在简要叙述坝址基本地质条件的基础上，指出了影响建坝岩体质量的主要因素是岩体卸荷程度；分析阐明了河谷两岸岩体卸荷分带特征及工程地质特性，明确了弱卸荷/未卸荷岩体均可作为工程可利用岩体；并将平硐宏观地质调查与地震波、声波测试成果相结合，综合判定两岸拱座岩体卸荷状况，为拱端嵌岩深度的合理选择提供了重要依据。

One of the important geological investigation and research for arc dam is how to select the properly buried depth of the arc abutment. The paper points out that the rock mass unloading degree is one major factor which influences the rock mass quality on the basis of analyzing the geological conditions of the dam site area. Meanwhile the paper describes the rock mass relief features of the both side banks of the valley. The slightly relief load rock mass and no-relief load rock mass can act as the available rock mass for arc abutment. The relief rock mass zones on both sides of the valley are classified according to the results of combining the geological investigation with, seismic prospecting and acoustic prospecting in the adit. Then the properly buried depth of the arc abutment is suggested for designing the high arc dam.