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An analytical approach to estimate the mechanical state of roof strata in underground longwall mining 地下长壁开采顶板受力状态的一种分析方法
IF 3.2 3区 工程技术 Q2 ENGINEERING, CIVIL Pub Date : 2021-10-10 DOI: 10.12989/GAE.2021.27.1.057
J. Zhang, Yansong Zhang, Wenzhou Du, Houwang Wang, M. Serati
The movement and collapse of roof strata in underground longwall mining is a key trigger factor for the occurrence of dynamic disasters. An accuracy estimation of roof strata mechanical state is critical for the prediction and control of dynamic disaster, such as coal burst and coal-and-gas outburst. An analytical approach is proposed in this work to estimate the mechanical state of roof strata in underground longwall mining. To do so, the unit width of roof strata is considered as a beam structure. A system of 4 simulations differential equations is proposed with 4 local slope data as input parameters to derive the mechanical expression of suspending roof strata. A differential evolution algorithm is further adapted to solve the equation system. In addition, a set of verification tests is carried out to showcase the feasibility and robustness of the proposed method. The results show that the average relative errors of 10 independent tests reach a high accuracy, which is less than 1% for the strata mechanical state control parameters. By using the estimated results, the slope, bending moment and shear force of suspending strata are derived. Moreover, the slope data sampling strategy is also devised. The parameters bound determination method is also proposed to ensure the calculation convergence. The local slope based analytical method proposed in this paper is a feasible approach to estimate the mechanical state of suspended roof strata before first weighting.
地下长壁开采顶板岩层的移动和坍塌是动力灾害发生的关键触发因素。对顶板岩层力学状态的准确估计对于冲击煤、煤与瓦斯突出等动力灾害的预测和控制至关重要。本文提出了一种估算地下长壁开采顶板受力状态的解析方法。为此,将单位宽度的顶板岩层视为梁结构。以4个局部边坡数据为输入参数,建立了一个由4个模拟微分方程组成的系统,推导出悬浮顶板岩层的力学表达式。进一步采用微分进化算法求解该方程组。此外,还进行了一组验证测试,以验证所提出方法的可行性和鲁棒性。结果表明,10次独立试验的平均相对误差达到了较高的精度,岩层力学状态控制参数的平均相对误差小于1%。在此基础上,推导了悬索层的边坡、弯矩和剪力。此外,还设计了斜率数据的采样策略。为了保证计算的收敛性,提出了参数定界方法。本文提出的基于局部斜率的分析方法是一种可行的方法来估计悬顶岩层在首次称重前的受力状态。
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引用次数: 3
Investigating of free vibration behavior of bidirectional FG beams resting on variable elastic foundation 变弹性地基上双向FG梁的自由振动特性研究
IF 3.2 3区 工程技术 Q2 ENGINEERING, CIVIL Pub Date : 2021-06-01 DOI: 10.12989/GAE.2021.25.5.383
Ismail Benaberrahmane, S. Benyoucef, M. Sekkal, M. Mekerbi, R. B. Bouiadjra, M. Selim, A. Tounsi, M. Hussain
In the present study, the free vibration of bidirectional functionally graded (FG) beams resting on variable elastic foundation are comprehensively investigated. The beam’s behavior is modeled using 2D displacement field that contain undetermined integral terms and involves a reduced unknown functions. The material properties of the FG beam are assumed to be graded in both the thickness and longitudinal directions according to a power law. The beams are considered simply supported and resting on variable elastic foundation. The differential equation system governing the free vibration behavior of bidirectional beams is derived based on the Hamilton principle. The problem is then solved using the Navier solution for a simply supported beam. The accuracy of the used model can be noticed by comparing it with other solutions available in the literature where a good conformance was obtained. A detailed parametric study is conducted to explore the influences of material composition and variable elastic parameters on the vibration characteristics of the beams. The results reveal that the grading indexes in one or both directions as well as the parameters of the elastic foundation strongly impact the fundamental frequencies.
本文对变弹性地基上双向功能梯度梁的自由振动进行了全面的研究。梁的行为是使用二维位移场建模的,该位移场包含未确定的积分项,并涉及简化的未知函数。FG梁的材料特性假定根据幂律在厚度和纵向方向上分级。梁被认为是简单支撑的,并放置在可变弹性基础上。基于汉密尔顿原理,导出了控制双向梁自由振动行为的微分方程组。然后使用简单支撑梁的Navier解决方案来解决该问题。通过将所用模型与文献中获得良好一致性的其他解决方案进行比较,可以注意到所用模型的准确性。通过详细的参数研究,探讨了材料组成和可变弹性参数对梁振动特性的影响。结果表明,弹性地基的一个或两个方向的级配指标以及参数对基频有很大的影响。
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引用次数: 1
Evaluation of grout penetration in single rock fracture using electrical resistivity 用电阻率法评价单岩缝中注浆的穿透性
IF 3.2 3区 工程技术 Q2 ENGINEERING, CIVIL Pub Date : 2021-01-01 DOI: 10.12989/GAE.2021.24.1.001
Hangbok Lee, T. Oh, Jong-Won Lee
In this study, a new approach using electrical resistivity measurement was proposed to detect grout penetration and to evaluate the grouting performance for such as waterproof efficiency in single rock fracture. For this purpose, an electrical resistivity monitoring system was designed to collect multi-channel data in real time. This was applied to a system for grout injection/penetration using a transparent fracture replica with various aperture sizes and water-cement mix ratio. The electrical resistivity was measured under various grout penetration conditions in real time, which results were directly compared to the visual observation images of grout penetration/distribution. Moreover, the grouting success status after the curing process was evaluated by measuring the electrical resistivity in relation to changes in frequency in fracture cells where grout injection and penetration were completed. Consequently, it was determined that the electrical resistivity monitoring system could be applied effectively to the detection of successful penetration of grouting into a target area and to actual field evaluation of the grouting performance and long-term stability of underground rock structures.
本文提出了一种利用电阻率测量方法检测注浆侵彻度并评价单岩体裂隙注浆防水效果等注浆性能的新方法。为此,设计了一套电阻率监测系统,实现多通道数据的实时采集。该系统使用了具有不同孔径大小和水灰混合比的透明裂缝模型进行注浆/渗透。实时测量不同灌浆侵入条件下的电阻率,并与灌浆侵入/分布的目视观测图像进行对比。此外,通过测量裂隙单元中电阻率与注浆贯入频率变化的关系,对固化过程后注浆成功状态进行评价。结果表明,电阻率监测系统可以有效地应用于注浆成功侵彻目标区域的探测,以及对地下岩体结构注浆性能和长期稳定性的现场实际评价。
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引用次数: 4
A novel preloading method for foundation underpinning for the remodeling of an existing building 一种新的预压方法用于既有建筑的改造基础支撑
IF 3.2 3区 工程技术 Q2 ENGINEERING, CIVIL Pub Date : 2021-01-01 DOI: 10.12989/GAE.2021.24.1.029
Chengcan Wang, Jin-Tae Han, S. Kim, Y. Jang
The utilization of buildings can be improved by extending them vertically. However, the added load of the extension might require building foundations to be underpinned; otherwise, the loads on the foundations might exceed their bearing capacity. In this study, a preloading method was presented aiming at transferring partial loads from existing piles to underpinning piles. A pneumatic-type model preloading device was developed and used to carry out centrifuge experiments to evaluate the load–displacement behavior of piles, the pile–soil interaction during preloading, and the additional loading caused by vertical extension. The results showed that the preloading devices effectively transfer load from existing piles to underpinning piles. In the additional loading test of group piles, the load-sharing ratio of a pile increased with its stiffness. The load-sharing ratio of a preloaded micropile was less than that of a non-preloaded micropile as a result of the reduction in axial stiffness caused by preloading before additional loading. Therefore, a slight reduction of the load-sharing capacity of an underpinning pile should be considered if the preloading method is applied. Further, two full scale preloading devices was developed. The devices preload underpinning piles and thereby produce reaction forces on a reaction frame to jack existing piles upward, thus transferring load from the existing piles to the underpinning piles. Specifically, screw-type and hydraulic-jack type devices were developed for the practical application of foundation underpinning during vertical extension, and their operability and load transfer effect verified via full-scale structural experiments.
通过垂直延伸,可以提高建筑物的利用率。然而,扩建工程增加的负荷可能需要加固建筑物的地基;否则,地基上的荷载可能会超过其承载能力。本研究提出了一种将既有桩的部分荷载传递给托存桩的预压方法。研制了一种气动预压模型装置,并进行了离心试验,对桩的荷载-位移特性、预压过程中桩土相互作用以及竖向延伸引起的附加荷载进行了评价。结果表明,预压装置能有效地将既有桩的荷载传递给托存桩。在群桩附加荷载试验中,桩的荷载分担率随桩刚度的增大而增大。预压微桩的荷载分担比小于未预压微桩,这是由于在附加荷载之前进行预压导致轴向刚度降低所致。因此,如果采用预压方法,应考虑承插桩的荷载分担能力略有降低。此外,还研制了两种全尺寸预压装置。该装置预压支撑桩,从而在反力架上产生反力,使现有桩向上顶起,从而将荷载从现有桩转移到支撑桩上。具体而言,针对垂直延伸过程中基础支撑的实际应用,开发了螺杆式和液压千斤顶式装置,并通过全尺寸结构试验验证了其可操作性和荷载传递效果。
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引用次数: 0
Seismic response of utility tunnels subjected to different earthquake excitations 不同地震激励下公用隧道的地震反应
IF 3.2 3区 工程技术 Q2 ENGINEERING, CIVIL Pub Date : 2021-01-01 DOI: 10.12989/GAE.2021.24.1.067
Chenglong Wang, Xuan-ming Ding, Zhi-xiong Chen, Li Feng, Liang Han
The influence of ground motions on the seismic response of utility tunnels was investigated. A series of small-scale shaking table model tests were carried out under uniform excitation in the transverse direction. Different peak accelerations of EL-Centro and Taft earthquake waves were applied. The acceleration responses, earth pressure, seismic strain, bending moment and structure deformations were measured and discussed. The results showed that the types of earthquake waves had significant influences on the soil-structure acceleration responses. However, the amplitude of the soil acceleration along the depth showed consistent variation regardless of the types of earthquake waves and tunnels. The horizontal soil pressure near the top and bottom slabs showed obviously larger values than those at other depths. In general, the strain response in the outer surface was more significant than that on the inner surface, and the peak strain in the end section of the model was larger than that in the middle section. Moreover, the bending moment at the corner points was much larger than that at middle point, and the bending moment was greatly affected by both input accelerations and seismic wave types. The opposite direction of shear deformation on the top and bottom slabs presented a rotation trend of the model structure.
研究了地震动对公用隧道地震反应的影响。在横向均匀激励下进行了一系列小尺度振动台模型试验。采用EL-Centro和Taft地震波的不同峰值加速度。测量并讨论了加速度响应、土压力、地震应变、弯矩和结构变形。结果表明,地震波类型对土体-结构加速度响应有显著影响。然而,无论地震波和隧道类型如何,土体加速度振幅沿深度的变化都是一致的。靠近顶底板的水平土压力值明显大于其他深度。总体而言,模型外表面应变响应比内表面应变响应更显著,且模型端部应变峰值大于中部应变峰值。弯矩受输入加速度和地震波类型的影响较大,且弯矩受输入加速度和地震波类型的影响较大。顶板和底板剪切变形方向相反,模型结构呈现旋转趋势。
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引用次数: 3
Analysis of the crack propagation rules and regional damage characteristics of rock specimens 岩石试件裂纹扩展规律及区域损伤特征分析
IF 3.2 3区 工程技术 Q2 ENGINEERING, CIVIL Pub Date : 2021-01-01 DOI: 10.12989/GAE.2021.24.3.215
Liu Yangyang, Xue Yadong, Shichuan Zhang, F. Jing, Du Guobin, Sukai Lu, Guangsheng Fu
To study the evolution mechanism of cracks in rocks with multiple defects, rock-like samples with multiple defects, such as strip-shaped through-going cracks and cavity groups, are used, and the crack propagation law and changes in AE (acoustic emission) and strain of cavity groups under different inclination angles are studied. According to the test results, an increase in the cavity group inclination angle can facilitate the initial damage degree of the rock and weaken the crack initiation stress; the initial crack initiation direction is approximately 90°, and the extension angle is approximately 75~90° from the strip-shaped through-going cracks; thus, the relationship between crack development and cavity group initiation strengthens. The specific performance is as follows: when the initiation angle is 30°, the cracks between the cavities in the cavity group develop relatively independently along the parallel direction of the external load; when the angle is 75°, the cracks between the cavities in the cavity group can interpenetrate, and slip can occur along the inclination of the cavity group under the action of the shear mechanism rupture. With the increase in the inclination angle of the cavity group, the AE energy fluctuation frequency at the peak stress increases, and the stress drop is obvious. The larger the cavity group inclination angle is, the more obvious the energy accumulation and the more severe the rock damage; when the cavity group angle is 30° or 75°, the peak strain of the local area below the strip-shaped through-going fracture plane is approximately three times that when the cavity group angle is 45° and 60°, indicating that cracks are easily generated in the local area monitored by the strain gauge at this angle, and the further development of the cracks weakens the strength of the rock, thereby increasing the probability of major engineering quality damage. The research results will have important reference value for hazard prevention in underground engineering projects through rock with natural and artificial defects, including tunnels and air-raid shelters.
为了研究多缺陷岩石中裂纹的演化机制,采用条形贯通裂纹和空腔群等多缺陷类岩石试样,研究不同倾角下裂纹扩展规律以及空腔群的声发射和应变变化。试验结果表明,增大空腔群倾角有利于岩石的初始损伤程度,减弱裂纹起裂应力;初始裂纹起裂方向约为90°,延伸角约为75~90°;因此,裂纹发展与空腔群萌生之间的关系得到加强。具体表现为:起裂角为30°时,空腔群内空腔间裂纹沿外荷载平行方向相对独立发展;当夹角为75°时,空腔组内各空腔之间的裂纹能够相互贯通,在剪切机制破裂的作用下,沿空腔组的倾斜方向发生滑移。随着腔群倾角的增大,峰值应力处声发射能量波动频率增大,应力下降明显。空腔群倾角越大,能量积累越明显,岩石破坏越严重;当腔群角度为30°或75°时,条形贯通破裂面下方局部区域的峰值应变约为45°和60°时的3倍,说明在该角度下,应变片监测的局部区域容易产生裂纹,裂纹的进一步发展削弱了岩石的强度,从而增加了重大工程质量破坏的概率。研究成果对隧道、防空洞等具有天然和人工缺陷的围岩地下工程的危害防治具有重要的参考价值。
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引用次数: 2
Vibration of multilayered functionally graded deep beams under thermal load 热荷载作用下多层功能梯度深梁的振动
IF 3.2 3区 工程技术 Q2 ENGINEERING, CIVIL Pub Date : 2021-01-01 DOI: 10.12989/GAE.2021.24.6.545
A. Bashiri, Ş. Akbaş, A. Abdelrahman, A. Assie, M. A. Eltaher, E. Mohamed
Since the functionally graded materials (FGMs) are used extensively as thermal barriers in many of applications. Therefore, the current article focuses on studying and presenting dynamic responses of multilayer functionally graded (FG) deep beams placed in a thermal environment that is not addressed elsewhere. The material properties of each layer are proposed to be temperature-dependent and vary continuously through the height direction based on the Power-Law function. The deep layered beam is exposed to harmonic sinusoidal load and temperature rising. In the modelling of the multilayered FG deep beam, the two-dimensional (2D) plane stress continuum model is used. Equations of motion of deep composite beam with the associated boundary conditions are presented. In the frame of finite element method (FEM), the 2D twelve –node plane element is exploited to discretize the space domain through the length-thickness plane of the beam. In the solution of the dynamic problem, Newmark average acceleration method is used to solve the time domain incrementally. The developed procedure is verified and compared, and an excellent agreement is observed. In numerical examples, effects of graduation parameter, geometrical dimension and stacking sequence of layers on the time response of deep multilayer FG beams are investigated with temperature effects.
由于功能梯度材料(fgm)在许多应用中广泛用作热障。因此,本文的重点是研究和呈现多层功能梯度(FG)深梁在热环境中的动态响应,这在其他地方没有得到解决。基于幂律函数,提出了每一层的材料性质与温度相关,并在高度方向上连续变化。深层梁受到谐波正弦载荷和温升的影响。在多层FG深梁的建模中,采用二维平面应力连续体模型。给出了具有相关边界条件的深层组合梁的运动方程。在有限元法框架中,利用二维十二节点平面单元,通过梁的长度-厚度平面对空间域进行离散。在求解动力学问题时,采用Newmark平均加速度法对时域进行增量求解。对所开发的程序进行了验证和比较,结果非常吻合。数值算例研究了分层参数、几何尺寸和层层叠加顺序对深层多层FG梁时间响应的影响,并考虑了温度效应。
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引用次数: 1
Experimental research on the effect of water-rock interaction in filling media of fault structure 断裂构造充填介质中水-岩相互作用影响的实验研究
IF 3.2 3区 工程技术 Q2 ENGINEERING, CIVIL Pub Date : 2021-01-01 DOI: 10.12989/GAE.2021.24.5.471
Dong Faxu, Peng Zhang, Sun Wenbin, Shaoliang Zhou, Kong Lingjun
Water damage is one of the five disasters that affect the safety of coal mine production. The erosion of rocks by water is a very important link in the process of water inrush induced by fault activation. Through the observation and experiment of fault filling samples, according to the existing rock classification standards, fault sediments are divided into breccia, dynamic metamorphic schist and mudstone. Similar materials are developed with the characteristics of particle size distribution, cementation strength and water rationality, and then relevant tests and analyses are carried out. The experimental results show that the water-rock interaction mainly reduces the compressive strength, mechanical strength, cohesion and friction Angle of similar materials, and cracks or deformations are easy to occur under uniaxial load, which may be an important process of water inrush induced by fault activation. Mechanical experiment of similar material specimen can not only save time and cost of large scale experiment, but also master the direction and method of the experiment. The research provides a new idea for the failure process of rock structure in fault activation water inrush.
水害是影响煤矿安全生产的五大灾害之一。在断层活化突水过程中,水对岩石的侵蚀是一个非常重要的环节。通过断层充填样品的观察与实验,根据现有的岩石分类标准,将断层沉积物分为角砾岩、动态变质片岩和泥岩。研制了具有粒径分布、胶结强度、水分合理性等特点的类似材料,并进行了相关试验分析。试验结果表明,水岩相互作用主要降低了相似材料的抗压强度、机械强度、黏聚力和摩擦角,单轴载荷作用下易产生裂缝或变形,这可能是断层活化诱发突水的重要过程。相似材料试件的力学实验,不仅节省了大规模实验的时间和成本,而且掌握了实验的方向和方法。该研究为断层活化突水作用下岩石结构的破坏过程提供了新的思路。
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引用次数: 4
On the effect of void ratio and particle breakage on saturated hydraulic conductivity of tailing materials 孔隙率和颗粒破碎率对尾矿材料饱和导流率的影响
IF 3.2 3区 工程技术 Q2 ENGINEERING, CIVIL Pub Date : 2021-01-01 DOI: 10.12989/GAE.2021.25.2.159
Changkun Ma, Chao Zhang, Qinglin Chen, Zhenkai Pan, Lei Ma
Particle size of tailings in different areas of dams varies due to sedimentation and separation. Saturated hydraulic conductivity of high-stacked talings materials are seriously affected by void ratio and particle breakage. Conjoined consolidation permeability tests were carried out using a self-developed high-stress permeability and consolidation apparatus. The hydraulic conductivity decreases nonlinearly with the increase of consolidation pressure. The seepage pattern of coarse-particle tailings is channel flow, and the seepage pattern of fine-particle tailings is scattered flow. The change rate of hydraulic conductivity of tailings with different particle sizes under high consolidation pressure tends to be identical. A hydraulic conductivity hysteresis is found in coarse-particle tailings. The hydraulic conductivity hysteresis is more obvious when the water head is lower. A new hydraulic conductivity-void ratio equation was derived by introducing the concept of effective void ratio and breakage index. The equation integrated the hydraulic conductivity equation with different particle sizes over a wide range of consolidation pressures.
尾矿在不同区域由于泥沙淤积和分选的影响,其粒度存在差异。孔隙率和颗粒破碎率对高堆垛滑石材料的饱和导电性有重要影响。采用自行研制的高应力渗固结试验装置进行了渗固结试验。随着固结压力的增大,水导率呈非线性降低。粗颗粒尾砂的渗流模式为通道流,细颗粒尾砂的渗流模式为分散流。不同粒径的尾矿在高固结压力下的水力导率变化率趋于一致。在粗颗粒尾砂中存在导流滞后现象。水头越低,水力传导迟滞越明显。通过引入有效孔隙比和破坏指数的概念,推导了新的导水率-孔隙比方程。该方程综合了不同粒径在大范围固结压力下的水力导电性方程。
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引用次数: 2
Three-dimensional finite element analysis of urban rock tunnel under static loading condition: Effect of the rock weathering 静载条件下城市岩石隧道三维有限元分析:岩石风化的影响
IF 3.2 3区 工程技术 Q2 ENGINEERING, CIVIL Pub Date : 2021-01-01 DOI: 10.12989/GAE.2021.25.2.099
Mohammad Zaid
Tunnel provide faster, safer and convenient way of transportation for different objects. The region where it is construction and surrounding medium has significant influence on the overall stability and performance of tunnel. The present simulation has been carried out in order to understand the behaviour of rock tunnel under static loading condition. The present numerical model has been validated with the laboratory scaled model and field data of underground tunnels. Both lined and unlined tunnels have been considered in this paper. Finite element technique has been considered for the simulation of static loading effect on tunnel through Abaqus/Standard. The Mohr-Coulomb material model has been considered to simulate elastoplastic nonlinear behaviour of different rock types, i.e., Basalt, Granite and Quartzite. The four different stages of rock weathering are classified as fresh, slightly, moderately, and highly weathered in case of each rock type. Moreover, extremely weathered stage has been considered in case of Quartzite rock. It has been concluded that weathering of rock and overburden depth has great influence on the tunnel stability. However, by considering a particular weathering stage of rock for each rock type shows varying patterns of deformations in tunnel.
隧道为不同的物体提供了更快、更安全、更方便的运输方式。施工区域和周围介质对隧道的整体稳定性和性能有重要影响。本文的模拟是为了了解岩石隧道在静荷载作用下的受力特性。本文的数值模型已通过室内比例尺模型和地下隧道实测数据进行了验证。本文考虑了有衬砌隧道和无衬砌隧道。利用Abaqus/Standard软件,采用有限元技术对隧道静力荷载效应进行模拟。采用Mohr-Coulomb材料模型来模拟玄武岩、花岗岩和石英岩等不同岩石类型的弹塑性非线性行为。岩石风化的四个不同阶段分为新鲜、轻度、中度和高度风化。此外,石英岩还考虑了极端风化阶段。研究表明,岩石风化和覆盖层深度对隧道稳定性影响较大。然而,考虑到岩石的特定风化阶段,每种岩石类型在隧道中显示出不同的变形模式。
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引用次数: 11
期刊
Geomechanics and Engineering
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