基于表面硬度的隧道围岩强度快速测试方法研究

Research on rapid testing method of tunnel surrounding rock strength based on leeb hardness

隧道工程建设日益增多,隧道围岩的强度直接影响着隧道工程的施工安全,是保证安全施工的前提条件,围岩质量就显得尤为重要。针对在现场无法对隧道围岩强度快速检测等问题,采用里氏硬度计测试隧道围岩表面硬度,首先根据拉依达准则剔除异常点后,通过引入变异系数弱化岩石的不规则性,确定了测试所需最小样本数。试验结果表明:隧道围岩表面里氏硬度符合正态分布变化,均值、样本标准差和离散系数三者变化均趋于平稳,且最小样本数为30时,数值可靠度最高。根据拉依达准则判断出异常点仅占0.52%,证明采用里氏硬度计对母岩测试是十分契合的。表面硬度测试方法可快速便捷地判别隧道围岩强度,对围岩稳定性评价和快速鉴别提供了重要参考。

With the increasing number of tunnel constructions,the strength of the surrounding rock of the tunnel directly affects the construction safety of the tunnel project.It is a prerequisite to ensure the safety of the construction.The importance of the quality of the surrounding rock is particularly obvious.Aiming at the inability to quickly strengthen the surrounding rock detection.In this paper,the leeb hardness tester is used to test the surface hardness of the surrounding rock of the tunnel,considering the irregularity of the rock itself,and by introducing the coefficient of variation,the minimum number of samples required for the test is determined.Combining the test results of the compressive strength of the surrounding rock of the tunnel,the relationship between the surface hardness of the surrounding rock of the tunnel and its own compressive strength is established,and the feasibility of using the hardness of the leeb hardness to indirectly characterize the compressive strength is analyzed.The test results show that the measured data are processed by mathematical statistics,and they are all in accordance with the normal distribution law.The data obtained on the leeb hardness value of the rock surface is true and reliable.The changes of the mean,sample standard deviation,and dispersion coefficient all tend to be stable,and the value is stable at 30 points.It is inferred that the minimum number of points taken is 30,and when the number of tests is greater than 30.According to the Rayda's criterion,the abnormal points only account for 0.52%,which proves that the use of the Leeb hardness tester is very suitable for the parent rock test.This research method can provide a quick and convenient method for determining the strength of tunnel surrounding rock in construction detection,and provide important reference significance for rapid identification in the evaluation of tunnel surrounding rock stability.