A Study on the Methods for Measuring In-situ Stresses at Great Depth by Use of Boring Cores

岩心大深度地应力测量方法研究

基本信息

批准号：
02805076
负责人：
MATSUKI Koji
金额：
$ 0.9万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1990
资助国家：
日本
起止时间：
1990 至 1991
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-02805076/
关键词：
In-situ Stress Measurement at Great Depth Rock Core Anelastic Strain Recovery Method Differential Strain Analysis Method コアの損傷非弾性ひずみ回復コンプライアンス

项目摘要

Anelastic strain recovery method (ASR method) and differential strain analysis method (DSA method) have been theoretically and experimentally investigated in order to enhance the reliability of the methods for measuring in-situ stresses at great depth. The main results obtained in this study were summarized as follows :1. ASR method(1) Anelastic strain recovery compliance (ASRC) ranges widely depending on the rock type. The ASRC in shear mode is greater than that in volumetric mode.(2) The ASRC of rocks depends on the mean stress. The mean stress increases the ASRC in shear mode and decreases that in volumetric mode.(3) A method for measuring three-dimensional in-situ stresses from anelastic strain recovery of a rock core has been proposed without assumptions except that the rock is isotropic and visco-elastic material.(4) The directions of principal in-situ stresses and the ratio of principal stress deviations in Yunomori district, Iwate Prefecture, have been successfully measured with the method developed in this study.2. DSA method(1) The physical Meaning of the crack parameters used in DSA method for measuring in-situ stresses have been clarified by theoretical consideration.(2) A testing system, whose main component is a pressure vessel of the capacity of 180 MPa, was constructed and the standard testing procedure for differential strain analysis has been established.(3) In-situ stresses have been evaluated by DSA method for the boring cores which were taken by over-coring technique for measuring in-situ stresses. The results from DSA method were not always consistent with those from over-coring methods.(4) The increase of crack parameters due to uniaxial tensile stress is not large enough compared to that measured by DSA for the rock speciments from in-situ. This suggests that the inconsistency described above is due to pre-existing cracks in the specimens.

为了提高大深度地应力测量方法的可靠性，对滞弹性应变恢复法（ASR法）和微分应变分析法（DSA法）进行了理论和实验研究。本研究取得的主要结果概括如下： 1． ASR 方法(1) 滞弹性应变恢复柔度 (ASRC) 的范围很广，具体取决于岩石类型。剪切模式下的ASRC大于体积模式下的ASRC。(2)岩石的ASRC取决于平均应力。平均应力增加了剪切模式下的ASRC，降低了体积模式下的ASRC。(3) 提出了一种测量岩心滞弹性应变恢复三维地应力的方法，除了岩石是各向同性的和(4)利用本研究开发的方法成功测量了岩手县汤之森地区的主地应力方向和主应力偏差比。2． DSA法(1)通过理论考虑阐明了DSA法测量地应力中裂纹参数的物理意义。(2)测试系统，其主要部件是容量为180 MPa的压力容器， (3)采用DSA方法对采用超取芯技术测量地应力的钻孔岩心进行了地应力评估。 DSA方法的结果与超取心方法的结果并不总是一致。(4)与原位岩石标本的DSA测量结果相比，单轴拉应力引起的裂纹参数的增加不够大。这表明上述不一致是由于样本中预先存在的裂纹造成的。