This paper discusses the applications of Finite Element Method on the basis of the elasto-viscoplastic model to landslide problems. Fluidity parameter “γ” is determined from the examinations of the analytical value in comparison with the observed data. Some results from this paper can be summed up as follows.
1) It can be inferred that the fluidity parameter “γ” of landslide area-A is 1×10^-5 (day^-1).
2) The effect of dewatering method in landslide area-C were proved by the above numerical method.
3) Using the above numerical model, it may be possible to make predictions on the future trend of deformation and time.

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We examine a prediction method of groundwater table fluctuations in landslide area by neural networks, through the data obtained from the Kuchisakamoto landslide, Shizuoka prefecture, for the purpose of making to be sure the properties of these methods. Obtained results are as follows.
1) We clarify that the groundwater table on the day before prediction day must be considered, through studies of some parameters needed in prediction of groundwater table fluctuations using statistical model.
2) We confirme that neural networks are efficient methods to grasp the character of non-liner functions, that “neural-net” is efficient method in case of enough teaching-data, and that “fuzzy-inference” is available method in case of not enough teaching-data, through the examination of numerical experimentation.
3) We show that considering of relation pattern between rainfall and groundwater table taking into the calculation is more efficient.

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Two different up-hole methods are proposed for measuring the wave propagations generated by the standard penetration test to investigate the shear wave velocity. The results are compared with the conventional PS logging test (down-hole method) to evaluate the reliability of the shear wave velocity measured by the up-hole methods. As a result, comparison of both shear wave velocity shows good agreement. Therefore, the shear wave velocity generated by the standard penetration test is found to be reasonable in engineering practice.

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The coast from the Ainuma to Toyohama, southern Hokkaido, is characterized by the following three landslides; Toyohama Slide on Oct. 17, 1962; Orito Slide on Dec. 20, 1985, and Tachimachi-misaki Slide on Aug. 9, 1991. Our research observations and analyses have revealed that the Orito Slide and Tachimachimisaki Slide are primary dip-slipping deep seated slides due to geological and geomorphic structures, such as gentle-dipping of hard siltstones intercalating clayey tuffs acting as slip-surfaces. While, the Toyohama Slide is secondary slipping from the debris toe of an ancient slide. The Tachimachi-misaki Slide and Toyohama Slide were also caused by long-term slope instabilization. Finally, the three slides were probably triggered by precursory and considerable durational precipitations, which possibly upheaved groundwater level in the sliding slopes.

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After the legislation of Landslide-Prevention-Law in 1958, the landslide prevention technique has somehow been enhanced to the scientific level. Although it has a history of only a few decades, it has been given the assured status as a field of civil engineering.
This achievement is a result of the great efforts put forth by its pioneers, whom for years, had been fighting against landslide disasters which threatened the inhabitants.
The author tried to trace back the history of the pioneers' efforts and the development of the landslide prevention technique. In this paper (1), the history from the dawn to the end of World War II will be described.

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