| Meihekou City is located in the south of Jilin Province and in the southern end of the Hada Ridge and Longgang Mountain northeast side engagement across two huge tectonic convergences zone of the Songliao depression and Changbai uplift. Experienced a history of geological development in different periods, a relatively great difference occurred in the geological tectonic. Due to natural factors and human unreasonable economic activity, it induced and exacerbated the geological disasters. Jilin Provincial Department issued a "Jilin Provincial Department carried out geological disasters investigation notice" in 2014 to prevent geological disasters, avoid or mitigate the losses caused by geological disasters and safeguard people’s lives and property safety. We decided to progress an investigation of Meihekou geological disasters. On the basis of geological disaster investigation work, a comprehensive study of geological disasters can explore the temporal evolution. It can provide a reference for local construction project site and help municipal government make a scientific decision-making to provide the basis for prevention the geological disasters. Therefore, Meihekou Geological Disasters Division and comprehensive study are necessary.In this paper,we collected comprehensive data of regional geology, regional hydrology and meteorology, then adopted the methods of remote sensing, ground surveys,geophysical prospecting to research, and got the following results:1. Meihekou main types of geological disasters include collapse,unstable slopes,debris flow,ground subsidence and ground fissures. The survey found that the 79 disasterpoints, which contained 48 collapsed,4 mudslides, 15 unstable slopes, 11 ground collapses and 1 ground fissure.2. Collapse and unstable slopes are mainly distributed in the low hills along the road.It is a small-scale, less harmful and weak structural control surfaces primarily jointed surface. The main structure type of the rock and soil is block-like fragmentation. The micro topography mainly is cliffs. The integrity of the granite is poor, and its surface experienced strong weathering, which will induce the disasters under the evoking of the engineering activities, such as roading and quarrying.Debris flow mainly distributes in the transition area between the hilly area and the mountain valley, belong to debris flow of valle which is consist of two mudslides and two stone streams. Faults widely develop in the area of debris flow, coupled with weathered fractured, broken rock, indirectly provide a rich source of material for debris flow. Debris flow occurred in the induced atmospheric precipitation;Ground subsidence and ground fissures are mainly distributed in the ShuguangZhonghe-Hongmei Mining Town area. The roof thickness of the subsidence area is ranging from 30 to 264 m. The spatial distribution coincides with the mine excavation plane. Forming a large area of mined-out area in underground mining process, it induced to produce ground subsidence and ground fissures.3. Using the Analytic Hierarchy Process, we selected 10 indicators including the relative elevation, landforms, rock and soil type,and mining activities and so on,and established of evaluation system to give judgment matrix to obtain the right to re-evaluation index by solving the matrix.According to the degree of disaster susceptibility, Meihekou can be divided into high, medium and low areas. The high-prone area has 514.07 km2, which located in coal mining region of the study area. The medium-prone areas have 353.40 km2, which located in Wanlong-Niuxinding town. The low-prone areas have 1307.53 km2, which located in Kangdaying-Xinhe-Shuguang town.4. We assessed the geological disaster status and potential economic losses of Meihekou City by using the cost-benefit method. The results show the current economic loss is 57.07 million yuan, and the potential economic loss is 51.7 million yuan. Theground subsidenc is the most severe factor to cause economic losses and should be controlled and prevented. |
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