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

原位三轴试验是1998年发明的一种测量岩体平均应力-应变关系的方法。由于试样是通过旋转钻孔在地面上制备的，因此对地面的干扰实际上是最小的。在2001财政年度，设计了使用CCD作为变形测量系统的先进版本的测试方法。该系统预计将允许整个试样的应变分布的测量，因此被认为是有用的研究不均匀或不连续的岩体behavior.In财政年度2002，单轴以及三轴压缩设备开发引进该CCD测量系统。此外，为了减少试样数量和避免分散数据难以解释的问题，研究了多步加载三轴试验方法。2003年度，利用CCD测量方法进行了两次三轴试验。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，改进了现场试验的测试设备。变形测量的精度和速度比以前的版本提高了10倍。还为现场试验选择了场地，并进行了初步地质调查。2004财政年度，在凝灰岩角砾岩场地进行了一系列现场试验。测量了典型非均匀岩体的平均应力和应变关系。为了研究岩体的尺度效应和其他特性，还进行了室内三轴试验，以获得补充资料。

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.