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分量式钻孔应变观测,是当今国际上地壳岩石应变相对测量的主流方法,由于应变需在岩石、水泥和仪器钢筒等三层介质中传递,故与无孔岩石不同,观测系统存在附加应变场,测得的面应变与剪应变并不等于钻孔围岩的真实应变,分别需要一个传递系数与之关联,所以分析外加应变向探头的传递过程很有必要.根据双衬套理论,首先推导出平面应力作用下岩石面应变与剪应变传递系数(β_m、β_j)的计算公式,分别对其影响机制进行讨论,并给出有关变化规律曲线和定量指标.继续给出三维空间应力作用下面应变传递系数(β_(m3))的计算公式,并讨论了β_(m3)与β_m的关系及适用范围;剪应变因不受垂直向应力的影响,传递系数仍为β_j.通过观测值和求解传递系数,最终可以确定地壳岩石的真实应变量.该项工作对观测数据的物理解释和仪器设计、安装参数的优化也能提供帮助.
Component borehole strain observation is the mainstream method for relative measurement of crustal rock strain in today’s world. Since the strain needs to be transmitted in three layers of medium such as rock, cement and instrument steel cylinder, different from non-porous rock, there is additional strain in observation system Field, measured surface strain and shear strain are not equal to the true strain of the surrounding rock, respectively, and need a transfer coefficient associated with it, so it is necessary to analyze the transfer process of the applied strain to the probe.According to the double liner theory, The calculation formulas of rock plane strain and shear strain transfer coefficient (β_m, β_j) under plane stress are deduced, and their influence mechanisms are discussed respectively, and the change rules and quantitative indexes are given. The relationship between β_ (m3) and β_m and its application scope are discussed. The shear strain factor is not affected by the vertical stress, and the transfer coefficient is still β_j. By the observation and solution The transfer coefficient finally determines the true strain of the crustal rock, and this work can also help with the physical interpretation of observational data and the optimization of instrument design and installation parameters.