Miniaturization of the system and improvement of the accuracy for Hemispherical Ended Borehole Technique

半球端钻孔技术系统的小型化和精度的提高

• 批准号: 62850116
• 负责人: OKAMURA Hiroshi
• 金额: $ 4.03万
• 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
• 财政年份: 1987
• 资助国家: 日本
• 起止时间: 1987 至 1988
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-62850116/
• 关键词: Hemispherical borehole technique; In-situ rock stress; 高精度; 球状孔底ひずみ法

In the construction of rock cavern, it is important for the design and stability estimations of the rock cavern to measure the state of intial stresses as well as distribution of induced stresses in the rock mass around the cavern with high accuracy. In this project, the Hemispherical Ended Borehole Technique is developed for measurement of in-situ rock stresses and the miniaturization of the system and the improvement of the accuracy are performed. This system are applied to measure rock stress in the rock mass around the cavern. The results obtained in this project are as follows:1) A new technique to measure the complete state of in-situ rock stresses in a single borehole are developed, which is called Hemispherical Ended Borehole Technique. The stress tensor is computed from 16 strains on the hemispherical bottom surface of a borehole. An arrangement of strain gauges to determin the stress tensor with high accuracy is discussed and a spherical strain cell to bond the strain gauges directly to the bottom surface at the designated stations is developed.2) It is confirmed that the rock stresses with higher accuracy can be determined by using of the proposed method in comparison with the conventional method from the theoretical analyses and experiments using rock spacimens.3) The in-situ rock stresses in the rock mass around the cavern are measured by the proposed method and the distribution of the stresses is determined. The extent of the failure zone around the cavern and the practical strength of the rock mass forming the ground arch can be estimated from the distribution of stresses.

在岩石洞穴的建造中，对于岩石洞穴的设计和稳定性估计很重要，以高精度测量洞穴岩石质量中的岩石质量的诱导应力分布。在该项目中，开发了半球形末端钻孔技术，用于测量原位岩石应力，系统的微型化和精度的提高。该系统用于测量洞穴周围岩石质量的岩石应力。该项目中获得的结果如下：1）开发了一种新技术来测量单个钻孔中原位岩石应力的完整状态，这称为半球形终端井眼技术。应力张量是从钻孔半球底部表面的16个菌株计算得出的。讨论了应变测量值以高精度来确定应力张量的排列，并开发了一个球形应变电池，将应变计直接粘合到指定站点的底部表面。使用拟议的方法与使用岩石太空素的理论分析和实验相比，使用所提出的方法确定。3）洞穴周围岩石质量的原位岩石应力是通过提出的方法和拟议方法的分布来测量的。确定应力。可以从应力分布中估算出洞穴周围的破坏区域和形成地面拱形的岩石质量的实际强度。