坝基岩土体力学参数是水电工程大坝结构设计和稳定性计算的重要依据,楞古水电站坝基出露了大量花岗伟晶岩脉,因此,研究其力学参数具有重要的工程意义。通过圆形刚性承压板试验和平推直剪试验研究了岩脉的变形特征和强度特征,试验结果表明岩脉承压板试验应力-变形关系曲线分为直线型(或准直线型)、上凹型2种,岩脉直剪试验τ-u关系曲线分为脆性、塑性和复合型3种。通过分析包络模量、割线模量的物理意义和水电工程的特点,以及最小二乘法、优定斜率法在强度试验数据统计分析中的代表性,确定了岩体力学参数标准值的取值原则。通过研究,最终提出了坝基花岗伟晶岩脉的力学参数。

Mechanical parameters of rock and soil at dam foundation are important for the design and stability calculation of dam structure. A large number of granite pegmatite dikes occurs at the dam foundation of Lenggu hydropower station. In view of this, the characteristics of deformation and strength of the dikes were studied by circular rigid bearing plate test and straight shear test. Test results show that stress-deformation curves obtained from bearing plate test are in two shapes, namely straight linear type (or quasi straight linear type) and concave type. The curves of τ-u obtained from direct shear test can be classified into three types brittleness, plasticity and composite type. According to the physical meaning of envelope modulus and secant modulus and the hydraulic project’s characteristics, as well as the representativeness of least square method and optimal slope method in analyzing strength test data, the principle of determining the standard value of rock mass is presented. Finally, mechanical parameters of pegmatite dike at the dam foundation are proposed.