Study on optical fiber layout optimization of DTS for detecting the integrity of cast-in-place piles
LIU Yongli1，HUANG Silu1，XIAO Henglin1，CHEN Weizhong2，MA Qiang1
(1. Hubei Provincial Ecological Road Engineering Technology Research Center，Hubei University of Technology，Wuhan，Hubei 430068，China；2. State Key Laboratory of Geomechanics and Geotechnical Engineering，Institute of Rock and Soil Mechanics，Chinese Academy of Sciences，Wuhan，Hubei 430071，China)
Abstract：The application of DTS on the integrity testing of cast-in-place piles has an economic significance which improves pile foundation quality and saves construction time. The optimization of the optical fiber detection system for DTS detection of the integrity of the cast-in-situ pile was studied by physical and numerical model test methods. According to the theoretical analysis，the basic principle that determines proper fiber spacing is proposed. The physical model test is used to set the heating power of the built-in fiber heat source by 4 W/m，8 W/m，12 W/m and 16 W/m. The meta-analysis is carried out by applying the corresponding central thermal loads in 22 ℃，24 ℃，28 ℃，32 ℃ to the physical model respectively. The results show that the higher the heating power is，the higher the centerline temperature is，and the larger the critical radius of the fiber heat source is. The closer the heat source is to the centerline，the higher the temperature rise value. The boundary conditions are different，and the temperature rise at the same distance from the heat source is different. The critical radius of the fiber is also different；the fiber structure has a significant influence on the heat conduction characteristics；when the fiber with a length of 28 m is heated by 4–16 W/m，the spacing of the U-shaped fiber is about 48 cm. The numerical model is in good agreement with the physical model test results and can effectively make up the insufficiency in the physical model test. The research results and methods provide a theoretical basis and technical guidance for the design of the detection system for DTS detection of the integrity of the cast-in-situ pile.
刘永莉1，黄思璐1，肖衡林1，陈卫忠2，马 强1. DTS检测灌注桩桩完整性的光纤布设优化研究[J]. 岩石力学与工程学报, 2019, 38(S2): 3841-3848.
LIU Yongli1，HUANG Silu1，XIAO Henglin1，CHEN Weizhong2，MA Qiang1. Study on optical fiber layout optimization of DTS for detecting the integrity of cast-in-place piles. , 2019, 38(S2): 3841-3848.
[1] 宛新林. 土力学与地基基础[M]. 合肥：合肥工业大学出版社，2006：12–28.(WAN Xinlin. Soil mechanics and foundation[M]. Hefei：Hefei University of Technology Press，2006：12–28.(in Chinese))
[2] 罗骇先. 桩基工程检测手册[M]. 北京：人民交通出版社，2003：181–258.(LUO Weixian. Pile foundation engineering testing manual[M]. Beijing：People?s Communications Publishing House，2003：181–258.(in Chinese))
[3] 宋人心，王五平，傅 翔，等. 灌注桩声波透射法缺陷分析方法一阴影重叠法[J]. 中南公路工程，2006，31(2)：77–79.(SONG Renxin，WANG Wuping，FU Xiang，et al. A method for defect analysis of acoustic wave transmission method for filling piles-shadow overlap method[J]. 中南公路工程，2006，31(2)：77–79.(in Chinese))
[4] 张 丹，施 斌，吴智深，等. BOTDR 分布式光纤传感器及其在结构健康监测中的应用[J]. 土木工程学报，2003，36(11)：83–87.(ZHANG Dan，SHI Bin，WU Zhishen，et al. BOTDR distributed optical fiber sensor and its application in structural health monitoring[J]. China Civil Engineering Journal，2003，36(11)：83–87.(in Chinese))
[5] 江 宏. PPP-BOTDA分布式光纤传感技术及其在试桩中应用[J]. 岩土力学，2011，32(10)：3 190–3 195.(JIANG Hong. PPP-BOTDA distributed optical fiber sensing technology and its application in test piles[J]. Rock and Soil Mechanics，2011，32(10)：3 190–3 195.(in Chinese))
[6] 刘永莉. 分布式光纤传感技术在边坡工程监测中的应用研究[博士学位论文][D]. 浙江：浙江大学，2011.(LIU Yongli. Application of distributed optical fiber sensing technology in slope engineering monitoring[Ph. D. Thesis][D]. Zhejiang：Zhejiang University，2011.(in Chinese))
[7] 蔡德所. 分布式光纤传感监测三峡大坝混凝土温度场试验研究[J]. 水利学报，2003，(5)：88–91.(CAI Desuo. Experimental study on temperature field of concrete in Three Gorges Dam by distributed optical fiber sensing[J]. Journal of Hydraulic Engineering，2003，(5)：88–91.(in Chinese))
[8] YOSEF T Y，SONG C R，CHANG K. Hydro-thermal coupled analysis for health monitoring of embankment dams[J]. Acta Geotechnica，2018，13(2)：447–455.
[9] 肖衡林，蔡德所，何 俊. 基于分布式光纤传感技术的岩土体导热系数测定方法[J]. 岩石力学与工程学报，2009，28(4)：819–826. XIAO Henglin，CAI Desuo，HE Jun. Determination of thermal conductivity of rock and soil based on distributed optical fiber sensing technology[J]. Chinese Journal of Rock Mechanics and Engineering，2009，28(4)：819–826.(in Chinese))
[10] 雷文凯，肖衡林. 基于分布式光纤测温技术的灌注桩完整性[J].湖北工业大学学报，2014，29(2)：19–22.(LEI Wenkai，XIAO Henglin. Integrity of cast-in-place pile based on distributed optical fiber temperature measurement technology[J]. Journal of Hubei University of Technology，2014，29(2)：19–22.(in Chinese))
[11] XIAO H L，LIU Y L. Detecting soil inclusion inside piles in the laboratory using DTS method[J]. Journal of Testing and Evaluation，2017，45(2)：452–459.
[12] 曹雪珂. 基于分布式光纤的桩基完整性检测技术研究[硕士学位论文][D]. 武汉：华中科技大学，2013.(CAO Xueke. Research on pile foundation integrity detection technology based on distributed optical fiber[M. S. Thesis][D]. Wuhan：Huazhong University of Science and Technology，2013.(in Chinese))
[13] 刘永莉，肖衡林，胡其志，等. 基于DTS的灌注桩完整性检测方法研究[J]. 长江科学院院报，2017，34(6)：124–127.(LIU Yongli，XIAO Henglin，HU Qizhi，et al. Research on integrity detection method for bored pile using distributed optical fiber temperature sensing technology[J]. Yangtze Academy of Sciences，2017，34(6)：124–127.(in Chinese))
[14] LIU Y L，XIAO H L. Research on the layout of optical fibers applied for determining the integrity of cast-in-situ piles[J]. Optical Fiber Technology，2018，45：173–181.
[15] 雷文凯，肖衡林，张金团，等. 基于光纤检测技术的夹泥灌注桩模型试验[J]. 岩土力学，2018，39(3)：909–916.(LEI Wenkai，XIAO Henglin，ZHANG Jintuan，et al. Model test of grouted filling pile based on optical fiber detection technology[J]. Geotechnical Mechanics，2008，39(3)：909–916.(in Chinese))
[16] XIAO H L，CUI X L，LEI W K. A bored pile deficiency detection method based on optical fiber temperature measurement[J]. Optical Fiber Technology，2015，21：1–6.
[17] 范 萌，雷文凯，肖衡林，等. 夹泥灌注桩的光纤传感检测模型试验[J]. 长江科学院院报，2016，33(4)：95–98.(FAN Meng，LEI Wenkai，XIAO Henglin，et al. Test of fiber sensing detection model for grouting pile[J]. Yangtze Academy of Sciences，2016，33(4)：95–98.(in Chinese))
[18] 魏广庆，施 斌，贾建勋，等. 分布式光纤传感技术在预制桩基桩内力测试中的应用[J]. 岩土工程学报，2009，31(6)：911–916.(WEI Guangqing，SHI Bin，JIA Jianxun，et al. Application of distributed optical fiber sensing technology in internal force testing of precast pile foundation[J]. Journal of Geotechnical Engineering，2009，31(6)：911–916.(in Chinese))
[19] 肖衡林，雷文凯，张金团，等. 光纤测温技术用于夹泥灌注桩完整性检测的试验研究[J]. 岩石力学与工程学报，2016，35(8)： 1 722–1 728.(XIAO Henglin，LEI Wenkai，ZHANG Jintuan，et al. Experimental study on the application of fiber temperature measurement technology in the integrity detection of grouted filling pile[J]. Journal of Rock Mechanics and Engineering，2016，35(8)： 1 722–1 728.(in Chinese))
[20] 范 萌，刘永莉，肖衡林，等. 光纤测温技术在断桩检测模型试验中的应用[J]. 传感器与微系统，2015，34(12)：153–160.(FAN Meng，LIU Yongli，XIAO Henglin，et al. Application of fiber temperature measurement technology in test of broken pile detection model[J]. Sensor and Microsystem，2015，34(12)：153–160.(in Chinese))
[21] 胡仁喜. ANSYS 14.0热力学有限元分析从入门到精通[M]. 北京：机械工业出版社，2013：32–38.(HU Renxi. ANSYS 14.0 thermodynamic finite element analysis from introduction to proficiency[M]. Beijing：Machinery Industry Press，2013：32–38.(in Chinese))
2019, Vol. 38 
