钻孔回填料粒径对传感光缆应变耦合性影响研究  

Effects of diameter of borehole backfill on strain coupling of sensing optical cable

作　　者：史淞戈 施斌[1] 刘苏平 张诚成[1] 顾凯[1] 何健辉 SHI Songge;SHI Bin;LIU Suping;ZHANG Chengcheng;GU Kai;HE Jianhui(School of Earth Sciences and Engineering,Nanjing University,Nanjing 210023,China)

机构地区：[1]南京大学地球科学与工程学院,江苏南京210023

出　　处：《岩土工程学报》2023年第1期162-170,共9页Chinese Journal of Geotechnical Engineering

基　　金：国家自然科学基金重点项目(42030701);国家重大科研仪器研制项目(41427801)。

摘　　要：钻孔全断面光纤监测技术已在地面沉降和矿山塌陷等地质灾害监测中不断得到推广应用,其中钻孔回填料与直埋式传感光缆之间的应变耦合性是影响光纤监测结果准确性的关键。利用可控围压光缆–回填料耦合性测试试验装置,探究了0~1.0MPa围压下传感光缆与不同粒径砂土回填料(0.5~4mm)之间的应变耦合性问题。结果表明:在相同围压与拉拔位移下,光缆与砂土之间的应变耦合性,随着粒径的增大而减弱,即0.5~1mm砂土与应变传感光缆间的耦合性最强。将10000με作为传感光缆最大应变监测量程,对传感光缆–砂土应变耦合性进行了评价。当光缆–砂土变形协调系数为0.9时,0.5~1,1~2,2~4 mm粒径砂料的临界围压依次为0.14,0.33,0.52 MPa。应变传感光缆与砂土的界面剪应力先增大后减小,随着拉拔位移的增大,光缆–砂土界面剪应力峰值与传递深度均有增加。研究结果可为确定钻孔全断面光纤监测的临界围压深度提供科学依据。The borehole full-section optical fiber monitoring technology has been widely applied in the monitoring of geological disasters such as ground subsidence and mine collapse.The strain coupling between the borehole backfill and the directly buried sensing cable is the key to the influence of the accuracy of optical fiber monitoring results.The strain coupling between the fiber optic cable and the backfill of sand with different particle sizes(0.5~4 mm) under the confining pressures of 0~1.0 MPa is investigated by using the coupling analysis device of controllable confining pressure cable and backfill.The results show that under the same confining pressure and pull-out displacement,the strain coupling between the optical cable and the sand decreases while the particle size increases,that is,the coupling between the sand of 0.5~1 mm and the strain sensing optical cable is the strongest.Using 10000 με as the maximum strain monitoring range of sensing cable,the strain coupling between the sensing cable and the sand soil is evaluated.When the deformation coordination coefficient of the fiber optic cable and the sand reaches 0.9,the critical confining pressures with particle sizes of 0.5~1,1~2,and 2~4 mm are 0.14,0.33,and 0.52MPa in order.The interface shear stress between the fiber optic cable and the sand first increases and then decreases.With the increase of the pull-out displacement,the peak value and the transfer depth of the interface shear stress increase.The results provide a scientific basis for determining the depth of the critical confining pressure of the borehole full-section optical fiber monitoring.

关 键 词：分布式光纤监测 钻孔回填料 界面剪应力 耦合性 粒径 

分 类 号：TU413[建筑科学—岩土工程]