• Journal of the Korean GEO-environmental Society
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• v.17 no.2
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• pp.41-49
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• 2016

This paper evaluates the interface shear strength of HDPE textured geomembrane. The interface shear strength between textured geomembrane and marl, and textured geomembrane and woven geotextile were measured; and the smooth geomembrane was used to evaluate the effect of "texture" on the interface shear strength. The interface shear strength was measured using a large direct shear testing device under several conditions including the presence of water, and the normal stresses that were 12, 24, 45, 100, 500, and 1,000 kPa. From testing results, it was found that there was meaningful reduction in the interface shear strength in the presence of water, but the effect of normal stress was not clear. The interface shear strength was measured to be significantly different for smooth geomembrane, whose strength was measured to be as small as half that of the textured geomembrane.

• Proceedings of the Korean Geotechical Society Conference
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• 2002.10a
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• pp.213-227
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• 2002

절토사면의 붕괴원인은 토질 및 지질조건, 지형, 강우, 지하수 및 지표수, 사면형상, 굴착 및 발파와 같은 인위적인 조건, 사면보호공 등과 같이 다양한 영향이 있을 수 있으나 가장 많은 영향을 주는 원인으로 토질 및 지질적인 조건이라고 할 수 있다. 본 논문은 이러한 지질조건에서 붕괴가 발생될 경우의 활동면에 대한 전단강도 추정하는 방법에 있어 역해석법에 의한 활동면의 전단강도 추정을 연구하였다 연구결과 붕괴된 사면에서 화성암은 마찰각 20$^{\circ}$~30$^{\circ}$, 점착력 0~2t/$m^2$의 범위를 가지며 퇴적암에서는 마찰각 $10^{\circ}$~17$^{\circ}$, 점착력 0~2.5t/$m^2$의 범위, 변성암에서는 마찰각 $10^{\circ}$~40$^{\circ}$, 점착력 0~4.0t/$m^2$의 범위가 우세한 것으로 나타났다. 그리고 지질구별 구분에 의하면, 절리에 의해 붕괴가 발생된 경우에는 마찰각 30$^{\circ}$~40$^{\circ}$, 점착력 0~3.5t/$m^2$, 엽리면은 마찰각 30$^{\circ}$~35$^{\circ}$, 점착력 0.5~3.0t/$m^2$, 단층면은 마찰각 11$^{\circ}$~38$^{\circ}$, 점착력 0~3.0t/$m^2$, 층리면은 마찰각 $10^{\circ}$~17$^{\circ}$, 점착력 0~2.5t/$m^2$ 정도의 범위를 갖는 것으로 나타났다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.31 no.6
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• pp.315-329
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• 2018

Recently, RC transfer slab systems have been used widely to construct high-rise wall-type apartments for securing parking space or public space. However, it is problem that the design method and structural performance evaluation method developed for thin RC flat slab are still used in the design of the transfer slab whose thickness is very thick and therefore structural behavior is expected to be different from RC flat slab. Thus, for the rational design of the transfer slab, the ultimate shear behavior of the RC transfer slab system is required to be analyzed properly. Accordingly, in the present study, the two-way shear behavior of the transfer slab was analyzed using nonlinear FEM according to various design parameters such as thickness of the transfer slab, strength of concrete, shear span ratio, and reinforcement ratio. In addition, the two-way shear strength evaluations of RC transfer slab by the existing evaluation methods were verified by comparing those with the results of nonlinear FEM analysis.

• Tunnel and Underground Space
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• v.13 no.3
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• pp.169-179
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• 2003

Anisotropic shear strength of rock joints is studied based on the artificially fractured specimens using experimental and analytical methods. Series of direct shear tests are performed to obtain the strength, stiffness and friction angle of joints under various low normal stresses and shearing directions. The results of shear strength and stiffness show anisotropic value according to shearing direction under low normal stress specially less than 2.45 MPa. But, the effect of joint roughness on strength decreases with increasing normal stress. To estimate more effectively the peak shear strength under low normal stress, the modified Barton's equation is suggested.

• Tunnel and Underground Space
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• v.23 no.3
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• pp.203-211
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• 2013

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.

• Journal of the Korean Geotechnical Society
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• v.18 no.4
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• pp.229-238
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• 2002

This paper introduces the surface roughness parameter, Rs to the characterization of joint roughness and quantitatively illustrates the influence of joint roughness on the joint shear strength. A new peak shear strength criterion for rock joints using Rs is suggested. The results show that the surface roughness parameter, Rs can appropriately reflect the degree of roughness for the rock joint surfaces tested in this study A measuring interval of 2mm and profile length of 5cm can be used to characterize the joint roughness of the rock core size surfaces; however, the scale of fluctuation, $\delta_\alpha$ should be considered to extend the surface roughness parameter, Rs to the large-scale field rock joint surfaces. For the smooth joint roughness, sliding of the rock cores is the principal shear mechanism; however, the breakage of roughness from the rock cores is inferred for rougher joint roughness.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.33 no.2
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• pp.103-111
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• 2020

Recently, the use of transfer slab system has increased greatly. However, several construction problems are being encountered owing to its excessive thickness. Therefore, in this study, a transfer slab system that uses a reverse drop panel, which can utilize the facility space of the pit floor by reducing the transfer slab thickness, was considered. To investigate the shear behavior of transfer slab system that uses the reverse drop panel, the two-way shear strength of transfer slab-column connection with the reverse drop panel was analyzed using nonlinear FE analysis. In addition, the two-way shear strength evaluations of transfer slab with the reverse drop panel conducted using the existing evaluation methods were verified by comparing the strengths predicted by those methods with the results of nonlinear FE analysis.

• Journal of Korean Tunnelling and Underground Space Association
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• v.14 no.4
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• pp.321-336
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• 2012

The shear behavior at the particle/surface interface such as rock joint can determine the mechanical behavior of whole structure. Therefore, a fundamental understanding of the mechanisms governing its behavior and accurately estimation of the interface strength is essential. In this paper, PFC, a numerical analysis program of discrete element method was used to investigate the effects of the surface roughness crushing on interface strength. The surface roughness was characterized by smooth, intermediate, and rough surface, respectively. Particle shape was classified into one ball model of circular shape and 3 ball model of triangular shape. The surface shape was modelled by wall model of non-crushing surface and ball model of crushing surface. The results showed that as the bonding strength of ball model decreases, lower interface strength is induced. After the surface roughness crushing was occurred, the interface strength tended to converge and higher bonding strength induced lower surface roughness crushing. Higher friction angle was induced in wall model and higher surface roughness induced the higher friction angle. From these findings, it is verified that the surface roughness and surface roughness crushing effect on the particle/surface interface shear behavior.

• Magazine of the Korea Concrete Institute
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• v.6 no.4
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• pp.161-168
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• 1994

Half-P.C. slab system is the composite structural system which utilizes precast concrete for lower portion and cast in situ concrete for upper portion slab. When the composite slab using Half P.C. slab is deformed by flexural moment, horizontal shear happened at the interface between Half P.C. slab and topping concrete. To resist horizontal shear strength a scratch method has tried. To determine ultimate interface shear strength, shear stress, and shear coefficient, high and normal strength concrete are used for topping concrete. Major variables are compressive strength of topping concrete with or without shear reinforcement, quantitative roughness of the P.C. :surface and tie or untie of the stud with welded deformed wire fabric in the P.C. member. The Icross sectional area on joints is 3,200 $cm^2$ in all specimens. Test results showed that shear stress increased, as the depth of the quantitative roughness increased. The horizontal shear strength could be resisted with safe by the quantitative roughness without shear tie. A shear coefficient determinant equation is proposed such that K = 0.025918 + 0.0068894$\cdot$R – 0.000182354${\cdot}R^2$

• Journal of the Korean Geotechnical Society
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• v.23 no.10
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• pp.65-72
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• 2007

Large-scale direct shear tests were conducted in order to investigate both the shear strength of soil itself and the friction behavior at the interface of soil/geosynthetics in respect of efficiency in this study. Sand, crushed stone and three types of geotextile (i.e. one woven geotextile and two nonwoven geotextiles) were used in the experimental program. The considered interfaces for the evaluation of interface shear strength in this study included sand/sand, crushed stone/crushed stone, sand/woven geotextile, crushed stone/woven geotextile, crushed stone/nonwoven geotextile-A and crushed stone/nonwoven geotextile-B. The results showed that the efficiency of 84% was obtained at the interface of sand/woven geotextile compared with the shear strength of sand itself (i.e. sand/sand interface). The efficiencies of 74%, 83% and 72% were obtained at the interface of crushed stone/nonwoven geotextile-A, crushed stone/nonwoven geotextile-B and crushed stone/woven geotextile, respectively compared with the shear strength of crushed stone itself (i.e. crushed stone/crushed stone interface).