Deformation mechanism and NPR anchor cable truss coupling support in tunnel through fault fracture zone

To address the issue of extensive deformation in the Tabaiyi Tunnel caused by the fault zone,nuclear magnetic resonance(NMR)technology was employed to analyze the physical and mechanical properties of waterabsorbing mudstone.This analysis aimed to understand the mechanism behind the significant deformations.Drawing from the principle of excavation stress compensation,a support scheme featuring NPR anchorcables and an asymmetric truss support system was devised.To validate the scheme,numerical analysis using a combination of the Discrete Element Method(DEM)-Finite Element Method(FEM)was conducted.Additionally,similar material model tests and engineering measurements were carried out.Field experiments were also performed to evaluate the NPR anchor-cable and truss support system,focusing on anchor cable forces,pressures between the truss and surrounding rock,pressures between the initial support and secondary lining,as well as the magnitude of settlement and convergence deformation in the surrounding rock.The results indicate that the waterinduced expansion of clay minerals,resulting from damage caused by fissure water,accelerated the softening of the mudstone's internal structure,leading to significant deformations in the Tabaiyi Tunnel under high tectonic stress.The original support design fell short as the length of the anchor rods was smaller than the expansion depth of the plastic zone.As a result,the initial support structure bore the entire load from the surrounding rock,and a non-coupled deformation contact was observed between the double-arch truss and the surrounding rock.The adoption of NPR asymmetric anchor-cable support effectively restrained the expansion and asymmetric distribution characteristics of the plastic zone.Considering the mechanical degradation caused by water absorption in mudstone,the rigid constraint provided by the truss proved crucial for controlling the stability of the surrounding rock.These research findings hold significant implications for managing large deformations in soft rock tunnels situated within fractured zones under high tectonic stress conditions.

Mechanism of high-preload support based on the NPR anchor cable in layered soft rock tunnels

The control of large deformation problems in layered soft rock tunnels needs to solve urgently.The roof problem is particularly severe among the deformation issues in tunnels.This study first analyzes the asymmetric deformation modes in layered soft rock tunnels with large deformations.Subsequently,we construct a mechanical model under ideal conditions for controlling the roof of layered soft rock tunnels through high preload with the support of NPR anchor cables.The prominent roles of long and short NPR anchor cables in the support system are also analyzed.The results indicate the significance of high preload in controlling the roof of layered soft rock tunnels.The short NPR anchor cables effectively improve the integrity of the stratified soft rock layers,while the long NPR anchor cables effectively mobilize the self-bearing capacity of deep-stable rock layers.Finally,the high-preload support method with NPR anchor cables is validated to have a good effect on controlling large deformations in layered soft rock tunnels through field monitoring data.

Deformation mechanism of rock mass and prestressed anchor cable support technology of Haidong soft rock tunnel

The Haidong Tunnel is one of the four soft rock tunnels of the Central Yunnan Water Diversion Project(CYWDP),where large deformation hazards of soft rock occur frequently,which seriously affect construction safety.The effect of highly prestressed anchor cable support was studied based on the active support test in the No.3 branch tunnel of Haidong Tunnel.Firstly,the geological conditions and failure causes were analyzed on the basis of the results of geological survey,in-situ test,and rock laboratory test.Then,the Mohr circle form of the highly prestressed anchor cable active support theory for the support of bedded rock mass was given in combination with the excavation compensation method.It is considered that the prestress active compensation value required for the bedded rock mass is larger than that for the homogeneous rock mass.The deformations of rock mass under both passive and active supports were analyzed by numerical simulations.Furthermore,the'pressure bubble'mechanical model for anchor cable support of bedded rock mass in Haidong Tunnel is given.Field monitoring results show that the highly prestressed anchor cable support can control rock mass deformation well,with a maximum deformation of about 200 mm.The prestressed anchor cable is effective in the bedded stratum,which makes the stress of rock mass uniform and reduces the risk of failure of steel arches due to local bias.Meanwhile,the expansion of plastic zone was efficiently controlled,which is of positive significance for the overall stability of rock mass.

Applied on bolting-cable anchor support of full-seam roadway in weaker thick coal seam

The designing method and the supporting mechanism of both bolt and small cable anchor for full seam roadway in the weaker thick coal seam are systematically analyzed, and the construction technology and the supporting results are briefly summarized.

Numerical simulation of rockburst disaster and control strategy of constant resistance and large deformation anchor cable in Gaoloushan tunnel

The Gaoloushan Tunnel in Longnan City,Gansu Province,China,frequently experiences rockburst disasters due to high in-situ stress.Managing rockburst in deep-buried tunnels remains a challenging issue.This paper employs RFPA(Rock Failure Process Analysis)software to establish a calculation model of constant resistance and large deformation(CRLD)anchorages and analyzes the effects of different support methods and pre-stress levels on rockburst.We simulate the process of tunnel rockburst disasters and find that ordinary anchor support incurs rockburst on the right arch waist and arch top,forming a V-shaped explosion pit.CRLD anchor support has several advantages in rockburst control,such as more uniform stress distribution in the surrounding rock,a uniform distribution of plastic zones,less noticeable damage to the tunnel,and effective control of the arch top displacement.The effectiveness of the CRLD anchor support under varying pre-stress conditions shows that a higher prestress results in a smaller plastic zone of the surrounding rock and arch top displacement and a lower number of acoustic emission signals,which better explains the excavation compensation effect.Moreover,adding long anchorages in the deep surrounding rock area can better control rockburst and reduce surrounding rock deformation.Based on these findings,we propose a comprehensive control system that combines long and short anchorages and provides the optimal scheme based on calculations.Therefore,by using high-prestress CRLD anchor support and the combination of long and short anchorages at critical positions,we can enhance the integrity of the surrounding rock,effectively absorb the energy released by the surrounding rock deformation,and reduce the incidence of rockburst disasters.

巷道帮部锚索外注式锚注支护技术试验研究

在煤矿巷道的帮部围岩加固技术中,以施加帮部锚索和围岩注浆为主要方法,考虑帮部锚索端锚强度较小、围岩注浆在锚索孔内扩散较困难等问题,本文提出帮部锚索外注式锚注支护技术,将普通帮部锚索与注浆相结合,实现帮部围岩加固的锚注一体化和锚索全长锚固,并对外注式锚注支护技术的物理性质进行阐述,利用相似模拟试验阐明了封孔料注入量的问题,利用井下试验验证了巷道帮部锚索外注式锚注支护技术的可行性,为锚注支护一体化的发展提供了支持。

注浆锚索在53081综采面超前支护中的应用

以长平煤业5308工作面为工程背景,在现场生产地质条件调研、临近工作面回采经验、理论分析的基础上,提出53081巷超前支护区“注浆锚索+工字钢”替代单体柱补强支护方案。现场监测数据表明:53081巷最大底鼓量、顶板下沉量和巷帮内挤量分别为530 mm、178 mm和275 mm,最大浅部离层值92 mm,深部离层值35 mm,“注浆锚索+工字钢”超前支护工艺可保持巷道围岩稳定,有效降低工人劳动强度,提高工作面生产效率。

鲍店煤矿5312胶带顺槽过断层破碎带支护优化研究

针对掘进巷道过断层破碎带时围岩破碎、支护困难、变形量大、维护成本高的问题,以鲍店煤矿5312胶带顺槽为研究对象,通过对断层破碎带围岩结构及力学特征和巷道原支护方案存在的问题分析,提出了“全锚索+槽钢+W钢带+金属网”的过断层破碎带巷道组合优化支护方案。现场应用结果表明:采用组合优化支护方案后,过断层段巷道顶板下沉量最大值为98.82 mm,两帮相对位移量最大值为126.76mm,分别为原支护方案时的13.6%和18.5%,且无网兜、掉顶及片帮现象发生,表明“全锚索+槽钢+W钢带+金属网”组合优化支护方案有效控制了过断层段巷道围岩变形,为巷道安全使用提供了保障。

复杂环境条件下深大基坑二次借力传力支护体系分析与实践

以北京某改造复建项目深大基坑工程为例,针对其周边存在障碍物影响支护的问题,提出不支护、半支护和全支护3种方案;通过Midas GTS/NX软件从变形和受力的角度对上述方案进行了分析,比选得到了最优方案,并将其应用于实际工程;同时对该方案提出的由斜拉锚索配合水平对拉锚杆形成的二次借力传力支护体系进行了重点分析。数值模拟研究发现,当不支护或半支护时,基坑将出现失稳现象;而全支护时,竖井北侧供力源斜拉锚索提供的拉力大于基坑侧借力源对拉锚杆稳定基坑所需的拉力,且在该支护体系作用下,基坑围护结构变形可以满足规范要求。此外,现场监测数据研究发现,监测结果与全支护模拟计算结果变化趋势一致且数值接近,文中提出的基于二次借力传力的全支护方案合理有效,建立的数值模型能有效反映工程实际。

厚煤层动压影响巷道围岩控制技术研究

为实现厚煤层动压影响巷道围岩变形的有效控制,以15202回风巷为研究对象,通过分析回风巷原支护设计存在的问题,提出了采用全断面强力锚索及施加高预紧力,以控制围岩的变形情况,并配套可调心W型托盘、 W型钢带、钢筋梁等护表结构。工程应用后,15202回风巷支护用锚索未出现失效情况,巷道顶板、左帮、右帮最大变形量分别为33、 28、 16 mm,围岩变形量整体较小,有效控制了动压影响下巷道围岩的变形。

煤层群采空区下回采巷道锚网索梁支护技术研究

为实现采空区下回采巷道围岩的有效控制,以9303运输巷为研究对象,提出采用锚网索梁方式支护围岩,并对工程应用进行了分析。分析了7#煤层回采后底板的破坏范围,发现9303运输巷处于底板破坏范围内,是导致运输巷掘进期间围岩破碎的主要原因。因此,采用了高预紧力锚杆、短锚索对围岩进行支护,并配合W型钢带、金属网、钢梁及钢带托盘等,为围岩提供了较大的支护作用力。同时,还通过强化顶板7#煤层采空区的积水疏排能力,降低了顶板淋水对支护的影响。应用结果表明,9303运输巷围岩控制效果显著,采用的支护方案可有效控制顶板离层和围岩变形情况,确保了9303运输巷后续的使用需求。

主动式超前支护下巷道围岩关键控制技术与稳定性评价

双龙煤矿采用锚索+钢带对109工作面的回采巷道进行了提前强化支护,以解决原有排距过大,影响井下人员安全和生产效率低的问题。为验证补强后的支护方式是否满足要求,对支护强度进行了校核和可行性研究。研究结果表明,在超前主动支护方案下,巷道顶板的支护安全系数达到了强度要求,分别为12.59和11.12,远高于原超前支护的安全系数7.43和6.69。根据双龙煤矿现场实际情况和围岩特征,结合理论分析和数值模型等方法,对109工作面的围岩安全潜在危险进行了分析,并提出了技术性的安全保障方案,分析了所存在的潜在危险,并进一步给出了安全保障的技术性方法,得到了实用的潜在危险控制思路,在巷道容易破碎的时侯选择采用合理有效的支护方式,在安全层面上选择采用锚索+钢带的补强支护方式是完全可以保证双龙煤矿的安全高效开采。

松软破碎厚煤层大跨度切眼围岩控制技术研究

为实现松软破碎厚煤层大跨度切眼围岩变形有效控制,以15303综放工作面切眼为研究对象,结合现场条件给出围岩支护技术方案并分析围岩控制效果。15303综放工作面切眼顶板采用全锚索支护,并配合长锚索、单体液压支柱提高支护效果。工程应用后,15303切眼围岩控制效果显著,至开采设备安装时切眼顶底板、两帮位移量分别为141、162 mm,切眼断面收敛较小,可为采面开采设备安装提供良好、安全的条件。

Model test on support scheme for carbonaceous slate tunnel in high geostress zone at high depth

The Muzhailing extra-long highway tunnel and corresponding inclined shafts in Lanzhou,Gansu Province,China passes through structurally complex carbonaceous slate that is under high ground stress.Rationally-designed and effective support is of high importance for achieving safe and efficient tunnel construction.The No.2 inclined shaft of Muzhailing Tunnel was taken as the engineering background prototype,for which,a similar model test was conducted to evaluate the effect of highly pretightened constant resistance(NPR,Negative Poisson’s Ratio)anchor cable support provision to the geologically complex carbonaceous slate at different depths.Two schemes were proposed during testing:one scheme was without support and the second was with asymmetric support from highly pre-tightened constant resistance anchor cable.Digital speckle displacement analysis system and micro-groundstress sensors were employed to measure the deformation and shear stress distribution of the tunnel.The results demonstrated that through the second support scheme,the deformation of the surrounding rock could be effectively ameliorated,while this support scheme was applied on the project site of the No.2 inclined shaft,to explore the rationality of the scheme through field engineering tests.On-site monitoring indicated that the deformation of the surrounding rock was within the reasonable design range and the problem of severe tunnel deformation was effectively controlled.The research methods and related conclusions can be used as a reference for the treatment of large deformation problems in deep-buried soft rock tunnels.

穿断层隧道NPR锚索支护体系抗震特性振动台试验研究

为研究具有负泊松比效应(negative Poisson’s ratio,NPR)的恒阻大变形锚索在地震作用下的吸能特性与动力响应规律,利用振动台开展含断层隧道使用普通锚索支护以及使用NPR锚索支护的振动台物理模型试验,对比分析地震作用下处于不同围岩条件中以及使用不同锚索进行支护时隧道结构的动力响应规律。研究结果表明:在同一地震波作用下,使用NPR锚索进行支护的隧道结构破坏程度与使用普通锚索进行支护的隧道结构相比有明显的改善,表明NPR锚索在地震作用下具有良好的吸能特性,能够为隧道结构提供有效支护;通过对比分析普通锚索与NPR锚索的锚索轴力时程曲线可知,在地震波作用下,普通锚索会发生破断现象,轴力突降至零,而NPR锚索的高恒阻力能够持续提供有效支护;分析隧道结构各测点的加速度、应变、土压力等动力响应可知,隧道断层区域在地震作用下的动力响应更为明显,隧道结构在地震作用下呈现出拱肩→拱腰→拱顶的破坏规律,这一研究成果为类似隧道工程的支护对策提供了理论参考。

深基坑双排微型桩-锚-撑组合支护结构受力与变形特性

为深入研究深厚杂填土地层深基坑微型桩-锚-撑组合支护结构随基坑开挖的受力与变形演化规律,首先,依托青岛市某深基坑工程开展双排微型桩-锚-撑原位试验,分析开挖工况下前、后排桩的桩身弯矩分布规律;然后,结合ABAQUS有限元模拟方法,明确微型桩、预应力锚索与钢支撑之间的协同作用及基坑变形规律;最后,揭示微型桩桩径变化、支护结构作用对桩身受力及基坑变形的影响机制。研究结果表明:增加开挖深度引起桩身正弯矩和负弯矩不断增大,极值点位置不断下移,桩身弯矩整体呈正“S”形分布;开挖至基底,前排桩的桩身反弯点分别位于钢支撑下方0.5 m和开挖面位置,后排桩的桩身反弯点分别位于钢支撑下方0.5 m和开挖面下方1.0 m范围内;基坑开挖竖向影响范围约为1.35H(H为基坑开挖深度),桩径增加近1倍,土体水平位移仅减少约51%,且随桩径继续增加,其对于限制基坑变形效果不显著;相较于桩锚支护结构,桩-锚-撑支护结构作用下,前、后排桩的最大水平位移分别减小34.9%和27.3%,基坑土体的最大水平位移减小46.0%。

基于总安全系数法的隧道支护“强度-变形-时机”一体化设计方法研究

为解决宜兴高铁兴山东隧道含炭质页岩段大变形问题,基于总安全系数法理论体系,以围岩变形和多层结构协同承载控制为目标,建立适用于主动和被动支护体系的支护“强度-变形-时机”一体化设计方法。在强度满足承载要求的前提下,通过调整支护构件本身的变形能力和支护时机,使支护可变形能力大于设计支护力下围岩必需的变形量(防止支护刚度过大),并小于最小支护力下围岩必需的变形量(防止支护刚度过小),从而使整体支护结构按设计意图以最经济的方式“工作”。采用该设计理论,设计“双层初期支护+可缩钢架方案”和“预应力锚索主动支护方案”2种支护体系,提出各分项支护构件的施作时机和安全控制要求,并在现场开展试验。试验结果表明:1)2种支护方案均有效实现了设计意图,解决了隧道含炭质页岩段大变形问题。2)采用双层初期支护+可缩钢架方案时初期支护安全系数最小值为1.83,隧道最大水平收敛为588 mm,满足设计要求;采用预应力锚索主动支护方案时围岩最大水平收敛为372 mm,锚索最大轴力为310 kN,满足设计要求。

锚杆钻车运行中支护承载结构及围岩受力变形分析

目的针对单轨液压锚杆钻车运行过程中支护承载结构及围岩受力变形难以观测分析的问题。方法利用研发的CMMD4-35煤矿用单轨液压锚杆钻车,结合长城五矿1902S回风巷巷道现场情况综合分析钻车在大断面大倾角巷道动态运行的支护、承载及围岩协同受力变形特征。结果研究表明,钻车运行过程中吊挂板的受力变形在悬吊点处均达到峰值,工字钢在悬吊点的部分位移最小,与钻车直接接触的部分受力最大;锚索中部主要受到拉应力,靠近巷道一侧主要受到剪应力,而巷道两帮的锚杆拉应力主要分布在靠近巷道内部一侧;巷道顶板悬吊点处位移最大,两帮靠近顶板位移高于底板处,而巷道偏向低帮处底板的位移大于高帮处;以单轨液压锚杆钻车为核心的新型配套工艺可以有效控制围岩变形,支护效果良好,比传统以掘锚一体机为中心的机器化工艺掘进效率更高。结论研究明确了CMMD4-35煤矿用单轨液压锚杆钻车在实际应用的可行性,解决了现有掘锚一体机难以在复杂地质条件下大断面煤巷自动化掘进支护的问题,提升了煤巷支护效果掘进效率,为CMMD4-35煤矿用单轨液压锚杆钻车的现场应用提供了理论依据。

乌兰木伦煤矿大断面硐室围岩变形破坏规律及控制

针对煤矿井下巷道大断面硐室的围岩变形破坏问题,以乌兰木伦煤矿井下分选及充填大断面硐室为研究对象,采用相似模拟实验方法,进行单调递增加载和恒定荷载加载单轴压缩实验,对大断面硐室围岩变形破坏规律进行了研究。结果表明:①2种加载方式在压密阶段、弹性变形阶段及微破裂稳定发展阶段破坏演化和变形位移趋势相似。②采用单调递增加载方式的试样裂纹较少但裂纹缝隙较大,试样沿着主裂纹突然发生破断,期间有大量碎屑飞出,试样变形位置主要集中在围岩边界,破坏时释放能量较多,但峰后释放能量持续时间较短。③采用恒定荷载加载方式的试样应力保持不变,应变缓慢增加,期间产生大量微小裂纹,试样变形位置主要围绕在硐室周围,破坏时释放能量较少,但峰后释放能量持续时间较长。依据大断面硐室围岩变形破坏规律,提出了锚杆索支护方案:硐室顶部打长锚索,将顶板和上方坚硬岩石连成整体;在硐室煤岩交界处打倾斜锚杆,将煤岩交界面与周围岩体紧密连接。数值模拟结果表明,支护后围岩应力、位移、塑性区均明显减小,围岩稳定性大幅提高,支护效果良好。

晋北煤业综采工作面高强锚索超前支护技术研究

为解决传统单体液压柱进行超前支护时出现的钻底问题,以晋北煤业3-503综采工作面为工程背景,进行高强锚索代替单体柱进行超前支护研究,通过矿压监测、数值模拟手段分析方案的可行性,并确定合理的支护参数,在3-503工作面回采巷道进行实践应用。实践表明,采动影响下巷道围岩变形得到有效控制,锚索工作性能良好,提高了工作效率,降低了工作强度,研究成果具有较好的借鉴和推广意义。