ISSN 1000-3665 CN 11-2202/P

    格构梁锚杆加固滑坡地震动力响应分析

    A study of the seismic response of landslide to the anchor lattice beam

    • 摘要: 挡墙、抗滑桩、锚杆等多种支挡构造物中,锚固系统抗震性能良好,其治理后的边坡失稳可能性极小。为研究地震作用下格构梁锚固滑坡的动力响应,开展大型振动台模型试验,以汶川波、El Centro波以及不同频率的正弦波为输入波,研究不同激励强度、不同频率条件下锚固滑坡及锚杆的动态响应特征。结果表明:地震激励作用下,锚固体的动力响应分为三个阶段:适应调整区段(0.05g~0.20g)→平和抗震区段(0.20g~0.40g)→激烈抗震区段(0.40g~0.60g);锚固系统的自振频率和PGA放大系数随之呈现高→低→高的走势。激励强度不同,激励作用的频谱不同,同列锚杆的应变振型也不同;自振频率附近的正弦波激励(15 Hz)由于共振作用,在锚固体上部产生的不协调变形较大,同列锚杆的应变走势随着激励强度的增加从中间小上下大的“C”型调整为上大下小的“Г”型;正弦波超低频率(5 Hz)激励作用下,同列锚杆的应变走势则一直保持上小下大的“L”型;实际的汶川波和EL Centro波由于组合了不同的频谱,同列锚杆的应变走势则呈现中间小上下大的“C”型。强震地区锚固系统设计时,建议同时加长坡顶与坡脚的锚杆设计,以抑制坡顶滑面处的拉张裂缝及坡脚的剪切裂缝。

       

      Abstract: Among the retaining wall, anti-slide pile, anchor rod and other retaining structures, the seismic performance of the anchoring system is better, and the possibility of slope instability is quite small. In order to study dynamic response of landslide to the anchor lattice beam under earthquake, large-scale shaking table model test is conducted. In this paper, the sinewave, Wenchuan wave and EL Centro wave are used as the input seismic wave, and the dynamic properties of the anchorage landslide and anchor rod under different excitation intensity and frequency are studied respectively. The results show that the dynamic response of the anchorage system under earthquake can be divided into three stages: the adaptive adjustment stage (0.05g-0.20g), the gentle anti-seismic stage (0.20g-0.40g) and the intense anti-seismic stage (0.40g-0.60g). The natural frequency and PGA amplification factor of the anchorage system shows the trend of "high→low→high". Under different excitation intensity and different excitation waves with different frequency spectrum, the strain mode of anchors in the same column is different accordingly. Under 15 Hz sine wave (close to the natural frequency of the anchorage system), obvious deformation in the upper part of the anchorage body occurs due to the resonance effect. The strain trend of anchors in the same column is changed from "C" shape to "Г"shape with the increasing excitation intensity. However, under the ultra-low frequency 5 Hz sine wave, the strain trend of anchors in the same column retains "Г" shape no matter what the excitation intensity is. Under the Wenchuan waves and El Centro waves, the strain trend of anchors in the same column shows "C"shape, for which the main reason is that the two seismic waves covers different spectral components. In the design of an anchorage landslide in the strong earthquake area, it is suggested that the top anchor and the foot anchor should be strengthened particularly to restrain the tensile cracks near the sliding surface and shear cracks at the slope toe.

       

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