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1.
《Computers and Geotechnics》1988,5(2):123-149
Large-scale rock reinforcement offers the prospect of flexible and effective control of rock displacements aroud large open mine excavations. Although the technology of rock reinforcement is well developed, reinforcement analysis and design methods are not. Analysis is presented here for the mechanics of two models of rock reinforcement, one based on local action of a reinforcing element at a slipping joint, the other on spatially-extensive action in rock subject to diffuse deformation. The principles of some finite difference methods of analysis of stress and displacement are outlined. The performance of a code modeling spatially-extensive reinforcement is examined in a parameter study of stope hangingwall reinforcement using long, grouted cables. 相似文献
2.
龙游石窟1-5号洞室群几百年来一直处于水下,1992年首次被抽干水用于开发旅游。由于抽水前后环境的强烈改变,以及洞内干湿交替明显,所以洞室围岩风化和破坏都十分严重。其中,本文所讨论的3号洞第3－2号岩柱就是已发生严重开裂,并亟待加固。为对该岩柱的加固提供科学依据,需准确把握变形破坏发展情况和据此研究它的变形破坏机理。为此,作者采用JSYCB-73系列电感式测缝仪和钢尺等手段对岩柱开裂的宽度和长度进行监测。根据监测所取得的大量数据和地质条件,对该岩柱的开裂机理进行了分析,得出了以下结论:（1）用来加固邻区的混凝土喷层的重力部分转移到该岩柱上,从而增加了荷载;（2）由于洞内渗水严重、干湿交替、温差变化较大等使风化作用加大。结果,导致该岩柱的强度降低。（3）该岩柱强度的降低和所施加荷载的增加等两个因素最终导致了岩柱被压裂。根据上述研究结论,并考虑文物保护和旅游的需要,提出了治水、地表卸荷、岩柱加锚、加箍等加固措施。加固后的监测数据表明,开裂已不再发展,岩柱已处于稳定 相似文献
3.
4.
Summary Significant increases in extraction ratio on the order of 6 to 8%, equivalent to as much as 142 t/m of panel advance, have occurred at the Big Island Mine during the last five years with the help of a practical rock mechanics program. This increase in resource recovery has also contributed to improvements in productivity. Both conventional and continuous machine mining have been used to mine two flat-laying trona beds at depths of 250 and 260 m in the Green River Formation in southwestern Wyoming.Conventional room and pillar mining originally was conducted in panels with extraction ratios of 58 to 60%. The use of yield pillars has allowed the panel extraction to increase to 66%. Continuous machine mining was introduced recently, with a 64% extraction ratio using long, narrow pillars and wide rooms. Further improvements in resource recovery seem feasible in the light of present mining experience.The rock mechanics program consisted of field instrumentation to determine the pillar and roof response to mining, and computer modelling to evaluate and help determine the stability of various layouts, which were then adopted for mining. 相似文献
5.
魁岐2号隧道位于福卅I国际机场高速公路二期工程A3标段,隧道跨度达到19．9m,中间岩柱最小净距为11．7m,为国内首座双向八车道小净距隧道工程。针对魁岐2号隧道工程的特殊性,利用离散单元法对节理岩体中特大断面小净距隧道的受力情况进行了分析,根据可靠度理论,通过对魁岐2号特大断面小净距隧道中间岩柱的可靠性分析发现,对于特大断面小净距隧道,中间岩柱最薄弱的部位主要集中在岩柱上部,因此,埘于特大断面小净距隧道施工过程中宜重点对岩柱上部进行加固处理。同时,根据不同围岩级别中中间岩柱的可靠度值显示,魁岐2号特大断面小净距隧道的净距取值基本上是合理的,整体上二能满足稳定性的要求。 相似文献
6.
E. Villaescusa I. Onederra C. Scott 《Fragblast: International Journal for Blasting and Fragmentation》2004,8(1):23-40
This paper presents the results of a comprehensive monitoring program designed to investigate the extent of blast induced damage experienced by rock masses extracted by bench stoping methods. An array of triaxial geophones and extensometers were used to monitor blast vibration attenuation and measure hangingwall deformations during stope extraction. In addition, pre and post surveys of the hangingwall rock mass were conducted using a TV borehole camera and cavity survey instrumentation. These surveys were later used to calibrate damage profiles into the stope hangingwalls.
Peak particle velocity, hangingwall deformation measurements and stope surveys were used to develop a site specific damage model that allowed engineers to asses drilling and blasting configurations to minimise the extent of pre-conditioning and damage. In addition the study included the analysis of the frequency response, displacements and accelerations experienced by the excavation as extraction and mine filling progressed. This work aimed at improving our understanding of the influence of blasting on the dynamic behaviour of stope hangingwalls.
The study demonstrated that estimates of the maximum extent of rock mass pre-conditioning and/or damage made through the application of the Holmberg-Persson approach compared well with measured results. In addition, the study found that dynamic loading imparted on an exposed hangingwall from subsequent stope blasting was also expected to contribute to rock mass weakening and that mine filling was crucial to arrest further deterioration. Hangingwall accelerations were used to demonstrate that larger openings may be more susceptible to dynamic loading. 相似文献
Peak particle velocity, hangingwall deformation measurements and stope surveys were used to develop a site specific damage model that allowed engineers to asses drilling and blasting configurations to minimise the extent of pre-conditioning and damage. In addition the study included the analysis of the frequency response, displacements and accelerations experienced by the excavation as extraction and mine filling progressed. This work aimed at improving our understanding of the influence of blasting on the dynamic behaviour of stope hangingwalls.
The study demonstrated that estimates of the maximum extent of rock mass pre-conditioning and/or damage made through the application of the Holmberg-Persson approach compared well with measured results. In addition, the study found that dynamic loading imparted on an exposed hangingwall from subsequent stope blasting was also expected to contribute to rock mass weakening and that mine filling was crucial to arrest further deterioration. Hangingwall accelerations were used to demonstrate that larger openings may be more susceptible to dynamic loading. 相似文献
7.
弹性地基条件下狭窄煤柱岩爆的突变理论分析 总被引：1，自引：0，他引：1
将未采煤层视为弹性地基条件下,运用maple9.5符号运算软件解得岩梁的挠曲线方程。根据能量守恒原理得到的功、能增量平衡关系式,求得岩梁–煤柱系统作准静态形变时的平衡方程--折迭突变模型平衡方程;用折迭突变总势能函数所作的稳定性判别表明,岩爆前兆阶段岩梁–煤柱系统处于不稳定平衡状态;煤柱岩爆的条件是Cook刚度准则,该准则可以动态地用煤柱形变增大时所需外界的能量输入率趋于0来表示;计算了煤柱岩爆地震能释放量,阐明煤柱岩爆机制是由于岩梁弹性能释放量超过峰后软化煤柱形变所耗的能量。通过岩梁弹性势能变化率曲线和煤柱耗能曲线,以几何形式描述了所得研究结果。计算表明,未开采煤层刚度变化对岩梁的等效刚度影响微弱。工作面开挖和采空区增大,将显著减小岩梁刚度Ke,对煤柱岩爆有重要影响。 相似文献
8.
Roger J. Missavage Yoginder P. Chugh Thomas Roscetti 《Geotechnical and Geological Engineering》1986,4(1):39-46
Summary A mathematical model has been developed utilizing the relative flexural strength of the strata overlying a coal seam to predict the vulnerability of shallow room and pillar mined areas to subsidence. The model assumes the failure of the immediate roof as the precursor of a subsidence event in shallow room and pillar mines. After the roof fails, either a sink hole subsidence event develops if the unconsolidated material is thin and dry; or a subsidence trough forms if the unconsolidated material is thick and wet. The model relates the Missavage number (Mn), which is dependent only on the stratigraphy and rock strength, to the extraction number, which is dependent only on the extraction ratio and maximum span of the opening. A high correlation coefficient (r=0.78) betweenMn and the extraction number for 27 subsidence events in a southern Illinois mine showed potential for using this model to delineate areas more vulnerable to subsidence. The developed and validated model was then subjected to a blind test on a 12.9 square kilometer area of an Illinois Coal Basin mine. The model successfully predicted 10 out of 12 subsidence events in the blind half of the study area and two of three additional subsidence events in the known half of the study area. 相似文献
9.
Summary The 3000 Orebody is one of two orebodies in the Deep Copper Mine at Mount Isa, Australia. Owing to concerns about potential shaft pillar instabilities, an integrated seismic system was introduced to monitor seismic activity associated with pillar and country rock deformation. Coupled with numerical modelling of the stress regime, the system may assist in the characterization of rock mass damage resulting from mining, and perhaps the identification of near- and far-field geological structures that affect stope performance. A study was undertaken to quantify the seismicity and to determine potential applications of the seismic technology. The relation between geological structure and seismicity is strong, suggesting good prospects for the use of the system in the ground-control activities noted above. The induction of seismicity, which involves small magnitude events, is associated with reduction of normal stress on planes of weakness, suggesting that stress path may be an important factor in the level of seismicity observed in hard rock mines. 相似文献
10.
黄土丘陵区房柱式开采地表塌陷特征及机理分析——以陕北府谷县新民镇小煤矿为例 总被引：2，自引：0，他引：2
通过对陕北府谷县新民镇小煤矿采煤地表大面积塌陷的调查和分析,总结出黄土丘陵区房柱式开采地表的塌陷特征,并以西岔沟煤矿房柱式开采为例,对其两种参数顶板岩梁应力、煤柱载荷、煤柱强度进行分析及对比,结果表明合理设计煤柱和煤房尺寸可以防止采煤地表大面积塌陷。 相似文献
11.
Summary The Bureau of Mines is investigating methods for evaluating and optimizing shaft designs for deep metal mines. This paper describes one such project at the Homestake Mine in Lead, SD. To determine a safe approach for the extraction of ore from the Ross Shaft pillar at Homestake, a basic rock mechanics approach has been taken that involves laboratory testing, field measurements, and computer modelling. The results of the study show that ore bodies in the Ross pillar can be mined safely and that the shaft will remain in elastic rock. On the basis of this work, other mines can develop finite-element modelling to evaluate the stability of mine openings and increase resource recovery. 相似文献
12.
作为具有大跨度、超浅埋等特点的千年古地下洞室群,龙游石窟吸引着众多前来研究的岩石力学家和工程地质学家。近些年来,龙游石窟的3号洞顶板多处出现了开裂和离层。安装在3-1号岩柱周围起支撑洞室作用钢柱上的应变片数值也发生了变化。据分析,这些现象出现的一个重要原因是3-2号岩柱强度降低引起洞室围岩受力条件的改变。利用FLAC3D数值软件,借鉴强度折减法,对3-2号岩柱强度降低引起上述变化的情况进行了模拟。数值模拟的结果可以较好地解释上述现象。在此基础上,进一步对3号洞顶板和其他岩柱的应力变化等进行了数值分析。结果表明:①3-2号岩柱的强度已有所下降,并有继续降低的趋势;②随着3-2号岩柱强度的降低,顶板的裂缝将不断增长、增多。其结果可为3-2号岩柱强度降低过程中洞室围岩力学行为的科学分析、预测及石窟的保护等提供依据。 相似文献
13.
从岩石强度理论出发,提出房柱式开采中矿柱安全留设尺寸的宽度折减法思想,通过不断折减矿柱宽度,研究矿柱由稳定状态向临界失稳状态演化过程,从而得到矿柱的临界宽度,引入矿柱安全系数,获得矿柱安全留设尺寸。采用宽度折减法对磨坊矿3#井房柱法开采矿柱安全留设尺寸进行研究,获得不同矿房跨度下矿柱的安全留设宽度。将宽度折减法得到的安全矿柱宽度与Lunder经验公式比较,研究发现,宽度折减法得到的安全矿柱宽度和Lunder经验公式的计算结果较为吻合且偏安全。结合磨坊矿3#井的开采条件和矿柱宽度折减法分析结果,确定矿房基本参数为：矿房跨度为13 m左右,矿柱宽度为5.0～5.5 m。通过对磨坊矿3#井采空区上覆岩层移动规律的监测,发现岩层相对稳定,地表沉降量控制在120～150 mm之间,用宽度折减法分析得到的矿房基本参数是合理的。 相似文献
14.
Asghar Siahmansouri Javad Gholamnejad Mohammad Fatehi Marji 《Arabian Journal of Geosciences》2014,7(3):1059-1066
Twin tunnels can be used for many applications. Interaction between two tunnels is an important problem in tunnel engineering that should be studied specially. Numerical investigations are well adapted to field data and numerical methods can be used in design of rock pillar of twin circular tunnels. So far, no relationship has been provided to estimate the minimum stable rock pillar width. In this paper, the interaction between twin circular tunnels has been studied using 2D finite element analysis. To do this, a great number of twin tunnels were modeled in Phase2 software with different conditions of rock mass (RMR value) and depth of tunnel. Models were analyzed and minimum stable rock pillar width was determined. This process was repeated for three different ratios of K (ratio of horizontal stress to vertical stress, 0.5, 1, and 1.5). Finally, according to the linear and nonlinear regression methods, the best merit function was fitted to result of numerical analysis. Then, new approximate formula was proposed to estimate the minimum rock pillar width according to RMR value and depth of twin circular tunnels with different K values. The formulae are very accurate (coefficient of correlation equals to minimum 0.96) that can be used for estimating the minimum rock pillar width of twin circular tunnels. 相似文献
15.
小净距隧道中夹岩受到两侧开挖的剧烈扰动,处于单向或双向受力的不利状态,严重影响施工安全,而预应力全长注浆对拉锚杆常用于中夹岩的主动支护。为阐明对拉锚杆的作用模式和控制机制,建立相应的力学模型和解析方法,开展实测验证,并进行参数分析和工程应用。研究表明：对拉锚杆为中夹岩提供强力水平约束,并提高岩体力学性能,发挥挤压加固作用;对拉锚杆利用剪切摩阻改善浅层围岩受力状态,同时锚固深部岩体,具有承载传力效果;对拉锚杆轴力和剪应力均由两侧向中间非线性衰减,作用范围局限于浅层中夹岩,实测结果验证了理论方法的合理性;进行了对拉锚杆的参数分析,提出了对拉锚杆临界长度、合理锚杆直径等工程建议;结合京张高铁长城站小净距隧道实践,主动增强对拉锚杆设计参数,变更后围岩压力、拱顶沉降和水平收敛的实测均值分别降低12.2%、14.1%和10.2%,保障了隧道开挖的安全。 相似文献
16.
Deformation and stability of an elasto-plastic softening pillar 总被引：6，自引：0，他引：6
Summary A model of rock pillar or coal seam is considered assuming linear elastic behaviour before reaching the maximum strength and post-peak behaviour characterized by the residual strength. The deformation and stress across the pillar height are assumed to be uniform and the interaction with overlying rock strata is treated assuming beam model of the strata. The elasto-plastic stress distribution within pillar and the onset of instability occurring for the critical opening span are determined. Comparison with a solution for a simplified spring model of pillar is also presented. 相似文献
17.
江西大布铀矿床溶浸地质条件及溶浸方法研究 总被引：1，自引：0，他引：1
本文围绕溶浸采矿这个主题,从岩、矿石的物质成分;矿石结构构造;铀的存在形式;岩、矿石物理力学参数;矿体形态、产状、规模及矿床水文地质等方面阐述了大布铀矿床溶浸的天然地质条件,并通过一系列矿石铀浸出工艺试验,获得了大量溶浸工艺参数,提出大布铀矿床以原地破碎浸出辅以堆浸为最佳采矿方案。 相似文献
18.
J. Sjöberg 《Rock Mechanics and Rock Engineering》1993,26(3):253-275
Summary The design of pillars in cut-and-fill mining and open stoping in vertical and subvertical orebodies is of vital importance in optimizing mining operations. The primary requirement for a good and reliable design technique is the ability to represent the actual physical behaviour of the pillar. In this paper, a new methodology for stope roof and sill pillar design is proposed for the Zinkgruvan Mine in Sweden. Studies of failure modes, local geology and rock mass characteristics were carried out to correlate failure modes to different geomechanical environments. For preliminary design, crude and ready-to-use stress level criteria were extracted from simple linear elastic modelling. More detailed modelling was used to simulate observed failures in a mechanically realistic manner and, at the same time, to help identify the fundamental failure mechanisms. Once the correct models and input parameters were identified, a set of guidelines on choice of model and parameter values were produced. The models can be used for design of new mining areas at Zinkgruvan, and the methodology could also be applied to other mines with similar geomechanical conditions. 相似文献
19.
S. Y. Wang S. W. Sloan M. L. Huang C. A. Tang 《Rock Mechanics and Rock Engineering》2011,44(2):179-198
Using a numerical modelling code, rock failure process analysis, 2D, the progressive failure process and associated acoustic
emission behaviour of serial and parallel rock samples were simulated. Both serial- and parallel sample models are presented
for investigating the mechanism of rock pillar failure. As expected, the numerical results show that not only the stiffness,
but also the uniaxial compressive strength of the rock plays an important role in pillar instability. For serial pillars,
the elastic rebound of a rock pillar with higher uniaxial compressive strength can lead to the sudden failure of an adjacent
rock pillar with lower uniaxial compressive strength. The failure zone forms and develops in the pillar with lower uniaxial
compressive strength; however, the failure zone does not pass across the interface of the two pillars. In comparison, when
two pillars have the same uniaxial compressive strengths but different elastic moduli, both serial pillars fail, and the failure
zone in the two pillars can interact, passing across the interface and entering the other pillar. For parallel pillars, damage
always develops in the pillar having the lower uniaxial compressive strength or lower elastic modulus. Furthermore, in accordance
with the Kaiser effect, the stress-induced damage in a rock pillar is irreversible, and only when the previous stress state
in the failed rock pillar is exceeded or the subsequent applied energy is larger than the energy released by the external
loading will further damage continue to occur. In addition, the homogeneity index of rock also can affect the failure modes
of parallel pillars, even though the uniaxial compressive strength and stiffness of each pillar are the same. 相似文献