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Multi-stage shear test has been performed using joint specimens of gneiss, granite and shale to investigate the influence of micro-scale asperity change on the shear strength of joint plane. For each shear test asperity degradation characteristics of joint specimens of different joint surface strength have been analyzed by utilizing the optimum asperity parameter which can reflect the sequential asperity degradation. Elevation of joint surface profile has been measured and both the changes of asperity parameters and micro-scale asperity distribution have been investigated. Two distinctive variation modes of cohesion and friction angle have been delineated and major cause of shear strength parameter change has been analyzed by considering the micro-scale asperity angle change resulting from the abrasion, fracturing and regeneration of micro-scale asperities. Effects of micro-scale asperity variation on the joint shear strength have been also investigated.

Shear behavior of joint plane has been investigated considering the magnitude of normal stresses and initial surface roughness. Shear strength of joint plane has been measured by performing the multi-stage shear test in which applied normal stress level has been increased stepwise. Multi-stage shear test within the specified normal stress range has been repeated and two types of strength parameter variation have been observed: type 1 -both cohesion and friction angle decrease, type 2 -cohesion decrease and friction angle increase. Trends of strength parameter variation for the three rock types, gneiss, granite and shale, have been investigated and the influence of initial roughness of joint plane on the sequential shear strength change for the repeated multi-stage shear tests also has been analyzed.

The performance criteria of rockfall protection fence and reliability index were investigated considering characteristic of rockfall energy occurred at 160 cut slopes in national highway. As a result of study on statistic of variables that decide rockfall energy using Monte-Carlo simulation, the degree of slope was normal distribution type, mass of rockfall and height of slope was lognormal distribution type. The rockfall energy follows lognormal distribution because of statistical characteristic of mass of rockfall. The reliability index of rockfall protection fence was 0.678 and the failure probability of was very high as 24.9%. Proposed performance criteria of rockfall protection fence considering the scale of domestic rockfall energy is maximum 500 kJ and the range of reliability index was from 1.028 to 1.956. the failure probability of rockfall protection fence was from 14.8 to 2.5 percent if applying the performance criteria using the reliability index.

In this study, the correlation of evaluation items and safety rating for 104 of large-scale slopes along the general national road was analyzed. And, we proposed the regression model to predict the safety rating using the multiple regressions analysis. As the result, it is shown that the evaluation items of slope angle, rainfall and groundwater have a low correlation with safety rating. Also, the regression model suggested by multiple regression analysis shows high predictive value, and it would be possible to apply if the evaluation items of excavation condition and groundwater

The patents trends registered in korea, the USA, Japan and Europe were analyzed to forecast the direction of R&D for the technology of sediment disaster. As a result of portfolio analysis, the number of patents in Korea have continued to rise, but have been placed behind the other countries. The level of technology of each country was investigated. In the survey technology and sensing technology, the Korean and USA situations were classified as a period of growth, and the Japanese situation was classified as a period of decline. In the control technology and protection technology, Korean situation was classified as a period of growth, and the Japanese situation was classified as a period of decline. As a result of analysis for a direction of R&D using blank technologies, standardization of analysis technologies for mechanism, fusion techniques between ICT and conventional techniques, development of eco-friendly materials and evaluation of structure should be developed by R&D in Korea.

Landslides that occur near residential regions are most commonly a result of shallow slope failure, which takes place as a consequence of heavy rainfall during the monsoon season, causing loss to human life and property. In this study, the characteristics of the volumetric water content (VWC) gradient were analyzed to predict shallow slope failure which was reproduced based on flume experiments performed at various slope conditions. The VWC gradient values were calculated for each measurement position and slope depth. Moreover, the VWC gradient characteristics during the occurrence and nonoccurrence of shallow slope failures were compared to those of an actual site that did not undergo slope failure. Our results show that the probability of failure increases with an increase in the VWC gradient value. Additionally, early warning criteria are proposed by dividing the range of the VWC gradient value into four stages in which the failure rate rapidly increased. Full-scale flume experiments were performed to simulate an actual site in terms of its scale, and the appropriate sensor installation positions were proposed to effectively predict the probability of failure.

This paper describes the Measurement Management Criteria (MMC) of a soil slope failure based on displacement using literature reviews, small-scale experiments, large-scale experiments, and field data. Two types of measurement management criteria were developed, i.e., short-term criteria for slopes under construction or requiring urgent measurements, and long-term criteria for slopes under continuous management. First, the measurement criteria for the short term were determined based on small- and-large scale experiments, and were determined to be “1 mm/min for the watch level,” “4 mm/min for the caution level,” and “21 mm/min for the alert level.” Next, the criteria for the long term were determined through a literature review and field data, and were “2 mm/day for the watch level,” “8 mm/day for the caution level,” and “56 mm/day for the alert level”.