岩体变形参数确定的经验方法研究

Empirical methods to determine the rock masses parameters

在岩体工程变形分析和稳定性评价时,确定合理的岩体变形模量至关重要。现场试验可直接确定岩体的变形模量,获取的数据相对可靠,但是所需周期长、费用高,当现场试验受到各种制约条件而无法进行时,通过工程岩体分级指标估算岩体变形参数的经验方法,不失为一种经济实惠的选择。目前,国外已有大量学者通过对岩体分级方法的研究,得到了相应的岩体变形参数计算的经验公式,但在国内相关研究的开展则较少。《工程岩体分级标准》是我国岩体分级的国家标准,自1994年颁布以来,在国内岩土工程界得到了广泛的应用,但基于此分级方法来进行岩体变形参数估算方面的研究则相对较少,因此研究基于国标工程岩体分级指标预测岩体变形参数的经验公式具有广泛的应用价值。通过参考国外节理岩体变形模量的经验确定方法,吸取了相关的经验和成果,在搜集国内大型水利水电工程现场试验成果与工程岩体分级指标等相关成果基础上,结合数理统计原理,通过相关性分析,得到基于国标《工程岩体分级标准》BQ值估算岩体变形模量的经验公式。为提高预测岩体变形参数的准确性,通过对实测数据统计分析,得到了根据BQ指标、岩块弹性模量Ei估算岩体变形模量经验公式,并经三峡工程现场变形试验数据验证了该经验公式的可行性。上述研究成果为通过BQ指标估算岩体变形模量提供了一条合理的量化途径。

The deformation modulus of rock mass is a very important input parameter in any analysis of rock mass behaviors which include deformation calculation or stability analysis. In-situ tests, which can determine this parameter directly and is the most reliable methods, are time consuming and expensive. When in-situ tests can＇t be made enslaved to something, empirical method, which estimates the value of rock mass deformation modulus on the basis of rock mass classification schemes, would be a good choice. A lot of foreign scholars had established empirical relationships between rock mass deformation modulus and classification system, but the domestic researchers pay little attention in this field. Standard for Classification of Engineering Rock Masses, which was issued in 1994, is the national standard of Chinese. It has been widely used in geotechnical engineering, but the research achievement which related to the rock mass parameters are so little that it is very necessary to study in this area. Using the data by a large number of in-situ tests from large-scale water conservancy and hydropower projects in China, a new relationship between the deformation modulus of rock mass and BQ index is proposed, based upon the principle of statistics and correlation analysis. In order to improve the precision of the empirical formula, a new relationship is proposed between the deformation modulus of rock mass and BQ index, the properties of the intact rock, and it is validated by data from the Three Gorges Project. It would be a useful reference for parameter determination of rock mass in our country.