中文摘要：

基于Biot两相介质理论,采用一种高精度的间接边界积分方程法（IBIEM）,研究了平面SV波在饱和半空间中隧道衬砌周围散射的基本规律,并给出了不同参数下地表位移幅值、衬砌动应力集中因子及表面孔隙水压分布图和相应的频谱结果。数值分析表明：饱和半空间隧道衬砌对SV波的散射特征取决于围岩介质孔隙率、入射波的频率和角度、隧道埋深等因素;隧道外壁透水状态对地表位移和隧道应力影响不大;不同角度SV波入射下,隧道应力集中部位有很大差别,且随半空间介质孔隙率增大,应力集中越发显著;衬砌外壁孔隙水压峰值可达到入射波应力幅值的4倍,且30°斜入射下幅值明显大于0°垂直入射情况;衬砌上方附近不同点位位移频谱特征差异显著,斜入射情况位移放大效应明显;随埋深增大,地表位移幅值和衬砌表面动应力谱振荡更为剧烈,但幅值会有所降低。另外,按波速比等效的单相介质模型可以近似计算SV波入射下隧道–饱和围岩的位移场和应力场。

英文摘要：

Based on the Biot＆#39;s theory of two-phase medium, a high-precision indirect boundary integral equation method （IBIEM） is proposed to solve the scattering of SV waves by a two-dimensional tunnel lining in saturated poroelastic half-space. The ground displacement amplitudes, dynamic stress concentration of the tunnel and pore pressure on the outer surface of the tunnel are investigated under different circumstances, and the frequency spectrum analysis is also made. Numerical analysis shows that the propagation and scattering characteristics of seismic waves depend on the porosity of the surrounding medium, frequency and angle of the incident waves, tunnel depth, etc. The drainage state of tunnel outer surface has little impact on the ground displacement amplitudes and dynamic stress concentration of the tunnel. The features of the dynamic stress concentration in the tunnel strongly depend on the incident angle and medium porosity; as the porosity increases, the dynamic stress concentration becomes more significant. The pore pressure on the outer surface of the tunnel can reach four times the peak stress amplitude of the incident waves, and that for incidence waves of 30° is significantly greater than that of the vertically incident case. The spectral characteristics at displacement of different points on ground surface may change within a small distance, and the amplification effect seems more obvious in the case of oblique incidence. With the increase of embedded depth, the spectral curves of ground displacement and dynamic stress concentration of the tunnel oscillate more rapidly, but the amplitude will decrease. In addition, according to equivalence of velocity ratio, the single-phase medium model can approximately simulate the displacement and stress fields of tunnel - saturated medium system for SV wave incidence.