水电工程坝基玄武岩体波速与变形模量关系

岩体变形模量是岩体工程设计最重要的参数之一.由于受到资金、时间、尺寸效应等限制, 在工程勘察设计阶段往往不可能大量开展岩体现场和室内变形模量试验, 试验结果也不具有普遍代表性.因此, 水电工程常常采用岩体纵波波速与变形模量之间的相关关系来估算大范围及深部岩体变形模量.根据波动微分方程从理论上解释了岩体纵波波速与变形模量之间内在的联系.以我国西南金沙江干流上坝基主要为玄武岩体的4个大型水电工程为例, 根据132组现场变形模量试验结果与同向波速测试结果建立玄武岩体波速与变形模量相关方程, 并与也有的研究成果对比分析.研究成果表明, 玄武岩体波速与变形模量具有较好的相关性.当波速小于4 500 m/s时, 不同类型玄武岩根据波速计算变形模量差别较小; 当波速大于4 500 m/s时, 差别逐渐增加.选取最优的相关方程用于估算坝基玄武岩体变形模量, 为水电工程坝基玄武岩体变形模量的快捷评价提供科学依据. 

Correlation between Wave Velocity and Deformation Modulus of Basalt Masses as Dam Foundation in Hydropower Projects

Deformation modulus is an important parameter for rock engineering design. However, the relation between longitudinal wave velocity and deformation modulus is often used to estimate the deformation modulus of large-scale and deep rock mass in the hydroelectric projects because it is difficult to conduct many in-situ and laboratory deformation modulus tests due to the limited funds, time and test size during the engineering survey and the test results have no general representativeness. In this paper, the intrinsic relation between longitudinal wave velocity and rock deformation modulus is theoretically explained based on the wave differential equation. Meanwhile, 132 in-situ test data derived from 4 hydropowers are used to set up an experience formula between longitudinal wave velocity and deformation modulus for basalt in the Jinsha River area. The results show that there is close relation between the basalt longitudinal wave velocity and its deformation modulus. The deformation modulus difference of different basalt rock masses by calculating of longitudinal wave velocity is small when V_p < 4 500 m/s. While it becomes larger when V_p > 4 500 m/s. The optimal equation is helpful to evaluate the deformation modulus of basalt rock mass, and it offers a quick and scientific method for selecting basic parameters of dam foundation in the hydropower projects.