近场地震动作用下背后空洞圆形隧洞的动力损伤特性试验研究

haking Table Test on Dynamic Damage Behaviors of a Circular Tunnel with Voids behind the Lining Subjected to Near-field Ground Motions

  • 摘要: 文章考虑近场地震动作用,对背后存在空洞的圆形隧洞进行了振动台模型试验,对比分析了地基场域加速度反应、土—结构接触动土压力、隧洞结构加速度反应及其动应变规律,并基于损伤模型研究了近场地震动作用对隧洞结构的动力损伤行为。研究结果表明:1)地震波加载过程中,圆形隧洞不同位置横截面处的加速度反应存在少许差别,隧洞结构的存在会对两侧地基土峰值加速度产生影响,但频谱特性变化并不明显;2)当输入近场地震动强度较小时,结构顶部空洞横截面的平均峰值加速度较小、平均动应变反应较大,而结构顶部密实状态横截面的平均峰值加速度较大、平均动应变反应较小;3)若采用应变损伤模型衡量结构的破坏程度,在衬砌背后存在空洞的横截面顶部±30°附近圆形隧洞损伤程度最大,这与已有的圆形隧洞震害现象吻合。

     

    Abstract: Considering the effect of near-field ground motion, a shaking table model test was conducted to the cir? cular tunnel with voids behind the lining. A comparative analysis was taken with aspects of acceleration response of foundation field domain, dynamic earth pressure of soil-structure contact surface, acceleration response of tunnel structure and dynamic strain rules. Meanwhile, the effect of near field ground motion on dynamic damage behaviors of the tunnel structure was studied based on a damage model. The results show that: 1) there is slight difference in the acceleration response at the different cross sections of the circular tunnel in the process of seismic wave loading,and tunnel structure affects the peak acceleration of subsoil at two sides while the changes of spectrum characteristics are not obvious; 2) when the intensity of input near-field ground motion is small, the average peak acceleration at the cross section with top voids is also small but the average dynamic strain response is large while the average peak acceleration at the cross section with dense top is large but the average dynamic strain response is small; 3) the damage is most serious at the scope of ±30° of the top of the cross section with voids behind the lining, which agrees with the seismic damage of existing circular tunnel.

     

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