饱和半空间中衬砌隧道对弹性波的散射及内源问题

发布时间：2018-04-18 02:08

本文选题：饱和半空间 + 衬砌隧道　；参考：《天津城建大学》2015年硕士论文

【摘要】：当今中国经济蓬勃发展,城市交通运输网络立体化不断完善。地铁已然成为了人们赖以出行的交通工具。因此,研究饱和土体中衬砌隧道对平面P、SV波的散射以及衬砌隧道在内部爆炸荷载作用下的瞬态反应对工程抗震、抗爆以及防灾减灾具有非常重要的理论和现实意义。(一)基于Biot两相介质理论,本文首先采用一种高精度的间接边界积分方程法研究了饱和半空间中衬砌隧道对弹性波(P1波和SV波)的散射问题,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:饱和半空间衬砌隧道对P、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;隧道上方地表位移幅值放大程度随孔隙率增大逐渐减小;随着入射频率的增加动应力分布更加复杂,出现多个峰值区域;对倾斜入射情况,隧道应力集中更为明显;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平面波入射下隧道-饱和围岩的位移场和应力场。(二)本文研究饱和半空间中弹性衬砌在内部爆炸荷载作用下的瞬态动力反应。通过算例给出了爆炸荷载作用下地表位移、衬砌动应力、围岩径向位移和孔压的时程响应结果,并对比分析了饱和半空间和全空间场地时程响应的区别。研究表明:透水和不透水条件对爆炸荷载的时程响应影响很小;随着孔隙率的增加,饱和场地受到的爆炸影响减小,衬砌受到的爆炸影响增大;随衬砌埋深的增加地表位移峰值减小,即覆土层越厚则地表受到的爆炸影响越小;爆炸荷载作用初期全空间衬砌和半空间衬砌的爆炸时程响应均相同,之后埋深较小的衬砌中上部点位明显受到地表反射波动的影响,使得动应力幅值、围岩径向位移相比全空间曲线出现大幅度增加。
[Abstract]:Nowadays, the economy of China is booming, and the urban transportation network is becoming more and more perfect.The subway has become the vehicle on which people travel.Therefore, it is of great theoretical and practical significance to study the scattering of plane PNSV wave from lining tunnel in saturated soil and the transient response of lining tunnel under the action of internal explosion load for engineering aseismic, anti-explosion and disaster prevention and mitigation.(1) based on the Biot two-phase medium theory, a high-precision indirect boundary integral equation method is used to study the scattering of elastic waves P1 and SV waves by lining tunnels in saturated half-space.The surface displacement amplitude, lining dynamic stress concentration factor, surface pore water pressure distribution and corresponding spectrum results are also given.Numerical analysis shows that the scattering characteristics of saturated half-space lining tunnel to PNSV wave depend on the porosity of surrounding rock, the frequency and angle of incident wave, the depth of tunnel, and so on, and the permeable state of tunnel outer wall has little effect on surface displacement and tunnel stress.The amplitudes of surface displacement over the tunnel gradually decrease with the increase of porosity, the distribution of dynamic stress is more complex with the increase of incident frequency, and there are many peak regions, and the stress concentration of tunnel is more obvious in the case of inclined incidence.With the increase of buried depth, the amplitude of surface displacement and the dynamic stress spectrum oscillation of lining surface are more intense, but the amplitude will decrease.In addition, the displacement field and stress field of tunnel-saturated surrounding rock under plane wave incidence can be approximately calculated by the equivalent single-phase medium model with wave velocity ratio.(2) in this paper, the transient dynamic response of elastic lining under internal explosive load in saturated half-space is studied.The results of time-history response of ground displacement, dynamic stress of lining, radial displacement of surrounding rock and pore pressure under explosive loading are given. The difference between saturated half-space and full-space site is analyzed.The results show that the influence of permeability and impermeability on the time history response of explosive load is very small, and with the increase of porosity, the effect of explosion on saturated site is reduced, and that on lining is increased.The peak value of surface displacement decreases with the increase of lining depth, that is, the thicker the overburden layer is, the smaller the explosion effect is, and the explosion time history response of the full space lining and half space lining are the same at the initial stage of explosive loading.The lower buried depth of the middle and upper part of the lining is obviously affected by the surface reflection fluctuation, which makes the amplitude of dynamic stress and the radial displacement of surrounding rock increase significantly compared with the whole space curve.
【学位授予单位】：天津城建大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U451.4

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