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Rock Stress Measurement by Means of Conical-ended Borehole

通过锥形钻孔测量岩石应力

基本信息

批准号：
03555136
负责人：
SUGAWARA Katsuhiko
金额：
$ 3.65万
依托单位：
Kumamoto University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Developmental Scientific Research (B)
财政年份：
1991
资助国家：
日本
起止时间：
1991 至 1992
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-03555136/
关键词：
Rock Stress Measurement Stress Relief Method Conical-ended borehole Technique Accuracy of Rock Stress Determination 岩盤応力応力測定応力解放

项目摘要

Rock stress is of fundamental importance for the construction of rock structures, such as underground openings, since the mechanical behavior of surrounding rock masses is mainly dominated by rock stress. Therefore, the rock stress measurement is considered to be an important field measurement in rock engineering. Particularly, recent developments in relation to the prediction of structural stability of underground openings have indicated th e need for systematic stress measurement, e.g. the systematic initial stress measurement.In order to determine the complete state of stress at a certain point within a rock mass, the conical-ended borehole technique is proposed to measure the three dimensional state of stress in a rock mass with a high accuracy and low costs by the stress relief method, and the optimum shape of the bottom surface is discussed as well as the gauge arrangement. It is shown how the stress tensor can be determined from the strains on the conical bottom surface of a single borehole, and how the error of stress determined can be evaluated theoretically. The sensitivity and the practicality of the present method are discussed, comparing the conventional methods of in situ stress measurement. Subsequently, by examining the stress distribution obtained by the multiple times stress measurement in a single borehole, it is discussed that the uniformity and the continuity of the field stress are frequently injured by the presence of the geological discontinuities like faults.

由于围岩的力学行为主要由岩石应力控制，因此岩石应力对于诸如地下开口的岩石结构的施工是至关重要的。因此，岩石应力测试被认为是岩石工程中一项重要的现场测试。特别是，最近在地下洞室结构稳定性预测方面的发展表明，需要进行系统的应力测量，例如系统的初始应力测量。为了确定岩体内某一点的完整应力状态，圆锥形的-提出了一种利用应力高精度、低成本地测量岩体三维应力状态的端孔技术讨论了最佳底面形状和保径布置。文中给出了如何由单个钻孔锥底表面的应变确定应力张量，以及如何从理论上估计应力确定的误差。通过与传统地应力测量方法的比较，讨论了该方法的灵敏度和实用性。然后，通过对单井多次应力测量得到的应力分布的分析，讨论了断层等地质不连续面的存在经常破坏地应力的均匀性和连续性。