锚固角度对节理岩体动态压剪响应的影响研究

Effect of anchorage angle on dynamic compression-shear response of jointed rock mass

  • 摘要: 为探究锚固角度对贯通节理岩体动态力学特性和锚固体破坏行为的影响。利用分离式霍普金森压杆系统,对锚固角度为15°、30°、45°、60°和75°的全锚节理岩体进行动载冲击试验,分析不同锚固角度下锚固岩体动态应力应变、锚固锚杆应变与锚固基体滑移压剪行为。结果表明:随锚固角度的增加,锚固体峰值应力呈先增大再减小的趋势,分别为15.8、18.1、20.9、24.7和23.3 MPa,在锚杆抵抗压剪作用下锚固体的动态应力应变曲线呈“双峰”形态;在岩体压剪行为下锚杆轴向应变呈降低趋势,冲击瞬间锚杆应变率随角度的增加出现下降,45°锚固角度下位于节理面左右侧的应变片所监测的应变幅值接近;锚固体受载端沿冲击方向位移呈现逐渐减小趋势,分别为4.84、1.71、1.40、1.01和0.84 mm,锚杆抵抗锚固基体沿节理面压剪滑移的能力逐渐增强。

     

    Abstract: This study aims explore the effect of different anchorage angles on the dynamic mechanical properties of jointed rock mass and the failure behavior of anchorage body. We conducted the dynamic load impact test on fully anchored jointed rock mass with anchorage angles of 15°, 30°, 45°, 60° and 75° by using the split Hopkinson pressure bar system to analyze the dynamic stress and strain of anchored rock mass, the strain of anchored bolt and the sliding compression-shear behavior of anchored matrix under different anchorage angles. Results show that with the increase of anchoring angle, the peak stress of anchorage body demonstrate initial increase and subsequent decrease, namely 15.8, 18.1, 20.9, 24.7 and 23.3 MPa, respectively. The dynamic stress-strain curve of anchorage body under compression and shear resistance of anchor rod exhibits a "double peak" shape. Under the compression-shear behavior of rock mass, the axial strain of bolt shows a decreasing trend, and the strain rate of bolt decreases with the increase of angle at the moment of impact. The strain amplitude monitored by strain gauges on the left and right sides of joint surface is close to each other at 45° anchoring angle. The displacement of the loading end of the anchorage body decreases gradually along the impact direction, namely 4.84, 1.71, 1.40, 1.01 and 0.84 mm, respectively. The ability of the bolt is gradually enhanced to resist the compression-shear slip of the anchorage body along the joint surface.

     

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