摘要
为解决地下空间微重力探测中常规反演结果较为模糊、不利于目标定位的问题,对微重力异常聚焦反演方法进行研究。基于目标空间最小的前提假设,引入目标与围岩的密度差作为已知信息,采用加权阻尼最优化算法,实现微重力异常的聚焦反演。与常规结果相比,聚焦反演能清晰显示目标边界。常规反演目标密度值偏低,空间位置发散的问题得到改善,反演质量提升明显。对模型分辨率、信噪比和先验密度差等反演中的关键参数进行分析,并给出具体设定方法和建议。理论测试结果表明,模型分辨率矩阵决定反演网格对观测数据的灵敏性,若网格对应的对角元过小,则应调整网格参数;信噪比对反演结果聚焦性能具有重要影响,可借助功率谱曲线对其进行估计;先验密度差对反演结果的准确性影响较大,明显错误的密度差将导致反演无法拟合或无法聚焦,应根据物性统计信息给出合理值。在北京门头沟某地下隧洞开展微重力测量,其布格重力异常整体幅值处于微伽级数量级,最大异常约为探测精度的5倍,可指示出目标大致的平面位置,但其断面面积和埋深较难估计。采用微重力聚焦反演方法对实测异常进行处理,获得与实际相符的隧洞断面面积及埋深信息。因此,聚焦反演可提升微重力方法探测地下空间的成效,具有较好的应用价值。
To address the issue that conventional inversion outcomes in underground space microgravity detection are ambiguous and detrimental to target localization,the microgravity anomaly compact inversion approach was investigated.With the precondition that the target size be minimun,the density contrast between the target and the host rock is incorporated as prior information,and the weighted damping optimization algorithm was employed to achieve the compact inversion of microgravity anomalies.In contrast to conventional results,the compact inversion can delineate the target boundary,which enhances the inversion quality.The impacts of key parameters such as model resolution,signal-to-noise ratio and prior density contrast on the inversion were analyzed,and specific setting methods and suggestions were provided.The synthetic test results indicated that the model resolution matrix determined the sensitivity of the corresponding inversion mesh to the observed data.If the diagonal element of the cell is overly small,the settings should be adjusted.The signal-to-noise ratio exerts a significant influence on the compact performance of the inversion,which can be estimated by means of the power spectrum curve.The prior density contrast has a considerable influence on the accuracy of the inversion results,and an obvious incorrect density difference will lead to the inversion being unable to fit or focus;thus,a reasonable value should be assigned based on physical property statistics.The overall magnitude of the Bouguer gravity anomaly is of the order of micro gal,and the maximum anomaly is approximately 5 times the detection accuracy.It can indicate the planar position of the target,but its cross-sectional area and burial depth are difficult to estimate.The microgravity compact inversion method was utilized to process the measured anomalies,and the cross-sectional area and burial depth of the tunnel were obtained.Consequently,compact inversion can enhance the efficacy of the microgravity method in detecting underground space an
作者
周俊杰
朱鹏飞
高爽
ZHOU Junjie;ZHU Pengfei;GAO Shuang(National Key Laboratory of Uranium Resources Exploration-Mining and Nuclear Remote Sensing,Beijing 100029,China;Beijing Research Institute of Uranium Geology,Beijing 100029,China;CNNC Key Laboratory of Uranium Resources Exploration and Evaluation Technology,Beijing 100029,China)
出处
《世界核地质科学》
CAS
2024年第5期977-987,共11页
World Nuclear Geoscience
基金
中国核工业地质局项目(编号:202346-8)
核工业北京地质研究院青年创新基金项目(编号:物QJ2104)联合资助。
关键词
地下空间
微重力异常
聚焦反演
反演参数
underground space
microgravity anomaly
compact inversion
inversion parameter
