为研究端锚粘结式锚杆锚固段力学特性, 以水泥水玻璃砂浆端锚锚杆体为研究对象, 采取小应变高频动荷载等效成大应变低频荷载的加载模式, 进行反复拉拔试验, 得出在不同的外载荷作用下, 端锚锚杆在锚固段各位置处拉应力与剪切应力变化趋势。结果表明采用小应变高频变动荷载加载模式的正确性和可靠性, 可满足端锚模型试验要求;在加载频率为430.882 Hz情况下, 端锚自由变形段应力应变的数值最大, 在锚固段远端产生波谷值, 最小值可以接近0, 沿锚杆体轴向产生的应力分布近似为正弦函数的λ/2波长之间的波形图;通过试验结果处理分析可求解出沿锚杆体的剪切应力分布、位移情况曲线和τ-u曲线, 在端锚锚固变形段的剪应力取得较大值, 同时伴随着循环加卸载增量百分比和次数的增加, 剪切应力峰值发生传递性, 逐渐缓慢向锚固段底端的方向移动, 最终导致锚固段的锚固特性失去工作效能。
Abstract
In order to study the mechanical behaviors of anchorage segment of end-anchored and grouted bolts, we took cement water glass mortar end-anchored bolt body as research object and carried out repeated pull-out test in which dynamic load of small strain and high frequency is made equivalent to the load of high strain and low frequency. The test results show that the mode of dynamic load with small strain and high frequency is correct and reliable, and meets the requirements of the end-anchored model test. When the loading frequency is 430.882Hz, the stress and strain of end-anchor’s free deformation segment reach the maximum, and reach the minimum (approaching zero) far from the anchorage section. The axial stress distribution along the bolt is in approximation to the waveform between λ/2 wavelength of sine function. By analyzing the test results, we obtain the shear stress distribution along the bolt body, the displacement curve and the τ-u curve. The shear stress achieve the maximum at the anchorage deformation segment of end-anchor, and with the increase of the percentage and number of cyclic loading and unloading increment, the peak shear stress transmits and moves slowly to the bottom of the anchorage segment, eventually disenables the anchoring effect of anchored segment.
关键词
端锚粘结式锚杆 /
加载模式 /
极限锚固力 /
室内试验
Key words
end-anchored and grouted bolts /
loading mode /
maximum anchor force /
laboratory test
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基金
国家自然科学基金(51008148);中国煤炭工业协会资助项目(MTKJ2012319);辽宁省大学生创新创业训练计划项目(201310147015);辽宁工程技术大学国家自然基金前期资助项目(11-163)
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