• Title/Summary/Keyword: Direct-shear test

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Engineering Properties of Tire Treads for Soil Reinforcement (지반보강재로서 타이어 트레드의 공학적 특성)

  • Yoon, Yeowon;Cho, Sungsoo;Kim, Keunsoo
    • Journal of the Korean GEO-environmental Society
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    • v.8 no.1
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    • pp.49-55
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    • 2007
  • In order to utilize treads of waste tire as reinforcement material it is necessary to know the interface friction angle between tread surfaces and soil and tensile strength of connection joint of tire treads. In this research large direct shear tests were performed to get the interface friction angle between the inner and outer surfaces of treads and soil for different degree of compaction. From the large direct shear tests, the ratio of interface friction angle to the shear friction angle of sand, ${\delta}/{\phi}$, were 1.06 in outside surface of tire tread and 0.93 in inside surface of tire tread. For weathered granite soil the ratio of interface friction angle was 0.98 and 0.92 for outside and inside of tread, respectively. Also tensile tests were performed using universal testing machine for the connection joint of treads and Tirecell units using bolts. The tensile strength of connection joint increased with the number of bolts and with the sizes of washers. Connection by polypropylene ropes showed lower strength than those of bolts.

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Direct shear behavior of concrete filled hollow steel tube shear connector for slim-floor steel beams

  • Hosseinpour, Emad;Baharom, Shahrizan;Badaruzzaman, Wan Hamidon W.;Shariati, Mahdi;Jalali, Abdolrahim
    • Steel and Composite Structures
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    • v.26 no.4
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    • pp.485-499
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    • 2018
  • In this paper, a hollow steel tube (HST) shear connector is proposed for use in a slim-floor system. The HST welded to a perforated steel beam web and embedded in concrete slab. A total of 10 push-out tests were conducted under static loading to investigate the mechanical behavior of the proposed HST connector. The variables were the shapes (circular, square and rectangular) and sizes of hollow steel tubes, and the compressive strength of the concrete. The failure mode was recorded as: concrete slab compressive failure under the steel tube and concrete tensile splitting failure, where no failure occurred in the HST. Test results show that the square shape HST in filled via concrete strength 40 MPa carried the highest shear load value, showing three times more than the reference specimens. It also recorded less slip behavior, and less compressive failure mode in concrete underneath the square hollow connector in comparison with the circular and rectangular HST connectors in both concrete strengths. The rectangular HST shows a 20% higher shear resistance with a longer width in the load direction in comparison with that in the smaller dimension. The energy absorption capacity values showed 23% and 18% improvements with the square HST rather than a headed shear stud when embedded in concrete strengths of 25 MPa and 40 MPa, respectively. Moreover, an analytical method was proposed and predicts the shear resistance of the HST shear connectors with a standard deviation of 0.14 considering the shape and size of the connectors.

Effect of Non-Plastic Fines Content on the Pore Pressure Generation of Sand-Silt Mixture Under Strain-Controlled CDSS Test (변형률 제어 반복직접단순전단시험에서 세립분이 모래-실트 혼합토의 간극수압에 미치는 영향)

  • Tran, Dong-Kiem-Lam;Park, Sung-Sik;Nguyen, Tan-No;Park, Jae-Hyun;Sung, Hee-Young;Son, Jun-Hyeok;Hwang, Keum-Bee
    • Journal of the Earthquake Engineering Society of Korea
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    • v.28 no.1
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    • pp.33-39
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    • 2024
  • Understanding the behavior of soil under cyclic loading conditions is essential for assessing its response to seismic events and potential liquefaction. This study investigates the effect of non-plastic fines content (FC) on excess pore pressure generation in medium-density sand-silt mixtures subjected to strain-controlled cyclic direct simple shear (CDSS) tests. The investigation is conducted by analyzing excess pore pressure (EPP) ratios and the number of cycles to liquefaction (Ncyc-liq) under varying shear strain levels and FC values. The study uses Jumunjin sand and silica silt with FC values ranging from 0% to 40% and shear strain levels of 0.1%, 0.2%, 0.5%, and 1.0%. The findings indicate that the EPP ratio increases rapidly during loading cycles, with higher shear strain levels generating more EPP and requiring fewer cycles to reach liquefaction. At 1.0% and 0.5% shear strain levels, FC has a limited effect on Ncyc-liq. However, at a lower shear strain level of 0.2%, increasing FC from 0 to 10% reduces Ncyc-liq from 42 to 27, and as FC increases further, Ncyc-liq also increases. In summary, this study provides valuable insights into the behavior of soil under cyclic loading conditions. It highlights the significance of shear strain levels and FC values in excess pore pressure generation and liquefaction susceptibility.

Analysis on Soil Reinforcement by Lespedeza cyrtobotrya Roots for Slope Stability (비탈면 안정을 위한 참싸리 뿌리의 토양보강 효과)

  • Hwang, Jin-Sung;Ji, Byoung-Yun;Oh, Jae-Heun;Cha, Du-Song
    • Journal of Forest and Environmental Science
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    • v.30 no.1
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    • pp.113-119
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    • 2014
  • To examine the soil reinforcement by the shrub with shallow root systems for slope stability, we developed insitu apparatus for direct shear test and conducted the insitu field tests for Lespedeza cyrtobotrya, a representative revegetation species for artificial hillslopes. The insitu field tests were conducted for two different soil conditions (the rooted soils and non-rooted soils) and we then compared the experimental values with those calculated from the Wu model. The results showed that the soil reinforcement derived from the insitu field tests ranged from 0.01525 to 0.1438 $kgf/cm^2$ while the one calculated from the Wu model ranged from 0.1952 to 0.2696 $kgf/cm^2$. Our finding suggests more field tests are needed to collect the related parameters in the model application thereby predicting the reliable soil reinforcement by the shrub root systems.

Behavior of Shear Strength of Coarse Grained Materials Based on Large Scale Direct Shear Test (I) (대형직접전단시험을 이용한 조립재료의 전단거동 특성 (I))

  • Lee Dae-Soo;Kim Kyoung-Yul;Hong Sung-Yun;Jo Hwa-Kyung;Whang Sung-Chun
    • Journal of the Korean Geotechnical Society
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    • v.21 no.6
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    • pp.81-91
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    • 2005
  • 'Coarse grained material' refers to crushed stones or gravels, and the behaviour of soil containing coarse grained material is not easily defined using the conventional soil mechanics theory due to the influences of large particles, therefore large scale test is essential to investigate their effects. Previous studies have identified the major factors affecting the properties of coarse grained materials by using large scale shear testing apparatus, such as maximum particle size, water content, density and uniformity coefficients. In this paper, the effect of variation of maximum particle size and water content on shear strength was analyzed from the results of large scale shear test. In addition, the fiction coefficient at critical state per vertical load was estimated using the equation proposed by Wood (1998). The sample for the test was obtained from the local quarry sites. Tests results show that the shear strength for 50.8 m maximum particle size is relatively larger than that of 76.3 m and air-dry sample has larger shear strength than saturated sample. In the meantime, the friction coefficient at critical state shows $1.0\sim1.6$ according to the test conditions.

Interface shear strength between Crushed Stone and Geotextile (쇄석-지오텍스타일간의 접촉면 전단강도 산정)

  • Lee, Seok-Won;Youn, Choo-Moon;An, Hyun-Ho;Seo, Byoung-Wook
    • Journal of the Korean Geosynthetics Society
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    • v.5 no.1
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    • pp.33-38
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    • 2006
  • Large-scale direct shear tests were conducted in order to evaluate both the shear strength of crushed stone itself and the interface shear strength between crushed stone and geotextile. Total three types of geotextile (i.e. one woven geotextile and two nonwoven geotextiles) were used in the experimental program, considering two different values for the unit weight of crushed stone. Total fifteen tests were conducted in this study. It has been found from the experimental results that the friction angles of crushed stone itself were $47^{\circ}$ and $57^{\circ}$ under the unit weights of crushed stone being $1.4t/m^3$ and $1.5t/m^3$, respectively. Interface friction angle between nonwoven geotextile and crushed stone showed $39^{\circ}$ for type A indicating an efficiency of 83% and $42^{\circ}$ for type B indicating an efficiency of 89%. Similarly, interface friction angle between woven geotextile and crushed stone showed $39^{\circ}$ indicating an efficiency of 83%.

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An Evaluation of Tree Roots Effect on Soil Reinforcement by Direct Shear Test (일면전단실험에 의한 수목뿌리의 토양보강효과 평가)

  • Cha, Du Song;Oh, Jae-Heun
    • Journal of Korean Society of Forest Science
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    • v.94 no.4 s.161
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    • pp.281-286
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    • 2005
  • Trees enhance slope stability against down slope mass movement through the removal of soil water by transpiration and by the mechanical reinforcement of their roots. To assess the magnitude of this reinforcement on natural slope stability, direct shear tests were made on dry sand reinforced with different array types of roots. Pinus koraiensis was used as root specimens. The peak shear resistance at each normal stress level was measured on the rooted and unrooted soil specimens. Increased soil resistance(${\Delta}S$) by roots was calculated using parameters like internal friction angle and cohesion of tested soil and also evaluated the effects of root array in tested soil. As results, we find that shear resistance increased in tested soil shear box as diameters and arrayed numbers of root specimen increased and cross root array in tested soil had a much greater reinforcing effect than other root arrays. Comparison of traditional root-soil model with experiments showed that simulated reinforce strength by the model was different with those obtained by the experiment due to its linearity.

Effect of Relative Density and Fines Content on Pullout Resistance Performance of Drilled Shafts (상대밀도와 세립분 함유율이 현장타설말뚝의 인발저항 성능에 미치는 영향에 관한 연구)

  • You, Seung-Kyong;Hong, Gigwon;Jeong, Minwoo;Shin, Heesoo;Lee, Kwang-Wu;Ryu, Jeongho
    • Journal of the Korean Geotechnical Society
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    • v.34 no.4
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    • pp.37-47
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    • 2018
  • This paper described a results of direct shear test and pullout test by using soil supported by drilled shafts in order to evaluate the effect of relative density and fines content on pullout resistance performance of drilled shafts. The result of direct shear test showed that the variation characteristics of internal friction angle and cohesion could be confirmed quantitatively. The result of pullout test also showed that the effect of relative density and fines content on pullout resistance performance of drilled shafts was confirmed. That is, the contribution of the internal friction angle and cohesion of soils on the pullout resistance performance of drilled shafts was found to vary, when the fines content was about 13% based on results direct shear test and pullout test. Therefore, at design of drilled shafts, the effect of skin friction resistance should be considered on the influence factor of strength parameters ($c-{\phi}$) according to the fines content of soil.

Effects of direct and indirect bonding techniques on bond strength and microleakage after thermocycling (직접 부착법과 간접 부착법이 열순환 후 부착강도와 미세누출에 미치는 영향에 대한 연구)

  • Ozturk, Firat;Babacan, Hasan;Nalcaci, Ruhi;Kustarci, Alper
    • The korean journal of orthodontics
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    • v.39 no.6
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    • pp.393-401
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    • 2009
  • Objective: The purpose of this study was to compare the shear bond strength (SBS) of brackets and microleakage of a tooth-adhesive-bracket complex bonded with a direct and an indirect bonding technique after thermocycling. Methods: Fifty non-carious human premolars were divided into two equal groups. In the direct bonding group a light-cured adhesive and a primer (Transbond XT) was used. In the indirect-bonding group, a light-cured adhesive (Transbond XT) and chemical-cured primer (Sondhi Rapid Set) were used. After polymerization, the teeth were kept in distilled water for 24 hours and thereafter subjected to thermal cycling (500 cycles). For the microleakage evaluation, 10 teeth from each group were further sealed with nail varnish, stained with 0.5% basic fuchsin for 24 hours, and examined under a stereomicroscope. Fifteen teeth from each group were used for SBS testing with the universal testing machine and adhesive remnant index (ARI) evaluation. Data were analyzed using the Mann-Whitney U test, Chi-square test, and Fisher's exact test. Results: There were no statistical differences on SBS and microleakage between the two bonding techniques. The indirect bonding group had a significantly lower ARI score. Bracket failures were obtained between enamel-resin interfaces. Conclusions: The type of bonding technique did not significantly affect the amount of microleakage and SBS.

Bearing Capacity Evaluation of Marine Clay Dredged Deposit Including Desiccated Crust Layer (건조 고결층이 형성된 준설 매립 지반의 지지력 산정에 대한 연구)

  • Park, Hyun-Ku;Byeon, Wi-Yong;Jee, Sung-Hyun;Lee, Seung-Rae
    • Journal of the Korean Geotechnical Society
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    • v.23 no.5
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    • pp.89-100
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    • 2007
  • In this study, various field and laboratory tests were performed to investigate the characteristics of shear strength and bearing behavior to be considered in the estimation of stability and trafficability in early stage of stabilization process in marine clay dredged deposit. Site characterization was carried out to grasp the basic properties of the deposit. Field vane test, unconfined compression test and direct shear test were conducted to evaluate the shear strength distribution for varied depths, and the characteristics of shear strength and stress-strain behavior of the crust layer. Plate load tests were also performed to estimate the bearing capacity and to assess load-settlement behavior and failure pattern of the deposit. The bearing capacity was also estimated using previously proposed methods for double-layered clay deposit. The estimated bearing capacity was compared with the results of the plate load tests and then, the applicability of the estimation method was discussed.