• Journal of the Korean GEO-environmental Society
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• v.23 no.2
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• pp.25-36
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• 2022

In this study, seepage control effect of relief well was evaluated quantitatively on embankment of small fill dam and levee. Seepage analysis of dam and levee were carried out according to the permeability of fill material and foundation and to analyze behaviour characteristics of seepage. The up-lift pressure at toe of embankment was analyzed which is generated by seepage according to relief well installation condition. The relief well could reduce pore water pressure which is to cause piping or up-lift pressure at foundation ground of embankment and it does not be influenced on geometric condition such as dam height and slope incline. In case of relative low permeable ground, the pore water pressure reduction effect of relief well was decreased compare with high permeable ground but it shows pore water pressure reduction effect compare with no relief well condition. The reduction effect of relief well shows relative gap according to diameter and penetration length of relief well and the installation length of relief well is the most effective factor for seepage control.

• Journal of the Korean earth science society
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• v.42 no.2
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• pp.164-174
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• 2021

The study examines the shearing and crushing characteristics of land-derived subaqueous granular materials in a gravel-bed river. A series of large-sized ring shear tests were performed to examine the effect of shear time and shear velocity on the shear stress characteristics of aquarium gravels with a 6-mm mean grain size. Three different shear velocities (i.e., 0.01, 0.1, and 1 mm/sec) were applied to measure the shear stress under the drained (long-term shearing) and undrained (short-term shearing) conditions. Different initial shear velocities, i.e., 0.01→0.1→1 mm/sec and 0.1→0.01→1 mm/sec, were considered in this study. The test results show that the grain crushing effect is significant regardless of drainage conditions. The shear stress of coarse-grained materials is influenced by initial shear velocities, regardless of the drainage conditions. In particular, particle breakage increases as grain size increases. The shearing time and initial shear velocity are the primary influencing factors determining the shear stress of gravels. The granular materials may be broken easily into particles through frictional resistance, such as abrasion, interlocking and fracture due to the particle-particle interaction, resulting in the high mobility of granular materials in a subaqueous environment.

• Journal of the Korean Professional Engineers Association
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• v.28 no.4
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• pp.54-75
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• 1995

This synthesis has been prepared from a review of literature on Truck Escape Ramps technology and a survey of current practice by state department of transportation. Their locations have been determined usually from a combination of accident experience and en-gineering judgement, but new tools are emerging that can identify needs and sites without waiting for catastrophic accidents to happen. The Grade Severity Rating Systems holds promise in this regard. Design Procedures for truck excape ramps continue to evolve. Gravel arrester beds are clearly the preferred choice across the country Rounded aggregate, uniformly graded in the approximate size range of 13 to 18mm. Tech-nical publications typically have dassified TER types as paved gravity, sandpile, and ar-rester bed ramps. The design speed for vehicle entry into the ramp in critical to the deter-mination of ramp length. An escape ramp should be designed for a minimum entry speed of 130km/hr, a 145km/hr design being preferred. The ramps should be straight and their angle to the roadway align-ment should be as possible. The grade of truck escape ramps show the adjustment of ramp design to local topography, such as the tradeoff of ramp length against earthwork requirements. A width of 9 to 12m would more safety acommodate two or more outof con-trol vehicles. Reguarding comments on the most effective material, most respondents cited their own specification or referred to single graded, rounded pea gravel. The consensus essentially Is that single graded, well -rounded gravel is the most desirable material for use in arrester beds. The arrester beds should be constructed with a minimum aggregate depth of 30cm. Successful ramps have used depths between 30 and 90cm.

• Journal of the Korean GEO-environmental Society
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• v.22 no.6
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• pp.17-26
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• 2021

Ground investigation and result analysis generally used to examine all sorts of structures' subsidence or stability can be classified into sandy soil and cohesive soil, and analysis on the liquid limit of soil is utilized to evaluate the physical properties of ground and types or technical behavior of soil. The most widely used method to analyze liquid limit is Casagrande with which liquid limit can be calculated relatively easily; however, it is fairly difficult to apply it to soil equipped with intermediate properties. Therefore, concerning the properties of soil having the intermediate properties of sedimentary ground, this researcher mixed the clay from Yangsan, Gwangyang, and Busan with sandy soil to make intermediate soil and then carried out the test of consistency limit and also evaluated applicability by using the suggested formula of consistency revision. The sample of intermediate soil was the mixture of clay and sandy soil, and to produce intermediate soil, the content (F_c) of fine soil was applied as 50%, 75%, or 100%. Regarding the physical properties of intermediate soil, to maintain the properties of clay in the natural state, bentonite was added at a fixed rate for controlling the properties of clay, and then, consistency was analyzed. By adopting the formula of consistency revision suggested in advanced research, this author analyzed consistency based on the experiment and consistency based on the suggested formula of revision. Also, about intermediate soil collected at the site, consistency based on the experiment and consistency based on the suggested formula of revision were analyzed comparatively, and about intermediate soil collected, this researcher analyzed particle size and calculated the content (F_c) of fine soil to analyze intermediate soil in diverse conditions. Moreover, about intermediate soil collected at the site, the suggested formula of consistency revision was applied to calculate the compression index, and the compression index based on the experiment and the compression index based on the suggested formula were analyzed comparatively to evaluate the applicability of the suggested formula.