Geosynthetic clay liner (GCL) is an impervious liner for the construction of a dam body. It consists of bentonite encapsulated between woven and non-woven geotextiles, which are needle-punched. This method constructs a widening of an embankment to a precast embankment that was laid with a GCL. However, its detailed construction, the internal shear strength of the GCL, and the shear strength between the GCL and the dam body soil have not been reported. In this study, a direct box shear test was carried out to clarify the shear strength of bentonite, the boundary between the bentonite and geotextiles, and the boundary between the dam body soil and geotextiles. In this study, the dam body soil was decomposed granite soil. In addition, this study was carried out to evaluate the stability state of the dam body that employs a GCL. The main conclusions are as follows: 1) a bentonite that swelled uniformly and a bentonite laminated sealing sheet had almost the same shear strength; 2) the shear strength characteristic between soil and geotextiles varies by the type of soil or water content; and 3) the maximum safety factor is the boundary between the decomposed granite soil and GCL, and the minimum safety factor is the boundary between the bentonite and the geotextiles.

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The work presents the results of studies of the deformed state of the dam of a new construction, with a slope of layered anisotropic structure, which consists from local geomaterials and geogrids filled with local soils and geotextiles.

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In Akita region along the northwest coast of Japan, about fifty tons of salt per kilometre of the highway is used to prevent the snow on the road surface from freezing every year. Reported in this paper is the estimate of the salt contamination in paddy fields adjacent to Akita Expressway. The speed of the travelling diffusion front of the possible saline ground water was estimated as low as 2 mm/year. In the paper, we also review the current operation of Akita Expressway in terms of snow removal and freeze prevention during the winter season.

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Water level fluctuation during dry and monsoon seasons might be the cause of river embankment condition changing. The insitu soil properties exhibits different behavior among these seasons, such as soil density, soil shear strength and soil suction. This paper is mainly the comparison between the Bengawan Solo river embankment's initial state and insitu conditions at Kanor village section, Bojonegoro, East Java, Indonesia. Furthermore, the field investigations at upper and lower embankment were conducted to obtain the insitu soil properties (dry density, shear strength and suction) during dry and monsoon season. In addition, soil sampling was also performed for laboratory investigation. The laboratory investigations were carried out to understand the initial fresh compacted soil (standard Proctor test) condition and to obtain soil properties. The results showed that the upper and lower insitu density condition were affected by the water level fluctuation. The upper and lower sections upon water fluctuation were found to be around 65-85 % and 60-80 % of the optimum Proctor. The soil suction was found to be greatly higher comparing to the soil shear strength during the dry season. Moreover the cracks was developed in upper embankment rather than in lower section embankment.

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As the age of waste changes, the strength of the waste varies during the service years of the landfill. On base of the upper bound limit analysis theorem, two mechanisms for stability analysis of landfills layered by aging are presented in this paper. The rotational-translational mechanism is generalized to analyze the multi-layer municipal solid waste (MSW) landfill slope. The other failure mechanism is comprised of irregular blocks undergoing translational movements. To examine the two mechanisms, the cases of a soil slope layered horizontally and a landfill slope layered by aging are taken into consideration in the case studies. In comparison with the results from the shear strength reduction finite element method (SSRFEM), it demonstrates that the validity of the two mechanisms in the stability analysis of landfill slope cases considering the aging of landfills. In addition, the stability of the Coll Cardús in Spain with complex layers by aging is analyzed, and the results are also compared with those from the SSRFEM.

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Soil erosion resistance is an important engineering parameter to assess scouring processes at bridge piers. Among other many methods for estimating erosion rate of soils, such as the hole erosion test and the submerged jet erosion test, the SRICOS-EFA (scour rate in cohesive soil-erosion function apparatus) method is often used to estimate soil erodibility in laboratory. This method measures the time taken to erode and remove a 1-mm-thick soil layer when the surface of a soil specimen is exposed to water flow with a constant flow rate. However, determining this duration time taken for the 1 mm erosion depth is a challenging task, causing measurement errors. This study explores the feasibility of implementation of a P-wave monitoring technique to more accurately determine the erosion time. P-wave monitoring results during the SRICOS-EFA erosion test were presented and the erosion rates obtained by a conventional method and by our new proposed technique were compared. By monitoring the arrival time of reflected P-waves, the changes in the depth of the soil surface during erosion process were precisely estimated. It revealed that this P-wave monitoring method provided more accurate measurement of the erosion rate.

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Two multi-storied occupied apartment buildings and a clinic of ‘ Red-Cross Society’ in Chandernagore-a former French colony, located very close to the banks of tidal river ‘ Hooghly’ (-the southernmost part of River Ganges- the major hydrodynamic system that formed the world's largest delta) are standing precariously, following some recurrent slides of high river-bank during the last year’s monsoons. The area where the ground caved in, is on the end of the famous Strand Bank Road (in Hooghly district of West Bengal in India); which is supposed to be the best decorated bank of the river ‘ Ganges’ along its entire length of 2500 km. The opposite river bank is an official sand mining site. The river over considerable stretch at both upstream and downstream apparently seemed stable when analyzed over an extensive temporal domain from old Survey of India toposheets, recent satellite imagery, digital elevation model, field hydrographical survey synthesized in Geographical Information System (GIS) platform. A closer look into the geotechnical aspects supported by subsurface exploration, post failure on-site exposures and stability analysis revealed certain startling facts when considered in association with the hydro-meteorological factors and fluvial dynamics. An in-depth study of the factors responsible for the localized erosion is presented based on site observations and evidences, analyzed in association with real time hydrological and meteorological data.

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