Influence of small diameter pipe jacking tunnel construction on surrounding environment in soft soil areas

Based on the 2.4 m small-diameter pipe jacking tunnel project in soft soil, the first step is to analyze the measured data. A three-dimensional numerical model is then established to study the impact of pipe jacking tunnel construction on the surrounding environment. The results indicate that during pipe jacking construction, due to the backfill effect, the ground surface will rise, and the soil will generate greater excess pore water pressure. The dissipation of excess pore water pressure will cause the ground surface to continuously sink. The construction of pipe jacking tunnels will primarily cause vertical displacement in existing pipelines. The presence of these pipelines will reduce the maximum ground surface subsidence and increase the affected area. The perforation will significantly impact the main tunnel, causing it to form a vertical ellipse shape at the joints. When the distance from the portal is more than four times the diameter of the main tunnel, the impact on the main tunnel is minimal, with the maximum internal force mainly concentrated at the connection between the portal and the steel pipe segments and the reinforced concrete segments. Compared to medium and large diameter pipe jacking tunnels, the thrust force in small diameter pipe jacking tunnels has a lesser impact on the structure.