碎石泥土混合体介电常数研究及隧洞软弱带FDTD正演

发布时间：2019-03-28 19:19

【摘要】：基于地质雷达方法对深长引水隧洞施工过程中出现的软弱带进行地质超前预报。以软弱带碎石泥土的混合介电常数为研究对象,研究碎石泥土混合体的相对介电常数值及变化趋势,推导含水率与混合介电常数经验公式及关系曲线;通过对2种软弱带的空间分布情形进行FDTD(finite difference time domain)正演,分析其典型成像规律及特征,从而达到以实测数据推算软弱带的空间位置的目的。分析结果为:碎石及泥土混合体的各成分体积比对其混合介电常数影响较大,混合体的水体对电磁波的反射特征明显并更容易形成多次波;通过建立FDTD模型正演对比隧洞内实测数据排除多次波干扰,修正地层含水率取值并建立地层三维切片图,可直观体现地层含水分布位置,从而对类似地质预报工作提供方法和指导。
[Abstract]:Based on the ground penetrating radar (GPR) method, the geological prediction of the weak zone in the construction of deep and long diversion tunnel is carried out. Taking the mixed dielectric constant of crushed stone soil with weak zone as the research object, the relative dielectric constant value and changing trend of crushed stone soil mixture are studied, and the empirical formula and the relation curve between moisture content and mixed dielectric constant are deduced. Based on the FDTD (finite difference time domain) forward modeling of the spatial distribution of the two soft zones, the typical imaging rules and characteristics are analyzed, so as to calculate the spatial position of the soft zone from the measured data. The results show that the volume ratio of the mixture of crushed stone and soil has a great influence on the dielectric constant of the mixture, and the reflection characteristics of the mixed body to the electromagnetic wave are obvious and it is easier to form multiple waves. By setting up FDTD model forward modeling and comparing the measured data in tunnel to eliminate multiple interference, correct the value of formation water cut and set up three-dimensional slice map of formation, the position of formation water-cut distribution can be directly reflected. As a result, the method and guidance for similar geological prediction work are provided.
【作者单位】：西安理工大学岩土工程研究所;空军工程大学工程学院;
【基金】：国家自然科学基金资助项目(51179153)
【分类号】：U452.1

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