Estimation of Physical Properties of Reclaimed Ground with coal ash using Resistivity, IP, and Micro-gravity Surveys

摘要

It has been conventionally difficult to estimate the physical properties of inhomogeneous grounds such as the reclaimed ground that consists of several kinds of coal ash by means of geophysical surveys. By laboratory test using artificial samples, we confirmed that resistivity of the ground was related to saturation. We also confirmed that IP was measured at the ground composed of much ignition loss rate. Physical tests of the samples showed that porosity and water content were related to unconfined compressive strength due to ignition loss rate. Based on these relationships, we demonstrate a flowchart to derive physical properties by combining resistivity, IP and micro-gravity survey data. Then, we have carried out these surveys in a area of 62 m X 30 m at a reclaimed site with coal ash, which contains two areas reclaimed by different operation methods. To estimate conductivity of pore water, specific gravity, and water content, several samples were collected from the survey area. We calculate water-saturation, porosity, and compressive strength profiles in the survey area using the flowchart. As a result, we can classify two reclaimed areas by these physical profiles. The compressive strength profiles roughly matched the dynamic strength estimated from N-values by the penetration tests within the area. These profiles can help us to estimate the distribution of compressive strength for reclaimed grounds.