Analysis Of Stratum Deformation Caused By Synchronous Grouting In Shield Tunnel

Synchronous grouting is an important process in subway shield construction.A large number of researches and field measurements show that the grouting process has great influence on the ground settlement caused by shield tunneling and it is of great significance for controlling stratum deformation.It is very important to synchronize grouting behind the lining in shield tunnel construction.By studying its influence rule and characteristic mechanism,we can provide some references for the safe and efficient construction of subway.Based on the theory of small hole expansion,the boundary stress correction for the expansion of cylindrical hole in infinite soil is carried out to solve the expansion displacement of cylindrical hole in semi-infinite soil.Combined with the construction process of synchronous grouting in subway shield,the paper establish the expansion model of grouting body column hole,and deduce the analytical solution of formation deformation caused by synchronous grouting.The paper study the influence of grouting parameters,soil properties and construction parameters on grouting effect,and consider the deformation condition of special displacement boundary condition.At the same time,the paper compare the ground subsidence value calculated by the theoretical calculation and numerical simulation method to prove the feasibility of theoretical analytical calculation.The results show that: The horizontal displacement of the soil caused by the expansion of the column hole in the semi infinite soil after stress correction is significantly larger.In the semi infinite soil,shield synchronous grouting of shield excavation caused by ground loss has some compensation.The main rule is that the lateral surface subsidence issymmetrical "groove".Stratum deformation decreases with increasing distance from the tunnel axis,and a certain range of deformation tends to be stable,also the deformation rate is close to zero.The surface deformation caused by synchronous grouting in shield tunnelling is related to grouting parameters and construction parameters.In a certain range,the surface subsidence depth increases with the increase of grouting rate and radius of tunnel excavation,and increases with the decrease of tunnel depth and soil Poisson’s ratio.When there are vertical rigiddisplacement boundaries such as underground continuous wall and lateral rigid displacement boundary or underground bedrock,the stratum has obvious uplift function in synchronous grouting construction.In this paper,the compensation for the loss of soil mass in the synchronous grouting construction of shield tunnel is theoretically analyzed and deduced.It provides a feasible prediction method for shield tunnel construction to control stratum deformation.The feasibility and feasibility of the method need further monitoring data validation.