Transverse seismic responses of Shiziyang shield tunnel in liquefiable soil and its shock absorption measures
Transverse seismic responses of Shiziyang shield tunnel in liquefiable soil and its shock absorption measures
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发表时间：
2009
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通讯作者：
Li Xing-long
中科院分区：
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作者：
Li Xing-long
基于有效应力分析方法，利用有限差分程序FLAC2D研究了液化土中狮子羊盾构隧道在不同地震激励和不同入射方向下的地震反应，以及加固地基土的减震效果。数值模拟结果表明，在相同强度的不同类型地震波作用下，衬砌的地震响应特征基本一致，只是由于波的频率和持续时间不同，最大响应出现的时间不一致；结构内力的分布和发展随波浪的入射方向变化很大。可见，水平地震作用造成的破坏比垂直地震作用造成的破坏严重得多。顶部和与衬砌结构垂直中轴线成45°左右的位置分别是出现最大拉应力1.61 MPa和最大压应力10.13 MPa的位置。狮子洋盾构隧道满足横向抗震要求，但顶部拉应力仍需加固，已达到抗拉强度的85.2%。通过对几种加固布置方式的对比研究,狮子洋盾构隧道经济合理的加固方式是5 m范围内围衬土体强度的2倍。
Based on the effective stress analysis method,the seismic responses of Shiziyang shield tunnel in liquefiable soil,under the condition of different seismic excitations and different incident directions,are studied by a finite difference code—FLAC2D,along with shock absorption effect of strengthening the foundation soil. The results of numerical simulation indicate that the characteristics of seismic responses of linings under different types of seismic waves with the identical intensity are in substantial agreement,except that the time when the maximum responses occur is not consistent because of different waves with different frequencies and durations; the distribution and development of structural internal force vary much with the incident direction of waves. It is obvious that the damage due to horizontal earthquake action is much heavier than that due to vertical earthquake action. The crown and the position at an angle of about 45 degrees to the vertical central axis of lining structure are the very place where the maximum tensile stress,1.61 MPa,and the maximum compressive stress,10.13 MPa,appear respectively. Shiziyang shield tunnel meets the requirements for transverse seismic resistance but the reinforcement is still needed for the tensile stress at the crown,which has reached 85.2 percent of its tensile strength. According to the comparative studies on several layouts of reinforcement,the economical and rational way for Shiziyang shield tunnel is 2 times the strength of the soil surrounding lining at the range of 5 m.