含流体的裂隙会对石窟文物造成破坏,而毫米级裂隙的探测是石窟文物保护中的一个难题。文中首先基于水文建模模拟了水在裂隙中的流动以及在围岩中的扩散现象,然后建立了不同渗流时刻的介电常数和电导率模型,并通过坐标旋转生成了一系列不同旋转角度的模型进行全极化探地雷达(FP-GPR)正演模拟。最后,分析了H-Alpha 分解和Freeman分解获得的H、α、Ps、Pd 及Pv 参数与测量角度和渗流时间的关系。结果表明:α、Ps 和Pd 三个参数与渗流时间呈现良好的一致性,而H 和Pv 两个参数与渗流时间没有表现出明显的变化关系;在渗流开始的一段时间,测量角度对五个参数会产生很大影响,这与所使用的电磁波的频率有关。文中的研究结果对实际中利用时移FP-GPR 探测渗流微裂隙提供了重要的理论支撑和技术指导。

The fractures with fluid flow will lead to the damage of rock cave artifacts and the detection of millimeter-scale fractures is a challenge in artifact conservation. The fluid flow in fractures and the infiltration in surrounding rocks based on hydrological modeling are simulated first in this paper. Based on the results, electric permittivity and conductivity models at different time lapse are established, and a series of models with different rotation angles are generated through coordinate rotation for full-polarimetric ground penetrating radar (FP-GPR) simulations. Subsequently, the relationships between H, α, Ps, Pd, and Pv parameters and measurement angles and infiltration time are analyzed. The results indicate that α, Ps and Pd have good variation consistency with infiltration time, while H and Pv do not show a significant relationship with the infiltration time. In addition, the measurement angle has significant impacts on the five parameters at the beginning of infiltration, which is related to the frequency of the adopted electromagnetic waves. The research results provide important theoretical support and technical guidance for the use of time-lapse FP-GPR to detect fractures with fluid flow in field cases.

TN959.1

国家重点研发计划(2021YFC1523401);国家自然科学基金资助项目(42304157);国家重点研发计划(2022YFC3003402);近地面探测技术重点实验室资助项目(6142414211606);吉林省科技发展计划资助项目(20220101148JC)