Study Of The Impact Of Underground Space Development On The Spring In Jinan City

In the development of urban modernization, Jinan city faces the same problem as well as other big cities- "the urban syndrome”. The rapid expansion of urban areas and the shortage of land resources make urban living space environment be under increasing pressure. It is an inevitable choice for the development and utilization of underground space as soon as possible. Scientific and rational, respectful for the natural law of underground space development will has no or a smaller impact on spring and unscientific development and utilization of underground space would destroy the aquifer and runoff channels of spring. Based on the collection and study of geological survey and engineering construction data of Jinan city and the analyzsis of the physical geography conditions and hydrogeology conditions, this paper studys the geologic environment characteristics within the the exploration depth of the first underground space and the second underground space. The evaluation index system established basic steps and index selection principle, We study the evaluation index system of impact of underground space development on the spring systematacially. By applying the method of fuzzy comprehensive evaluation based on GIS platform we divide regions of the impact of the first underground space development on spring and the second underground space development impact on spring respectively in study area. The research results, for the scientific and rational, respectful for the natural law underground space development and spring protection in Jinan city, has reference significance. The main conclusions of this paper are as follows:(1)We analyze the geologic environment characteristics of the underground space development and utilization in Jinan city. By the classification and summary of some data like drilling and hydrology etc., which is collected in study area, combining with the depth of the underground space development, we respectively draw the quaternary soil thickness contour, magmatic rocks top surface depth contour, the limestone top suface depth contour,the underground water level elevation contour,the minimum depth of groundwater level contour of study area and analyze the groundwater recharge and runoff of the spring groups nearby in Jinan. The results show that the quaternary soil thickness increases gradually from the south east to north west on the whole in study area, magmatic rock body is mainly distributed in the north, northeast and northwest of the study area. The buried depth of limestone on either side of the contact zone of limestone and magmatic rock body has a bigger difference. The minimum buried depth of groundwater level in the study area decreases gradually on the whole from the south east to the north west, being consistent with the terrain slope on the whole.(2)We propose and establish the evaluation index system of the impact of underground space development on spring. Based on AHP(analytic hierarchy process) and the impact of underground space development and on spring in Jinan city as the target layer, we select three aspects of natural geographical conditions, hydrogeologic conditions, engineering geological conditions as the first stage subsystem(subject level) and the target factors of each subsystem as the second stage(indicator layer), establish the evaluation index system of the impact of underground space development on spring and study to determine the importance of each factor in which the evaluation index with the greatest impact on the target layer is the limestone top suface depth and the least impact one is terrain slope, the results of the study in accordance with the hydrogeological conditions of the jinan spring protection.(3)We analyze the impact of underground space development on spring in Jinan city. We introduce GIS fuzzy comprehensive evaluation method, based on the GIS platform to carry on the spatial operation of the vector models, have been obtained the zone maps of the impact of the first underground space and the second underground space development on spring respectively of the study area,that is, different area of impact area, distribution position.The results show that the area where the impact of first underground space development on spring in case of the strongest influence area, the stronger influence area, general area, smaller influence area accounted for about 1.036%, 1.001%, 0.371%, 97.591% of the total area of the study area, respectively. And the area where the impact of second underground space development on spring in case of the strongest influence area, the stronger influence area, general area, smaller influence area accounted for about 4.156%, 2.906%, 1.143%, 91.794% of the total area of the study area, respectively. Partition results conform to the hydrogeological conditions of jinan spring area.(4)Based on the zone maps of the impact of the first underground space and the second underground space development on spring respectively of the study area, we put forward geologic environment protection measures of the first underground space, the second underground space and advice from the control of the city to the direct recharge area expansion and recharge source, rain flood utilization, reducing expenditure and optimize the mining layout,water source conservation of karst dry valley, engineering construction of sewage effluent water environmental protection aspects to strengthen the protection of the spring. For the strongest influence area of engineering construction project, need to work in a timely manner to carry out the spring protection demonstration, find out the depth of the foundation where the degree of karst development, fracture density distribution. It is forbidden to foundation construction of karst aquifer. For the exposed limestone region pollution enterprise should be banned from the planning and construction, from two aspects of water quality, water quantity protect Jinan spring.