锚固长度对加锚边坡地震动力特性的影响
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摘要
现场调查发现,框架锚杆支护的边坡其地震稳定性要比采用挂主动网防护和锚喷支护的边坡优越。采用拟静力法对汶川震区内锚杆支护边坡的地震稳定性进行检算后得知,地震作用下边坡的安全系数随锚杆长度的增加而增大。利用FLAC3 D分析了地震作用下锚杆长度对边坡动力特性的影响。结果表明:锚固措施能有效抑制坡表加速度的放大作用,且PGA放大系数随锚杆长度的增加而减小,但在锚杆长度相差不大的情况下,PGA放大系数差异很小。地震作用下锚杆支护边坡的水平峰值位移出现在边坡坡顶,随着锚杆长度的增加,边坡的水平峰值位移沿坡高明显减小。锚杆轴力在地震作用下放大显著,且锚杆的长度越长,其在地震作用下的轴力越小。
Field investigations show that slope supported with framed anchor has better effect on resisting earthquake than slope supported with anchor-shotcrete and active protection nets.The pseudo-static method is used to analyze the stability of anchored slopes in the Wenchuan earthquake regions.The results show that the safety factor increases with the increasing anchor length.A dynamic numerical simulation model of anchored slope is established based on the FLAC3D program,and the influence of bolt length on dynamic response of anchored slopes is analyzed.The results indicate that:(1) anchoring structures can restrain surficial accelerate response,and the PGA amplification coefficients along the slope surface decrease with the increasing anchor length,the PGA amplification coefficient has little change when the differences in anchor length are not significant;(2) the maximum displacement of the anchored slopes occurs at the crest under earthquake,and the peak displacement decrease with increasing anchor length;(3) the anchor axial force is significantly amplified,and the axial force decrease with increasing anchor length.
引文
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