In this study, a series of centrifuge model tests was carried out to study the mechanical behavior of the slope reinforced by a soil nailing method using rock bolts with prestressed facing plate. For that purpose, a centrifuge model test system was developed, in which the preloading process of rock bolts with facing plate in a model slope can be simulated by hoisting jacks in a centrifuge and pseudo static seismic force can be also imposed on the slope by an inclining table. The tests were performed with various preloading forces. Lateral displacements and settlements of the facing plates, lateral displacements of the slope surface and facing stresses were measured during both the preloading process and the inclining tests. It was found that the reinforcement of slopes by the rock bolts with facing plate could effectively prevent deformation and failure. The larger the prestress was, the better the reinforcement effect. However, the effect of prestress increment on the slope stability became smaller as the prestress increased, especially after large deformations occurred. The deformation of the slope was deeper and wider for the reinforcement with smaller prestress, and shallower in limited local areas for the reinforcement with larger prestress.

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Several centrifuge model tests are conducted on the purpose of exploring the failure trend or failure mode of the deposits slope under itself weight and rainfall. Deposits are special geological body between soil and rock which contains the components of complex structures such as soil with gravel, debris and detritus. Because of the looseness of soil structure and the large soil void ratio, the landslide easily takes place in the deposit slope, especially under rainfall. The rainfall during the centrifugal operation is simulated by air-blast atomizer. The slope surface is observed through the real-time monitoring system. The displacement field of the slope section caused by the rainfall is used to reveal the deformation and failure mechanism. Furthermore, it takes into consideration the deposit slope reinforced with slope protection network. The Particle Image Velocimetry method is used to analyze the changes of displacements of deposits slope before and after treatment comparatively. The tests results show that the failure mode of deposits slope is different from the traditional circular slide under middle rainfall conditions, whereas the slope protection methods such as slope protection network plays an important role in reinforcing the deposits slope.

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A series of shaking table model tests using two different size shaking tables was conducted to develop a procedure to evaluate seismic slope stability. It was found from the model tests that the type of slope failure could be categorized into two groups. One is the sliding failure, which could trigger the catastrophic failure of the slope and the other is the progressive deformation mode in which the displacement of the sliding mass of the slope would increase gradually. Based on the model test results, it was attempted in this study to propose an index to evaluate the degree of seismic slope instability. In this study, the normalized sliding displacement was applied as an index to assess the slope instability based on the observation from the shaking table model test. Based on the investigation into the correlation between the failure processes of the model slope and the values of normalized sliding displacement, it was found that the proposed index could be used to evaluate the degree of slope instability by setting the proper threshold value.

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Debris flows caused by heavy rainfall occur along long watersheds and travel at extremely rapid velocity. These debris flows can impact large areas and often cause economic and societal damages. For this reason, barriers against debris flows have been widely constructed. In particular, slit-type barriers are popularly used because of the minimum environmental disturbance. However, the performance of such slit-type barriers is not fully understood. This paper explores roles of spacing and angle of slit-type barriers on velocity reduction of debris flows. The scaled physical modeling experiments were performed to identify reduction of debris velocity and to assess the performance of debris flow barriers. The results indicate that the performance of barriers is heavily affected by spacing between slit-type barriers and angle of barriers from flow direction.

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Some of the geotechnical parameters used in the analysis may not be accurately measured directly from laboratory tests due to effects of sample disturbance and errors of tests. The back analysis or the observational method are thus often applied to determine the representative and/or dominant strength parameters based on field observations in practice. Based on the Hoek-Brown failure criterion, it was known that the disturbance factor (D) should be determined with caution. The difficulty of measuring rock mass disturbance accurately has been shown. Three rock slope failures will be investigated in this paper using back-analysis technique. In addition, various rock mass strength parameters are taken into consideration.

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The aim of this study is to reveal failure mechanisms of volcanic slopes in cold regions and to propose a prediction method on the failures. In order to achieve the purposes, a full-scale embankment slope which was 5 m in height, 3 m in width and 4 m in length and the angle of 45 deg., was constructed in Sapporo city, Japan. A typical volcanic soil in the field was adopted as an engineering material. After the construction of the embankment, the changes in soil moisture, temperature, pore water pressure in the embankment were investigated until slope failure by using several monitoring devices such as soil moisture meters, etc. Simultaneously, a series of model tests was performed on small size slopes constructed by the same soil material as that in the field. As a result, a reasonable prediction method of slope failure was proposed based on change in water content, and its validity was confirmed in the behavior of the full-scale embankment.

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Physical models of undercut slope have been successively studied in order to cope with the mining problem at the Mae Moh open-pit coal mine in Lampang province of Thailand, where the layers of coal working as counterweight along to toe of the slope are excavated without prior removal of unstable rock masses. Previous research has convinced the mechanical idealization by validating with the results of physical models with sufficient reliability for practical designs. However, the effects of faults existing at the actual site have not included in the previous study. Therefore, undercut slope models were improved by inserting faults to the physical model in the present study. This paper focuses on the maximum undercut width of physical models in regard to both symmetrical and unsymmetrical discontinuous planes. Experimental procedures and controlled conditions were clarified including water content and bulk density as well as construction sequences of the modeled slope. The results observed from the experiments were compared with the theoretical idealizations based on the beam failure assumptions and the existing arch failure assumptions which are strip arch with soil slip, segmented arch with stable scarp, and circular arch with upheaval buckling. Formulation of the derived equations for predicting the maximum width were explained and discussed with an aim to identify the factors causing agreement and disagreement with the experimental results.

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