基于光纤光栅的深部硬岩隧洞三维扰动应力测试系统研制及工程应用

Development and engineering application of three-dimensional disturbed stress measurement system for deep hard rock engineering based on fiber bragg grating

扰动应力及其演化是深埋隧洞围岩稳定性及灾变的最重要因素,目前对硬质围岩三维扰动应力的研究局限于解析解和数值模拟,缺乏可靠的原位测试技术与装备。考虑深部硬岩隧洞工程复杂地质环境,系统分析扰动应力的测试原理和理论基础,研发基于光纤光栅与空心包体的扰动应力综合传感技术,研制三维扰动应力单孔多点分布式原位测试系统;通过密封油压高精度标定设备,实现对空心包体单元光栅和传感器装置的整体精确标定,结合室内混凝土模型试验,验证了应力测试系统的准确性。以锦屏地下实验室二期隧洞工程为依托,开展扰动应力现场测试,首次原位测试获得深部硬岩隧洞开挖过程中不同深度的三维扰动应力变化,系统分析扰动应力大小、方向的演化特征、规律及其与施工活动的关系,并进一步验证光纤光栅空心包体应力测试系统的工程适用性和可靠性。研究成果为深部硬岩工程扰动应力测试和演化特性研究提供了科学方法和技术支撑。

The evolution characteristics and laws of surrounding rock disturbance stresses in deep tunnels are the most important factors for engineering stability and disaster analysis.At present,the research on the disturbance stress characteristics of hard surrounding rock is limited to analytical and numerical simulation,and there is a lack of reliable in-situ testing technology and equipment.In view of the complex geological environment of deep hard rock tunnel engineering,the disturbance stress comprehensive sensing technology based on fiber bragg grating and hollow inclusion was developed on the basis of the systematic analysis of the measurement principle and theory of the disturbance stress,and a multi-point three-dimensional disturbance stress testing system was developed.The seal oil pressure calibration device was designed to carry out the overall calibration of the sensor,and the indoor concrete model test was designed to verify the accuracy and reliability of the stress testing system.Based on the China Jinping Underground Laboratory phase II project,the in-situ test of the corresponding disturbance stress was carried out.The three-dimensional disturbance stress distribution and evolution characteristics during the excavation of deep hard rock tunnels were obtained for the first time,the evolution characteristics and laws of the magnitude and direction of the disturbance stress and their relationships with construction activities were systematically analyzed,and the applicability and reliability of the fiber bragg grating hollow inclusion stress testing system were further verified.The research provides a scientific method and technical support for deep hard rock engineering disturbance stress test and evolution characteristics research.