Interaction of cavities and underground structures on subsidence

The expansion of urbanization, the need to expand underground structures is obvious. One of the threats to the construction of underground structures is impact of these construction on the ground surface which includes a wide range of types of subsidence. If the underground structure is constructed correctly , these effects can be expected to be minimized. But there are some factors such as buried structures ,Qanats, wells, water pipes, etc. cause the large deformations called subsidence on the ground. In this research, an attempt has been made to investigate the effect of the geometry and position of empty spaces (cavities) above the tunnel, the amount and the geometry of the subsidence created on the ground and provided a relation in this regard. Numerical modeling has been used for this purpose. The results showed that the strain energy of the soil mass between the cavity and the tunnel affects the displacement of the tunnel crown. Also, the shape and volume-to-depth ratio of the cavity affect the amount of subsidence, and cavities that have an equal volume-to-depth ratio will apply the same conditions to tunnel stability.