Simulation experiment on sinkhole formation caused by soils disintegration and the advance-forecasting of sinkhole risk

Sinkholes are a common geological hazard around the world. However, it is difficult to carry out the associated indoor simulation experiments because of the complicated factors involved. Our previous research showed that sinkholes in the aerated zone caused by soil disintegration exhibit accurate critical conditions. Therefore, the kind of sinkhole formation is simulated in the paper. Before the simulate experiment, the critical value of the disintegration of clay samples is tested, which helps to control the simulation conditions. With a designed simulation apparatus, soil disintegration was conducted 70 times from October 23, 2017, to June 1, 2018, and a sinkhole formed. This experiment results indicate two developmental laws of sinkholes forming in the aerated zone. One is the forming process which has three stages, soil-void formation, soil-void expansion, and roof collapse. Second is that the two conditions water content is less than the critical value and contact between water and soil, causing the sinkhole formation. At the forming, two conditions are clear, and can easily be monitored by the associated factors in the field where sinkholes have occurred or are about to occur. According to the principle, another simulation experiment was carried out. As a result, an advanced prediction of a sinkhole is achieved in the aerated zone.