排序方式: 共有38条查询结果,搜索用时 15 毫秒
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B. Stimpson 《Geotechnical and Geological Engineering》1987,5(3):299-305
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. 相似文献
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U.?M.?Rao?KaranamEmail author S.?K.?Dasyapu 《Geotechnical and Geological Engineering》2005,23(3):297-308
Rock bolts are widely used for rock reinforcement in hard-rock mining and civil engineering since a long time. However the use of fully grouted rock bolts and cable bolts is limited in coal mines. In order to improve performance of the rock bolts as a supplementary roof support system for any type of roof condition in coal measured formations, it is necessary to have a good understanding of the behavior of the bolt–grout and grout–rock interactions as well as the mechanism of load transfer in rock bolts.As the performance of grouted bolts depends on bond strength, extensive laboratory pullout as well as pushout tests were conducted in the present investigations with the variations in the bolt diameters, length and cement–water mixing ratios of grout. The load–displacement curves were developed and were verified with the numerical results obtained from finite element analysis using ALGOR software.Numerical models were validated for pushout tests and a detailed analysis was carried out to know the displacement, stress, strain distribution along the bolt. 相似文献
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An analytical model on the general behaviour of a tunnel head, reinforced by finite length bolts is proposed. This model is based on the homogenization method and spherical symmetry assumption. Despite its simplicity, and in consequence its limits of validity, it does allow a quick estimation of the key design parameters: frontal displacement, extension of decompressed zone, ground stresses and bolt tension, and constitutes thereby a very useful and handy tool for design engineers. In particular, the influence of the reinforcement length, as well as other important design parameters, are studied by the proposed model. The charts resulting from the parametric studies are directly applicable. Otherwise, the comparison to a 3D numerical model is also presented in this paper. The first results provide the validation of the analytical solution, at least in terms of average extrusion movements. Copyright © 2000 John Wiley & Sons, Ltd. 相似文献
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强风化软硬互层岩质高边坡属岩质边坡特殊情况,其结构面组成及性质复杂,与支护结构相互作用的复杂程度较高,相互影响较大,顺倾结构面临空等情况下破坏可能性很大。以兰永一级公路某深挖路堑边坡的治理工程为依托,对边坡支护过程中及支护结束后的锚杆应力、锚索内力、坡体位移进行了原位监测,并利用岩土分析软件PLAXIS,采用节理岩模块对该边坡工程进行了数值模拟分析。监测及模拟结果表明:该边坡由节理裂隙与岩层面形成折线形潜在滑面,且具有相同滑动可能性的潜在滑面不止一个;支护结构穿透组成滑面折线的任何折线段部分均对结构面稳定有显著影响,但支护结构穿透泥岩面对结构面的影响较穿透节理裂隙更大;支护锚索预应力变化具有一定规律,预应力变化过程对坡体位移及支护结构内力具有一定影响;坡体的主动变形对支护结构内力的影响较坡体被动变形大,结构面产生滑动趋势对坡面位移影响的敏感程度较支护结构内力影响的敏感程度低。该边坡支护稳定,支护设计合理,可为同类边坡支护设计提供相应建议。 相似文献
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软弱围岩隧道取消系统锚杆的现场试验研究 总被引:1,自引:0,他引:1
在软弱围岩隧道中,提出初期支护结构由钢架+喷射混凝土+钢筋网+锁脚锚杆+纵向连接筋组成,即取消系统锚杆用钢架联结处的锁脚锚杆代替。以包家山隧道为依托工程,采用现场试验的方法,选取2个试验段,进行锁脚锚杆取代系统锚杆后,有、无拱部锚杆的对比试验研究。对比试验的内容包括:隧道初期支护的净空收敛、围岩压力、钢架应力、喷射混凝土应力、锚杆轴力和纵向连接筋应力等。研究结果表明:2个试验段初期支护变形趋于稳定,结构受力安全,说明取消系统锚杆不影响初期支护结构的安全与稳定;拱部锚杆有受拉,也有受压,但受力都不大,最大拉应力仅为钢材极限强度的11.8%,其支护作用不明显;锁脚锚杆大部分受拉,最大值达到191 MPa,钢架支护作用明显,在支护体系中发挥着重要作用。取消系统锚杆减少了施工工序,降低了工程造价,缩短了工序循环时间,有利于及早封闭围岩以形成完整的支护结构。经济价值和社会效益显著。 相似文献
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