Experimental study on stratum disturbance of shield construction under different tunnel depth conditions

With the continuous expansion of urban underground space development, stratum disturbance induced by shield construction has an important impact on the safety of existing underground structures and surrounding environment. Through the independent research and development of the shield tunneling test device, the load of different stratum stress levels was realized, and the change law and influence range of the stratum disturbance in shield construction under different burial depth conditions were analyzed. The results show that the change rate of earth pressure in the strata around the tunnel decreases with the increase of the horizontal distance from the tunnel. The ratio of soil pressure after shield tunneling to initial soil pressure is about 60%-80%. The change of buried depth ratio has little influence on the soil stress path at the vault and bottom. The stratum disturbance degree based on the change of stress is defined, and the stratum disturbance degree gradually decreases with the increase of the burial depth ratio, indicating that the deep burial condition will reduce the disturbance effect of shield excavation on the stratum. After the completion of the shield tunneling, the height of the vertical influence range of the disturbance is between 0.5D and 0.8D above and below the tunnel (D is the diameter of tunnel), the width of the horizontal disturbance range is about 0.5D when the shield reaches the monitoring section, and approximately 1.2D to 1.5D when the shield passes far away.