一种新型光纤光栅局部位移计在小应变测量中的应用

发布时间：2018-05-10 07:17

本文选题：光纤 + 布拉格光栅　；参考：《岩土工程学报》2017年07期

【摘要】：小应变下的土体模量的变化对基坑周围既有建筑物的变形和路基沉降分析具有重要意义。土体模量会随土体的应变呈非线性变化,特别是应变范围为10~(-5)~10~(-3),土体模量随应变的增加显著降低。由于土体应变的变化范围广,传统的单一测量仪器无法连续量测土体从微小应变到小应变的模量变化情况。通常测量土体小应变模量的方法有弯曲元和局部位移计方法。弯曲元方法能有效测量土体微小应变的模量,但不能得到土体模量在小应变情况下变化规律,因为弯曲元方法无法得到和控制土体的应变。设计了基于布拉格光纤光栅传感技术的局部位移计。通过设计和标定试验,成功将布拉格光纤光栅局部位移计应用于改装的三轴试验仪器中。为进一步的对比分析,在改进的三轴试验装置中安装了弯曲元试验系统。基于改装的三轴试验仪器,进行了不同围压下的固结不排水试验,得到了土体从微小应变到小应变下模量的变化曲线。试验结果验证了光纤光栅局部位移计能有效的测量土体在小应变情况下的模量非线性变化特征。
[Abstract]:The variation of soil modulus under small strain is of great significance to the analysis of deformation and subgrade settlement of existing buildings around the foundation pit. The modulus of the soil is nonlinear with the strain of the soil, especially the strain range of 10 ~ (-5) ~ 10 ~ (-3), and the modulus of the soil decreases significantly with the increase of the strain. Because of the wide range of soil strain, the traditional single measuring instrument can not continuously measure the variation of soil modulus from small strain to small strain. The methods of measuring the small strain modulus of soil are bending element and local displacement meter. The bending element method can effectively measure the modulus of small strain of soil, but it can not get the variation rule of soil modulus in the case of small strain, because the bending element method can not obtain and control the strain of soil. A local displacement meter based on fiber Bragg grating sensing technology is designed. Through the design and calibration test, the fiber Bragg grating local displacement meter is successfully applied to the modified triaxial test instrument. For further comparison and analysis, the bending element test system was installed in the improved triaxial test device. Based on the modified triaxial test instrument, consolidation undrained tests under different confining pressures were carried out, and the curves of soil modulus changing from small strain to small strain were obtained. The experimental results show that the fiber grating local displacement meter can effectively measure the nonlinear variation characteristics of the modulus of soil under small strain.
【作者单位】：华中科技大学土木工程与力学学院;
【基金】：国家自然科学基金项目(51508215) 中央高校基本科研业务费专项资金资助项目(2017KFYXJJ138)
【分类号】：TP212;TU198

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