深埋隧洞板裂化围岩预应力锚杆锚固效应试验研究及机制分析

发布时间：2018-10-13 08:27

【摘要】：采用高强石膏配制板裂化模型试样,选用铝棒制作预应力锚杆模型,通过一侧约束条件下的单轴压缩试验,研究板裂化模型试样的预应力锚杆锚固效应。试验结果表明:加锚试样的峰值强度、残余强度及弹性模量均有不同程度的提高,试样峰后侧向变形显著减小,且随着预应力值的增大效果更为显著;与无锚试件岩板压折、岩片弹射的失稳破坏现象相比,加锚试件保持了较好的完整性,局部发生岩板断裂、脱落现象;试样变形破坏过程中,锚杆轴向应力变化分为线性缓慢上升期、非线性增长期和急剧上升期3个阶段,锚杆轴向应力的变化规律反映了其自身工作机制及板裂化模型试样变形特征。分析锚固机制认为,预应力锚杆的施加不仅有效降低了预制裂隙尖端拉应力集中程度,体现出抑制裂隙扩展的止裂作用,而且将试样劈裂形成的岩板加固为整体,有效抑制了岩板向临空面的屈曲变形,进而提高了试样的临界失稳荷载值。最后,基于试验结果的认识,提出针对板裂化围岩的"及时支护、区域控制及重点加固"的锚喷支护控制策略。
[Abstract]:In this paper, high strength gypsum is used to prepare the plate cracking model sample and aluminum bar is used to make the prestressed anchor rod model. The anchoring effect of the plate cracking model sample is studied by uniaxial compression test under the condition of one side restraint. The test results show that the peak strength, residual strength and elastic modulus of anchored specimens are increased in varying degrees, and the lateral deformation after peak decreases significantly, and with the increase of prestress value, the effect is more remarkable, and the compression of rock slabs without anchoring is more obvious than that of unanchored specimens. Compared with the failure phenomenon of rock sheet ejection, the bolted specimen maintains better integrity, and local rock slab fracture and shedding occur, and the axial stress change of the anchor rod is divided into linear slow rising period during the deformation and failure of the specimen. In the three stages of the nonlinear growth period and the rapid rising stage, the variation of the axial stress of the anchor rod reflects its own working mechanism and the deformation characteristics of the plate cracking model sample. By analyzing the anchoring mechanism, it is concluded that the application of prestressed anchor not only effectively reduces the tensile stress concentration at the tip of prefabricated fractures, but also inhibits the crack expansion, and strengthens the rock slabs formed by the specimen splitting as a whole. The buckling deformation of rock slabs to the face of face is restrained effectively, and the critical unstable load value of the specimen is increased. Finally, based on the understanding of the test results, the control strategy of "timely support, regional control and key reinforcement" for rock mass cracking is put forward.
【作者单位】：中国科学院武汉岩土力学研究所岩土力学与工程国家重点试验室;
【基金】：国家重点基础研究发展计划(973)项目(2014CB046902) 中国科学院知识创新工程重要方向项目(KZCX2 EW QN115) 国家自然科学基金资助项目(51279201)
【分类号】：TU476

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