Based on the similarity model material, the trifarious FBG strain sensor which is suitable for model test is developed. It overcomes the shortages of traditional fiber strain sensors. It simplifies the mechanics transferring process. The finite element method is adopted to emphatically analyze the effect of colloid elastic modulus to strain transfer characteristics of the FBG strain sensor. Then the colloid with elastic modulus 300MPa is selected in the experiment. The strain transferring coefficient of the sensor is 0. 662, and the sensitivity is 0. 794pm · με . The FBG strain sensors are used in tunnel excavation model test to explore the strain distributing situation in surrounding rock by supporting-step-excavation method, supporting-whole-section-excavation method and non-support and whole-section excavation method. The monitoring results of the FBG strain sensors show that surrounding rock is more stable when the supporting-step-excavation method is adopted. The experiment provides reliable data support for research different excavation method and supporting method of the tunnel.%基于模型相似材料,研制了适用于模型试验的三向FBG(fiber Bragg grating,光纤光栅)应变传感器,克服了传统的光纤应变传感器力学干扰大等缺点,且简化了力学传递过程.采用有限元方法重点分析了胶体弹性模量对传感器力学传递特性的影响,试验中选择了弹性模量为300MPa的胶体,其应变传递系数为0.662,传感器的灵敏度为0.794pm·με-1.将该FBG应变传感器用于隧道开挖模型试验中,分别研究支护台阶法开挖、支护全断面开挖及无支护全断面开挖方式下的围岩应变分布状况.传感器监测结果表明,支护台阶法开挖围岩的稳定性较好.该试验为研究隧道不同开挖方式与支护方式提供了可靠的数据支撑.
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