Land subsidence has threatened the safety of municipal infrastructures and even that of inhabitants. As one of the deformation monitoring methods, distributed optical fibre sensing (DOFS) technology has been developed for the investigation of land subsidence. The deformation coordination between the optical fibre and soil (DC_f-s) under different conditions is critical for land subsidence monitoring with DOFS. In this paper, a medium-sized triaxial apparatus was modified for testing the DC_f-s. Consolidated drained triaxial tests were conducted to investigate the effect of sand types on the DC_f-s. By linearly fitting the deformation of the sensing cable with that of the triaxial specimen, the other factors that affect the DC_f-s, such as the confining pressure, dry or wet state of the soil and cyclic variation of the loads, can be discussed. The experiments reveal that better DC_f-s comes with a larger particle size, poor gradation of sand and larger confining pressure. The DC_f-s of wet sand is better than that of dry sand. The DC_f-s coefficient tends to be stable with an increase of loading cycles. The DC_f-s obtained and its dependence on influencing factors can be used to modify the measured cable strain in practical land subsidence monitoring with DOFS.

中文翻译：

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光纤与钻孔砂回填变形配合研究

地面沉降威胁着市政基础设施乃至居民的安全。作为变形监测方法之一，分布式光纤传感（DOFS）技术已被开发用于地面沉降的调查。不同条件下光纤与土壤之间的变形协调（DC _f-s）对于 DOFS 地面沉降监测至关重要。本文对中型三轴装置进行了改造，用于测试直流_f-s。_{进行固结排水三轴试验来研究砂类型对 DC f-s}的影响。通过将传感电缆的变形与三轴试件的变形进行线性拟合，可以得到影响直流_{f-s 的其他因素}，例如围压、土壤的干湿状态以及荷载的循环变化，都可以进行讨论。实验表明，较好的DC _f-s伴随着较大的粒径、较差的砂粒级配和较大的围压。湿砂的DC _f-s优于干砂。随着加载次数的增加，直流_f-s系数趋于稳定。获得的DC _f-s及其对影响因素的依赖性可用于修改 DOFS 实际地面沉降监测中测量的电缆应变。