盾构隧道同步注浆纵环向整体扩散理论模型

Theoretical Model of Synchronous Grouting Longitudinal-Circumferential Integrated Diffusion of Shield Tunnels

针对目前现有的盾尾同步注浆扩散模型以浆液纵环向流动相互独立为前提,未考虑浆液流动的关联性问题,基于Bingham流体本构模型和流体力学原理,分析盾构隧道同步注浆扩散模式机理,建立了盾尾同步注浆纵环向整体扩散理论模型。基于时空离散概念,设计求解该理论模型的数值算法。结合工程实例,对理论模型和数值算法进行了验证,并与现有的环向独立扩散模型计算结果进行对比和分析。分析结果表明:纵环向整体扩散模型相较于环向扩散模型,改进了假定条件,不需引入环饼厚度等敏感假定参数,更加贴近工程实际情况;浆液压力整体上呈现着上小下大重力主导的趋势,竖向梯度约为16 kPa·m^-1,而在注浆孔附近局部区域浆液压力分布较为复杂,与注浆孔位、浆液流动方向以及注浆压力与环境压力之间的压力差等因素有关。

In view of the present synchronous grouting diffusion model of shield tail,whose premise was that the longitudinal and circular flow of slurry was independent of each other,without considering the correlation of slurry flow,the mechanism of synchronous grouting diffusion mode in shield tunnel was analyzed,and the theoretical model of synchronous grouting longitudinal-circular integral diffusion of shield tail was established,which was based on Bingham fluid constitutive model and fluid mechanics principle. Through space and time domains discrete approach,a numerical algorithm to solve the theoretical model was designed. Combined with engineering examples, the theoretical model and numerical algorithm were validated. The results were compared and analyzed with the existing circumferential independent diffusion model. The results show that:compared with the circumferential diffusion model,the longitudinal-circular integral diffusion model improves the assumed conditions,and is more close to the actual situation of the project,which does not need to introduce sensitive assumption parameters such as the thickness of the ring cake. As a whole,the slurry pressure trends to be dominated by gravity,small in the upper part and large in the lower part. And the vertical gradient is about 16 kPa·m^-1. But the slurry pressure distribution in the local area near the grouting hole is relatively complex,which is related to many factors such as the grouting hole location,the direction of slurry flow and the pressure difference between the grouting pressure and the environmental pressure.