Reinforcement of rock mass with cross-flaws using rock bolt

Rock bolting is one of the most effective and economical means of rock mass reinforcement. Existing studies of rock bolt reinforcement are mostly focused on rock masses without flaw, with a single flaw, or with parallel flaws. However in rock masses, cracks or flaws usually exist in the form of cross-flaws. In order to understand the impact of cross-flaws on rock bolt reinforcement and to further explore the differences of bolt reinforcement between rock mass with cross-flaws and rock mass with a single flaw, reinforced analog specimens with cross-flaws and with a single flaw were tested under uniaxial compressive condition. The experimental results show that the uniaxial compressive strength of the reinforced rock mass with cross-flaws in this research is higher than that of reinforced rock mass with a single flaw. This observation can be explained by the difference in the failure modes of reinforced specimens: the reinforced rock masses with a single flaw fail due to the formation of a shear crack while reinforced rock masses with cross-flaws fail as a result of a tensile fracture or interaction between tensile fracture and shear fracture.     

软岩巷道高强锚杆和锚注支护加固机理分析

基于软弱围岩的变形破坏规律，采用有限差分软件FLAC^2D，对普通锚喷支护、高强锚杆和锚注共同支护前后围岩变形破坏规律进行了数值模拟分析，结果表明，锚注支护利用锚杆与注浆相结合的方法，显著提高了围岩的强度和承载能力，扩大了锚杆的使用范围，能有效地控制软岩巷道的围岩变形，具有显著的经济效益。     

端锚式锚杆-围岩耦合流变模型研究

针对端锚式锚杆-围岩结构体在长时条件下支护作用的演化机制,建立了端锚式锚杆-隧洞围岩耦合作用的结构模型。进行了结构模型的基本假设：①圆形隧洞;②深埋;③各向等压原岩应力;④均质且各向同性黏弹性围岩模型;⑤一维黏弹性锚杆模型;⑥锚杆对围岩作用力整体为面力。基于基本假设建立了端锚式锚杆-围岩耦合流变理论模型。假设围岩和锚杆均为Maxwell模型时,求解了圆形隧洞围岩应力和位移的径向分布随时间变化的解析解,获得了锚杆轴力随时间演变的理论公式。基于锚杆（索）流变模型,进行了FLAC^3D数值模拟软件的二次开发;并通过数值模拟与理论计算的对比分析验证了理论模型的合理性,分析了端锚式锚杆-围岩耦合流变规律及其影响因素。该模型对于研究地下隧洞的流变力学行为,分析锚固支护结构的长期稳定性,指导工程支护设计具有重要的基础理论价值。     

锚杆在顺层岩石路堑边坡加固中的应用

通过不同类型加固防治工程的技术、经济比较 ,总结出采用剪力锚杆加固该类型顺层路堑边坡的工程措施 ,避免了强支挡 ,减少了工程投资 ,缩短了工期     

Rock mass characterization for underground hard rock mines

Rock mass characterization is an integral part of rock engineering practice. There are several classification systems used in underground mine design, however, most Canadian mines rely on only one of three classification systems. It is interesting to note that these systems—RQD, RMR and Q system—have their origins in civil engineering. This paper reviews the current state of these classification systems as employed in the mining industry. The first part focuses on the determination of the field parameters, with emphasis on the modifications to each parameter over the last 20 years. The difference between classification parameters that influence rock mass strength estimation and those that influence engineering design is emphasized. The second part of the paper focuses on the design recommendations based on these systems, such as maximum span, opening geometry, and support recommendations. The paper concludes with reference to errors that may arise in particular conditions.     

溪洛渡地下厂房施工开挖的弹塑性损伤及岩锚支护计算

根据建立的弹塑性损伤本构模型及岩锚支护模型对溪洛渡地下厂房洞室群施工开挖稳定性进行了三维非线性有限元计算,获得了一些有益的工程结论。     

Rock slope stability assessment through rock mass classification systems

Over the last several decades, rock mass classification systems have been proposed in order that cuttings at high risk for failure be identified, and preventive measures be effectively prioritized. The present paper attempts a review of the systems in question, illustrating the main differences and similarities among them, which are focused on the types of failures considered and the factors involved. The reliability of these systems is discussed as well. Relatively, these systems contain factors which raise queries about their suitability or the manner by which they are attributed into them. Moreover, although a rock cut failure event presupposes the action of a triggering factor (e.g., earthquake, precipitation), rock mass classification systems, by omitting it, do not classify cuttings according to their actual hazard (potentiality) for failure. Groundwater, when it is not erroneously ignored, is taken into account as instability factor with limited effect upon the systems (<15%) and not as a triggering factor for failure. Additionally, a number of suggestions regarding rock mass classification systems are given. Relatively, it is recommended rock cuttings to be classified according to their failure hazard taking into account both their condition and the influence of triggering factors upon stability. Moreover, each type of failure should be examined independently, as each one of them is governed by specific instability factors. Finally, some recommendations concerning amalgamation of factors, the possible ways that water may trigger a failure and the quantification of the most common triggering factors for failure (earthquake and precipitation) are provided.     

节理发育岩体隧道锚杆支护参数优化研究

结合内蒙古窑沟隧道,通过UDEC离散元软件数值模拟手段研究锚杆环向布置范围、间距对隧道结构变形与稳定性的影响,进而将锚杆原设计参数——环向布置范围216°、间距1.0 m优化为环向布置范围90°、间距1.0 m,并证明了其合理性,对类似工程具有一定的参考价值。     

锚杆支护技术发展现状与展望

对现有锚杆支护技术进行了介绍,分析了锚杆支护技术的支护机理、支护特点和存在的问题,对我国现阶段锚杆支护技术的发展现状进行了归纳总结,同时对未来锚杆支护的发展提出建议。     

土钉墙及锚杆支护的监理控制要点

结合深基坑支护工程实例,阐述了土钉墙、锚杆支护工程监理过程中的质量控制要点,包括土方开挖的控制、注浆的控制、锚杆支护材料的控制等内容,并介绍了施工阶段监理工作方法,以期指导实践。     

Rock mass response for lined rock caverns subjected to high internal gas pressure

The storage of hydrogen gas in underground lined rock caverns (LRCs) enables the implementation of the first fossil-free steelmaking process to meet the large demand for crude steel. Predicting the response of rock mass is important to ensure that gas leakage due to rupture of the steel lining does not occur. Analytical and numerical models can be used to estimate the rock mass response to high internal pressure; however, the fitness of these models under different in situ stress conditions and cavern shapes has not been studied. In this paper, the suitability of analytical and numerical models to estimate the maximum cavern wall tangential strain under high internal pressure is studied. The analytical model is derived in detail and finite element (FE) models considering both two-dimensional (2D) and three-dimensional (3D) geometries are presented. These models are verified with field measurements from the LRC in Skallen, southwestern Sweden. The analytical model is inexpensive to implement and gives good results for isotropic in situ stress conditions and large cavern heights. For the case of anisotropic horizontal in situ stresses, as the conditions in Skallen, the 3D FE model is the best approach.     

锚杆参数对围岩稳定性影响的数值分析

结合强度折减法对隧道开挖过程中围岩稳定性进行模拟分析,研究了随着折减系数的变化,隧道围岩塑性区的变化情况。对于不同的工况,通过对锚杆参数(锚杆长度、锚杆间距和锚杆直径)的模拟比较,得出锚杆长度对改善围岩稳定性效果最明显,其次是锚杆间距,最后是锚杆直径。结合后云台山隧道工程实例,分析后云台山隧道开挖后围岩稳定性变化,其稳定性良好,满足施工要求。     

喷锚网技术在路基防护中的应用

结合工程实践，介绍了从路基防护中心方案设计、施工方法及技术措施喷锚网支护技术，提出喷锚网支护可提高路基岩土的结构强度和抗变形刚度，增强边坡的整体稳定性。     

极限状态下岩体受拉锚杆锚固承载力的计算

从分析岩体中受拉锚杆的锚固机理及破坏形态出发,研究了承载能力极限状态下受拉锚杆的受力模型,建议在锚杆的锚固承载力计算公式中考虑锚固长度对平均粘结强度的影响,推导了能够反映极限状态下剪力传递机理的受拉锚杆锚固承载力计算公式,并结合岩壁吊车梁受拉锚杆锚固的工程实例与GB 50086公式的计算结果进行了比较、分析和探讨。     

Experimental study and stress analysis of rock bolt anchorage performance

A new method was developed to apply pull-and-shear loads to the bolt specimen in order to evaluate theanchorage performance of the rebar bolt and the D-Bolt. In the tests, five displacing angles （0°, 20°, 40°,60°, and 90°）, two joint gaps （0 mm and 30 mm）, and three kinds of host rock materials （weak concrete,strong concrete, and concrete-granite） were considered, and stressestrain measurements were conducted.Results show that the ultimate loads of both the D-Bolt and the rebar bolt remained constantwith any displacing angles. The ultimate displacement of the D-Bolt changed from 140 mm at the0
displacing angle （pure pull） to approximately 70 mm at a displacing angle greater than 40
. Thedisplacement capacity of the D-Bolt is approximately 3.5 times that of the rebar bolt under pure pull and50% higher than that of the rebar bolt under pure shear. The compressive stress exists at 50 mm from thebolt head, and the maximum bending moment value rises with the increasing displacing angle. The rebarbolt mobilises greater applied load than the D-Bolt when subjected to the maximum bending. Theyielding length （at 0
） of the D-Bolt is longer than that of the rebar bolt. The displacement capacity of thebolts increased with the joint gap. The bolt subjected to joint gap effect yields more quickly with greaterbending moment and smaller applied load. The displacement capacities of the D-Bolt and the rebar boltare greater in the weak host rock than that in the hard host rock. In pure shear condition, the ultimateload of the bolts slightly decreases in the hard rock. The yielding speed in the hard rock is higher thanthat in the weak rock.
2014 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Production and hosting byElsevier B.V. All rights reserved.     

软岩巷道网壳衬砌力学性能试验研究

针对地下工程新型支护方式——网壳支护,根据模型试验和理论,进行围压作用下相似模型试验,研究网壳衬砌力学性能和承载能力。通过试验结果分析,证明网壳支护结构具有良好的力学性能和较高的支撑能力,是一种可靠的支护形式,能弥补现有软岩巷道支护结构的不足。     

网壳锚喷支护理论分析及其在兖州矿区的应用

跨采及软岩巷道地压强度高、变形强烈,支护较为困难。传统支护方式成本高、工艺复杂。根据地面大跨度板壳原理设计出网壳结构,该结构稳定性强,能承受较大变形地压及冲击荷载。钢筋网壳结构是巷道支护工程中一种新型的支护形式,既可在巷道内单独组装对围岩进行连续支撑,又可先撑后喷,在围岩表面形成半刚性钢筋混凝土薄壳衬砌结构。能承受强大变形地压及采动荷载,达到用较少材料又提高喷层支撑能力与让压的目标。介绍了钢筋网壳锚喷支护的技术特色与支护原理,并对其进行理论分析,推导出钢筋网壳锚喷结构的计算模型及其内力与主要应力的计算表达式。完成了室内整架载荷试验,成功应用于兖州矿区跨采巷道。