饱和半空间中隧道动力响应研究及在地铁振动预测中应用

China's subway construction is undergoing rapid development, however the environmental issue caused by underground moving trains has become increasingly prominent. A correct understanding of propagation mechanism for ground-borne vibrations is necessary to assess and mitigate environmental vibrations from underground railways. The closed-form analytical solution for vibrations from single and twin-bore tunnels embedded in the saturated poroelastic ground is proposed by the wave transformation and translation. The law of wave propagation in the tunnel-saturated soil system under moving loads is investigated and the dynamic interaction between twin circular tunnels, as well as the multi-scattering effect is analyzed. Meanwhile, the train-track-tunnel-ground model for calculating vibrations of the track structure and the saturated ground is established by coupling the analytical method and the finite element method. The vibration mechanism of the train-track-tunnel-ground system and the propagation and attenuation characteristics of ground vibrations will be revealed, which promotes the optimal design for the railway track and the tunnel structure to reduce the environmental vibrations. The analysis model is validated by comparing the model predictions with the field measurements. The proposed research provides a new analysis method for calculating vibrations from underground, which combines both accuracy and computational efficiency. It also serves as the theoretical basis and technical support for solving the problem of environmental vibrations from underground railways.

我国地铁建设日新月异，地铁列车振动环境影响问题日益突出，正确认识地铁列车引起的地基振动传播机理是评估和控制地铁运营环境影响的关键。本项目基于波函数转换和平移理论首次提出饱和半空间中单、双孔圆形衬砌隧道在移动荷载下动力响应的解析闭合解，研究衬砌隧道及周围饱和土体波动的传播规律，分析双孔隧道间相互作用机理及波动的多重散射特性。在此基础上，采用解析-有限元耦合法建立地铁列车-轨道-衬砌-饱和地基耦合振动分析模型，求解地铁列车下轨道结构和饱和地基动力响应，揭示地铁线路系统-衬砌-饱和土地基耦合振动机理，分析地基振动传播规律与衰减特性，优化轨道和衬砌结构设计，从而降低地铁运营引起的环境振动影响，并通过现场测试验证研究模型的正确性。本项目研究成果可为地铁振动预测提供一套兼顾计算效率与精度的分析方法，为解决地铁环境振动问题提供理论依据和技术支持。

地铁列车振动环境影响问题日益突出，正确认识地铁列车引起的地基振动传播机理是评估和控制地铁运营环境影响的关键。本项目针对地铁列车荷载引起的地基振动问题，原创性地提出了一种新型计算均质/成层弹性/饱和半空间中单/双孔衬砌隧道地基振动的解析方法（原创性工作-Wave function method named by Yuan and Boström），该方法将不含有隧洞土层单元的总波场表示为上行波和下行波之和，将含有隧洞土层单元的总波场写为上行波、下行波和外行波之和，采用波函数转换和平移技术实现柱面波函数和平面波函数间自由变换。该方法优雅而不失一般性，在传统计算效率不高的2.5D数值法和计算精度不高的虚拟力法中完美地找到了最优的折中方案。采用波函数法理论模型，研究了浅埋振源激励下的面波、地下水位变化、水相饱和及近距双洞隧道对地基振动响应的影响规律；在此基础上建立了考虑轮轨不平顺的地铁列车-浮置板轨道-衬砌-成层地基耦合振动分析模型，系统研究了地铁列车荷载轨道、隧道和成层地基的动力响应，揭示地铁线路系统-衬砌结构-成层地基耦合振动机理，并通过现场振动测试验证了新型振动预测模型的正确性。