埋入式应变感测光缆-冻土界面渐进破坏机制研究  

Progressive failure mechanism of embedded strain sensing cable-frozen soil interface

作　　者：刘天翔 朱鸿鹄[1,2] 吴冰 李豪杰 胡乐乐 LIU Tian-xiang;ZHU Hong-hu;WU Bing;LI Hao-jie;HU Le-le(School of Earth Sciences and Engineering,Nanjing University,Nanjing,Jiangsu 210023,China;Institute of Earth Exploration and Sensing,Nanjing University,Nanjing,Jiangsu 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 [2]南京大学大地探测与感知研究院,江苏南京210023

出　　处：《岩土力学》2024年第1期131-140,共10页Rock and Soil Mechanics

基　　金：国家杰出青年科学基金(No.42225702);国家自然科学基金(No.42077235);冻土工程国家重点实验室开放基金(No.SKLFSE201814)。

摘　　要：冻胀融沉作用引起的地基土体变形是冻土地区工程建设的典型地质灾害,光纤传感技术为冻土变形的精细化、分布式实时监测提供了重要的技术手段。为探究分布式光纤应变传感在监测冻土变形方面的可行性,利用自主研制的光缆-冻土界面力学特性试验仪,探究了不同干密度和初始含水率的冻土试样中缆-土界面的破坏机制。试验结果表明,光纤应变监测结果准确地反映出缆-土界面呈现渐进性破坏特征,应变软化模型能够较好地描述界面的力学特性。在冻结过程中,土体内液态水相变成冰,引起了冻结锋面移动和水分迁移,使得界面的力学特性存在显著的差异性。不同深度处缆-土界面剪应力的演化过程反映了在光缆拉拔过程中与冻土的变形协调状态,表明光缆测量范围、界面耦合性与土体干密度、初始含水率密切相关。该研究为光纤传感技术在寒区冻土地基变形监测中的应用提供了参考。The deformation of foundation soil caused by freeze-thaw cycles is a typical geological disaster in engineering construction in permafrost areas.Fiber optic sensing technology provides an important technical means for accurate and distributed real-time monitoring of frozen soil deformation.To explore the feasibility of distributed fiber optic strain sensing in monitoring frozen soil deformation,this study utilized a self-developed optical cable-frozen soil interface mechanical characteristics tester to investigate the failure mechanism of the cable-soil interface in frozen soil samples with different dry densities and initial water contents.The experimental results indicate that the fiber optic strain monitoring results accurately reflect the progressive failure characteristics of the cable-soil interface,and the strain softening model can better describe the mechanical properties of the interface.During the freezing process,the liquid water in the soil becomes ice,causing the movement of the freezing front and water migration,and resulting in significant differences in the mechanical properties of the interface.The evolution process of the shear stress at the cable-soil interface at different depths reflects the deformation coordination state with the frozen soil during the cable pullout process,indicating that the measurement range of the cable and the coupling of the interface are closely related to the dry density and initial water content of the soil.This study provides a reference for the application of optical fiber sensing technology in deformation monitoring of frozen soil foundation in cold regions.

关 键 词：岩土工程监测 冻胀作用 光缆-冻土界面 渐进性破坏 分布式光纤传感技术 

分 类 号：TU445[建筑科学—岩土工程]