Numerical simulation research on reasonable range of grouting reinforcement for soft soil tunnel

The subway tunnel´s unstable settlement caused by long-term operation brings an unfavorable influence on the stability of tunnel. Therefore, researches on dynamic response analysis of tunnel foundation and reasonable range of grouting reinforcement are important to the safe operation of subway. Based on the vehicle dynamic load conditions during operation of subway, the tunnel dynamic stability analysis model of shield tunnel was established, and the numerical simulation was used to carry on the dynamic stability calculations of tunnel underlying soil which consist of silty clay. The calculation results showed that, when the tunnel depth was determined, the amplitude and frequency of dynamic load had some influence on the stability of tunnel underlying soil. The effect of dynamic load amplitude was more remarkable. The final settlement of tunnel reduced with the increase of tunnel depth and diameter of tunnel lining, the final settlement increased with the increase of the amplitude and frequency of dynamic load. The dynamic response range of tunnel underlying soil was mainly related to amplitude of dynamic load and tunnel depth. Through numerical simulation, the empirical formula of influence range was obtained by regression analysis, and it was useful to determine the reasonable range of grouting reinforcement.