• Advances in nano research
• /
• v.11 no.6
• /
• pp.641-648
• /
• 2021

In this article, the dynamic parameters (frequencies, mode shapes, damping ratios) of the scaled concrete structure and the dynamic parameters (frequencies, mode shapes, damping ratios) of the entire outer surface of titanium dioxide, 80 micron in thickness are compared using operational modal analysis method. Ambient excitation was provided from micro tremor ambient vibration data on ground level. Enhanced Frequency Domain Decomposition (EFDD) was used for the output only modal identification. From this study, a good correlation between mode shapes was found. Titanium dioxide applied to the entire outer surface of the scaled concrete structure has an average of 11.78% difference in frequency values and 10.15% in damping ratios, proving that nanomaterials can be used to increase rigidity in structures, in other words, for reinforcement. Another important result determined in the study was the observation of the adherence of titanium dioxide and similar nanomaterials mentioned in the introduction to concrete structure surfaces was at the highest level.

• Journal of the Korean GEO-environmental Society
• /
• v.24 no.12
• /
• pp.19-29
• /
• 2023

The main problem with roads is that cracks and settlement occur over time due to loads acting from the surface layer. One way to solve this problem is to use Geocell. Geocell can be used for structural reinforcement for erosion prevention, ground stabilization on flat and steep slopes, load bearing, and ground preservation. In this study, analyzed road pavement application cases using Geocell and purpose of this study is to analyze the bearing capacity of a road paving method including Geocell using field tests and LFWD(Light Falling Weight Deflectometer) equipment. In addition, the bearing capacity was compared and analyzed with the existing traditional road pavement method.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.23 no.5
• /
• pp.42-49
• /
• 2009

The effects of various forces acting on concrete pole are analyzed using finite element method how the forces affect on ground displacement. The soil types, wind load location of anchor block embedded depth of pole, and distance between poles are varied to find out effects on lateral displacement. Anchor block is effective when it is located at 1/4 of embedded depth The displacement is decreases as elastic modulus increases. Concrete reinforcement for loosened ground is necessary for double poles because double poles cause large excavation. When embedded depth ratio decrease, lateral displacement increase as closer to ground surface. Large embedded depth is effective to reduce lateral displacement, and the distance between poles is not much large factor.

• Journal of the Korean Geotechnical Society
• /
• v.21 no.1
• /
• pp.115-121
• /
• 2005

At present, continual road constructions to connect from city to city are needed due to the geographical feature of Korea that about $70\%$ of the territory is mountainous area. Thus, the generation of large cut-slope has been inevitably formed. As a means of reinforcement on the cut-slope, in case of destructive disasters such as a snowstorm, pile embedment method is widely adopted. The pile embedment method is to resist possible move of soil by embedding piles from the surface to the immovable ground and then delivering the load from the piles to the immovable ground. In this study this writer analyzes the limitation of empirically used pile construction depth and its spacing through the numerical analysis. As a result, he suggests the most effective pile construction depth and space.

• Journal of the Korean GEO-environmental Society
• /
• v.18 no.7
• /
• pp.13-20
• /
• 2017

Soil nailing is ground reinforcement method using the shear strength of ground and the pullout shear resistance force of nail. It is mainly used for reinforcement of cut slopes, earth retaining structures and retaining walls, etc. It may be designed considering the pullout resistance of nail in the case of earth retaining structure and retaining wall, but it should be designed considering not only pullout resistance but also shear and bending resistance in the case of slope. However, conservative designs considering only pullout resistance are being done and most of the studies are about increasing pullout resistance by improving of material, shape and construction method of nail. Actually, Shear bending deformations occur centering on the active surface in ground reinforced with the nail. The grout with relatively low strength is destroyed and separated from the reinforcing material. As a result, the ground is collapsed while reducing the frictional resistance rapidly. Therefore, it is necessary to develop the method to increase the shear resistance while preventing separation of nail and grout body. In this study, an experimental study was conducted on new soil nailing method which can increase shear resistance by forming protrusions through pressurized grouting after installing a packer on the outside of deformed bar.

• 보존과학연구
• /
• s.27
• /
• pp.215-226
• /
• 2006

In the field conservation treatment, it is important that the method chosen to lift an object out of the ground depends on its surrounding weather, strength, size, composition, and condition. This paper describes a physical support(Urethane bandage, De naturation - polyisoprene resin) created for lifting delicate relics in this field. The advantage of Urethane bandage method is of conveniently portable size, and it's convenient for use, while curing time is very fast.(approx. 5~10minute)Denaturation -polyisoprene resin is able to be soft by the hot water(approx. $60^{\circ}C$ ). so it's good to stick to the relic surface of an indeterminate form. The results of use of these reinforcement methods are of utility value.

• Land and Housing Review
• /
• v.2 no.4
• /
• pp.553-558
• /
• 2011

Existing method protruding strands that are embedded in PHC pile to connect pile head and foundation slab shows poor constructibility. As this causes crack and damage in pile head and casualties often occurs in construction site during the work, alternative method called one-cutting method, in which pile above the ground surface and strands embedded in pile are completely cut and pile head is reinforced with rebar for connection with foundation slab, is currently adopted. However, the capacity of details for these methods are not mechanically proved. In this study, in order to suggest proper details of reinforcement for one-cutting method, failures due to lack of shear resistance between infilled concrete and PHC pile are analyzed through experiments and embedded depth with infilled concrete inside PHC pile is suggested. Assuming that slip failure strength is 0.4MPa, which is obtained from experiment conservatively, to have rebar yielded before slip failure, minimum depth of infilled concrete for PHC 450 and PHC 500, need to be 600mm above, and for PHC 600, 1,000mm above.

• 보존과학연구
• /
• s.27
• /
• pp.103-128
• /
• 2006

Rock properties of the five storied stone pagoda in the Mooryangsa temple are consist mainly in medium grained biotite granite with partly pegmatite veinlet. A part of the foundation stone is substituted in identical rock properties of the pagoda. The upper part of the pagoda is used purples and stone, gray shale and granodiorite. The most serious problem of the pagoda is structual instability from centered subsidence of the ground in northwestern direction remarkably. In southern view, the upper part of the pagoda also is slanted a little in right, it will need reinforcement by engineering method for structual stability of the stone pagoda. Weathering states of the stone pagoda are affected results of natural and artifical factors due to the surface-exfoliation, fine-fissure, crack, falling offs. On the rock surface of the pagoda, ferro-manganese hydroxide compounds are coated along the rainpathway. Also, bryophyte range concentration spreads raindrops face of roof rock properties, which areadd biological weathering effects. For the synthetic evaluation of the deterioration state, we make detailed surface weathering maps, it will be contribute to investigation for future conservation schemes.

• Journal of the Korean Geosynthetics Society
• /
• v.17 no.1
• /
• pp.1-10
• /
• 2018

We conducted research to develop a solidification agent for the ground surface reinforcement method in which activator is fused by recycling pig iron slag, which is a byproduct generated in the steel making process. The purpose of this research is to solve the problems of surface soil by improving the strength and durability of foundation soil such as soil loss, settlement, sinkhole, etc. by recycling pig iron slag from disused or landfilled steelworks. For this purpose, the possibility of using pig iron slag as a solidification soil was evaluated by the compressive strength, elution test of harmful materials, permeability coefficient test. As a result of the compressive strength test, the values of the strength of the curing 28 days of the solidified soil having the solidification agent mixing ratio of 12% were found to be 0.93, 0.96 and 1.3 MPa, respectively, satisfying the required strength value of 1 MPa, In the case of permeability coefficients, the minimum values were $4.1{\times}10^{-8}$, $7.0{\times}10^{-7}$, and $1.7{\times}10^{-7}cm/sec$, respectively, at the solidification agent mixing rate of 12%. In addition, as a result of the elution test of harmful materials, a small amount was detected in the item of hexavalent chromium but satisfied the inclusion criteria, and in the remaining items, heavy metals were not eluted.

• Tunnel and Underground Space
• /
• v.25 no.3
• /
• pp.244-254
• /
• 2015

The tunnel is excavated through the alluvial layer composed of sand and gravel with groundwater deposited on rock. A portion of upper part of the tunnel is located in the alluvial layer and there are several buildings just above the curved section of the tunnel. It is necessary to prevent from sand-flowing into the tunnel due to low strength of the alluvial, high groundwater level and shallow depth of the tunnel from the ground surface. For this, the alluvial around the tunnel is pre-reinforced by umbrella arch method with multi-stage grouting through large diameter steel pipes or jet grouting before excavating the tunnel. The effect of the pre-reinforcement of the tunnel and the safety of the buildings are monitored by measurement of ground deformation occurred during tunnelling.