金山店铁矿玻璃钢锚杆支护试验及存在问题

金山店铁矿矿岩松软破碎,因支护的金属锚杆腐蚀失效较多,巷道变形垮冒严重。玻璃钢锚杆具有抗腐蚀、抗拉强度高等优点,为此采用玻璃钢锚杆替代螺纹钢锚杆进行了支护试验。数值分析表明全长锚固预应力玻璃钢锚杆相比螺纹钢锚杆可以有效改变锚杆中性点位置,改善水泥浆应力分布特征,提高锚杆及水泥浆抵抗围岩向壁面变形的能力。工业试验及试验巷道变形监测表明采用玻璃钢锚杆支护后在控制巷道变形方面可以取得与螺纹钢锚杆相同的巷道变形控制效果;且采用玻璃钢锚杆可以更好控制巷道离层破坏,减少矿岩中硫化物对锚杆的腐蚀,从而提高整体支护可靠性。但玻璃钢锚杆尾部托盘螺母承载力较低,难以抵抗巷道较大变形以及爆破冲击波破坏,还需做进一步研究和改进。     

Support of weak rock with grouted bolts and shotcrete

This paper presents a closed form elastoplastic analytic solution of grouted bolts considering four different approaches to bolt performance. The equations consider bolt loads and displacements round a circular opening subjected to hydrostatic pressure. The solutions allow for the interaction of bolts and a shortcrete lining. The analytic results are compared with bolt load data and readings obtained from instrumented bolts and extensometers in the Kielder Experimental tunnel excavated in mudstone. Two different support systems are included in the study, one with grouted bolts and one with grouted bolts together with shotcrete.The bolt load distribution obtained from the analytic solutions show good consistency with the measured results for two of the four different theoretical solutions. The analytic solutions that correspond to the measured values take into account the existing low bond strength between rock mass and bolt and the effects of local deformations in the rock mass under the end plate. It is shown, that a good contact between the rock surface and the end plate have effects on the magnitude of the bolt load and that it is important to use grout of high quality to secure the transfer of load from rock mass to the bolt.The displacement values, obtained from extensometers installed together with the two different support systems, coincide with the deformations obtained from the corresponding analytic solution.     

矿用预应力钢棒力学性能试验研究

预应力钢棒具有预紧力等级高、延伸率高、受力状态好等优点,越来越广泛地应用于煤矿巷道支护工程中。为了进一步探究矿用预应力钢棒材料力学性能,在实验室进行了矿用预应力钢棒拉伸试验、金相组织分析、冲击韧性测试、预应力损失试验、偏载试验、安装推进阻力试验及配套锁具性能试验。结果表明:直径20 mm矿用预应力钢棒拉伸时极限承载能力为422 kN,与直径20 mm、牌号HRB335锚杆杆体相比,增幅达176%,断后伸长率平均为13.3%,为锚索断后伸长率的2.4倍,断后呈杯锥状断口;钢棒拉断前后冲击吸收功分别为46.0 J和23.3 J,材料组织结构为回火索氏体,晶粒度为9.5和8.5,属于超细晶粒度;受力长度为1 230 mm和1 500 mm时,预应力损失为38.37%,和36.74%,随着载荷的加大,预紧力损失率减小;受力长度的增加,钢棒预紧力损失率减小;偏载角度为5°、10°、15°、20°及25°时,极限承载能力降幅分别为18. 3%、22. 5%、26. 4%、26. 9%及27. 5%;采用28 mm钻孔时,直径18 mm和直径20 mm钢棒平均最大推进阻力分别为179 N和453 N,两者相差274 N,但两者推进均比较容易;预应力钢棒锚具平均承载能力为398.2 kN,锚环与夹片的洛氏硬度分别为27.78和58.39,能够满足国标和钢棒材料力学性能要求。     

基于FLAC3D的管缝锚杆与玻璃钢锚杆支护效果对比

高峰矿大部分巷道采用管缝锚杆支护，但受巷道支护环境以及防腐措施不当影响，支护的管缝锚杆常因腐蚀而失效，需要进行二次支护，大大增加了支护成本和劳动强度。玻璃钢锚杆具有高强、轻质、耐腐蚀和抗疲劳的优点，能有效克服锚杆易腐蚀的问题。通过采用FLAC^3D有限差分软件对高峰矿管缝锚杆和玻璃钢锚杆支护进行数值分析，对比了2种锚杆在相同支护条件下的巷道变形、岩体应力场、塑性区以及安全度，充分分析了2种锚杆在高峰矿巷道的支护效果。研究表明高峰矿采用玻璃钢锚杆取代管缝锚杆进行支护具有可行性。     

胶结锚杆的二维有限元分析

本文根据应用较广的胶结锚杆的变形特性和荷载形式,考虑到胶结锚杆杆体、胶结层和岩体的不同物理力学性质,建立了一种新的模拟单元,它包括模拟胶结锚杆的胶结层、锚头部位的胶结层、杆体以及对岩体不连续面的锚钉效应的六节点等参数胶结单元、五节点等参数胶结单元、三节点等参数的杆体单元和二节点锚钉单元。     

基于注浆试验的深井软岩CT分析

深井注浆围岩内部结构复杂而隐蔽,目前尚缺乏对其强度等特性定量测试分析的有效方法,通过三轴压力相似模型试验,制作了高应力深井破坏软岩等效试件,采用优化的浆液配比和自主研发的MYZJ-2型实验室液压注浆系统对破坏软岩进行了实验室注浆试验,测试注浆后试件单轴抗压强度,利用CT扫描技术对注浆试件裂隙变化情况进行了观测研究,并分析了试件内部裂隙分形维数变化规律。研究结果表明,采用水灰比1∶0.6,膨润土比例为水泥重量4%的超细水泥浆液对等效破坏泥岩试件注浆加固后,试件承载能力得到一定程度恢复,且峰后残余强度较注浆前提高约40%,韧性能力提高,试件内部裂隙基本被浆液填充,裂隙分形维数由注浆前1.385减小到注浆后1.074,注浆效果较好。     

Support characteristics of eco-spiral pile with respect to twisting angle and ratio of borehole diameter to pile width

This study numerically analysed the characteristics of eco-spiral piles (Eco-SPs) as multi-purpose geotechnical supports. The behaviour of eco-spiral piles in the ground was studied with respect to their twisting angle and the ratio of borehole diameter to eco-spiral pile width using FLAC-3D based on the finite-difference method. A cement mortar grout was modelled to sustain the eco-spiral pile in a sandy soil. Relationships were found among the eco-spiral pile’s twisting angle, pull-out load and maximum shear stress. The results should aid the further design of the bolts for application in a range of circumstances.     

四种锚杆的现场试验和工程应用

根据砂浆锚杆、快硬水泥卷锚杆、管缝锚杆和长锚索在武钢金山店铁矿几种矿岩条件下所做的现场拉拔试验情况，提出了在该矿今后应用的合理锚杆类型。     

巨高巷道巷帮稳定机理及支护技术

以山西某矿5203轨道巷的巨高巷道为研究对象,采用对比分析方法,描述了巨高巷道巷帮水平位移和下沉特征及塑性区的分布特征。通过分析巷帮片帮力学模型、巷帮锚固墙的对深部围岩约束原理、巨高巷道金属支架腿部易产生压杆失稳等,最终采用高强锚杆、带、网、索支护方式加固巷帮并确定了合理支护参数。实践结果表明,巨高巷道巷帮稳定原理适用于巨高巷道巷帮支护。     

粘土水泥浆性能及其堵水机理的研究

为了取代单液水泥浆，促进粘土水泥浆的推广应用和控制不同注浆条件下浆液参数达到理想的堵水效果，研究了粘土水泥浆的密度规律、流变性及其影响因素，粘土水泥浆的稳定性、塑性强度测定原理，分析了粘土水泥浆的凝结特性及原理、堵水机理．粘土水泥浆具有粘性、塑性、弹性三态变化规律，粘性是浆液扩散、流动的前提，浆液属于宾汉姆流体；塑性状态下，塑性强度增长，可防止浆液超扩散和被水稀释冲走；弹性状态确定了防水帷幕的强度     

The shear strength of reinforced rock joints

The evaluation of the shear strength of rock joints, reinforced by means of steel dowels, by both experimental measurements and numerical modelling with the aim of determining a provisional tool for optimization of dowel design is presented. The influence of some important parameters of both the rock and the steel type on the mechanical behaviour of the reinforced structure has been studied. The analysis of the mechanical behaviour of the discontinuous rock mass-dowel system presented in this paper involved the following theoretical and experimental studies:

• ••|laboratory tests on reinforced rock joints,
• ••|Finite Element Method (FEM) modelling of the laboratory tests,
• ••|analytical models for determination of the reinforced joint shear strength,
• ••|comparison between the experimental and analytical results.

The tests have been carried out in order to evaluate the influence of some important parameters on the mechanical behaviour of the reinforced structure:

• ••|steel type,
• ••|bar diameter,
• ••|reinforcement type (bars and tubes),
• ••|rock material type.

Shear resistance is heavily influenced by the quoted parameters. Yielding steel provides the highest contribution to the global reinforced joint shear resistance when using bars or tubes. Stronger and stiffer rock materials lead to higher shear stresses in the steel and consequently lower overall resistance.Two different mechanisms of reinforcement failure have been observed while varying the rock material characteristics. The analytical model has been set up in order to reproduce these two failure mechanisms, one involving a strong and stiff rock material with bar failure determined by shear and tensile stresses at the joint intersection; and the other involving weaker rock and the formation of two symmetric plastic hinges in the bar, with failure being due to either the tensile strength or the ultimate elongation of the reinforcement being reached. Finally, the analytical model has been validated by comparison with experimental results.     

Effect of stress change on the bond strength of fully grouted cables

The bond strength of fully grouted cable bolts is primarily frictional and depends on the pressure at the cable-grout interface. Thus, any change in this interface pressure must affect the bond strength. The interface pressure increases with (load induced) dilation and may increase or decrease with the stress change due to nearby mining activities (excavation induced). In this paper, the effect of stress change on the bond strength is studied in the context of the bond strength model (BSM) previously established in a companion paper. A laboratory testing program was executed to evaluate the stress change effect on the frictional resistance of the steel-grout interface of a smooth bar and the laboratory results confirm the theory. It is concluded that mining induced stress change is one of the most important parameters controlling the cable bond strength. Theoretical results indicate that cables should be most affected by stress change in relatively soft rocks. Stress reductions of −40 MPa, often measured in deep mines, can cause the cables to lose most of their bond strength in low to medium stiff rocks. This study provides a new perspective on cable design and provides a methodology to increase the stability of openings.     

锚固参数对地震作用下岩质边坡锚固界面剪切作用影响的数值分析

基于FLAC~(3D)建立锚固岩质边坡数值分析模型,并用优化的cable单元建模分别模拟分析锚杆-砂浆界面上和砂浆-岩体界面上的剪切作用,通过改变全长黏结锚杆的锚固参数(锚固角、锚固段长度、锚杆竖向间距、锚杆直径、锚孔直径),对地震作用下锚固岩质边坡锚固界面上的剪应力及动力响应规律进行研究。研究发现:在地震作用下,随着锚固角的增大,锚固界面上的峰值剪应力减小,边坡永久位移增大;当锚杆在结构面两侧的长度相等时锚杆界面的锚固作用最大化;当锚杆竖向间距减小,峰值剪应力和边坡永久位移均减小;随锚杆和锚孔直径的增大,峰值剪应力和边坡永久位移总体呈减小的趋势。在考虑安全性、经济性的前提下,建议适当减小锚固角和锚杆竖向间距,保持锚杆拉拔段与锚固段长度相等,锚杆和锚孔直径保持合理的比值。该研究可为相关理论、试验研究和锚固边坡抗震设计提供参考。     

混凝土植筋群锚效应试验分析

文章通过植筋试件的拉拔试验,研究了混凝土植单筋与植群筋在拉拔力作用下的破坏形态、极限荷载、植筋滑移、群锚效应和刚度延性分析,讨论了多根植筋组合效应对混凝土植筋锚固极限承载力的影响。结果表明:随着植筋数量的增加,群锚效应越加明显,植筋初始滑移量明显减少,当植筋数量为两根或三根时,表现效果最好。     

锚杆静-动力学特性及其冲击适用性

利用自主研制的静-动加载试验系统开展了等强与非等强螺纹钢锚杆的静力拉伸实验及有无预应力加载的动力冲击实验。结果表明:在静荷载作用下等强与非等强螺纹钢锚杆都经历了“线弹性变形-屈服平台-强化阶段-径缩破坏”的4个阶段;冲击加载时锚杆的屈服阶段可划分为瞬态屈服与稳态屈服,瞬态屈服的峰值载荷明显高于稳态屈服载荷,且相同直径条件下与静力加载相比锚杆屈服伸长量减小;当冲击能量低于9 kJ时,锚杆杆体能承受多次冲击扰动,且冲击后能够保证足够的杆体强度,但当冲击能量高于9 kJ时,锚杆抗冲吸能性能显著下降,低能量冲击时非等强螺纹钢锚杆的抵抗能力明显优于等强螺纹钢锚杆;无论从锚杆的动态轴力-位移曲线还是从锚杆的峰值载荷与伸长量上看,预应力对冲击载荷下锚杆的动力响应特征无明显影响,但进行防冲支护时,有必要提高预应力加载水平。     

用声波法判定注浆土体固结时间的试验研究

利用超声波探测仪对土层注浆土体固结时间的变化进行了测试试验研究.土质为细砂和砂质土,浆液为水泥-水玻璃双液浆.根据波速随固结时间的变化规律得知,注浆4d后土体即可具有稳定的固结强度.     

砂层渗透注浆加固效果模型试验研究

渗透注浆是煤矿井筒穿越砂层段防渗加固的重要手段之一,为研究砂层渗透注浆加固效果,研发了一套砂层渗透注浆模型试验装置,该装置具备多个试样同时注浆、不拆模测试注浆试样渗透系数等功能;以抗压强度、变形模量、渗透系数作为评价砂层渗透注浆加固效果的性能指标,选取砂层粒径级配、黏性土含量、浆液水灰比、注浆压力4个因素作为渗透注浆效果的影响因素,开展了砂层渗透注浆加固效果正交试验,获得了影响砂层渗透注浆效果的主控因素以及不同条件下砂层注浆加固体的变形破坏特征。研究结果表明:砂层经渗透注浆加固后,3 d抗压强度可达到0.5~8.5 MPa,3 d变形模量可达到35~750 MPa,1 d渗透系数可达到10-6~10-7 cm/s数量级;浆液水灰比是控制砂层注浆加固效果的主控因素,随着浆液水灰比的增加,砂层注浆加固体抗压强度、变形模量及抗渗性能均显著降低;砂层注浆加固体破坏模式受浆液水灰比影响显著,低水灰比(W/C=0.8左右)对应整体破坏模式,高水灰比时(W/C=1.6左右)水泥浆液析水效应对加固体破坏过程产生影响,使其呈现出局部破坏模式,在砂层渗透注浆加固工程中应尽可能选用低水灰比的水泥浆液。     

磁致伸缩扭转导波在纤维增强塑料锚杆中的应用

针对电磁超声信号信噪比低、回波特征不明显的问题,本文对磁致伸缩扭转导波特性进行了分析,扭转导波非频散适合信号处理,且在传播过程中能量衰减较小。利用ANSYS有限元仿真软件分析了扭转导播在纤维增强塑料(FRP)锚杆内的位移、功率流特性;搭建了物理实验平台,在FRP锚杆内激励和接收磁致伸缩扭转导波信号,对采集到的回波信号进行CEEMD-LMS算法滤波;实验数据验证了数值分析结果的有效性。结果表明:磁致伸缩扭转导波在FRP锚杆内的传播功率趋向于表面,适用于FRP锚杆表面缺陷检测;经CEEMD-LMS滤波算法处理后的磁致伸缩导波信号信噪比得到提升;磁致伸缩扭转导波技术可对有周向缺陷的FRP锚杆长度、缺陷位置进行识别。     

井巷工作面注浆孔口管的长度确定与埋设

论述了井巷工作面注浆时,利用混凝土止浆垫止浆和预留岩帽止浆情况下,孔口管长度的确定方法以及其安设方法。用混凝土做止浆垫时,孔口管的长度根据混凝土的抗压强度或者孔口管与混凝土的粘结力计算;用止浆岩帽止浆时,根据孔口管与水泥浆的粘结强度计算。孔口管的安设方法有预埋式和后埋式。为了安全,预埋时可在孔口管上焊上钢筋,以增大摩擦力;后埋时可利用锚杆进行固定。     

联合支护技术在高速公路上的应用

预应力锚杆和喷射砼联合支护技术在日东高速公路段边坡治理工程中 ,通过对预应力锚杆的施工组织、所用机械、施工工艺及流程、施工要点、故障处理和质量保障措施等进行详细的阐述 ,为解决类似工程问题提供了可借鉴的经验。