역학적 모형에 의한 지오그리드의 장기성능 평가

전한용,정영인,Jeon, Han-Yong,Chung, Youn-In 한국섬유공학회 2006 한국섬유공학회지 Vol.43 No.4

Long-term performance of geogrid should be dependent on the mechanical behaviors during the service periods. Mechanical properties of geogrids are mainly influenced by not only creep deformation behaviors at the constant confining load and temperature but also stress relaxation behaviors at the constant strain and temperature as viscoelastic deformation. In this study, new concept mechanical model was suggested and applied to analyze the long-term performance of geogrid with instantaneous and asymptotic responses. Experimental results of creep and stress relaxation tests of geogrids were compared each other to verify this suggested mechanical model.

지오그리드의 크리프 한계 변형률에 관한 해석학적 고찰

전한용,정연인,Jeon Han-Yong,Chung Youn-In 한국섬유공학회 2006 한국섬유공학회지 Vol.43 No.3

New procedure for the evaluation of creep reduction factor using performance limit strain concept was introduced and confirmed through the creep test results. To determine the performance limit strain of the textile geogrid used in this study, the Sherby-Dorn Plots were applied and the results were compared with the results that applied existed limit strain criteria (GRI test method GG-4). The creep-limited strain of the geogrid samples that was deter-mined by using the Sherby-Dorm Plots was all 11%. This value is higher than the existing creep-limited stran value of 10%. From this 11% limit strain, the creep reduction factors were calculated at 100,000 hours design. It resulted in 1.45 for all of the geogrid samples (8 t/m, 10 t/m). Finally, when it was compared with the creep reduction factors using 10% criteria, there was slight decrease in reduction factor values of about $0.06{\sim}0.14$.

소형직접전단시험에 의한 토목합성재료의 계면마찰특성 평가

전한용,정구,정진교,Jeon, Han-Yong,Jung, Gu,Chung, Chin-Gyo 한국섬유공학회 2003 한국섬유공학회지 Vol.40 No.1

In this study, the frictional properties between geotextiles and geomembranes were estimated for utilization in the design of waste landfill systems. The shear stress at three different types of shear rates and each normal stress were evaluated by direct shear test. All eight geomembrane/geotextile interfaces showed post-peak reductions in shear strength and similar stress-strain curve patterns regardless of the type of materials. These post-peak strength reductions were apparently the polishing effects on the geomembrane surface. The shear rate showed no significant effects on the shear strength in each geosynthetic interface regardless of the type of geotextiles. The shear strength between geosynthetics interfaces increased proportional to the increasing normal stress. The parameters influencing the interface frictional properties between geomembrane and geotextile were the fiber length and type and the fiber diameter. The filament type in nonwoven geotextile exhibited higher frictional forces than other geotextiles.

NaOH용액중에서 PET필름의 응력완화거동에 관한 연구

전한용,최영엽,임승순,Jeon, Han-Yong,Choe, Yeong-Yeop,Im, Seung-Sun 한국섬유공학회 1988 한국섬유공학회지 Vol.25 No.1

The relaxation behaviors of PET film in NaOH solution were investigated in view of chemorheology under the various temperatures and those of the film with draw ratio and temperatures were examined phenomenologically in relation to the decomposition effect of NaOH. As the experimental results, the initial relaxation stress was decreased and relaxation rates rfrb were increased with temperatures at constant draw ratio. The relaxation spectra were composed of box and wedge types distribution and the relaxation time t1,t2 from constitutive eq. were shifted to a shorter time side with temperatures.

Evaluation of Tensile Properties of HDPE Geomembranes with Temperature under Exposure to Chemical Solutions

전한용,Khan, Belas Ahmed,Jeon, Han-Yong 한국섬유공학회 2013 한국섬유공학회지 Vol.50 No.1

In most conventional applications, geosynthetics are exposed to highest mechanical stress during installation. A series of laboratory simulation test for installation damage of geomembrane (GM) was carried out at different loading cycles on HDPE GMs where ISO 10722:2007 was used as a guide. The tensile properties of the samples were tested. The result of the test is reported and it has been found that number of loading cycle has irregular influence on installation damage. It is known that the service life of a GM depends on the exposure conditions, which in a landfill may involve adverse chemical exposure, elevated operating temperatures, and potentially large physical stresses. New equipment was developed and the installation damaged GM samples were exposed to pH solutions under different stress at elevated temperature for hours. Tensile tests was performed to get the residual strength and analyzed. It has been noticed that as the applied stress on GM samples increases, residual tensile strength decreases and they showed higher tolerance to acidic condition than alkali condition.

보강토 옹벽 공사용 지오그리드의 제조 및 물성(I) -역학적 및 인발 특성-

전한용,김정효,김홍택,이은수,김영윤,이형규,Jeon, Han Yong,Kim, Jeong Hyo,Kim, Hong Taik,Lee, Eun Soo,Kim, Young Yoon,Lee, Hyung Kyu 한국섬유공학회 1998 한국섬유공학회지 Vol.35 No.10

Geogrid for reinforcement soil retaining wall was constructed with a raw grid woven from 1,000 denier polyester yarns. Low density polyethylene (LDPE) resin dissolved in ethylbenzene was coated to improve the junction strength between warp and weft of raw grid. The weight increase on coating the raw geogrid was about 30~60%. Tensile, junction strength and pullout resistance of geogrids in installation within soil were estimated to verify the reinforcement properties. Tensile strength per unit rib of LDPE coated geogrid was about 30% higher than that of raw grid. For each geogrid, pullout force increased with higher vertical stress, and Grid-M (PVC coated geogrid) had the highest pullout force at constant vertical stress. The induced displacements decreased with higher vertical stress, and Grid-E (LDPE coated geogrid) has the lowest difference range of induced displacement at constant vertical stress.

채움재의 입자크기를 고려한 표면결합에 의한 지오멤브레인의 안정성 평가

전한용,정연인,Jeon Han-Yong,Chung Youn-In 한국섬유공학회 2006 한국섬유공학회지 Vol.43 No.3

To confirm the effects of surface defects on the stability of high density polyethylene geomembranes in waste landfill construction conditions, mechanical properties, chemical resistance and failure times of geomembranes under different temperatures were examined. The number of surface defects was increased with the smaller size of scratch induced particles, and the more scratch addition numbers at the shear rate of scratch induced mechanism, 100 mm/min. The tensile strength was decreased but the tensile strain was increased with the above conditions. In chemical resistance of defective geomembranes, the tensile strength was decreased but the tensile strain was increased with the longer immersion period and the higher temperature under the same scratch induced conditions. Finally, failure times of defective geomembranes by 'Notched Constant Tensile Load Test' were shifted to the shorter time ranges by increasing temperatures.

지오텍스타일의 마모특성이 화학저항성에 미치는 영향

전한용,류중재,유충식,김의화,Jeon Han Yong,Ryu Jung Jae,Yoo Chungsik,Kim Eui Hwa 한국섬유공학회 2005 한국섬유공학회지 Vol.42 No.3

Effect of abrasion damage on the chemical resistance of geotextiles were evaluated. Three types of geotextiles were adopted for the abrasion damage test and four types of sandpapers were used to consider the soil particle size. After abrasion damage test, the chemical resistance of damaged geotextile was evaluated by the change of tensile strength of geotextile after immersion in acid solution of pH 3 and 12 at $25^{\circ}C$ or $50^{\circ}C$ for 30 days, respectively. From the results of abrasion damage test, it was seen that geotextile surface showed serious damage with increase in the particle size of sandpaper. Especially, the surface of needle punched nonwoven geotextile was easily abraded. For the $\#100,\;\#220$ sandpapers having large grain size, the retention ratio of tensile strength of the needle punched nonwoven geotextile decreased most seriously in the 200 cycle abrasion. But, for the $\#400\;and,\;\#800$ sandpapers having small grain size, the retention ratio of tensile strength of the woven geotextile decreased most seriously in the 200 cycle abrasion. Finally, it was seen that geotextiles showed no change in the tensile strength on immersion in acid solutions of pH 3 and pH 12 at $25^{\circ}C\;or\;50^{\circ}C$ for 30 days, respectively.

Tensile Property Evaluation of Nonwoven Geotextiles in Simulated Sea Water Solution

전한용,공학봉,강세구,김종훈,정성훈,Jeon, Han-Yong,Gong, Hak-Bong,Kang, Se-Gu,Kim, Jong-Hoon,Jeong, Sung-Hoon The Korean Fiber Society 2009 한국섬유공학회지 Vol.46 No.6

Four types of nonwoven geotextiles were used to examine the applicability for the coastal engineering field and tensile properties were reviewed in 10% NaCl solution as a simulated sea water. The immersion conditions were 96, 192, 500 hours at 35, 45, 55, 65, 75, $85^{\circ}C$ respectively. For the case of 10% NaCl solution immersion for 96 and 192 hours, nonwoven geotextiles showed little decrease in tensile strain although the temperature increased. However, as immersing time was expanded to 500 hours, the tensile strain decreased seriously as the temperature increased. Tensile strain and strength of geotextiles decreased by increasing temperature and NaCl solution resistance of nonwoven geotextiles is significantly dependent on temperatures such as higher the temperature, lower the NaCl solution resistance.

Short-Term Compressive Properties and Transmissivity of Geonets

전한용,Jeon, Han-Yong The Korean Fiber Society 2014 한국섬유공학회지 Vol.51 No.2

The relationship between the manufacturing parameters and the compressive behaviors of a traditional bi-planar geonet, the effect of various test conditions on the compression test results for bi- and tri-planar geonets, and the correlation between the normal pressure and the transmissivity of bi- and tri-planar geonets were investigated. The geonet strand inclination can mainly affect the after-compressive strength, i.e., roll-over behavior. For both bi- and tri-planar geonets, the compressive strength decreased and the strain at the yield point increased gradually with temperature. A significant reduction in flow capacity was observed for the traditional bi-planar geonet, and this value was consistent with the compressive strength. These decreases were anticipated owing to the abrupt thickness decrease in the geonet caused by roll-over. On the other hand, no significant decrease was observed in the transmissivity for the tri-planar geonet, which did not roll over.