张松, 施斌, 张诚成, 刘苏平, 顾凯, 张磊. 2019: 低围压下锚固点应变传感光缆与土体变形耦合性试验研究. 工程地质学报, 27(6): 1456-1463. DOI: 10.13544/j.cnki.jeg.2018-384
    引用本文: 张松, 施斌, 张诚成, 刘苏平, 顾凯, 张磊. 2019: 低围压下锚固点应变传感光缆与土体变形耦合性试验研究. 工程地质学报, 27(6): 1456-1463. DOI: 10.13544/j.cnki.jeg.2018-384
    ZHANG Song, SHI Bin, ZHANG Chengcheng, LIU Suping, GU Kai, ZHANG Lei. 2019: EXPERIMENTAL STUDY ON MECHANICAL COUPLING BETWEEN ANCHORED STRAIN SENSING OPTICAL CABLE AND SOIL DEFORMATION UNDER LOW CONFINING PRESSURES. JOURNAL OF ENGINEERING GEOLOGY, 27(6): 1456-1463. DOI: 10.13544/j.cnki.jeg.2018-384
    Citation: ZHANG Song, SHI Bin, ZHANG Chengcheng, LIU Suping, GU Kai, ZHANG Lei. 2019: EXPERIMENTAL STUDY ON MECHANICAL COUPLING BETWEEN ANCHORED STRAIN SENSING OPTICAL CABLE AND SOIL DEFORMATION UNDER LOW CONFINING PRESSURES. JOURNAL OF ENGINEERING GEOLOGY, 27(6): 1456-1463. DOI: 10.13544/j.cnki.jeg.2018-384

    低围压下锚固点应变传感光缆与土体变形耦合性试验研究

    EXPERIMENTAL STUDY ON MECHANICAL COUPLING BETWEEN ANCHORED STRAIN SENSING OPTICAL CABLE AND SOIL DEFORMATION UNDER LOW CONFINING PRESSURES

    • 摘要: 应变传感光缆与被测土体之间的耦合性是决定分布式光纤监测准确性的关键。为解决土工模型试验中传感光缆与被测松填砂土间的变形耦合性问题,本文研制了一种锚固点应变传感光缆,并利用自制的光缆-土体耦合性试验装置,开展了相关的光缆拉拔试验,探究了低围压下锚固点对应变传感光缆与砂土之间耦合性的影响及作用机理。研究结果表明:光缆的轴向应变随拉拔位移的增大而增大,但应变传递被限制在0.35 m以内;相同拉拔位移下,锚固点应变传感光缆比普通传感光缆需要更大的拉拔力;锚固点大大降低了应变梯度,使应变在一定范围内呈现出平均化的特征,影响范围为锚固点前后0.05~0.075 m以内。提出了耦合性的提升率指标,以此定量评价锚固点对增强光缆与土体耦合性的作用效果。本次试验中锚固点的提升率为97.41%,表明锚固点可有效增强光缆与土体的耦合性;同时,提出了一个力学模型来模拟锚固点应变传感光缆在松填砂土中的拉拔过程,准确地描述了光缆拉拔力与锚固点受力和光缆表面摩擦力之间的关系。研究成果对于土工模型试验中分布式光纤测试技术的应用提供了科学依据。

       

      Abstract: The mechanical coupling between strain sensing optical cable and soil deformation is vital to determine the accuracy of distributed fiber-optic strain data. An anchored strain sensing optical cable is designed to enhance the cable-soil mechanical coupling for the use in geotechnical model test. Using a newly devised pullout apparatus, optical cable pullout tests are carried out to explore the influence and mechanism of anchor on the cable-soil coupling under low confining pressures. Test results show that the axial strain increases under increasing pullout displacements, but the strain propagation is limited to a length of 0.35 m. The anchored strain sensing optical cable requires more pullout forces than the unanchored cable under the same pullout displacement. The anchor averages the measured strain within a range of 0.05~0.075 m near the anchor. An increase ratio is proposed to characterize the effect of anchor on enhancing the cable-soil coupling. The ratio is calculated to be 97.41%in this test, which indicates that the anchor can effectively enhance the mechanical coupling between cable and soil. A mechanical model is proposed to simulate the pullout process of anchored strain sensing optical cable in loose sand, which accurately describes the relationship between pullout force and anchor force and surface friction of cable. This study provides a basis for the application of distributed fiber-optic monitoring technology in geotechnical model tests.

       

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