预应力锚索加固技术的力学行为与群锚效应分析

预应力锚吲技术是现代岩土工程加固技术的重要手段。通过对锚索、灌注锚固体和锚孔周围岩土体进行三维弹塑性有限元分析，研究了锚索、锚固体、岩体的轴向应力分布规律，以及锚固体与岩体中的剪应力、锚固体的位移和塑性区的变化趋势：并对群锚效应下锚固体的位移、正应力、剪应力的影响范围进行了分析，探讨了考虑群锚效应下锚索间距的布置原则，为在锚固工程中合理施锚和优化布锚提供了依据。     

预应力群锚高边坡增稳机理研究

本文阐述国家"八五"重点科技攻关项目"高边坡预应力群锚加固机理研究"中加锚岩体的变形体传力特征。通过现场群锚试验,室内模型试验和数值计算验证研究,发现群锚增稳不同于刚体法加锚的岩体的受力传力动态机理效应,提出了依安全度布锚增效的新参数理论,探讨了判别加锚效果的岩体表层新生压应力层的"岩壳效应"场的机理依据     

加锚岩体的界面应力元模型

基于不连续介质变形体的界面应力元法建立了加锚岩体新的数值模型，该模型可以仿真各种加固锚件的复杂几何布局，对加固锚件的位置、长度、倾向、倾角等均无任何限制和要求。数值算例表明：文中的计算模型能够较好地揭示加锚岩体的工作性态，具有广阔的应用前景。     

高应力软岩巷道锚注一体化联合支护技术应用

介绍了国家专利注锚剂、中空注浆锚索等产品,以国家能源麦朵山煤矿11采区2煤辅助运输巷为研究对象,采用数值模拟、理论分析、现场测试及井下试验相结合的综合研究方法,对11采区2煤辅助运输巷采用锚注一体联合支护技术,来实现对岩体裂隙注浆,使浆料与岩体结为一体,在围岩与支护体共同作用过程中,实现强岩增荷的作用,维护巷道的稳定性,实现工作面的安全生产。     

四渡河特大桥隧道锚碇三维弹塑性数值分析

四渡河特大桥隧道锚碇以锚洞围岩为研究对象,采用三维显式有限差分法(FLAC3D)对锚碇与围岩进行三维弹塑性数值分析,模拟岩体与锚碇之间的相互作用,研究锚碇结构和岩体变形机制以及可能的破坏模式,通过超载和弱化岩体与混凝土胶结面强度参数研究隧道锚碇的极限承载力或安全系数,并对整个山体进行稳定性分析,从而为设计提供依据。     

重庆鹅公岩大桥隧道锚碇围岩稳定性

重庆鹅公岩长江大桥设计采用悬索桥方案。东锚碇为隧道锚，布置在粉质砂岩和砂质泥岩互层岩体中，锚碇及围岩体的变形状态直接影响大桥的稳定和安全。为了了解锚碇及围岩体在张拉荷载下的变形状态及围岩极限承载能力，对围岩及锚碇进行了较全面的试验研究，包括岩体参数试验、1：12．5实地结构模型张拉试验、数值分析及灰色GM（1，1）模型预测等。研究表明：锚碇及围岩变形较小，变形处于弹性阶段；灰色GM（1,1）预测出岩体极限承载力为设计荷载的6．09～6．15倍。锚碇处于安全状态。并有足够安全储备。试验研究成果为设计提供了可靠依据。     

狮子山南坡危岩体防治设计及三维数值模拟

详细介绍了狮子山南坡危岩体的稳定性分析及其防治设计，并应用快速拉格朗日法对危岩体进行三维数值模拟，比较了支护前与支护后的位移场和应力场。研究结果表明，FLAC能够直观地反映出危岩体的治理效果，其作为危岩体治理的评价手段是可行的。     

高速铁路隧道穿越断层破碎带加固方法的数值模拟

高速铁路隧道具有大断面的特点，其穿越断层破碎带时更易引发围岩坍塌和涌水的发生。本文通过对某高速铁路隧道围岩的物理力学特性试验，得到其岩体力学参数，然后采用数值模拟计算方法，分析了断层破碎带对隧道稳定性的影响程度。最后，通过对关键部位的支护进行计算，表明喷锚支护能有效地抑制围岩位移，能保证隧道结构的稳定性。     

锚固后岩体稳定性分析的能量法初探

现有常规的锚固后岩体稳定性分析方法是建立在传统岩体稳定性分析方法的基础上，仅把锚杆的作用简化为一个抗滑力，没有考虑锚杆的锚固作用对岩体滑移面上应力分布的影响。作者以一种新的思路来分析加锚岩体的稳定性，其中的一个重要思想是：滑裂面的极限抗剪强度是在滑裂面发生一定相对错动后才能完全发挥。根据新的思路并考虑锚杆锚固效应对滑裂面上应力分布的影响，新方法将从能量角度判定岩体的稳定性。     

“八五”攻关预应力群锚加固边坡机理研究

本文通过现场试验、室内模型试验和数值分析，重点介绍了边坡单根预应力锚索加固和群锚加固的机理。     

宜兴抽水蓄能电站地下厂房锚杆承载力现场试验研究与计算方法

简要介绍了一次大型洞室锚杆支护设计现场拉拔试验的研究成果，内容包括所采用的拉拔试验方法和主要试验结果。给出了锚杆体轴应变测试方法及其测试结果、岩体层面夹角对锚杆受力状态的影响、岩体表面及杆端位移特征、锚杆注浆体与孔壁之间的粘结力等试验结果，并根据试验结果提出了锚杆承载力峰值剪应力计算方法。与传统方法相比，所提出的方法建立在现场试验测试结果基础上，计算中考虑了锚杆体上剪应力不均匀分布的特点，锚杆长度按张拉段与锚固段之和计算，锚杆承载能力按杆体上的峰值剪应力计算，计算结果可较好地反映锚杆的实际受力状态。     

外部连接全长黏结式锚杆和弹力式锚杆 抗爆加固效果模型试验研究

 利用实验室抗爆模型试验装置，研究在平面装药爆炸应力波的作用下，外部连接全长黏结式锚杆和弹力式锚杆对洞室围岩的不同加固效果。通过分析自由场爆压时程曲线，发现该试验仪器测试效果较好，并分析和比较2种锚杆加固所造成的洞室围岩拱顶位移、洞壁应变和拱顶、底板及侧墙加速度的差别。试验结果表明：经过外部连接全长黏结式锚杆加固的洞室比弹力式锚杆加固的洞室拱顶位移峰值减少明显；在平面波的作用下，3个洞室洞壁各个位置都是产生压应变，最大应变出现在拱脚处；拱顶加速度是振动最激烈的地方，底板加速度在变形不大时加固洞室增加较大，必要时应该采取减震措施；对比2个加固洞室的最大应变峰值和加速度，发现外部连接全长黏结式锚杆相对较小，说明对洞室围岩的加固宜采用外部连接全长黏结式锚杆。     

水下浅埋暗挖软岩隧道拱部系统锚杆功效

软岩隧道常常在拱部设置系统锚杆,但对于地质条件和支护方式不同的软岩隧道,拱部系统锚杆的功效不尽相同,目前还很少研究水下浅埋暗挖软岩交通隧道中拱部系统锚杆的功效。以长沙浏阳河公路隧道段施工为对象,综合运用理论分析、数值模拟和现场测试等手段,对浏阳河隧道拱部系统锚杆在暗挖法施工时的锚杆轴力、初衬内力、开挖安全系数以及地下水渗流软化围岩对锚杆功效的影响进行系统研究。结果表明:在浏阳河隧道所处的地质环境中,采用台阶法暗挖施工时,拱部系统锚杆所起的作用较小,其功效不能有效发挥,建议在上台阶型钢拱架拱脚处设置锁脚锚杆,取消拱部系统锚杆。该成果已成功地应用于浏阳河隧道施工中,缩短了施工周期,降低了工程造价。     

拱顶端部加密锚杆支护洞室抗爆加固效果模型试验研究

采用抗爆模型试验方法,研究了在集中装药爆炸应力波的作用下,拱顶端部加密锚杆支护洞室抗爆效果。通过分析压力时程曲线,证明测试数据规律性合理,数据可靠。分析和比较了拱顶端部加密锚杆支护洞室与不加密锚杆支护洞室所造成的洞室围岩拱顶位移、洞壁应变、顶底板加速度和洞室宏观破坏形态,得出拱顶端部加密锚杆支护洞室抗爆加固效果不佳。     

黄土隧道锚杆受力与作用机制

 为探讨黄土隧道锚杆作用效果及机制,对陕西省吴堡-子洲高速公路上3座黄土隧道中的48根锚杆应力进行现场测试和统计分析,结果发现：黄土隧道在钢架支护条件下,拱部系统锚杆受压且应力值较小;拱脚处锁脚锚杆以受拉为主,锁脚锚杆应力普遍大于拱部锚杆应力。从土体的变形和锚杆与土体的锚固效果2方面分析黄土隧道拱部系统锚杆的力学状态,分析认为隧道开挖后,浅埋黄土隧道拱部发生整体沉降,锚杆并不存在锚固段;深埋黄土隧道开挖后土体产生较大塑性区,目前以“短而密”原则设计的系统锚杆也不存在锚固段;锚杆与土体采用水泥砂浆或药卷式锚固剂黏结效果差,因而黄土隧道锚杆锚固力不大;锚杆锚固于初期支护上,并伸入土体中,从内部约束土体变形,在初期支护施作后,相对于土体的后续变形,拱部系统锚杆受到土体向下的摩阻力,相当于桩承受负摩阻力,因而拱部系统锚杆受压。综合以上分析表明,在黄土隧道中,钢架支护条件下的系统锚杆支护效果不明显,可以取消。工程实践证明,钢架支护条件下黄土隧道取消系统锚杆,可减少施工环节,更有利于隧道施工安全和结构稳定,可缩短工期和降低工程造价,有着特别显著的社会经济效益。     

灌浆楔型锚杆在广告牌基础中的应用

介绍了水泥灌浆楔型锚杆在某广告牌岩石基础中的设计计算方法和应用效果。     

Effects of frequency and grouted length on the behavior of guided ultrasonic waves in rock bolts

Experiments were conducted to study the behavior of guided waves in free and grouted rock bolts. Ultrasonic waves with frequencies from 25 to 100 kHz were used as excitation inputs. Tests were first conducted on free bolts to help understand the behavior of guided waves in non-grouted bolts. The effects of wave frequency and grouted length on the group velocity and attenuation of the guided ultrasonic waves were then evaluated. The test results indicated clear but different trends for the group velocity in the free and the grouted bolts. The attenuation in free bolts was not affected by bolt length and frequency. However, in grouted bolts it increased with frequency and grouted length. It was also found that the two main sources of attenuation are the setup energy loss, which has a fixed quantity for a specific type of test setup, and the dispersive and spreading energy loss which varies with frequency and bolt length.     

Utilizing a novel fiber optic technology to capture the axial responses of fully grouted rock bolts

Rock bolts are one of the primary support systems utilized in underground excavations within the civil and mining engineering industries. Rock bolts support the weakened rock mass adjacent to the opening of an excavation by fastening to the more stable, undisturbed formations further from the excavation. The overall response of such a support element has been determined under varying loading conditions in the laboratory and in situ experiments in the past four decades; however, due to the limitations with conventional monitoring methods of capturing strain, there still exists a gap in knowledge associated with an understanding of the geomechanical responses of rock bolts at the microscale. In this paper, we try to address this current gap in scientific knowledge by utilizing a newly developed distributed optical strain sensing (DOS) technology that provides an exceptional spatial resolution of 0.65 mm to capture the strain along the rock bolt. This DOS technology utilizes Rayleigh optical frequency domain reflectometry (ROFDR) which provides unprecedented insight into various mechanisms associated with axially loaded rebar specimens of different embedment lengths, grouting materials, borehole annulus conditions, and borehole diameters. The embedment length of the specimens was found to be the factor that significantly affected the loading of the rebar. The critical embedment length for the fully grouted rock bolts (FGRBs) was systematically determined to be 430 mm. The results herein highlight the effects of the variation of these individual parameters on the geomechanical responses FGRBs.     

锚拉支架中锚杆横向效应分析

研究了锚拉支架中锚杆的横向抗力，分析了锚杆横向效应对加固破碎圈岩石的成拱作用，推求了锚拉支架的拉杆拉力、锚杆横向抗力与加固作用的关系，获得的理论公式可以用于锚拉支架的分析设计，应用实例证实了其可行性。     

Full 3D modelling for effects of tunnelling on existing support systems in the Sydney region

The assessment of the interaction between a new tunnel and existing structures is an important issue in urban areas. In this study, the effect of tunnelling on the existing support system (i.e. shotcrete lining and rock bolts) of an adjacent tunnel is firstly investigated using ABAQUS and TUNNEL3D through full three-dimensional (3D) finite element calculations coupled with elasto-plastic material models, which takes into account the tunnelling procedure, the interaction between the shotcrete lining and rock mass, the interaction between the rock bolts and rock mass, and the elasto-plastic behaviour of the rock mass, the shotcrete lining and the rock bolts. Then, on the basis of the calculated results, it is concluded that the driving of the new tunnel significantly affects the existing support system when the advancing tunnel face passes the existing support system and is minor when the face is far from it. Moreover, the support system in the side of the existing tunnel closest to the new tunnel is more significantly affected than that on the side opposite to the new tunnel. It is also found that in a region such as Sydney with relatively high horizontal regional stresses, the driving of the new tunnel will not cause considerable adverse effects on the existing support system, if the new tunnel is driven horizontally parallel to the existing tunnel with a sufficient separation, since both the tensile stress in the existing shotcrete lining in the lateral sides of the preceding tunnel and the compressive stress at the crown decrease although noticeable tensile stress increments are observed on some parts of the existing rock bolts. Finally, it is pointed out that the effects of tunnelling on the existing support system strongly depend on the position between the original and new tunnels. In terms of the stress increments on the existing support system, especially the maximum tensile stress increments on the existing shotcrete lining, the driving of the new tunnel causes increasingly adverse effects on the existing support system in a sequence of: (i) horizontally parallel tunnels with a separation of 30 m; (ii) horizontally parallel tunnels with a separation of 20 m; (iii) staggered tunnels with a separation of 30 m; (iv) vertically alignment tunnels; and (v) staggered tunnels with a separation of 20 m in the cases investigated in this study. For the relatively high regional stresses in the Sydney region, the obtained results qualitatively agree with other’s published observations from the construction of closely parallel subway tunnels.