Investigation and modeling of mechanical characteristics of non-uniform and discontinuous rock mass in deep ground by in-situ triaxial tests

原位三轴试验法是在1998年发明的，目的是测量岩体的平均应力应变关系。由于试件是通过旋转钻探在地下制备的，因此预计对地面的干扰实际上是最小的。2001财年，使用CCD设计了高级版本的测试方法，用于变形测量系统。该系统有望测量整个试件的应变分布，因此被认为对研究非均匀或不连续的岩石特性很有用。在2002财年，引入了这种CCD测量系统，开发了单轴和三轴压缩设备。此外，为了减少试件数量和避免解释散乱数据的困难，研究了分步加载三轴试验方法。2003财年，利用人造岩石试件进行了几次三轴试验。结果表明，随着轴向压缩的进行，试件的变形逐渐局部化。此外，还改进了现场测试的测试设备。变形测量的精度和速度比以前的版本提高了十倍。对现场试验进行了选址，并进行了初步地质调查。2004财政年度，在凝灰岩角砾岩现场进行了一系列现场试验。对于典型的非均匀岩体，测量了平均应力和应变关系。还进行了一些室内三轴试验，以获得研究尺度效应和其他一些岩体性态特征的补充数据。

In-situ triaxial test method was invented in 1998 for the purpose to measure average stress and strain relationships of rock masses. Since the test specimens are prepared in the ground by rotary drilling, disturbance of the ground is expected to be as practically minimal.In the fiscal year 2001,the advanced version of the test method was devised using CCD for deformation measuring system. This system was expected to allow measurement of strain distribution throughout the test specimen, thus believed to be useful for studying non-uniform or discontinuous rock mass behavior.In the fiscal year 2002,uniaxial as well as triaxial compression devices were developed introducing this CCD measuring system. Furthermore, multi-step loading triaxial test method was investigated to reduce the number of test specimens and to avoid the difficulties of interpreting scattered data.In the fiscal year 2003, a couple of triaxial tests were conducted with CCD measurement using artificial rock specimens. The results demonstrated that the deformation of specimens became progressively localized as the axial compression proceeded. Moreover, test equipment for the field test was improved. The accuracy and speed of deformation measurement were enhanced as ten-fold as the previous version. Selection of site was also made for the field tests and preliminary geological investigation was conductedIn the fiscal year 2004,a series of field tests were carried out at the site of tuff breccia. Average stress and strain relationships were measured for typically non-uniform rock masses. Some laboratory triaxial tests were also done to obtain the complimentary data to study scale effect and some other features of rock mass behavior.