地下隧洞开挖和支护的三维数值分析计算

根据地下工程锚固支护原理,采用隐含锚杆柱单元的三维有限元和混凝土喷锚支护的三维数值计算方法,对复杂的地下泄洪隧洞的开挖和支护进行了分析计算。该方法不仅能够有效地反映锚杆的长度、密度、倾角对洞室开挖的影响,而且能够较好地模拟钢拱架和锚杆的时间施加效应。由于隐含锚杆柱单元和喷层单元是隐含在岩体单元中的,所以锚杆和喷层单元不受岩体单元划分的影响,能够有效地模拟各种支护方案,加快计算速度,合理反映锚固支护所作用的位置和时间影响。通过对构皮滩泄洪洞施工开挖和锚固支护的模拟计算,论证了施工开挖的稳定性和锚杆、喷层、钢拱架的支护作用,提出了洞室结构的加固措施,为工程施工开挖提供了有效的设计依据。     

深部破碎软岩巷道围岩稳定性分析及控制

针对深部破碎软岩巷道围岩稳定性控制难题,以邢东矿-980车场巷道为研究对象,采用现场调研、数值模拟、井下试验及现场观测等方法分析围岩变形破坏特征,揭示其破坏机制,针对性地提出了以高强锚杆密集支护、新型喷层结构护表、滞后注浆加固为主体的多层次锚喷网注联合支护系统,详细阐明了具体支护措施的围岩控制机制,并用数值方法分析了锚杆间距、喷层厚度对于围岩应力场和位移场的影响规律。研究表明：（1）随着锚杆间距减小（0.7 m→0.3 m）,锚杆承压拱和喷层结构的承载能力呈幂函数增长趋势,锚固区围岩压应力呈线性增长趋势,围岩变形量明显降低;（2）随着喷层厚度增大,喷层结构承载能力近似线性增长,锚固区围岩压应力亦呈增长趋势,各部位围岩位移量显著降低;（3）当喷层厚度达到200 mm时,非锚固区内围岩大部分处于压应力状态,拉应力区大幅减少。基于上述研究,结合现场地质、生产条件确定试验巷道围岩支护方案,并进行现场应用。工程实践表明,多层次锚喷网注联合支护技术可有效控制深井破碎软岩巷道围岩大变形,实现深井巷道围岩的稳定性控制。     

高切坡超前支护锚杆作用机制研究

人工高切坡开挖常常导致边坡失稳破坏,甚至诱发滑坡发生,为此提出了高切坡超前锚杆支护的设计新方法。超前支护锚杆能够约束边坡变形和开挖卸荷带的发展,维持边坡的稳定,对超前支护锚杆的作用机制问题进行了研究,阐述了超前支护锚杆的荷载传递特性,为超前支护锚杆设计提供了理论依据。     

复杂环境中深基坑综合支护设计与施工技术

以广西柳州一处于复杂环境中的深基坑综合支护为对象,结合工程地质条件及勘察试验,提出了“注浆微型钢管桩 注浆微型树根桩 挂网喷砼 锚杆 预应力锚索”及“钢筋混凝土排桩 旋喷桩 挂网喷砼”2种综合支护方案进行支护,并阐述了方案的设计参数选取和施工工艺要求。实践表明,支护方案具有较好的适用性和安全性,可为类似基坑工程的设计和施工提供参考。     

新型生态边坡治理支护形式现场试验研究

边坡治理工程常用到喷锚支护形式。护坡面层采用素混凝土或者钢筋混凝土,耗用建材量大,不经济。公路边坡往往还需要环保观感要求,灰色的混凝土跟周围环境不协调。本文提出一种“锚杆加固+土工格栅护坡+客土喷播绿化”的新型生态边坡复合支护形式,并设计试验段进行研究。通过理正岩土软件计算,边坡稳定性、锚杆承载力均满足设计要求。试验段锚杆采用GFRP锚杆,面积100 m2。施工完成后,对比传统土钉墙混凝土面层和格构梁锚杆护坡支护形式,该形式具有施工快捷、经济适用等优势,既可用于加固边坡又具备绿色环保功能。     

核废料地质处置概念库锚喷支护坑道热-水-应力耦合效应的二维离散元分析

假定一个核废料地质处置库位于具有一定水头的饱和节理岩体中,开挖完闭施作系统锚杆和喷混凝土支护。对坑道建造和一个50年期的热-水应力（T-H-M）耦合运营过程,使用UDEC程序进行数值模拟,分析无、有支护时近场围岩中的应力、变形、塑性区、温度、渗流的变化状态,以及不同场（温度、渗流、应力）耦合条件下的锚杆和喷混凝土中的承载情况。结果显示,喷混凝土和系统锚杆支护不仅具有常规的支护功能,并且可阻滞地下水从坑道表面的自由渗出,使得围岩中塑性区减小,裂隙水压力和温度升高;相比于应力单场作用的情况,在热-水-力耦合的条件下洞室围岩的稳定性下降,支护结构的受力状况变差。     

光纤Bragg光栅传感技术在隧道模型试验中应用

在模型试验中,锚杆一般尺寸较小,应变监测较为困难,可将光纤Bragg传感技术（FBG）应用于隧道模型试验中解决该问题。基于西安地铁二号线4个典型断面实际工况进行隧道模型试验,将自行设计封装的光纤Bragg光栅传感器粘贴在锚杆模型表面,监测其在不同应力状态下的应变。根据隧道开挖前、隧道开挖后、衬砌支护后、抗裂极限状态和极限破坏状态5个应力状态的实测数据,得到锚杆轴力在隧道受力过程中的变化规律。试验结果表明,锚杆受力大小在隧道开挖前后有一定变化。衬砌支护后,随围岩压力增加,锚杆轴力基本呈增加趋势,拱顶附近锚杆承受压力,支护后压力变化不大;拱肩到墙角的锚杆承受拉力,衬砌支护后受力开始增加;锚杆在含水率大的黄土隧道中受力较大,更能发挥其作用。文中方法在模型试验中的应变监测方面提出新的可靠途径。     

输电线路节理化岩体注浆锚杆基础抗拔力模型试验研究

针对输电线路注浆锚杆基础特点,根据相似理论设计了节理化岩体注浆锚杆基础抗拔模型试验,模型设计中考虑了岩石弹性模量、浆体弹性模量、节理迹长、节理倾角、锚杆埋深5个因素的变化,选择5因素4水平的正交试验方法进行了模型试验研究。结果表明,岩石弹性模量对注浆锚杆基础抗拔力的影响最大,其次为锚杆埋深、节理倾角、浆体弹性模量、节理迹长。试验过程中以剪切破坏和开裂破坏为主,并以此分析了注浆锚杆的传力机制,得出浆体与锚杆和岩体之间的黏结强度是控制试验结果的主要因素,影响着锚杆的极限抗拔力和破坏状态,在施工过程中应注意质量控制。     

高应力深部软岩巷道支护方案设计及其数值模拟分析

基于岩体破坏准则和Hoek-Brown曲线分析了软岩巷道围岩的受力特征。结合山脚树煤矿的实例,选择中空注浆锚索巷道支护方案,模拟了高应力深部软岩巷道支护形式。研究结果表明:结合经济效益和支护效果,2.3m长的锚杆支护效果最好,且能节约巷道围岩支护的成本。同时随着巷道支护锚杆的长度逐步减小,深部高应力软岩巷道的最大竖向位移和变形也在逐渐增加。     

地震作用下锚固边坡稳定性数值分析

地震诱发的边坡失稳是一种重要的地震地质灾害类型,本文结合工程实例,利用有限差分软件FLAC3D 建立了一个边坡的数值分析模型。对比分析了静力状态下锚固前后边坡的塑性区、水平位移和滑移面,地震作用下锚固前后边坡的塑性区、各个时刻的水平位移、锚杆轴力分布和塑性状态,然后分析了边坡的稳定性,并探讨了边坡破坏的机理。数值分析结果表明:锚杆对边坡的加固效果十分显著; 锚杆在发挥锚固作用时主要受拉,且随着锚杆位置高程的增加,锚杆的轴力减小; 有无锚杆支护的边坡在地震作用下的破坏方式不同。研究结果为锚固边坡的抗震设计提供了参考依据。     

爆破振动下围岩支护锚杆动力响应解析解

为了研究爆破掘进施工对巷道支护锚杆的影响,采用结构动力学理论,从理论上推导出了锚杆在爆破地震波作用下的振动规律,计算出锚杆上的位移、振速、轴力随时间的变化,研究了黏结式锚杆在爆破动荷载作用下的动力响应特征。结果表明：自由段锚杆的轴力和轴向振速呈现指数型衰减,而锚固段锚杆的轴力和轴向振速以及剪应力呈现正弦变化,整体表现为先增大后减小。锚固长度对锚杆振动效应影响较大,不同锚固长度时锚杆受力状态不同,在锚杆满足抗拉强度的前提下,可以适当减小锚固段长度。剪切刚度对锚杆的振动有一定的影响,剪切刚度越大,锚杆与锚固砂浆之间的剪应力也越大。故为了防止锚杆不发生剪切破坏,尽量选择剪切刚度较小的锚固剂材料。研究成果对掘进爆破安全技术的提高具有一定的指导意义。     

Performance of D-bolts Under Static Loading

D-bolt is a type of energy-absorbing rock bolt. It is made of a smooth steel bar with anchors spaced along the bolt length. A typical section between adjacent anchors is approximately 1-m long, but it can be adjusted to adapt to the rock conditions. The bolt is fully encapsulated with either cement or resin grout in a borehole. The anchors are firmly fixed into the grout, while the smooth bolt sections can freely deform to absorb deformation energy. Full-scale static pull tests were carried out at different testing facilities in two laboratories. The tests show that a smooth bolt section between anchors may elongate by 110–167 mm depending on the section length. Field trials of the D-bolt were conducted in deep metal mines. The measurements showed that the D-bolts were equally loaded within every anchor-between section, avoiding load peaks and premature bolt failure due to stress concentrations caused by fracture/joint opening. The field trials of rebar and D-bolts in a largely deformed mine tunnel showed that the D-bolts behaved satisfactorily, with only a few failed bolts, while a number of the rebar bolts failed at the thread.     

动力扰动下全长黏结锚杆的力学响应特性

深部岩体工程中,锚杆在围岩变形后处于高承载应力状态,受到爆破振动、矿震等动载荷作用后极易失效,因此,亟待研究动力扰动下锚杆的力学响应机制。基于SHPB试验平台,自行研发了一套研究锚杆动力响应的试验装置,开展动力扰动下全长黏结锚杆的力学响应特性研究。结果表明：初始动载荷作用下锚杆滑移量随着入射能的增加而增加,锚杆中应力波的波峰值随着传播距离的增加而逐渐减小,当应力波传播至锚杆最里端时,应力波峰值衰减较大;第2次动载荷后锚杆SG1处与SG2处应力波峰值差明显比第1次减小,表明动载荷下锚固界面从锚杆外端开始损伤;锚杆失效与锚固界面损伤有关,锚杆承载后初次受到动载荷的影响导致锚固界面产生损伤,损伤锚固段又受到外部载荷（如二次冲击、岩体挤压）作用时会进一步劣化,其不能抵抗围岩的变形而失效。研究结果为揭示锚杆支护失效行为,采取合理的设计与施工提供新的思路。     

An analytical method for determining shear stiffness of an inclined grouted bolt installed across an open discontinuity

Summary The shear stiffness of a grouted, rock bolt intersecting a discontinuity controls the amount of shear movement that can occur for a given shear force. In this paper an analytical model is developed for estimating the shear stiffness of a single bolt as a function of bolt inclination, hole and bolt diameter, bolt, grout and rock Young's moduli, and aperture (opening) across the discontinuity, and sensitivity studies conducted to determine the most significant of these variables as predicted by the model.     

A simplified rock mass-rock bolt interaction analysis for horizontally layered strata

Summary A ground convergence-support reaction analysis is extended to the case of an opening excavated in horizontally layered strata. Simplifying assumptions include linear elastic behaviour and classical beam theory. The method is used to demonstrate the influence on bolt loads of a number of factors including the timing of support installation, failure of the roof, number, thicknesses and flexibilities of the rock layers, type of rock bolt, bolt spacings, bolt lengths, roof span, and roof beam thickness.     

粘结式锚杆在爆炸动载下轴向应力分布研究

通过物理模型试验,研究在爆炸动载作用下临近工作面支护锚杆的应力状态。根据相似条件和简化假设,采用集中装药进行工程掏槽爆破模拟,利用粘贴在锚杆上的应变片测得近区端锚和全锚锚杆的轴向应变波。测试结果表明,爆破引起锚杆振动时间约为6 ms,经过9 ms的缓降期锚杆变形趋于稳定值;动载期间端锚锚杆在杆体中部锚固段测得峰值应力比杆体尾部自由段的值大,但相差不大,动载过后尾部的残余应力较大;全锚锚杆在杆体尾部测得的峰值应力和残余应力都远大于杆体中部测得值。利用无限体内一点受法向集中力作用的位移势函数,推导锚固体及周围岩体的轴向应力分布,并计算一定预应力在锚固区产生的附加轴向应力,结合动应力的作用分析锚杆的受力状态     

Performance of D-Bolts Under Dynamic Loading

In this work, dynamic test results of D-bolts are presented. The rock bolt specimens studied are 20 and 22 mm in diameter and 0.8–1.5 m in section length. The bolts were tested at an impact velocity of 5.4–6.2 m/s and with impact energy varying from 10 to 60 kJ. In total, over 50 drop tests were conducted during a period of three years. The dynamic tests show that a D-bolt section of 22 mm × 1.5 m can sustain an impact of 56 kJ of a dynamic impact and absorb 60 kJ of energy prior to failure. The maximum impact energy of the 22 mm bolt is thus 37 kJ/m of bolt and the maximum energy absorption is 40 kJ/m. The displacement of the D-bolt increases linearly with the impact energy. A theoretical solution has been obtained for the relationship between the impact energy and the displacement of the bolt. It states that the energy absorption of a D-bolt section is proportionally related to the volume of the bolt section and the tensile strength and ultimate strain of the bolt material. It was also found that the magnitude of the impact energy determines whether or not the bolt fails, while the impact momentum determines how long the impact lasts. The impact duration increases linearly with momentum as long as the bolt shank does not fail.     

Analytical model for the design of grouted rock bolts

An analytical model which represents the behaviour of a reinforced rock mass near a circular underground opening in a homogeneous, uniform stress field has been developed. The theory adopts the concepts of elastoplasticity and considers a proper interaction mechanism between the ground and the grouted (or friction) bolts. It highlights the influence of the bolt pattern on the extent of the yield zone and tunnel deformation. A dimensionless parameter is introduced as a design tool which relates the tunnel convergence to the bolt spacing for a given bolt length. This publication contains the derivation of the analytical model and an illustration of the effect of bolts on the stress and displacement field near an opening. Its application to tunnel design is discussed briefly. The verification of the theory by laboratory simulation and field measurements will be presented, in detail, in a future publication.     

均质边坡离心试验锚杆的应力响应及布设探究

以低碳钢片模拟全长黏结锚杆,开展均质岩质边坡离心模型试验,研究了锚杆的应力响应规律。基于试验模型锚杆应力响应规律启发及实际均质边坡变形破坏演变规律,提出仅针对边坡松弛区进行局部强度折减,数值模拟探讨了均质岩质边坡单锚应力监测的较佳位置。结果表明:均质岩质边坡变形破坏起始于坡脚的剪切破坏,且随着边坡变形破坏的开展,靠近坡脚的全长黏结锚杆会较早产生明显的应力响应,锚杆应力增长速率会不断增加;锚杆应力监测点距离边坡潜在滑动面（塑性变形区）越近,锚杆应力响应时间越早,且量值越大;建议在距离坡脚0.25~0.35 H（H为边坡高度）的坡面处布设监测锚杆,但对于具体监测边坡对象,应具体问题具体分析。研究成果可为均质岩质边坡的锚杆监测工作提供一定的参考借鉴。      

Discrete element analysis of the influence of bolt pattern and spacing on the force-displacement response of bolted steel mesh

Steel wire mesh held by a pattern of bolts can be used to stabilize a rock slope. Knowledge of the force-displacement response of steel mesh is essential in the design of this support system. Laboratory tests have been used to test mesh that is held to rigid steel frames. These testing conditions differ from how steel mesh is held in the field by bolts. The existing laboratory test data may underestimate the deformation and overestimate the load-bearing capacity of the steel mesh. This paper focuses on the response of the high tensile strength steel mesh held by commonly used bolt patterns. Discrete element models were used to study the force-displacement response of the steel mesh pinned by bolts. The influences of different bolt patterns and varying ratios of bolt spacing on the effectiveness of steel wire mesh were analyzed. Relationships between the resistance force of steel mesh and bolt density at various mesh deformations were developed. These relationships can help engineers choose the bolt spacing and provide an estimate of the resistance force that a steel mesh can mobilize at a desired deformation limit for a given bolt pattern.