孟底沟水电站蚀变岩密集带综合变形模量研究

拟建雅砻江孟底沟水电站坝基花岗闪长岩体中,密集发育有单条宽度为0.5~3m的黏土化热液蚀变岩带。变形试验表明,微新花岗闪长岩的变形模量平均值高达31.50GPa,而强黏土化蚀变岩及弱黏土化蚀变岩变形模量仅分别为6.79GPa、11.10GPa,故蚀变岩密集带的存在必将对坝基岩体的变形特性产生重大影响。目前对于这种变形特性差异显著的复杂组合岩体综合变形模量尚无成熟的评价方法。因此,本文在刚性承压板变形试验及声波测试基础上,采用非线性回归法分析了岩体声波与变形模量的相关性,建立了岩体Vp-E0的相关性公式,进而采用算术平均法计算了典型蚀变岩密集带的综合变形模量,其值为18.03GPa,较微新花岗闪长岩变形模量降低了42.76%;同时,根据带内各种蚀变岩所占比例,采用加权平均法求得蚀变岩密集带综合变形模量值为19.40GPa,较微新花岗闪长岩变形模量降低了38.41%。两种方法所得的综合变形模量值相差仅为7.60%,且对比刚性承压板法所得变形模量值,前者更加安全可靠。故建议采用非线性回归法对孟底沟水电站蚀变岩密集带综合变形模量进行计算。

INTEGRATED DEFORMATION MODULUS OF INTENSIVE ALTERED ROCK ZONE AT MENG DIGOU HYDROPOWER STATION

Most of the dam foundation rock mass is granodiorite in the proposed Yalongjiang Mengdigou hydropower station, where intensive development of Hydrothermal alteration rock zone has a single width of 0.5~3m. Deformation test shows that the average deformation modulus of new micro-granodiorite is up to 31.5GPa. The deformation moduli of strong clay alteration rock and weak clay alteration rock are 6.79GPa and 11.10GPa, respectively. Therefore, the existence of intensive altered rock zone can have a significant impact on the deformation characteristics of the dam foundation rock. There are no mature methods to calculate the deformation modulus of the complex combination of rocks with deformation characteristics of significant differences. Therefore, this article is based on the rigid bearing plate deformation test and acoustic test. It uses the nonlinear regression method to analyze the correlation of rock deformation modulus and acoustics. It establishes the rock Vp-E0 correlation formula. Then, it uses the arithmetic average method to calculate the deformation modulus of typical intensive altered rock zone. The result is 18.03GPa and decreases by 42.76%to that of new micro-granodiorite rock. Meanwhile, according to a variety of altered rock band percentage, it uses the weighted average method to calculate deformation modulus of intensive altered rock zone. The result is 19.40GPa and decreases by 38.41%to that of new micro-granodiorite rock. The difference of the two methods is only 7.60%.Comparing with the rigid bearing plate result, the former is more safe and reliable. Thus, the method of nonlinear regression is suggested to calculate the deformation modulus of intensive altered rock zone at Mengdigou hydropower station.