Characteristics and formation mechanism of the July 25, 2013, Tianshui group-occurring geohazards
- 177 Downloads
A field investigation was conducted for the group-occurring mountain torrent geohazards that took place on July 25, 2013, in Tianshui City, China. The formation causes, range, development characteristics, and distribution laws of these geohazards were systematically revealed. In addition, a three-dimensional dynamic numerical continuum model was established to simulate the motion characteristics of the typical landslides in Tianshui City. The field investigation and simulation results show that the mountain torrent geohazards that occurred on July 25, 2013, had five major characteristics: universality and evident group occurrence, local outbreak, strong concealment, considerable potential damage, and a significant hazard chain mode. The hazards’ intensity was aggravated by the superposition effects of intense rainfall and earthquakes. Most of the landslide-prone slopes in these geohazards had a concave geometry. The landslides occurred mainly within a slope gradient range of 35°–45°; the most common slope angle was 40°. The loess landslides had a narrow-strip shape and ranged in width from several meters to 10 m and in length from 10 s of meters to 100 s of meters. These landslides were relatively small scale, with volumes from 10 to 100 s of cubic meters. The mean velocity, frontal velocity, total kinetic energy, and total potential energy of the typical landslide masses all increased sharply during the downslope motion and decreased gradually in the deposition zone. Entrainment was a very important factor in these landslide events, as it caused the mass of the hazard bodies to increase; the increased mass, together with a high motion velocity (30 m/s), enhanced the destructiveness of the hazard bodies.
KeywordsGroup-occurring geohazards Development characteristic Disaster formation mechanism Tianshui City
This research was funded and supported by the National Natural Science Foundation of China (Grant Nos: 41530640, 41330858, 41302224) and the Sha’anxi Province Science and Technology Research and Development Program of China (Grant No: 2014KJXX-20). We are grateful to the anonymous reviewers for their valuable suggestions in improving the manuscript. We thank LetPub (www.letpub.com) for its linguistic assistance during the preparation of this manuscript.
- Derbyshire E, Meng XM, Dijkstra TA (2000) Landslides in the thick loess terrain of north–west China. Wiley, Chichester, pp 1–256Google Scholar
- Guo FY, Meng XM, Li ZH, Xie ZT, Chen G, He YF (2015) Characteristics and causes of assembled geo-hazards induced by the rainstorm on 25th July 2013 in Tianshui City, Gansu, China. Mt Res 33(1):100–107 (in Chinese with English abstract) Google Scholar
- He YF, Wang JH, Zhao C et al (2010) Torrents and geo-hazards survey of emergency in Tianshui city. Institute of Geo-environment Monitoring of Gansu Province, 07. On July 25 2013 (in Chinese) Google Scholar
- Hungr O, Evans SG (1996) Rock avalanche runout prediction using a dynamic model. In: Proceedings of the 7th international symposium on landslides. pp 233–238Google Scholar
- Liu DS (1985) Loess and environment. Science Press, Beijing, pp 1–43Google Scholar
- McLellan PJ, Kaiser PK (1984) Application of a two parameter model to rock avalanches in the Mackenzie Mountains. In: Proceedings of 4th international symposium on landslides, Toronto, vol 1. pp 135–140Google Scholar
- Sun GZ (1989) Engineering geological and mechanical characteristics of loess in northwestern china and related problems in geological engineering. Lanzhou University Press, LanzhouGoogle Scholar
- Yu G, Zhang M, HU W (2014) Analysis on the development characteristics and hydrodynamic conditions for the massive debris flow in Tianshui. Northwest Geol 47(3):185–191 (in Chinese with English abstract) Google Scholar