浅埋饱和土任意形状隧道动力响应研究

Analysis of Dynamic Response of the Arbitrary Shaped Tunnel in Shallow-buried Saturated Soil

研究目的:我国东部沿海地区的隧道围岩富含水分,地震波的破坏作用将对隧道的安全施工及运营构成极大威胁。目前隧道的横断面形状设计复杂多变,分析研究饱和土介质中任意形状隧道的波动响应,对于这些地区隧道结构的安全抗震设计及施工起着重要指导价值。本文通过解析求解方法,基于Biot饱和多孔介质动力学理论,利用共形映射和波函数展开方法,首先建立浅埋任意形状隧道的平面波散射解析解,在通过验证表明模型及计算过程正确有效后,以某一公路两车道隧道为模型,研究入射波数、围岩介质孔隙率、泊松比等参数对隧道动力响应的影响规律。研究结论:(1)入射波数对隧道的动应力集中有显著影响,低波数下隧道的动应力响应显著大于高波数情况,且相比之下,高波数下的动应力响应分布形态更为复杂;(2)围岩介质的孔隙率对隧道孔压动力响应影响不大,不同孔隙率下隧道的孔压动力响应分布规律基本保持一致,但在较高孔隙率的情况下,边墙处的孔压动力集中系数较大,因此设计和施工过程中应当考虑边墙处围岩的加固处理;(3)泊松比对隧道孔压动力响应的影响较为显著,泊松比增加不仅影响隧道孔压响应分布规律,还影响响应的幅值大小,可能导致拱顶、拱底、拱肩、拱脚等部位孔压的局部升高;(4)本研究成果可为富水地区任意形状隧道的抗震设计和安全施工提供指导。

Research purposes:The surrounding rock of tunnels widely distributed in the eastern coastal areas of China is rich in water,which will pose a great threat to the safe construction and operation of tunnels under the action of seismic waves.At present,the shape of tunnel cross-section is complex and changeable,so the analysis and study of the dynamic response of arbitrary shaped tunnel in saturated soil plays an important value for the seismic design and construction of these areas.Based on the analytical solution method,this paper first establishes the analytic solution by common mapping and wave function expansion method under Biot saturated porous media dynamics theory.After the model and calculation process are verified to be correct and effective,the effects of incident wave number,porosity of saturated soil medium and Poisson’s ratio on dynamic response of tunnel are studied.Research conclusions:(1) Incident wave number has significant influence on the dynamic stress concentration of tunnel.The dynamic stress response at low wave number is significantly greater than that at high wave number,and the distribution pattern of dynamic stress at high wave number tends to be more complex.(2) The porosity has little influence on the pore pressure response,and the pore pressure response distribution is basically consistent.In the case of higher porosity,the pore pressure concentration coefficient at the side wall increases,so the reinforcement treatment of surrounding rock at the side wall should be considered in design and construction.(3) The influence of Poisson ratio on pore pressure response is significant.The increase of Poisson’s ratio not only affects the distribution law of tunnel pore pressure response,but also affects the amplitude of the response,which may induce the local increase of pore pressure in the vault,arch bottom,arch shoulder and arch foot.(4) The research conclusions can provide support for seismic design and safety construction of tunnels with various shapes in water-rich area.