Atsuo Takeuchi

Displacement Monitoring and Physical Exploration on the Shuping Landslide Reactivated by Impoundment of the Three Gorges Reservoir, China

The Three Gorges Dam construction on the Yangtze River in China is the largest hydro-electricity project in the world. After the first impoundment in June 2003, many landslides occurred or reactivated. Shuping landslide is one of the most active landslides among them. In this paper, the deformation of the Shuping landslide monitored by GPS, extensometers, and crack measurements are summarized. Also, for the investigation of the groundwater situation, 1 m depth ground temperature measurement was conducted, and the groundwater veins were estimated. Based on the monitoring data and exploration results, a deformation model of the landslide caused by impoundment of reservoir was proposed.

On the Significance of Temperature Logging in Horizontal Drainage Bore Holes

Ground water drainage works by horizontal bore holes occupies very important position in landslide preventive works. And a large sum of expense is required for carrying out this works. Nevertheless, it is very grave problem that ground water does not drain from some horizontal drainage bore holes in the rainy season.Temperature logging was carried out in some horizontal drainage bore holes as an effective means for investigating the cause of this problem. This logging is recognized as very effective means for detecting flowing ground water strata in vertical bore holes.As a result of these investigation, next matter are cleared:1) By means of comparing with normal ground temperature curve taking account of thickness of soil layer and obtained temperature curve in situ, we can obtain some significant information on places of flowing and leaking positions of ground water in horizontal drainage bore hole.2) Furthermore, we can obtain useful data which are able to discuss that the horizontal drainage bore hole carried out temperature logging is exist in ground water vein stream or not.The last of in this paper, we propose some improvable measures on the basis of the result of investigation in this time.

On the Availability of Investigation of Old-river Channels by Using Underground Temperature Survey

Electrical Resistivity survey has been carried out hitherto in order to find out places being easy to flow ground water in an old-river channel. According to the interpretation of the results, all of high resistivity zones have had to be regarded as places being easy to flow ground water. Therefore we had to consider very wide zone as flowing ground water with unsatisfactory. Accordingly, the survey method was not so desirable in the case of considering a concrete counterplan for conservation of banks. It was necessary to improve such a condition.We adopted a new method “Investigation Method by Measuring Underground Temperature” in order to detect places being easy to flow ground water in a old-river channel which had possibility to have bad influence on banks. It was shown the some abnormal temperature parts existed in the high resistivity zone by the results of the new method. In this fact, it is elucidated that places being easy to flow ground water is detected more accurately by carrying out the underground temperature survey than by carrying out the electrical resistivity survey.Some bore holes were dug in each parts of an abnormal temperature part and a normal temperature part in a same high resistivity zone with the object of inspecting this point, and a few test which were concerned with ground-water (observation of ground-water level, temperature logging, different temperature logging, and pumping test) were carried out by using these bore holes. By the results of these test, we could recognized clearly flowing ground water in an abnormal temperature part, but could not recognized flowing ground water in a normal temperature part in the same high resistivity zone.As mentioned above, we estimated that the investigation method by measuring underground temperature was better than the electrical resistivity survey method in order to detect places being easy to flow ground water in old-river channels.

On the Possibility of Judging the Effectiveness of Groundwater Drainage Works by Measuring One-meter-depth Temperature

Investigating method of one-meter-meter-depth temperature measurment was carried out in the Oh-ishi landslide area belonging to the metamorphic rocks zone for the first time in February 1980. On the basis of the results, groundwater drainage works were carried out. In this time, the investigating method was carried out again in the same area in February 1983 for examining the reproducibility of temperature distribution and the introduced variation by groundwater drainage works.As the results, next matters were shown:1) The reproducibility of the temperature distribution was recongnized clearly in a landslide area belonging to the metamorphic rocks zone.2) The effectiveness of groundwater drainage works was recognized satisfactorily by the observed results of groundwater level and the quantity of drainage in groundwater-vein streams.3) The possibility of judging the effectiveness of groundwater drainage works was shown by comparingwith the φz=1-y diagrams and the distributing diagrams of underground temperature before and aftergroundwater drainage works.

On the Possibility of One-meter-depth Temperature Survey in Indonesia Jawa and Taiwan

The possibility of application of one-meter-depth temperature measurement for investigating groundwater vein streams in Jawa and Taiwan was examined by measuring one-meter-depth temperature and temperature of flowing groundwater in some landslide areas in both countries on April 1982.As a result of this investigation, next matter are shown:1) Normal one-meter-depth temperature (θu) and temperature of flowing groundwater (θw) are influenced by elevation and latitude in Japan, but both temperature in Jawa and Taiwan are influenced only by ele vation of each investiaated area. The relation between θu and θw was shown in Table-3.2) Converted values into elevation of zero meter of θu are 29.8°C in Jawa and 25.3°C in Taiwan and the values of θw are 26.3°C in Jawa and 22.6°C in Taiwan. These values in both countries are very higher than those in Japan. θu and θw in both countries lower 0.5°C per 100 meters. This fall rate is a little lager than that of Japan on April (0.45°C/100m).3) Difference between θu and θw is 2.7-4.2°C in Jawa and 0.9-3.5°C in Taiwan in this investgating time. Application of investigation by measuring of one-meter-depth temperature is possible in every landslide areas in J awa, but this application is not possible in a part in Taiwan.4) The effectiveness of this investigating methode was shown at Cianjur Seratan in Jawa and Jiau Lin Pyng and Lung Tan in Taiwan (Figs. 8 and 9).

On the Result of the Investigation of Groundwater-vein Streams by Measuring One-meter-depth Underground Temperature in Winter Season in the Fractured-zone Type Landslide Areas

Effectivity and the practical use have been hitherto indicated mainly in the Tertiary type landslide areas using the method of investigating groundwater-vein streams by measuring one-meter-depth underground temperature, which was carried out in the Oh-ishi landslide area, one of the fractured zone type landslide areas as the test location.The existence of the groundwater-vein streams presumed has been confirmed by the groundwater-flowing-trata logging, vertical temperature logging and the quantity of drainage from horizontal bore holes, etc., and it was demonstrated that this method was possible to be applied enough in the fractured zone type landslide areas, too. As compared this surveys result with that of the electrical resistivity survey, the former was also cleared to give us more profitable information than those of the latter, concerning the shallowdepth-flowing groundwater.

On the Investigation of Ground-water Veins in the Marumi Landslide by Underground Temperature Survey at One Meter Depth

竹 内 篤 雄*・ 島 通 保* Atsuo TAKEUCHI Michiyasu SHIMA Abstract Underground temperature survey at one meter depth was conducted at the Marumi landslide area in Hyohgo Prefecture with the purpose of investigating the flowing channels of the waters Parts of low temperature probably caused by the flow of ground-water were determined after the effect of various factors have been taken off from the obtained data. As the result of the investigation, it was found that there were three zones of the low temperature mainly in the investigated area. We examined the means of those zones with aid of the distribution of vertical temperature in bore-holes drilled in this area and the water temperature in flowing layer. As the result of the examination, it was assumed that those three zones were the place that the usual ground temperature at one meter depth was lowered by the effect of the flowing ground-water.

Drainage Works on the Basis of the Result of Underground Temperature Survey at One Meter Depth and its Effectiveness in the Miyagami Landslide Area

In order to estimate the location fveins of ground-water, udergroud temperature survey at one meter depth was conducted at the Miyagami land slide area in Hyogo Prefecture. On the basis of he result of the survey, four water-collecting wells were constructed inand aroud the vein (shown Fig.4). The Effectiveness of these work, was examined by the results ofthe observation fground-water level of nineteen bore holes in the land slide area-from 1973 to 1977. The following important results could be drawn from the investigations. 1. Alarge quantity of water which cu be collected by dramage works exist in the vein of groud-water estimated by the survey. 2.A small water was observed in the well constructed outside the vein, but a large quantity of gushing wate was observed when some draining bore holes were made toward the vein from the well. On the other hand, the works of the well through the vein was troubied with gushing water and extfusion of soil during construction. 3. The water-level of some bore holes digged in the vein falled remarkably in comparison with other bore holes

On the Specific Upheaval Phenomenon at the Tip Part of the Landslide Area(1)

Upheaval phenomenon at the tip part of landslide is not so rare. But the upheaval at the opposite side of the river which runs at the tip part of landslide seems to suggest the factor of cause of the landslide.Accordingly, for the purpose of making clear the phenomenon, the study was carried out.In beginning, the electric survey was carried out at some landslide areas which had the specific upheaval phenomenon.As the result of the investigation, the next facts were revealed:(1) In some cases, the difference of the apparent resistivity between the upheaval area and the non upheaval area was caused by the occurence time of the upheaval phenomenon.(2) In other cases, the difference of the apparent resistivity between the upheaval area and the non upheaval area was caused by the geological factor.