To reveal the mechanical deterioration mechanism of coal-rock masses during blasting excavation in gas tunnels, dynamic impact tests were performed on coal-rock composites with dip angles of 0 degrees-90 degrees using a triaxial SHPB system under 10 MPa confinement. Results demonstrate that the interface dip angle strongly governs the stress-strain behavior. Specimens with 0 degrees-45 degrees dips exhibited a pronounced nonlinear stage driven by interface closure and shear slip, while 60 degrees-90 degrees specimens displayed near-linear elasticity. Dynamic peak strength and elastic modulus followed a U-shaped trend, reaching a minimum at 45 degrees, indicating significant mechanical weakening. High strain rates further enhance the stress responses. Failure analysis showed that 45 degrees and 60 degrees specimens dissipated the most energy through coupled interface slip-shear failure, whereas 0 degrees and 90 degrees specimens retained higher integrity with only non-through cracks. A viscoelastic-plastic damage constitutive model accounting for strain-rate effects and interface closure/slip behavior was established by combining Maxwell and Bingham elements with Weibull statistics and the Drucker-Prager criterion. The model accurately reproduced the experimental evolution of strength and stiffness degradation (R-2 >= 0.89). These findings provide a crucial theoretical basis for optimizing blasting parameters and designing support systems for gas tunnels intersecting inclined coal seams.

The fracture speed of a high-grade gas pipeline subjected to high gas pressure is usually very high, such that the gas pressure near the crack-tip could not decompress rapidly. It is difficult for a high-grade pipeline to arrest crack propagation by itself; hence, an arrestor should be installed to prevent the pipeline from fracturing continuously. Because the optimization of the geometric size of the arrestor has not been well-recognized at present, it is of interest to study the dependence of crack arresting ability on arrestor size and obtain a satisfactory method to design the geometric size of the arrestor. Based on Hill's yield theory and a plastic strain-dependent damage evolution law, a transversely isotropic elastic-plastic damage model is established. The mechanical responses of X80 pipeline material under static and dynamic loadings were successfully simulated by the proposed constitutive law. Using the cohesive zone model, the high-speed dynamic fracture and crack arresting ability of the X80 gas pipeline were simulated. The dependences of crack arresting ability on the thickness and length of the arrestor were numerically investigated. The simulation results showed that the crack arresting performance increases significantly with the thickness of the arrestor. The satisfactory geometrical size of an arrestor is economically suggested.

Thin Spray-On Liner (TSL) has been widely used in underground engineering support such as mining due to its convenient operation and good support effect. The TSL applied to the rock is inevitably affected by dynamic loads from excavation. In order to study the support effect of TSL on a rock under dynamic load, a series of uniaxial compression experiments under static and dynamic loads are carried out on the TSL-coated specimen, and the costing thickness is 1 mm, 3 mm and 5 mm, respectively. The results showed that the TSL can improve the strength and peak strain of sandstone, and the degree of improvement is more obvious with the increase of costing thickness under static and dynamic load, and the loading rate of the dynamic load is about 70 similar to 110 s(-1). It was also found that the dynamic strength increases exponentially with strain rate, with the costing thickness increases, the strain rate index of sandstone increases. The good bonding ability and tensile properties of TSL ensure support to rock. Application of TSL can delay the time for cracks to appear in the specimen and increase the energy required for the failure of the specimen. The phenomenon was also simulated using ABAQUS, and the simulations show that TSL provides passive support that the pressure of TSL gradually increases with the deformation of the sandstone during the impact, and can delay the failure time of the specimen and reduce the number of cracks. That is consistent with the experiment.

土石混合料是山区高填路基工程常见的填筑材料,其剪切变形特性及模拟方法是路基填筑设计的重要依据,但其研究仍存在诸多问题.[目的]为了更全面弄清多因素影响下土石混合体剪切变形特性,建立一种能够模拟土石混合体剪切变形过程的本构模型.[方法]首先,考虑含石量、含水率、岩性和土性等四种因素,采用正交设计试验方法,开展多因素多水平下土石混合体大型三轴剪切试验研究;然后,引入统计损伤力学理论,建立土石混合体轴向损伤模型和轴向损伤演化模型,进而建立土石混合体统计损伤本构模型,给出模型参数的确定方法;最后,将理论模型曲线与土石混合体剪切试验曲线进行比较.[结果]结果显示:土石混合体轴向剪切变形呈明显的阶段性特征;随着含石量由25％增加至70％,内摩擦角由35.5°近似线性增加至46.8°;内摩擦角不随土性和岩性的改变而显著变化;随着含水率由0增加至5％,内摩擦角由40.2°增加至42.4°,但随着含水率持续增加至试样饱和,内摩擦角逐渐减小至36.8°;此模型能够较好地模拟不同围压条件下土石混合体应力-应变试验曲线.[结论]结果表明:随着围压的增大,应变类型由软化型不断向硬化型转变,体应变由剪胀型不断向剪缩型转变;土石混合体内摩擦角的影响因素主次排序为含石量→含水率→岩性→土性;统计损伤理论能够应用于阐释土石混合体变形力学特性.

页岩的吸附能力依赖于其孔隙结构、矿物组成、气体压力及储层温度等.采用蒙特卡洛法,对6种主要页岩成分纳米孔隙中的甲烷吸附行为进行了分子模拟,研究了压力、温度对甲烷吸附量的影响规律,对比了甲烷在有机质、石英、蒙脱石、高岭石、伊利石中的吸附差异,分析了甲烷分子在纳米孔隙中的分布特征和吸附比例.分子模拟结果表明,虽然甲烷吸附量随着温度的升高而线性降低,并随着压力的增大而逐渐提高,但其增加速率会逐渐放缓,其依赖关系可以采用联合的幂函数进行描述.甲烷分子在纳米孔隙中同时表现为吸附态和游离态,吸附态所占比例随着压力的增大而逐渐降低.主要页岩成分的吸附比例存在较大差异,其大小关系为高岭石>伊利石>蒙脱石>有机质(C5H4O2、石墨烯)>石英.

桥梁设计与施工需要高度关注装配式桥墩的抗震性能,以某公路桥梁墩柱为例,基于时程分析法研究装配式桥墩的抗震性能.建立灌浆套筒连接式桥墩的钢筋混凝土结构模型,对该装配式桥墩在人工地震波作用下的动力时程响应进行有限元模拟,分析其混凝土损伤与钢筋受力特征.结果表明,该装配式桥墩的抗震性能良好,在设防地震下混凝土保护层不会损坏,在设防地震下墩柱中下部的混凝土保护层会发生损伤,但主筋应力远低于屈服强度,墩柱结构仍具有较高的安全性.

针对多孔岩体蠕变诱发的延迟压实局部化失稳问题,提出了一种基于弹黏塑性及可控性理论的压实局部化失稳判别准则.通过构建局部常微分方程系统,定义定常外部摄动条件下的弹黏塑性本构算子,用于识别自发传播压实局部化带内的不稳定加速变形.通过检查方程系统的可控性损失,得出了多孔岩体压实局部化的失稳指数.基于弹黏塑性本构模型,分析了平面应变条件下多孔岩体中的拟瞬时和延迟压实局部化,对所提出的失稳指数进行验证.进一步地,利用有限元数值模拟,验证了该失稳指数在分析边值问题中延迟压实局部化失稳的适用性.

针对吊装多体系统,建立了考虑刚柔耦合效应的动力学模型,并提出了抑制系统振动的双模输入整形控制法.分别利用等效弹簧质量阻尼系统和空间悬吊系统模拟了吊臂弹性振动和吊物空间摆动,结合递推列式和浮动坐标系对各部件开展运动学描述;基于拉格朗日方程,推导并建立了计及多体吊装系统刚柔耦合效应的动力学模型.同时对某大型轮式起重机进行了动态响应分析,并与实测结果对比验证了模型有效性.根据耦合系统振动特性,设计了能同时抑制吊臂振动和负载摆动的双模零阶振(ZV_2)输入整形器和双模零阶振微分(ZVD_2)输入整形器.通过振动控制分析得到:对于大型柔性臂架系统,双模输入振型控制法的振动抑制效果相对于传统单模输入整形法得到了极大提升,ZVD 2整形器作用下系统的残余振动幅值低于5％.

页岩气的吸附特性主要依赖于甲烷分子在纳米孔隙中的吸附行为.本文运用巨正则蒙特卡洛法(GCMC)分析甲烷分子在石英、蒙脱石、有机质纳米孔中的吸附行为,研究气体压强、环境温度、孔径对甲烷吸附性能的影响规律.分子模拟结果表明:甲烷分子在有机质纳米孔中的吸附量明显大于在蒙脱石和石英纳米孔中的吸附量.在孔壁附近0.5nm范围内,甲烷分子近似平行于孔壁分布;而在远离孔壁面,甲烷分子的分布比较分散.三种纳米孔中吸附气所占比例在46.56％～82.20％之间.在相同温度和压强下,甲烷吸附量随着孔径的增大而线性增加;在相同温度和孔径下,甲烷吸附量随着压强的增大而增大,二者之间的物理关系可以近似采用幂函数进行描述,甲烷分子的吸附比例随着压强的增大而近似于线性减小;在相同压强和孔径下,甲烷吸附量随着温度的升高而线性降低.

针对大型吊装多体系统在回转作业时的刚柔耦合动力学行为,开展了简化模型构建和动态响应分析.利用等效弹簧质量阻尼系统描述吊臂臂头弹性振动,利用空间悬吊系统模拟吊物空间摆动;以浮动坐标系对系统各部件开展运动学描述,基于拉格朗日方程,采用递推列式推导并建立了吊装多体系统的等效简化分析模型,并给出相应数值计算方法.针对某大型轮式起重机开展了仿真分析,通过与实测数据对比分析表明,简化模型能较好地评价柔性吊装多体系统的非线性动力学行为;对柔性臂架振动频谱分析表明,在轻载长绳状态下,吊臂振动幅值受吊物偏摆激励和自身惯性激励的共同影响,但在重载短绳状态下,响应幅值主要取决于吊物偏摆激励,且系统刚柔耦合效应明显增强.

Based on the analysis of the deformation and growth of a representative elliptical microcrack with arbitrary orientation and geometrical size embedded in a representative volume element subjected to triaxial stress and pore pressure, the additional compliance tensor induced by an embedded opening/closed elliptical microcrack is derived. Assuming numerous elliptical microcracks, and introducing an appropriate probability density function to describe the distribution of orientation and geometrical size of microcracks, the additional compliance tensor induced by microcracks system is analyzed in Taylor’s scheme, and a three-dimensional micromechanics model for gas saturated coal materials is obtained. The validity of the proposed micromechanics model is verified by the agreement between the theoretical and experimental results of gas saturated coal under triaxial compression. The effect of pore pressure and confining pressure on the damage behavior induced by microcracks is investigated. The calculations show microcracks of coal under higher pore pressure will be more inclined to slide and grow, and induce larger additional strain in the last deformation stage.

Based on the finite element simulation of tectonic stress field,the distribution of coal gas in Panxian Basin is investigated in this paper.The finite element results show that the areas with larger maximum principal stress in Panxian Basin are mainly distributed at the area of Tucheng skew,the southeast area of Zhaozihe skew,and the east area of Jiupuan skew.The areas with larger Mises stress are similar of those with larger maximum principal stress.Since the areas with larger maximum principal stress are usually enriched of coal seam gas,it is suggested these areas should be geologically explored.

A simulation model considering mountain shape, backfilling vertical shaft, embanks and slab track was built using dynamic theory and numerical simulation theory. Train was considering as a moving load. The spectral characteristics of high-speed rail loading were analyzed. Natural frequencies and mode shapes characteristic of the model were displayed. Response of displacement and stress of the vertical shaft lining was studied under different train speed and two trains passing each other. Results show: train loads are high, medium and low frequency components; since the higher order vibration, the corresponding more complex shapes, and the excitation energy is higher required; the first order vibration mode is up and down with vibrating in phase (tension / compression), and the second order vibration mode is torsional, left up and right down with inverting vibration; vertical displacement, horizontal displacement and stress of the backfill shaft are reduced with the reduction of train speed; vertical displacement and additional dynamic vertical stress are reduced more effectively; the additional dynamic displacement and dynamic stress are larger at the top of the shaft for the freedom surface; comparing with the single train moving, vertical displacement and vertical stress of vertical shaft increases significantly under two trains passing each other, especially in the mouth of the shaft and range 200m depth below the surface.

提出了对工科专业弹性力学课程教学的具体建议，以提高学生对弹性力学课程的学习积极性和主动性。针对不同专业合理选取教学内容，在教学环节中注重引入工程实例，注重解题思路、多学科结合教学以及综合考核学生应用能力。

Making use of internal variables and a proper generalized time scale to describe the irreversible deformation history of salt rock, a constitutive model coupled of creep deformation and damage development of salt rock is formulated. A creep correlated function is defined to describe the effect of loading time on creep deformation of salt rock, and a fourth order damage tensor is introduced to formulate the anisotropic development of material damage. The creep experiments of salt rock under triaxial compression are simulated by the proposed constitutive model. The good agreement between the calculated and experimental results shows the proposed constitutive model can well describe the creep behavior of salt rock.

Based on the analysis of the deformation field caused by elliptic crack embedded in infinite isotropic elastic matrix, the additional compliance tensor induced by a single opening/closed elliptic microcrack in a representative volume element and its growth is deduced, respectively. Considering the deformation of microcracks system, a macro-micro damage model for brittle rocks under arbitrary loadings is obtained by making use of statistical mechanics and a probability density function. The effect of elliptic ratio on material damage is investigated, and it is shown that the material damage increases with elliptic ratio, and the dependence of material damage on elliptic ratio increases with loading force. The tests of uniaxial tension for concrete and uniaxial compression for granite are simulated by this model, and good agreement is achieved between the calculated and experimental results.

The stress intensity factor depends on the geometric sizes of finite plate,while the corresponding empirical formula by Brown has not discussed the application scope or computational accuracy.Based on the finite element procedure,the stress intensity factor of centre crack in finite plate is calculated.The dependence of the width and length of plate on stress intensity factor is investigated.The calculated results show the stress intensity factor of central crack increases with the width and length of finite plate.The correction coefficient of stress intensity factor from finite element calculation is compared with that from Brown,Feddersen,and Dixon's methods,and the computational accuracy of Brown,Feddersen,and Dixon's methods has been discussed.Both the comparison of the finite results and the calculation results of three empirical formula show Feddersen's method has the highest computational accuracy.Dixon's result is better than that of Brown's when the ratio of crack length is lower than 20%,while Brown's result is better than that of Dixon's when the ratio of crack length is higher than 20%,and Dixon's method is not accurate when the ratio of crack length is higher than 40%.

基于无限大体深埋平片状椭圆形裂纹的变形场及其扩展条件,分别推导了脆性岩石材料内部具有任意空间取向的单个张开型或闭合型椭圆形微裂纹及其扩展引起的附加柔度张量；考虑微裂纹系统对材料变形的影响,引入了概率密度函数,得到了任意应力状态下脆性岩石材料的宏细观损伤模型；分析了椭圆形微裂纹的短长轴比率对材料损伤的影响.计算结果显示:材料损伤随着短长轴比率的增大而增大,短长轴比率对材料损伤的影响会随着载荷的增大而提高.将本文模型应用于混凝土的单轴拉伸和花岗岩的单轴压缩,结果表明本文模型能够对实验现象给予很好地解释.

Recent tests based on different types of drop weight tear tests show that fracture energy per fracture area and crack tip opening angle of high grade pipeline steel dependent on fracture speed. In order to investigate if this dependence is induced by the difference of fracture toughness and geometric property of specimens, and quantitatively to investigate the dependence of dynamic fracture toughness on fracture speed, the standard and modified drop weight tear tests of X80 pipeline steel are simulated by three dimensional finite element analysis (FEA) which is based on a properly designed constitutive law of cohesive zone model. The comparison between FEA results and test results shows that the loading curve, fracture speed and crack tip opening angle in finite element simulation agree well with the corresponding experimental results, respectively. The presented constitutive law of cohesive zone model describes the dynamic fracture of X80 pipeline steel well. The fracture toughness of standard specimen is higher than that in modified specimen, while the fracture speed of standard specimen is smaller than that in modified specimen. The FEA results show that the dependence of fracture energy per fracture area and crack-tip opening angle on fracture speed is mainly induced by fracture toughness, not by geometric property. Making use of standard and modified specimens, seven simulations of drop weight tear test are conducted, respectively. The FEA results of both the standard and modified specimens show that the fracture toughness decreases with steady-state fracture speed, and their relation can be described by the suggested empirical relation.

已有的不同类型落锤撕裂实验数据表明，高钢级管线钢的单位断裂能和裂尖张开角依赖于断裂速度。本文进一步确定了其依赖关系是由断裂韧性而非试件几何差异所引起，并且定量分析了基于断裂准则所定义的断裂韧性与断裂速度之间的关系。利用所提出的黏结本构法则分别对X80管线钢标准试件和修正试件的落锤撕裂实验进行了三维有限元模拟，并将有限元结果与实验结果进行了对比。结果表明：有限元计算的加载曲线、断裂速度、裂尖张开角与对应的实验结果吻合较好，故本文提出的黏结本构法则能较好地应用于X80管线钢的动态断裂分析；标准试件的断裂韧性高于修正试件的断裂韧性，而标准试件的断裂速度则低于修正试件的断裂速度；七次有限元计算结果都表明断裂韧性随稳态断裂速度的增大而减小，且二者的关系可以由本文提出的自然指数函数进行描述。