深厚覆盖层地区工程物探方法技术探讨

Discussion on Physical exploration technoilogy for the Projects in the regions with deep and thick overburden layer

在深厚覆盖层地区开展工程物探工作，物探方法选择、测网布置、方法技术采用，对于提高水电工程物探解决地质问题的能力显得十分重要。结合金沙江向家坝水电站的工程物探任务，进行了专门的探索。通过试验和研究，在坝区布置电法、地震、弹性波测试、钻孔测井等综合物探工作。选用较密的测网，水上地震采用互换法和遥控计时技术，资料整理运用电算成图技术，查明了覆盖层、断层、张裂带、夹层等工程地质问题，实测出各岩组的弹性波速度。物探成果为评价坝址的工程地质条件，为坝址的选定提供了科学的依据。与钻探资料相比，物探精度为８２．９％。

For enhancing the physical exploration of hydropower projects and the capacity to solve the geological problems, it is very important for the regions with deep and thick overburden layers to develop the engineering physical exploration, to select the physical exploration method and to arrange the measurement network. Combining with the engineering physical exploration in Xiangjiaba Hydropower Station in Jinsha River, special study has been conducted. On the basis of test and study, the comprehensive physical explorations of electrometric method, earthquake, elastic wave measurement and borehole logging have been set in the damsite. The intensive measurement network has been adopted.The exchange method and remote-controlling timing technique have been used in water earthquake. The computer image formation technique has been used in the data processing. Therefore, the engineering geological conditions of coverage layer, fault, tension-crack zone and intercalated layer have been explored. Theelastic wave velocity of various rock formations has been measured. These physical exploration results provide scientific basis for evaluating engineering geological conditions of damsite and for selecting the damsite. Comparedwith the drill exploration data, the accuracy of physical exploration is 82. 9%.