软岩隧道锚变形破坏机理缩尺模型试验研究

为了研究软岩中隧道锚变形破坏机理及破坏模式,通过对隧道锚现场1∶10缩尺模型进行超载破坏试验,对加载过程中锚体模型的外观变形、内观变形、钻孔测斜以及破坏裂缝进行分析,获得了锚体模型在推力作用下载荷-变形全过程曲线以及变形破坏特征,并结合数值模拟的超载试验结果进行了综合分析。研究成果表明锚体模型变形破坏全过程类似于软岩载荷试验变形破坏3个阶段;锚塞体底部与岩体接触面部位受拉剪破坏形成破坏底边界,锚塞体上方岩体受锚塞体向上挤压形成纵向拉裂缝以及与锚塞体成约45°夹角的剪裂缝。隧道锚极限承载能力主要取决于锚塞体底界面以及上部岩体抗拉能力和抗剪能力。

Scale Model Test on the Deformation and Failure Mechanism of Tunnel-type Anchorage Surrounded by Soft Rock

To study the failure mechanism and failure mode of tunnel -type anchorage at soft rocks, overloading fail-ure test was conducted through 1 ∶10 scale field model of tunnel-type anchorage.The surface deformation and inter-nal deformation, the results of borehole inclinometers and the cracks of tunnel -type anchorage model in the overloa-ding process were analyzed.The deformation-load curve and the characteristics of deformation failure of tunnel -type anchorage model under thrust were obtained .Furthermore, the results were comprehensively analyzed in association with numerical simulation results.Research results showed that: similar with the deformation failure of soft rock un -der loading test, the whole process of the deformation failure of tunnel -type anchorage model experienced three sta -ges.Destructive bottom boundary was formed by tension -shear between the bottom of anchorage and contact area of rocks.Due to upward extrusion, longitudinal tensile cracks of rocks above the anchorage and shear fractures with angle of about 45 degrees to the anchorage were formed.The ultimate bearing capacity of tunnel -type anchorage is mainly decided by the tensile capacity and shear capacity of rocks on the bottom boundary and top of the anchorage .