土壤砾石含量的电阻率断层扫描技术应用研究

砾石含量是土壤质量评价与分类的基本参量。但传统的测定采用了随机采样的方法,一些特殊和极端区域的土样难以获得,进而制约了对土壤砾石含量评价的客观性和完整性。本研究基于土壤由细土和砾石二相介质组成的假设,采用了电阻率断层扫描技术,结合该技术对土壤中砾石体积含量的评价,对土壤砾石含量做了系统性研究。结果表明细土样品的电阻率值主要受土壤含水量的影响,容重及有机质含量对其影响较小。土壤砾石体积含量和有效电阻率之间的关系与Bussian's Law模型预测结果相吻合,且细土电阻率值对该关系影响较大。在细土和砾石的电阻率值分别为160Ωm和3000Ωm条件下,对砾石体积含量估算结果的绝对误差为22%。电阻率断层扫描技术提供了土壤学基础研究的重要工具,对其应用的研究将会对土壤学相关研究提供重要的帮助。

Application of Electrical Resistivity Tomography to the Rock Fragments Content Evaluation

Rock fragments content is a fundamental parameter concerning the soil quality evaluation and classification.However,measuring the content of rock fragments in an objective and precise way has been proved difficult for the absence of available methods,which encounter practical problems such as hardness of soil sample and representativeness of sampling points.This paper deals with the application of electrical resistivity tomography to the volumetric rock fragments content estimation.By assuming the soil to be biphasic media with rock fragments embedded in fine earth,rock fragments content can be derived from the effective electrical resistivity of the media by inverting a mixing law.Electrical resistivity of fine earth and rock fragment samples are measured by four-electrode method,and laboratory measurements made on fine earth samples have shown that the electrical resistivity varies primarily with the soil moisture rather than the soil bulk density and the organic matter content.The relationship between the rock fragments content and the electrical resistivity is well modeled by the mixing law,and the electrical resistivity of the fine earth has a strong impact.Considering a single electrical resistivity for fine earth and rock fragment to be 160 Ωm and 3000 Ωm,respectively,we obtain an absolute error for the volumetric rock fragments content of 22%.Electrical resistivity tomography can be an important tool for soil fundamental research and provide some aid for soil related research.