We applied the Time Domain Electro-Magnetic method (TDEM) in site assessment for civil engineering projects, especially tunnel construction. While TDEM method had been used for natural resource exploration thousand of meters below the ground, we appleid this method to accurately resolve the subsurface geoelectric structure between 10 meters and 200 meters below the ground surface. Rock resistivity is related to lithology and hydrogeology, and TDEM resistivity sounding is a valuable geological mapping tool. We will describe the technical report of this method.

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To judge if there exists any cavity by a tapping test is very easy but lacks objectivity. In order to attain more objective results, we have developed a method to judge by inspecting a scalogram (spectrum) of Wavelet transformed signals, rather than auditory evaluation, of recorded sound. With this method, a clear distinction could be made between scalograms of a solid ground and the one with cavities. No special measurement is required with this method. It is only necessary to hit the wall of a structure being surveyed in succession with a hammer, just like an auditory judgment.
The principle and theoretical background of Wavelet Transform, the instrumentation, and the relationship between vibration and sound are explained in this paper. In addition, application tests using real-sized models, basic laboratory experiments of sound generation by hitting and some successful field examples are to be introduced.
These are principal results from our works:
1) This method at present is especially effective against dry or water-saturated grounds. A cavity behind concrete pipe walls could be detected, if it is of considerable size.
2) This method has been applied successfully to underground structures like a power station to examine the quality of cement grouting between the machine housing and its surrounding base rock.
3) Location of cavities and their width (area) could be obtained with this method. As for their thickness (depth), however, decisive conclusion must be postponed until further experiments are conducted.
4) The factory produced pipes, of thickness 30cm or less, are especially favorable for this method. The acoustic response of their wall itself is generally stable due to well-controlled manufacturing, and enables us to recognize abnormal sound clearly, if cavities exist behind the wall.

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The shallow seismic reflection method has been used increasingly since 1980 in applications shallower than a few hundred meters for geotechnical and active fault surveys. The free-fall and accelerated types of weight drop have been used generally as a seismic source, however, it is difficult to operate such sources in urban areas because of damaging to paved roads.
The sweep type source by using a electro-magnetic vibrator has been developed by one of the authors, which is based on the principle of the Vibroseis^® system. This type of seismic source, in which received signal is compressed into a wavelet by cross-correlation with transmitted signal, is characterized by higher S/N ratio, adjustable frequency range and possible operation in urban areas.
The shallow seismic reflection method by using the sweep type source was applied to geotechnical surveys and some faults are detected in urban areas in Kinki district.

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In the field of engineering geology, rock color is described by sensuous manner. In this paperthe relationships between numerical color change of rock which were measured by chronometer and degree of weathering are described. Measured samples are a variety of different geologial ground types (granite, sandstone and felsic volcaniclastic rock).
As the results, the turning of rock color to yellowish-brown with weathering is responsible for progressive accumulation of iron hydroxides into microcracks and pores. And then above process is also related to the change of rate of moisture absorption and absolute dry specific gravity.
It is accounted that the numerical rock color is effective for an accurate and objective evaluation of rock ground.

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This paper begins with a review about geoelectrical monitoring based on subsurface visualization for investigation of geological and geotechnical environments using electrical potential and resistivity data by surface and subsurface electrode array systems, especially deals with consideration of simple predictable models in order to investigate very complex field cases of target or nontarget inhomogeneities.
At first, a watertank experiment with single Cu or plastic plate model has been studied as an aid to new resistivity information processing such as data composition approach, structure shift approach and data density methods by surface four electrode arrangement. Next, single prism sturucture simulation data based on surface and boreholes electrode arrays have been studied by the finite element 2D-3D algorithm in the cases of target and nontarget inhomogeneities. Furthermore, an advanced problem solving methods including electric field monitoring for waste low resistivity leakage has been proposed for the earth resources information engineering and the system predictive design.

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Recently, a digital camera diffuses and is utilized in various fields. The system, that combined the camera and image processing technology in the field of rock tunnels is being utilized to document preparation of face observation and quantitative analysis of face information.
This image processing system was applied to uncomposed mass that uses sixth partition CD-NATM. As a result, labor-saving in a document preparation business was materialized, and the display function of geological change expressed the change activity of geological defective zone, effective measure was enforced by it.
However, it was not able to do evident geological classification with only hue analysis, because a color change of geological defective zone is small in uncomposed mass. Therefore, various image analysis methods were conducted, and the example of the analysis method that matched to an uncomposed mass was shown.

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