高拱坝拦蓄水体巨大,要求建基岩体应具有较高的承载力及抗变形能力,但坝基嵌入深度过大,坝基大量开挖会影响坝基上下游高边坡的稳定,此外,存在高地应力导致的坝基岩体卸荷松弛问题等。在对比研究国内外设计标准对建基面的要求基础上,结合锦屏一级特高拱坝建基面的确定进行分析,总结出几点新的认识在采取可靠基础处理措施的前提下,可适当降低对建基岩体的质量要求;可采取适当增加坝体厚度、降低拱坝应力水平的方式,降低建基岩体受载;采取在拱坝下游抗力体区域施加横向锚索锁固的方式,可提高建基岩体承载能力。

Bearing capacity and anti-deformation ability of rock mass in the foundation of high arch dam must be fulfilled to design requirement , because water volume impounded by the dam is giant. But excavation on a large scale at the foundation will be harmful to stability of high slopes at the upstream and downstream of dam foundation , as well as stress relaxation of rock mass due to high geostress. Based on the comparison of the standard requirements of foundation surface at home and abroad, we analyzed the determination for dam foundation surface of the highest dam, Jinping arch dam, and summarized some new viewpoints as follows1)in premise of reliable measures for foundation treatment ,we can reduce the quality requirements of rock mass in specific projects; 2) we can increase the thickness of arch dam and decrease the stress of arch dam to reduce the load of rock mass in the foundation; 3) transversal anchor locking imposed in the resistance body region at the downstream of arch dam can improve the bearing capacity of rock mass in the foundation.