Zipingpu Water Conservancy Project Abandoned Coal Mines In The Stability Of Hydraulic Structures And Countermeasures Research

Zipingpu water conservancy is located on the northwest 60km Minjiang River, in upriver Shajinba segment of Chengdu City Sichuan province. It is a water conservancy mainly used for agricultural irrigation, civil water supply. It also has the synthetically social benefit such as to prevent flood, protect environment and develop tourism etc. The strata are Triassic Xujiahe group sand-shale stratum which containing coal layer. It is nearly three-century history about the coal layer exploitation. In that time, because of the outdated technique and inorganization, the coal caves have the characteristic of randomicity, concealment, universality, no obviously regularity and the small scale for single cave. The existence and treatment of the abandoned coal caves is related to the construction safety. In this paper, taking the Zipingpu hydropower station as example, on the basis of the former studied results, the influence of the coal cave to the hydro-building stability has been investigated, the relevant treatment measure has been given, and some productions have been acquired, which will be the beneficial instruction for the construction design.1. According to the basic geological condition such as the coal cave data collected in-site and the strata lithology, the distribution rule and characters of the coal cave are analyzed. On the basis of the excavated coal cave characteristic, the deformation destroy type and the effect factors are investigated, and the mined out area has been extrapolated and determined2. According to the experiential formula, the caving-in zones and fracturing zones of the coal cave mined out area have been calculated.3. The relationship between the coal cave and the engineering slope has been analyzed, the entering water slope of the transmitting water cave has been selected as the typed slope and using flac3d to do the numerical simulation. According to the distance 10m, 20m, 30m of the coal cave to the slope, combined with the multi-engineering situation, the slope stability has been analyzed. The conclusion has been get that within 30m coal cave to the slope must been fully treated.4. The relationship between the coal cave and the tunnel has been analyzed, and 4 # transmitting water cave has been selected as an example to set up a numerical model. The coal caves in the surrounding rock scope of the tunnel have been treated in two schemes, which were the method of fully treated, and half-length treated. The conclusion has been gotten that the coal cave within 30m to the slope must been fully treated.5. According to the studied result, the coal cave treatment measures such as the height, length and measure have been discussed, and the advice for the potential influence of the coal caves in later has been given.The studying results have the better instruction meaning in the coal cave actual treatment of the hydropower station slope or near the tunnel.