设计具有重要指导意义。为探究不同瓦斯压力下煤岩的脆性演化特征,本研究提出了一种基于统计损伤本构模型和能量演化机理的含瓦斯煤岩脆性评价方法。首先,结合有效应力原理与Hoek-Brown准则,建立了含瓦斯煤岩的统计损伤本构模型,并通过不同瓦斯压力下的三轴压缩试验进行了验证。随后,基于能量演化机理,分析了两个能量特征参数：弹性能量比例P_e和耗散能量比例P_d,并结合损伤应力阈值σ_ea和σ_eb,探讨了含瓦斯煤岩的损伤演化特征。最后,将能量特征参数与损伤参数相结合,提出了一种新的脆性指数BIE。结果表明,统计损伤本构模型得到的理论曲线与试验曲线具有较高的吻合度,准确反映了含瓦斯煤岩的应力-应变特性,并揭示了煤在峰值后阶段的应力下降特征和软化特征。形状参数n和尺度参数F₀分别表征煤岩的脆性和宏观强度。随着瓦斯压力从1 MPa增加到5 MPa,n和F₀分别降低了22.18%和60.45%,表明煤岩的脆性和强度降低。最大损伤速率D′_max与峰值弹性能储存极限U_e^max与煤岩的脆性呈正相关。新建立的脆性指数BIE有效地反映了含瓦斯煤岩的脆性特征,揭示了在较高瓦斯压力下煤岩脆性降低及对塑性变形敏感性增加的现象。     

水压轴压联合作用下煤岩的统计损伤本构模型研究

从煤岩内部节理、裂隙和物质分界面等缺陷的随机性分布特征出发,基于反映煤岩内部缺陷的微元强度服从weibull分布的概念,建立了水压和轴压联合作用下煤岩的损伤本构模型.以东庞北井9#煤静态压缩试验为基础确定了模型里面的相关参数,并得出了与峰值应力对应的累积损伤度(即临界损伤度).研究结果表明:(1)模型参数少且易于确定;(2)模型能反映围压效应,即可以体现煤岩体强度随水压变化的规律;(3)模型参数确定方法揭示了模型参数的物理意义;(4)可以通过不同围压下煤岩体应力-应变全曲线特征及在不同围压下峰值应力与应变之间的关系来确定模型参数;(5)在弹性矩阵中引入孔隙水压力影响因子来考虑孔隙水压力对煤岩损伤本构模型的影响,这种方法被证明是可行的.     

对铰杆增力机构中滑柱力学模型的修正

对<机床夹具设计>[1,2]中抽象的滑柱力学模型,进行了分析,指出其错误在于滑柱承受的是一个非平衡力系,建立了基于平衡力系的力学模型,并推演出了相应的力学计算公式.     

对铰杆增力机构中滑柱力学模型的修正

对《机床夹具设计》[1,2 ]中抽象的滑柱力学模型 ,进行了分析 ,指出其错误在于滑柱承受的是一个非平衡力系 ,建立了基于平衡力系的力学模型 ,并推演出了相应的力学计算公式     

对铰杆增力机械中滑柱力学模型的修正

对《机床夹具设计》＾「１,２」中抽象的滑柱力学模型,进行了分析,指出其错误在于滑柱承受的是一个非平衡力系,建立了基于平衡力系的力学模型,并推演出了相应的力学计算公式。     

损伤塑性模型的耦合关系

由于ABAQUS软件的强大分析能力和模拟复杂问题的可靠性,已经在土木领域中得到广泛应用。分析了软件中能有效模拟混凝土非线性行为的损伤塑性模型(CDP)的耦合关系,并总结比较两种模型理论中损伤的物理意义。     

混凝土塑性损伤模型损伤因子研究及其应用

在有限元软件ABAQUS中,为混凝土材料定义了一种材料模型:塑性损伤模型,它可以模拟混凝土材料的拉裂和压碎等力学现象,而且使用也较为方便.本文基于能量损失原理,编制相关的计算程序,获得了现行《混凝土结构设计规范》提供的混凝土受压和受拉应力-应变关系曲线对应的混凝土损伤因子随应变增长的变化曲线.基于本文的研究成果,介绍了损伤因子在钢筋混凝土构件、新型钢管混凝土-钢筋混凝土梁节点和整体结构弹塑性分析中的应用实例.本文的有关论述和方法可为同类研究提供参考.     

A damage-based constitutive model for rock under impacting load

Using the Splitting Hopkinson Pressure Bar (SHPB) experimental system, investigations were made into the dynamic mechanical performances of underground soft rocks. The experiments proved that the measured stress–strain curves display the characteristics of plastic deformation. By making use of a revised overstress constitutive formula for the stress model and by taking into account that the strain rate and strain are a function of 1 − E(t)/E₀, a revised overstress constitutive formula for the stress model was simplified by applying dimensional analysis and consequently, a simplified overstress formula was obtained for the stress model. Then, by taking into consideration the effects of damage under a dynamic load on the dynamic loading strength of the rock, the continuous damage theory and the statistical strength theory were introduced into the development of the simplified overstress constitutive formula for the stress model. Hence, a damage-based constitutive formula for an overstress model, which can be appropriately applied to the analysis of full dynamic stress–strain curves, was developed. By using the simplified damage-based constitutive formula for an overstress model, the actually measured curves are fitted, indicating that the fitting curves and those actually measured are in good agreement.     

岩石在压应力作用下的裂纹扩展模型

在分析压应力作用下裂纹扩展模型的基础上,指出了目前几种常用的岩石中平面分支裂纹尖端应力强度因子的近似解析式所存在的问题,并给出了应力强度因子的较为简便且合理的近似表达式.     

冻融受荷岩石唯象损伤扩展特性探讨

针对工程地质和岩土工程中所涉及到的冻害问题,从细观力学机理出发,将冻融循环次数及应变和岩石的损伤变量联系起来,得到宏细观相结合的冻融受荷岩石损伤演化方程及损伤扩展本构关系;对冻融荷载作用后的岩石进行唯象损伤扩展特性分析.研究发现:岩石的冻融损伤是一个疲劳损伤破坏过程,在寒区岩体工程设计和施工中,必须考虑冻融损伤的影响;寒区工程结构受荷岩石的岩性、初始损伤状态及力学性质的不同,造成冻融循环和荷载对损伤扩展的影响差别非常大,并表现出终态的宏观差异.     

岩石软化的细观损伤模型

通过分析岩石材料应变软化的细观损伤力学过程 ,建立了岩石软化阶段的细观损伤力学模型 ,从而得到单向拉伸状态下岩石软化过程的应力应变本构关系 .     

Catastrophe model and its experimental verification of static loading rock system under impact load

According to the catastrophe model for impact buckling of static loading structures, a new catastrophe model for impact loading failure of a static loading rock system was established, and one dimension （1D） catastrophe model was analyzed. The analysis results indicate that the furcation collection where catastrophe may take place is not only decided by mechanical system itself but also relates to exterior loading, which is different from the results obtained under mono-static loading where the bifurcation collection is only determined by mechanics of the system itself and has nothing to do with exterior loading. In addition, the corresponding 1D coupled static-dynamic loading experiment is designed to verify the analysis results of catastrophe model. The test is done with Instron 1342 electroservo controlled testing system, in which medium strain rate is caused by monotony rising dynamic load. The parameters are obtained combining theoretical model with experiment. The experimental and theoretical curves of critical dynamic load vs static load are rather coincided, thus the new model is proved to be correct.     

Thermal-hydro-mechanical coupling damage model of brittle rock简

Based on fluid mechanics, thermodynamics and damage mechanics, thermal-hydro-mechanical （THM） coupling damage model of brittle rock is established by analyzing THM coupling mechanism, where THM coupling damage variable DTHM is dominated by TH coupling damage variable DTH, TM coupling damage variable DTM and HM coupling damage variable DHM, and DTH is firstly expressed in term of dimensionless total thermal conductivity of the water Nu. Permeability test, uni-axial compression test and THM coupling test are conducted to measure the permeability, elastic modulus and THM coupling stress-strain curves of brittle rock. The tested values of THM coupling elastic modulus E＇HM are in good agreement with the predicted values of THM coupling elastic modulus ETHM, which can verify the newly established THM coupling damage model.     

Damage and fragmentation of rock under experiencing impact load

1 INTRODUCTIONThe dynamic fragmentation of brittle materialsexperiences an extremely complex process ,invol-ving micro-cracks nucleation,propagation and coa-lesce , which breaks the solid into fragments . Butthe process canfall into two successive phases gen-erally : damage stage and fragmentation phase .The most widely applied theoretical models of theprocess , such as those based on the pioneeringstudies of Grady[1], Glenn et al[2],involve sometype of relatively si mple global energy ba…     

爆炸荷载作用下锚固围岩稳定性分析

通过对爆炸波在岩体中的传播与衰减特性以及与锚固围岩的相互作用分析,基于正交设计理论,以洞室跨高比、锚杆长度、锚杆密度、围岩类别、一次爆炸炸药量、炸药距离洞室顶端的距离等因素设计了18组正交参数,对爆炸荷载作用下锚固围岩稳定性数值模拟计算,得到了锚固围岩应力、质点振动速度峰值和振动主频率的分布规律,分析了锚固围岩最大主应力、质点振动速度峰值、振动主频率受一次起爆炸药量、炸药距洞顶距离、围岩力学性质、支护方式、洞室形状等因素的影响,据此建立了以最大主应力为标准、质点振动速度峰值和振动主频率为主要指标的锚固围岩稳定性评价标准.     

爆破载荷作用下的岩质边坡动力稳定系数

采用动力有限元软件,对所选工程实例中的岩质高边坡危险滑移面节点动应力进行计算,并与相应节点的静应力叠加,通过稳定系数公式计算出边坡滑体各时刻的稳定系数,得出边坡动力稳定系数时程曲线。工程应用表明,该稳定系数用于衡量边坡爆破开挖时的安全性切实可行。     

Damage statistical mechanics model of top coal in steep top caving coal

Damage statistical mechanics model of horizontal section height in the top caving was constructed in the paper. The influence factors including supporting pressure, dip angle and characteristic of coal on horizontal section height were analyzed as well. By terms of the practice project analysis, the horizontal section height increases with the increase of dip angle β and thickness of coal seam M. Dip angle of coal seam β has tremendous impact on horizontal section height, while thickness of coal seam M has slight impact. When thickness of coal seam is below 10m, horizontal section height increases sharply. While thickness exceeds 15m, it is not major factor influencing on horizontal section height any long.