摘要
季节性冻土的冻融循环控制着土壤水热过程,是高纬度寒冷地区气候变化的重要指标.监测冻土结构与物质组分的动态变化对于基础设施建设、土壤保护治理以及碳储调控等具有关键意义.相比于原位钻孔与遥感探测,浅地表地球物理方法可获得不同深度的冻融过程空间变化特征.本文采用高密度电阻率成像与背景噪声地震监测技术在我国东北地区冻土试验场开展季节性冻融周期探测与监测实验.完整冻融周期的地球物理监测数据揭示了土壤结构与水热特性响应规律,物性参数与水文信息具有很好的一致性.不同冻融阶段电阻率变化与温度、含水量以及溶质浓度相关.地震相对速度变化(dv/v)和面波相速度变化(dc/c)与累积温度、地下水位呈负相关,指示了土壤孔隙冻结程度与深部环境的水热状态.同时,实测数据验证了dc/c相比dv/v具有更高的时空分辨率.灵敏度分析讨论了电阻率与地震速度变化分别对浅层热交换以及深层水文特征变化敏感.结合孔隙几何特征与水冰相变机制,通过水文与地球物理数据给出了季节性冻土的冻融演化模型.研究结果验证了地球物理方法在冻土探测与动态监测中的适用性,为冻融过程的相变机制和定量解释提供了技术支持.
The seasonal freeze-thaw cycle of frozen soil regulates soil hydrothermal processes and serves as a crucial indicator of climate change in high-latitude cold regions.Monitoring the dynamic evolution of frozen soil structure and composition is essential for infrastructure development,soil conservation and carbon storage regulation.Compared to in-situ borehole measurements and remote sensing,near-surface geophysical methods offer spatially resolved insights into freeze-thaw processes at different depths.In this study,we applied electrical resistivity tomography and ambient noise seismic monitoring to investigate seasonal freeze-thaw cycles at a frozen soil test site in Northeast China.Geophysical data collected over a complete freeze-thaw cycle reveal the coupling between soil structure and hydrothermal properties,with strong consistency observed between physical parameters and hydrological information.Resistivity variations correlate with temperature,water content,and solute concentration across different freeze-thaw stages.Seismic relative velocity changes(dv/v)and surface wave phase velocity changes(dc/c)were negatively correlated with accumulated temperature and groundwater levels,reflecting soil pore freezing and the hydrothermal state of the deep subsurface environment.Meanwhile,the measured data verify that dc/c offers higher spatiotemporal resolution than dv/v.Sensitivity analysis indicate that resistivity is more responsive to shallow thermal exchange,while seismic velocity changes are more sensitive to deep hydrological variations.Integrating pore geometry and water-ice phase mechanisms,we construct a freeze-thaw evolution model for seasonally frozen soil based on combined hydrological and geophysical data.The results validate the effectiveness of geophysical methods for detecting and monitoring frozen soil,and provide technical support for quantifying phase transition mechanisms in freeze-thaw processes.
作者
李静
白利舸
刘辉
张凯文
张臣纲
曾昭发
LI Jing;BAI LiGe;LIU Hui;ZHANG KaiWen;ZHANG ChenGang;ZENG ZhaoFa(College of Geoexploration Science and Technology,Jilin University,Changchun 130016 China;Key Laboratory of Deep Earth Exploration and Imaging,Changchun 130026 China)
出处
《地球物理学报》
北大核心
2025年第8期3011-3024,共14页
Chinese Journal of Geophysics
基金
国家自然科学基金优秀青年基金项目(42222407)
吉林省教育厅重大自然科学项目“季节性冻融过程黑土地关键参数监测研究”(JJKH20241295KJ)联合资助.
关键词
季节性冻土
电阻率监测
被动源地震
水文地球物理
Seasonal frozen soil
Electrical resistivity monitoring
Ambient noise seismic
Hydrogeophysics
