Analysis of situation and trend of sinkhole collapse

The karst area is more than 3.4 million km2 in China, accounting for about 36% of the country’s land area, in which sinkhole collapse and associated disaster frequently occur. A comprehensive and systematic analysis of current situation and research trend of sinkhole collapse at home and abroad is of great significance to accurately grasp the current hot topics, and to carry out scientific and effective work towards the disaster prevention and reduction. In this paper, we analyzed current research status and trend in the field of sinkhole collapse at home and abroad using big data tool on three aspects, namely, genesis mechanism, identification and evaluation, as well as monitoring and early warning, based on the CNKI database, WOS database and China karst collapse investigation and research project database. The results show that in the past five years, the international research hotspot areas in relation to sinkhole collapse are mainly concentrated in Italy, the United States, China and Spain, among them Italy is the most concerned. Foreign countries pay more attention to the erosion and corrosion of groundwater to the genetic mechanism of sinkhole collapse, and the main factors considered include rainstorm, pumping, surface runoff and sewer leakage. Among them the use of advanced equipment such as centrifuge to study the causes of karst collapse is more distinctive. Domestic studies on the causes of karst collapse can be summarized into 10 models, including gravity, erosion, suction corrosion, blasting, vibration, load, dissolution, root corrosion, pressure difference and etc. Meanwhile, mechanical and mathematical methods, such as soil arch theory and numerical simulation, have been used to gradually improve the quantification study. In terms of early identification and evaluation, remote sensing and aerial geophysical exploration methods, such as geological radar, drilling radar and Light Detection and Ranging (LiDAR), have been widely used at home and abroad. In respect of the sinkhole monitoring and early-warning, geological radars are frequently used to scan regularly in foreign countries, while in China, groundwater dynamic and chemical conditions are mainly monitored. There have been successful cases at home and abroad such as optical fiber sensing, aerial geophysical prospecting and other new technologies and methods. In terms of research trends, the current international research hotspot of sinkhole collapse mainly focuses on the interaction between human engineering activities and karst environment, which is reflected in forecasting, risk management and emergency response. In terms of project support, the largest proportion of project financial support for sinkhole collapse research mainly comes from the National Natural Science Foundation of China (NSFC) and Geological Survey Project (GSP). At present, the NSFC accounts for the largest proportion at 43%, and GSP account for 39%, showing an increasing trend in GSP. To sum up, we should combine with human engineering activities and ecological environmental protection of the study of the karst collapse closely, pay close attention to hotspots area, and focus on scientific and technological research work in the aspects of quantitative genetic mechanisms, rapid identification of hidden hazards, fine monitoring and early warning, and aging of risk prevention and control.