基于钻孔变形法的无线地应力测量系统及测试分析

Development and testing analysis of in-situ stress measurement technology based on borehole deformation method

随着电子技术的发展,各种不同的地应力测试设备也在逐渐往无线测量方向发展。设计基于钻孔变形法原理的无线地应力测量变形计,研发具备自动测量及采集数据的数字集成系统,并详细介绍该变形计的组成结构、测试原理、测量方法及标定验证。利用卡尔逊变形计标定台对变形计的钢环应变传感器进行标定,得到每个钢环变形时电压信号与钢环变形的Q值关系,结果显示,测量时钢环电压变化与钢环变形之间有良好的线性重复关系,单个钢环的分辨率可达0.025μm,测量精度提高约3倍;用铝质立方体及花岗岩试样进行探头整体标定试验,结果显示,变形计测量误差小于5%,绝对误差小于0.6 MPa,说明变形计测量结果测量准确,可以满足现场使用要求。地应力测量变形计的无线设计为深孔地应力的测量提供一条新途径,并且可以实现对套芯应力解除全过程中测量数据的连续读取,克服人工测读仅获得有限离散数据而导致测试精度不足的缺陷。

With the development of electronic technology,various in-situ stress testing equipment is gradually developing towards wireless measurement.This paper develops a digital integrated system that can automatically measure and collect data,a wireless in-situ stress measuring deformeter based on the principle of aperture deformation method is designed,and the composition,testing principle,measurement method and calibration verification is introduced in detail.In order to demonstrate the reliability of this probe,all four steel ring strain sensors are calibrated by using Carlson deformation gauge calibration station,and the relation between the voltage signal and the deformation of the steel ring is obtained.The results show that there is a good linear repetition relationship between the voltage change of the steel ring and the deformation of the steel ring.The resolution of a single steel ring can reach 0.025μm,and the measurement accuracy is improved by about 3 times.The overall calibration test of the probe with aluminum cube and granite cube show that the measurement error of the deformeter is less than 5%and the absolute error is less than 0.6 MPa,indicating that the measurement result of the probe is accurate and can meet the requirements of field use.The wireless design of in-situ stress measuring deformeter facilitates the measurement of in-situ stress in deep holes,and can realize the continuous reading of the measured data in the whole process of over-coring,thus avoiding the precision shortage of limited discrete data obtained by manual measurement and reading.