• Title/Summary/Keyword: direct shear strength

Search Result 409, Processing Time 0.024 seconds

Sand-Nonwoven geotextile interfaces shear strength by direct shear and simple shear tests

  • Vieira, Castorina Silva;Lopes, Maria de Lurdes;Caldeira, Laura
    • Geomechanics and Engineering
    • /
    • v.9 no.5
    • /
    • pp.601-618
    • /
    • 2015
  • Soil-reinforcement interaction mechanism is an important issue in the design of geosynthetic reinforced soil structures. This mechanism depends on the soil properties, reinforcement characteristics and interaction between these two elements (soil and reinforcement). In this work the shear strength of sand/geotextile interfaces were characterized through direct and simple shear tests. The direct shear tests were performed on a conventional direct shear device and on a large scale direct shear apparatus. Unreinforced sand and one layer reinforced sand specimens were characterized trough simple shear tests. The interfaces shear strength achieved with the large scale direct shear device were slightly larger than those obtained with the conventional direct shear apparatus. Notwithstanding the differences between the shear strength characterization through simple shear and direct shear tests, it was concluded that the shear strength of one layer reinforced sand is similar to the sand/geotextile interface direct shear strength.

Shear strength behaviour of coral gravelly sand subjected to monotonic and cyclic loading

  • Vu, Anh-Tuan
    • Geomechanics and Engineering
    • /
    • v.25 no.2
    • /
    • pp.89-98
    • /
    • 2021
  • The paper presents an experimental study on the strength behaviour of a coral gravelly sand from Vietnam subjected to monotonic and cyclic loading. A series of direct shear tests were carried out to investigate the shear strength behaviour and the factors affecting the shear strength of the sand such as relative density, cyclic load, amplitude of the cyclic load and loading rate. The study results indicate that the shear strength parameters of the coral gravelly sand include not only internal friction angle but also apparent cohesion. These parameters vary with the relative density, cyclic load, the amplitude of the cyclic load and loading rate. The shear strength increases with the increase of the relative density. The shear strength increases after subjecting to cyclic loading. The amplitude of the cyclic load affects the shear strength of coral gravelly sand, the shear strength increases as the amplitude of the cyclic load increases. The loading rate has insignificantly effect on the shear strength of the coral gravelly sand.

Direct Shear Test of Retrofit Anchors Using Deformed Reinforcement and Adhesive

  • Choi, Dong-Uk;Kim, Yong-Gon
    • KCI Concrete Journal
    • /
    • v.12 no.1
    • /
    • pp.91-99
    • /
    • 2000
  • A new type of retrof=t anchor bolt that uses deformed reinforcing bars and a commercial adhesive was developed and then an experimental study was carried out to determine the behavior of the anchors in direct shear. The steel-to-concl몫ete interface was tested. Plain concrete slabs with about 20-MPa compressive strength were used for 23 direct shear tests performed Test variables were anchor diameters (D16, D22. and D29) and edge effect. Three different shear tests were completed: simple shear, edge shear where anchors were pulled against the concrete core, and edge shear where anchors were pushed against the concrete cover In the simple and the edge shear tests where the anchors were pulled against the core, the theoretical dowel strength determined by (equation omitted) was achieved but with relatively large displacements. The shear resistances increased with the increasing displacements. In the edge shear test where the anchors were pushrd against the cover, the peak shear strengths signif=cantly lower than the theoretical dowel strength were determined due to cracks developed in concrete when the edge distance was 80 mm. The peak strengths were about 50% of the dowel strength for Dl6 bar. and about 25% or less of the dowel strength for D22 and D29 bars. Test results revealed that the edge shear where the anchor was pushed against the cover controled.

  • PDF

Direct Shear Test of Undisturbed Weathered Residual Soils (불교란 풍화잔적토의 직접전단시험)

  • 오세붕;이영휘;정종혁
    • Proceedings of the Korean Geotechical Society Conference
    • /
    • 1999.03a
    • /
    • pp.423-430
    • /
    • 1999
  • A weathered residual soil is a soil-like material derived from the in situ weathering and decomposition of rock which has not been transported from its original location. Undisturbed sampling of residual soils is extremely difficult, which has an important effect on investigating the strength and compression characteristics. Thus, a special undisturbed sampling device (direct shear box with shoe) was developed and undisturbed samples were successfully obtained for direct shear tests, Direct shear testing was conducted under unsoaked and soaked condition. As a result, the shear strength of soaked samples was less than that of unsoaked samples, and it was verified that direct shearing of undisturbed samples can evaluate reasonably the shear strength and the slope stability.

  • PDF

The Characteristics of Shear Strength on Weathered Residual Soils for the Effect of Soaking and Disturbance (수침 및 교란 효과에 따른 풍화잔적토의 전단강도 특성)

  • 오세붕;정종혁;이영휘
    • Journal of the Korean Geotechnical Society
    • /
    • v.15 no.5
    • /
    • pp.125-139
    • /
    • 1999
  • It is difficult to evaluate the shear strength of weathered residual soils because of the difficulties of undisturbed sampling. In this study, a sampling device, direct shear box with shoe, was developed in order to get undisturbed samples easily for direct shear tests, and undisturbed samples could be successfully obtained. Through direct shear tests on undisturbed samples, the shear strength was evaluated with the variation of saturated conditions. In order to consider the effect of disturbance on the shear strength, a static compaction device was developed, and then it was found that undisturbed samples show greater shear strengths than the disturbed ones under natural water contents and similar strengths to the ones under soaked conditions. Further, the shear strength evaluated from direct shear tests was compared with the result of triaxial tests on undisturbed samples, and soaked strengths of the former were similar to the latter. As the result of stability analyses on an actual failed slope, it was found that the shear strength can be evaluated reasonably using direct shear box with shoe.

  • PDF

Comparison of Shear Strength Characteristics of Unsaturated Soil From Triaxial Compression Tests with Direct Shear Tests (삼축시험과 직접전단시험에 의한 불포화토의 전단특성 비교)

  • Hwang, Hui-Seok;Choi, Young-Nam;Park, Byung-Soo;Yoo, Nam-Jae
    • Journal of the Korean Geosynthetics Society
    • /
    • v.15 no.4
    • /
    • pp.63-69
    • /
    • 2016
  • In this paper, shear strength characteristics of an unsaturated soil were compared using triaxial compression tests(CD) and modified direct shear tests and thus feasibility of the newly modified direct shear testing apparatus was confirmed. The shear strength tests of unsaturated state with a soil sample, obtained from a slope where debris flow occurred at Yangpyeong in Kyeunggi province during 2010, were performed. Both tests showed a linear relationship of matric suction with the shear strength under low level of matric suction. The apparent cohesion of the unsaturated soil was also increased linearly with increase of matric suction. As results of comparing two different testing apparatus, estimated values of shear strength parameters of unsaturated soil($c^{\prime}$, ${\phi}^b$) were slightly larger in the modified direct shear tests due to constraint effect of shear box.

Evaluation of interface shear strength between geosynthetics using three kinds of testing methods (다양한 시험법에 의한 토목섬유 사이의 접촉 전단 강도 평가)

  • Seo, Min-Woo;Park, Jun-Boum;Park, Inn-Jun
    • Proceedings of the Korean Geotechical Society Conference
    • /
    • 2004.03b
    • /
    • pp.356-363
    • /
    • 2004
  • In this research, the shear behavior of four different interfaces consisting of 4 types of geosynthetics was examined, and both static and dynamic tests for the geosynthetic interface were conducted. The monotonic shear experiments were performed by using an inclined board apparatus and large direct shear device. The interface shear strength obtained from the inclined board tests were compared with those calculated from large direct shear tests. The comparison results indicated that direct shear tests are likely to overestimate the shear strength in low normal stress range where direct shear tests were not performed. Curved failure envelopes were also obtained for interface cases where two static shear tests were conducted. By comparing the friction angles measured from three tests, i.e. direct shear, inclined board, and shaking table tests, it was found that the friction angle might be different depending on the test method and normal stresses applied in this research. Therefore, it was concluded that the testing method should be determined carefully by considering the type of loads and the normal stress expected in the field.

  • PDF

THE COMPARISON OF SHEAR STRENGTH AND BRACKET PLACEMENT BETWEEN BONDING TECHNIQUES (접착술식에 따른 전단강도 및 Bracket위치의 비교)

  • Pak, Yun-Kyong;Kook, Yoon-A;Kim, Sang-Cheol
    • The korean journal of orthodontics
    • /
    • v.21 no.3
    • /
    • pp.513-520
    • /
    • 1991
  • The purpose of this study was to compare the bracket placement and the shear bond strength of indirect-bonded brackets with those of direct-bonded ones. Forty eight extracted human teeth were collected and attached with brackets and tested on shear bond strength, using Instron. Fourteen patients from Wonkwang University Dental Hospital were selected for direct bonding of brackets and their teeth were measured on bracket angulation and bracket height. The obtained results were as follows: 1. The shear bond strengths of incisors were higher in direct-bonding,group, rather than in-direct-bonding group. But, the shear bond strength of premolars showed no significant differences between groups. 2. The bracket angulations of indirect-bonding group were preciser than those of direct-bonding group, especially in upper first premolars, lower lateral incisors, canines, premolars. 3. In bracket height, there were no significant differences between groups.

  • PDF

Estimation of Shear Strength and Rheological Parameters of Fine-Grained Soil Using Direct Shear Test (직접전단실험을 이용한 세립토의 전단강도 및 유변학적 정수 산정)

  • Park, Geun-Woo;Hong, Won-Taek;Lee, Jong-Sub
    • Journal of the Korean GEO-environmental Society
    • /
    • v.18 no.2
    • /
    • pp.29-37
    • /
    • 2017
  • As the behavior of the debris flow due to the torrential rains in mountain is affected by shear strength and rheological properties of the fine fraction in the ground, the evaluation of both properties is necessary to estimate the behavior of the debris flow. The objective of this study is to evaluate the shear strength and rheological properties using the direct shear apparatus. The direct shear tests are conducted for two kinds of fine-grained soil specimens, which are in dry state and liquid limit state. From the direct shear tests, shear strengths are measured according to the normal stresses applied on the specimens to evaluate the cohesion and internal friction angle. In addition, reversal shear tests are performed for the fine-grained soil specimens in liquid limit state according to the shear rate to evaluate the residual shear strength. The results of direct shear tests show that the specimen at the liquid limit state has lower internal friction angle and higher cohesion compared to the dry stated, and the residual friction angle and cohesion at the residual state are lower than those at the peak state. In the result of reversal shear test, the residual shear strength is directly proportional to the shear rate and viscosity is calculated as $73.60Pa{\cdot}s$. This study demonstrates that the direct shear apparatus can be effectively used for the evaluation of the shear strength and rheological properties of the fine-grained soils related with the debris flow.

Interpretational Consideration of Geosynthetics Shear Behaviors (지오신세틱스 전단거동의 해석학적 고찰)

  • Jeon, Han-Yong;Kim, Cho-Rong
    • Proceedings of the Korean Geotechical Society Conference
    • /
    • 2010.09a
    • /
    • pp.293-302
    • /
    • 2010
  • 2 types of geogrids and geotextiles was used to evaluate shear behaviors after installation damage test. Shear behaviors were compared after installation damage test and coefficient of resistance to direct sliding($f_{ds}$) was estimated by theoretical shear analysis. Shear strength of damaged geogrid decreased under high normal stress of 150kPa and shear strength of geotextile decreased with increasing normal stress. It is seen that $f_{ds}$ values after installation damage decreased than before installation damage through comparison calculated $f_{ds}$ by direct theoretical shear analysis. $f_{ds}$ values to be calculated by theoretical shear analysis were changed with before and after installation damage.

  • PDF