灌浆岩石锚杆 拉拔变形和刚度的理论解析

岩石锚杆的变形计算是锚固工程设计中的一个关键因素。基于协调剪切变形段锚杆和岩体间剪切变形刚度的线性假定,不协调剪切变形段锚杆和岩体间剪应力沿杆长呈幂函数型分布的假定,通过荷载传递微分方程,对全灌浆锚杆和有自由端灌浆锚杆的拉拔变形和刚度进行了理论分析,推导出沿杆长剪应力分布函数、轴力分布函数和位移分布函数,进而可获得锚杆最大拉拔力和拉拔荷载–位移曲线。根据剪滞理论,由灌浆锚杆周围岩体单元应力平衡微分方程,推导出 锚杆与岩体之间剪切弹性变形刚度 的计算公式。与其它理论结果比较,表明本分析方法是合理的、可行的, 对于灌浆锚杆变形、刚度及强度设计具有参考价值。     

An analytical analysis of the full-range behaviour of grouted rockbolts based on a tri-linear bond-slip model

This paper presents an analytical solution for predicting the full-range mechanical behaviour of grouted rockbolts in tension based on a realistic tri-linear bond-slip model with residual bond strength at the grout–bolt interface. The full-range behaviour consists of five consecutive stages: elastic stage, elastic–softening stage, elastic–softening–debonding stage, softening–debonding stage and debonding stage. For each stage, closed-form solutions for the load–displacement relationship, interfacial shear stress distribution and bolt axial stress distribution along the bond length were derived. The ultimate load and the effective anchor length were also obtained. The analytical model was calibrated and validated against two pullout experimental studies. The predicted load–displacement curves as well as the distributions of the interfacial shear stress and the bolt axial stress are in close agreement with test results. A parametric study is also presented, providing insights into the behaviour of the rockbolts.     

Analytical approach for the design of active grouted rockbolts in tunnel stability based on convergence-confinement method

Assuming that grouted rockbolts increase internal pressure within a broken rock mass, a new procedure for computation of ground response curves for a tunnel reinforced with active grouted rockbolts is presented, while the effect of distance of bolted section to tunnel face has been also considered. This analytical solution for a circular underground excavation under hydrostatic stress field, and with consideration of a non-linear strength criterion for rock mass and on the basis of two material behavior models has been developed. In this work, the equation of the ground response curve for a tunnel which has been reinforced with passive grouted rockbolts is also derived. The proposed model allows one to take, the effect of the distance of the bolted section to the tunnel face, the effect of increasing rockbolts spacing, the influence of increasing pretension load in calculating of the ground response curve, and the effect of increasing the cross-section area of rockbolts, into account. The results show that decreasing rockbolts spacing increase the support system stiffness rather than preloading of them.     

A theoretical approach for analysis of the interaction between grouted rockbolts and rock masses

Rock-support interaction concepts, which are applied to support systems such as concrete linings and ungrouted rockbolts, cannot be applied to grouted rockbolts, because of the nature of the structural interaction of the rock mass and grouted rockbolts. In this paper, with consideration of a non-linear strength criterion for rock mass and on the basis of two material behavior models and rock-support interaction concepts, corresponding relationships are derived. In this method, the equation of the ground response curve which has been reinforced with grouted rockbolts is also derived for a circular underground excavation under hydrostatic stress field. Because of algebraic complexity, it is not possible to obtain closed-form solutions; therefore a computer program was prepared for solving the problem on the basis of numerical methods.     

爆破振动对结构物的影响分析

根据工程实例,分析了爆破振动对建筑物的安全影响,研究了在不同爆破参数作用下,振动波对建筑结构内部可能造成的房屋墙面抹灰脱落、结构体裂缝开裂或延伸等现象。     

A new analytical solution to the mechanical behaviour of fully grouted rockbolts subjected to pull-out tests

A new analytical approach able to predict the mechanical behaviour of fully grouted rockbolts subjected to pull-out tests is proposed in this paper. Input parameters of such approach are: bolt radius, bolt’s Young modulus, displacement of the free end of the bolt and the constitutive law of the rockbolt–grout joint interface. The limited circumstances under which it is accurate to determine such constitutive law from pull-out tests are also presented. A solution for the load–displacement curve obtained during pull-out tests has been developed and is detailed in the case of a tri-linear bond-slip model. Comparison with experimental results obtained via in situ pull-out tests has led to the validation of this approach.     

城市地铁隧道掘进爆破对既有燃气管道的影响

以下穿燃气管线的北京地铁16号线西马区间风井至马连洼北路站北端隧道工程为背景,对矿山法施工中管线处地表的爆破振动强度进行了监测,分析了该段施工爆破地震波地表质点振动波形以及频率特性,并拟合计算了该段爆破地震波衰减参数,为同类工程提供参考。     

The holding mechanism of under-reamed rockbolts in soft rock

The holding mechanism of under-reamed rockbolts differs from that of conventional rockbolts, in which the bonding or the friction along the element–rock interface provides the holding capacity. The under-reamed end is kinematically blocked by the surrounding rock mass and can provide a greater holding capacity, especially in soft rock, whereas the strength of a soft rock frequently controls the bonding strength of the element–rock interface. Both an experimental study and numerical analyses were performed to examine the holding mechanisms of model under-reamed rockbolts subjected to direct pull out loading and pre-tensioning.When subjected to direct pull out loading, the holding capacity originates from the capacity of the rock resisting tensile fracture. Failure is characterized by the formation of a smooth, conical region bounded by a tensile crack, which subsequently separates from the surrounding rock. Correspondingly, the holding capacity is related to the tensile strength of the rock, bolt length and size of the under-reamed end.When subjected to pre-tensioning, the holding mechanism is provided by the ability of the rock to form two conical zones between the faceplate and the under-reamed end, and to prevent subsequent indentation of the two cones. Major factors influencing the holding capacity of under-reamed bolts include the size of the under-reamed end, bolt length and properties of the rock.     

小净距交叉隧道爆破振动响应研究

新建隧道从既有公路隧道上方穿过,在空间上形成交叉隧道。上下隧道最小净距为8.1 m,为评价新建隧道爆破施工对既有公路隧道结构的影响,进行了数值模拟研究。结果表明:当新建隧道在距离隧道交叉点10 m以外位置以全断面法爆破施工时,下方既有公路隧道仅受到较小的影响;当其在距离交叉点10 m以内位置以全断面法爆破施工时,既有公路隧道二次衬砌振动速度超标,而采用台阶法爆破施工时,新建隧道可安全通过。     

施工隧道爆破对某住宅楼的影响分析

针对实际发生的某一具体案例,对该工程进行了详细的现场检测、鉴定,并结合实际具体检测结果深入分析了外界人为因素产生的震动对附近建筑物的影响,并得出科学的结论,为确保施工安全提供了重要依据。     

土石方爆破对周边环境的影响及防治

通过对惠安县聚龙小镇土石方爆破震动测试和分析研究,得出爆破震动对周边环境的影响因素,进而提出减小土石方爆破对周边环境影响的保护措施,为有效控制土石方爆破对环境的影响以及合理控制爆破参数提供了关键性依据。     

A review on the performance of conventional and energy-absorbing rockbolts

This is a review paper on the performances of both conventional and energy-absorbing rockbolts manifested in laboratory tests. Characteristic parameters such as ultimate load, displacement and energy absorption are reported, in addition to load-displacement graphs for every type of rockbolt. Conventional rockbolts refer to mechanical rockbolts, fully-grouted rebars and frictional rockbolts. According to the test results, under static pull loading a mechanical rockbolt usually fails at the plate; a fully-grouted rebar bolt fails in the bolt shank at an ultimate load equal to the strength of the steel after a small amount of displacement; and a frictional rockbolt is subjected to large displacement at a low yield load. Under shear loading, all types of bolts fail in the shank. Energy-absorbing rockbolts are developed aiming to combat instability problems in burst-prone and squeezing rock conditions. They absorb deformation energy either through ploughing/slippage at predefined load levels or through stretching of the steel bolt. An energy-absorbing rockbolt can carry a high load and also accommodate significant rock displacement, and thus its energy-absorbing capacity is high. The test results show that the energy absorption of the energy-absorbing bolts is much larger than that of all conventional bolts. The dynamic load capacity is smaller than the static load capacity for the energy-absorbing bolts displacing based on ploughing/slippage while they are approximately the same for the D-Bolt that displaces based on steel stretching.     

爆破地震引起质点振动的影响因素分析

利用LS-DYNA软件,建立了仿真模型,分析了不同装药情况下,距离爆心不同水平距离处的质点振动速度差距和衰减规律,指出在工程实际中应根据具体情况采用不同的装药方式,以达到最优的爆破水平。     

Effect of bar shape on the pull-out capacity of fully-grouted rockbolts

This paper presents experimental results obtained from the direct pull-out test using different types of rockbolts having different shape of lugs. These are smooth surface bars, ribbed bars, single conical lugged bars, double conical lugged bars and triple conical lugged bars. It is found that the failure mechanism of the conical lugged rock bolt is different from that of conventional rockbolts, in which the adhesion or the shear strength at the bolt–grout interface provides the load bearing capacity. From the results of experimental study, the use of the conical lugged rock bolts is suggested, because it provides a greater anchorage strength due to wedging effect that is a combination of the shear and compressive strength of the grouting material.     

某水坝灌浆防渗工艺与实践

针对工程的实际地质条件及其渗漏特点,对灌浆浆液配合比的调整及操作办法进行了介绍,并制定了专门的注浆工艺,实践表明,该施工工艺对其他类似工程具有重要的参考价值。     

露天矿山中深孔爆破边坡稳定性影响研究

为了分析露天矿山中深孔爆破对边坡稳定性影响机理,结合福建某小型露天矿山工程实际,在确定炸药及爆破孔网参数的基础上,引入降振技术并运用LS-DYNA有限元分析程序对中深孔爆破边坡影响情况进行数值模拟试验,得出了有指导意义的结论。     

钢筋套筒灌浆连接研究进展

钢筋套筒灌浆连接是当前预制混凝土结构钢筋连接的主要方式。从材料、界面、连接的角度,针对其国内外相关研究成果开展系统分析与总结。结果表明：套筒可为金属、非金属材质(如FRP),锥形套筒的连接性能优于圆柱形的,套筒长度不应短于临界长度,内径越小越有利,壁厚不应小于被连接钢筋直径的1/13,但也不宜过厚;低温、负温灌浆料适用的环境温度分别不超过-5、-10℃,耐高温灌浆料可通过掺入聚丙烯纤维进行制备;灌浆料与钢筋界面的黏结强度主要与灌浆料抗压强度的平方根相关,并受到套筒约束能力、高温作用的显著影响;钢筋套筒灌浆连接受拉失效模式包括套筒外钢筋断裂、灌浆料与钢筋界面黏结失效以及套筒与灌浆料界面黏结失效;荷载类型对钢筋套筒灌浆连接力学性能的影响较小,失效模式转变的关键温度是400℃,灌浆缺陷率不超过20%能确保连接接头的可靠性;界面、钢筋黏结长度对钢筋套筒灌浆连接力学性能的影响显著。基于此,提出全黏结长度和双界面两个概念,以控制钢筋套筒灌浆连接的承载性能与失效模式。同时,提出有待开展的研究：灌浆料的本构关系、率敏感性、热工参数等;受高温作用、侧向约束的影响,灌浆料与钢筋界面的黏结应力-滑移本构关系...     

隧道爆破对地表房屋的影响

结合工程实例,详细地介绍了隧道爆破技术措施,阐述了爆破作业方法,对爆破地震影响进行了深入分析计算,得出了高阳寨隧道进口爆破不会对地面房屋造成危害的结论。     

导爆管起爆网路在公路爆破施工中的运用

随着公路爆破向安全、环保、科技方面发展,导爆管起爆网路便应运而生,该网路可根据爆破要求选择不同的起爆网路;该起爆网路可避免误爆事故的发生,可减少有害气体的排放,控制最大振峰,提高炸药的利用率,对爆破技术人员有一定的参考价值,对预防爆破安全事故有一定的借鉴作用。     

灌芯混凝土砌块砌体的受剪强度研究

本文在Hoffman强度准则基础上,分析灌芯混凝土砌块砌体的抗剪强度,推导出灌芯混凝土砌块砌体的抗剪强度公式,本文公式具有一定的理论和试验基础,可以为设计和研究提供参考。