FULL SECTION MONITORING OF LAND SUBSIDENCE BOREHOLE USING DISTRIBUTED FIBER OPTIC SENSING TECHNIQUES
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摘要: 本文介绍了一种钻孔全断面分布式光纤监测技术,可以获得地面沉降过程中多场多参量数据,实现钻孔全断面的精细化监测。阐述了钻孔全断面分布式光纤监测技术的概念,并重点介绍了该技术涉及的传感光缆和传感器选择、钻孔回填材料、光缆-土的耦合性评价和光缆及传感器植入方法等关键技术。在此基础上,构建了钻孔全断面光纤监测系统。最后,结合苏州盛泽地面沉降光纤监测案例,介绍了钻孔全断面光纤监测过程和技术特点。Abstract: This paper introduces a full section monitoring of land subsidence borehole using distributed fiber optic sensing(DFOS)techniques, which can obtain data on multi-fields and multi-parameters and provide delicate monitoring of land subsidence. The concept of full section monitoring of borehole using DFOS is firstly introduced. The key techniques on the application of this method include the selections of cables and sensors, the backfill materials, the coupling of cables and soils and the installation of cables and sensors in boreholes. A system frame of the full section monitoring of borehole with DFOS is built. Finally, the whole process of full section monitoring with DFOS and its features are illustrated with a case in Shengze Town, Suzhou.
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Key words:
- Borehole /
- Full section /
- DFOS /
- Land subsidence /
- Key techniques
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表 1 钻孔全断面光纤监测常用传感元件及解调设备
Table 1. Common used sensors and demodulators for borehole full section monitoring using DFOS techniques
传感元件 可选解调设备 应力场和变形场监测 FBG埋入式应变计 灵敏度高,稳定性高,用于测量土体内部应变 MOI(美国)SM-125型FBG解调仪;南智(中国)A03、A04、A05型便携式FBG解调仪 FBG位移计 安装方便,适用于地裂缝、形变位移等测量 金属基索状光缆 具有极好的机械性能和抗拉抗压性能,适合各种恶劣工况 中电四十一所(中国)AV6418、AV6419型BOTDR解调仪;ANDO公司AQ8603型BOTDR解调仪;DVANTEST(日本)N8511型BOTDR解调仪;Neubrex(日本)PPP-BOTDA解调仪 紧包护套传感光缆 富有弹性,极为柔软,易与监测物协调变形;弹性模量较小,铺设过程中不宜过分拉伸 定点传感光缆 独特内定点的设计,实现非连续非均匀应变分段均一化分布式测量,适于大变形监测 水分场和渗流场监测 FBG渗压计 尺寸小,适用于地下孔隙水、油气、液体压力监测 MOI(美国)SM-125型FBG解调仪;南智(中国)A03、A04、A05型便携式FBG解调仪 碳纤维加热感测棒 测试精度高,适用于室内模型含水率监测 碳纤维内加热传感光缆 适用于短距离测试(< 500m),可监测水分场、渗流场 NZS-DTS-M06 DTS解调仪 碳纤维内加热感测管 缠绕方式提高测量精度,适用于地下水位监测 地温场监测 测温光缆 用于温度补偿测量 FBG温度计 多点串联,可用于岩土体内外部温度测量 MOI(美国)SM-125型FBG解调仪;南智(中国)A03、A04、A05型便携式FBG解调仪 表 2 Neubrex产NBX-6050A型BOTDA参数
Table 2. Testing parameters for NBX-6050A type BOTDA from Neubrex
空间分辨率/m 采样间隔/m 应变测量范围/×103με 测量精度/με 测量重复性/με 0.1 0.05 -30~+40 ±7.5 ±7.5 表 3 第四纪地层划分
Table 3. Segmentation of quaternary strata
地层 深度/m 承压含水层组分布 土层性质 全新统Qh 5.3 上更新统Qp3 37.0 第Ⅰ组 隔水层(Ad1) 黏性土 41.2 含水层(Af1) 粉细砂 中更新统Qp2 45.0 第Ⅱ组 隔水层(Ad2) 黏性土、粉土 74.35 87.7 含水层(Af2) 细-中砂 下更新统Qp1 97.1 第Ⅲ组 隔水层(Ad3-1) 黏土 137.9 弱透水层(Ad3-2) 粉土、黏土夹细砂 上新统N2 151.0 含水层(Af3) 细-中砂 165.1 弱透水层(Ad4) 粉土、黏土夹细砂 中新统N1 200.0 半固结层(S-S) 固结成岩 -
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