Study On The Evaluation System Of Negative Effects On Groundwater Environment Resulted By Tunnel Construction In Karst Area

More and more tunnels will be constructed in karst area to raise road grade and improve the regional traffic environment, along with the rapid development of transportion and technology. However, negative effects on groundwater environment resulted by tunnel construction is not uncommon, and it not only jeopardizes the safety while tunnel constructing, but also puts the schedule off. even resulting in civil litigation because of water resource. In view of this, an evaluation system is built to assess the negative effects on groundwater environment resulted by tunnel construction in karst area, aiming at objectively demonstrate and scientificly evaluate the major environmental hydrogeological problem caused by tunnel construction before offering scientific basis for choosing a tunnel's location and ensuring safety from tunnel construction to operation.The root of negative effects on groundwater environment resulted by tunnel construction is water inrushing. On the basis of summarizing the factors which influence tunnel inflow, an indices system, composed of physical geography, geology and hydrogeology, also with tunnel engineers, is proposed to evaluate groundwater negative effects resulted by tunnel engineering in karst areas. This achievement has been appended on the Code for Hydrogeological Investigation of Railway Engneering which will be published at soon.A methods collection is built, concluding using G1 method to calculate the indice weight, adopting fuzzy mathematics to comprehensive assessment and using onscene investigation, flow monitoring, water source identification, inflow predication and precipitation responsing model to prove the conclusion after the assessment being made. Of all the models applicated in this research, weighted gray relation analysis model for tunnel inrush source identification and the response model of tunnel inflow to precipitation are new,the former one can help determine the impacted area of tunnel construction and offer basis for solution of water resource dispute, when the latter one is able to quantitatively indicate the response of recipitation and water inflow, offering scientific reference on the management of tunnel waterproof and drainage.Visual Basic language is used to develope a program for assessment of negative effects on groundwater environment resulted by tunnel construction in karst area, because of so many complex mathematic calculation when evaluating. This program can build indices system, calculate indice weight, assess the result,and comprehensively prove the result. It supplies the rearchers with a flexiable platform.The evaluation system is used to evaluate the negative effects on groundwater environment resulted by the Tongluoshan tunnel of Dianjiang-Linshui expressway and Xulingguan tunnel of Naxi-Guizhou expressway. It indicates that Tongluoshan tunnel gets a weakerâ…¢level, and Xulingguan tunnel get aâ…¡level. These results accord with the fact. This research can be used to identify and evaluate the impact on groundwater environment of tunnel engineering in karst area.