Experimental analysis on the interaction between underground structures and sand layer under groundwater level change

Groundwater level change stands a momentous role in affecting the geotechnical construction stability and safety of underground structures. Global warming and active underground construction cause conspicuous changes in the groundwater level, which further leaves an impact on the underground structures’ serviceability. To reveal the interaction between underground structure and soil under groundwater level change in the sand layer, model tests of circular transportation tunnel and rectangular utility tunnel were carried out. With the self-designed experimental equipment and innovative experimental methods, the changes in tunnel stress, bending moment, buoyancy, and vertical displacement of the rise and drawdown of the groundwater level in the sand layer were studied. The results revealed the developments of concentrated structural forces during the rising and falling process of the groundwater water level, indicating critical locations that should be strengthened. Meanwhile, both tunnels showed the same movement trend: settling first, floating afterwards and settling at last. And it is concluded that no reduction is required when calculating buoyancy in sands using measured pore pressure. Conclusions can provide a notable reference for future related research and engineering designs.