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为研究填土边坡锚杆的动力响应特征与失效模式,进行了锚杆格构支护土质边坡振动台模型试验,采用正弦激励,分别对边坡的加速度和锚杆的轴向应变进行了监测。分析结果表明:在同一振动频率下,锚杆轴向动应变幅值随加速度峰值的增大而增大;加速度峰值较小时,应变基本在固定正负值之间往复循环,边坡处于稳定状态;随着加速度峰值增大,锚杆的最大与最小应变不再稳定,但变化不是很大,边坡仍处于稳定状态;当加速度峰值达到破坏峰值时,锚杆轴向应变不再具有规律性,滑面处锚杆轴向应变突变最明显,滑体与稳定体之间发生明显的相对位移。加速度峰值较小时,中下层锚杆轴向应变较大,中层锚杆应变约为顶层锚杆应变的2倍;随着加速度峰值的增大,顶层锚杆轴向应变逐渐变大,主要由中上层锚杆承受荷载;当加速度峰值达到破坏峰值时,各层锚杆的动应变最大值急剧增大,中层锚杆应变变化幅度最大,振动过程中滑体与滑床之间出现明显分离,锚杆被拔出。可见,传统的边坡锚杆设计思想“强腰固脚”适合于地震设防烈度较小地区,对于设防烈度较大地区,锚杆设计时需适当增加上层锚杆和腰部锚杆的锚固长度。
In order to study the dynamic response characteristics and failure modes of rock bolts on fill slope, a shaking table test on rock slope supported by anchor lattice was carried out. Sine excitation was applied to the slope acceleration and axial strain respectively Monitoring. The results show that under the same vibration frequency, the amplitude of axial dynamic strain increases with the increase of acceleration peak. When the peak of acceleration is small, the strain basically reciprocates between fixed positive and negative values, and the slope is in steady state ; With the increase of acceleration peak, the maximum and minimum strain of anchor is no longer stable, but the change is not very big, the slope is still in steady state; when the peak of acceleration reaches the failure peak, the axial strain of anchor is no longer regular , The axial strain at the sliding surface is the most obvious, and the relative displacement between the sliding body and the stabilizing body occurs obviously. When the acceleration peak is small, the axial strain of the middle and lower anchors is larger, and the strain of the middle anchors is about twice as that of the top anchors. With the increase of the acceleration peak, the axial strain of the top anchors gradually increases, When the peak value of acceleration reaches the peak value of failure, the maximum value of dynamic strain of each layer of rock bolts increases sharply, the strain of middle layer rock bolt changes greatly, and there is a clear separation between slide body and slide bed during the vibration process. The lever is pulled out. It can be seen that the traditional design idea of “slope with strong waist” is suitable for areas with less seismic fortification intensity. For areas with strong fortification intensity, anchors of upper and lower anchors should be appropriately increased in the design of anchors length.