• Journal of the Korean GEO-environmental Society
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• v.14 no.1
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• pp.23-32
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• 2013

Currently, the west coast has focused on large-scale investment and development, such as harbor construction work and land reclamation projects, with soft ground grouting issues being the major concern. In addition, grouting for soft ground reinforcement is definitely considered that construction purpose, soil condition, construction situation, and construction costs. The SRC method, which is a high pressure injection method, can easily produce well-distributed strength regardless of soil characteristics and is environmentally friendly. Therefore in this study, the SRC method was applied to marine clay on the west coast where located Jeongok-ri, Seosin-myeon, Hwaseong-si, Gyeonggi-do, Korea as well as estimated of the ground reinforcement and the application on the site. The results of the application on the site by SRC method indicated age 28 day strength is $14,700{\sim}31,800kN/m^2$ which is satisfied the criterion of unconfined compressive strength that more than $5,333kN/m^2$. Therefore the result that the SRC method constructed marine clay on the west coast indicated the outstanding strength as well as excellent durability.

• The Journal of Engineering Geology
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• v.18 no.2
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• pp.227-232
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• 2008

In this study, the pull out resistance characteristics of an anchor bar to support a spillway installed in a slope are investigated by field tests. The injection materials were a cement mortar and cement milk. Unconfined compression strengths of those materials under several conditions were measured. As the result of compression test, the unconfined compression strengths of the cement mortar and the cement milk have positive proportional relation-ship with the water-cement ratio. They also have negative proportional relationship with increasing the curing time. In the same condition of water-cement ratio and curing time, the unconfined compression strength of cement milk is larger than that of cement mortar. In order to reduce the eccentricity in anchor bar during pull-out test in the field, the installation apparatus was improved by inserting a nut type of steel fixing coupling into the anchor bar. As the result of the pull-out test, the strength modification of cement milk was increased steeply at the early curing time. However, that of cement mortar was increased gradually with passing the curing time. Therefore, the cement milk has to use as the injection material for a prompt construction of anchor bar because the strength modification of cement milk is occurred at the early curing time.

• 한국신재생에너지학회:학술대회논문집
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• 2006.11a
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• pp.40-43
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• 2006

Public demand for the heat pump system as a next generation energy equipment is increasing for its eco-friendly and cost-effective advantage. Many researches have been concentrated on how to calculate and develop its own efficiency, while the possible effect of the heat pump operation on the whole subsurface temperature distribution is relatively less considered, During the current study, subsurface temperature disturbance caused by seasonal surface temperature cycle in Busan area and general W-tube heat pump operation is simulated in 3-dimensional heterogeneous medium. It shows that subsurface deeper than 10m from the surface remains nearly unchanged throughout the 4 seasons and groundwater convect ion in highly permeable layer near the surface acts like a main path of heat plume from heat pump system, This implies the significance of detail descript ion in shallow sedimentary layer or highly permeable layer which plays an important role on the regional flow advection and heat transfer. Also, the effect of groundwater convection increases when the arrangement of the 2 injection pipes and 2 extract ion well is maintained parallel to groundwater flow. Therefore, more careful and detail investigation is required before installation and operation of heat pump system that it may not cause any possible change of microbial ecosystem in the shallow subsurface environment or 'contamination of temperature' for groundwater use as well as the loss of efficiency of the equipment itself. This can also help to design the optimized grouting system for heat pump.

• Journal of Korean Tunnelling and Underground Space Association
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• v.7 no.3
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• pp.219-226
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• 2005

The result that analyze for 6 years a groundwater influx quantity of total 60 catch-pit established in subway line 5 appeared with $0.77m^3/min$. When comparing design approaches of the catch-pit with design approaches of the box structure $2m^3/min$ and the tunnel structure $3m^3/min$, it is found that it has a surplus. Red sedimentation substance contains large portion of Fe. The earth retaining structure of a tunnel and groundwater containing more portion of Fe than other area rue the major factor of this substance. In case of white sedimentation substance, the most frequently founded ingredient is CaO, which is occurred in case grouting injection materials for ground reinforcement is transmitted into a tunnel system by ground water. This substance is doesn't affect safety of a tunnel.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.449-452
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• 2008

Reinforced concrete structure with supplementary relation is a distinguished material. But in this structure, crack is generated by many factors and caused decadence of durability, safety, function, and so on. Hence structure is in need of repair. Preexistence injection of chemical grouting for using repair of crack not enough performance. In this study, Setting time test of Acryl Gel was carried out According to a Catalyzer quantity. The result of test showed that gel time of Acryl Gel decreased with the increased of catalyzer quantity. The result of this study could be used as the basic data for the repair of crack using Acryl Gel.

• Geomechanics and Engineering
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• v.20 no.5
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• pp.399-410
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• 2020

Cavities often develop behind the vault during the construction of double-arch tunnels, generally in the form of various defects. The study evaluates the impact of cavities behind the vault on the mechanical and failure behaviors of double-arch tunnels. Cavities of the same sizes are introduced at the vault and the shoulder close to the central wall of double-arch tunnels. Physical model tests are performed to investigate the liner stress variation, the earth pressure distribution and the process of progressive failure. Results reveal that the presence of cavities behind the liner causes the re-distribution of the earth pressure and induces stress concentration near the boundaries of cavities, which results in the bending moments in the liner inside the cavity to reverse sign from compression to tension. The liner near the invert becomes the weak region and stress concentration points are created in the outer fiber of the liner at the bottom of the sidewall and central wall. It is suggested that grouting into the foundation soils and backfilling injection should be carried out to ensure the tunnel safety. Changes in the location of cavities significantly impact the failure pattern of the liner close to the vault, e.g., cracks appear in the outer fiber of the liner inside the cavity when a cavity is located at the shoulder close to the central wall, which is different from the case that the cavity locates at the vault, whereas changes in the location of cavities have a little influence on the liner at the bottom of the double-arch tunnels.

• Journal of the Korean GEO-environmental Society
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• v.14 no.1
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• pp.53-60
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• 2013

On this study, engineering properties of SGR method and SMI method, which are typical sodium silicate methods, were compared through the laboratory test and durability, strength, waterproof characteristic and environmental effects were compared and analyzed with period and condition of curing on each case. As a result of durability test, volume change of SGR is approximately 23-times greater than SMI and the effects on environment are appeared safe on all method. In case of waterproof characteristic test, permeability coefficient is decreased about 24% on SMI, whereas on SGR permeability coefficient is showed to increase because rapid volume change make wider void. Strength characteristics of SMI are appeared higher about 11-times in case of homogel and 3.9-times in case of sandgel than SGR. Which is because volume change of SMI, caused by leaching, is smaller than SGR.

• Tunnel and Underground Space
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• v.15 no.2 s.55
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• pp.102-110
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• 2005

○ ○ tunnel that is located at Iksan - Jangsu freeway ○ ○, has collapsed during construction at the valley with shallow depth. Although, the site investigations, such as TSP, drilling exploration and so of indicated the presence of discontinuities in this section. The RMR was upgraded and the construction were carried out because that not only actual rock qualities were relatively good during construction but also the tunnel foe was stabilized. However, the tunnel was collapsed at the same time blasting of full face, and surface and underground water was infiltrated due to the settlement of the upper part of the tunnel face. To restore the collapsed section, 3-d tunnel stability analysis was performed and suitable reinforcement methods were chosen. The cavity of the upper tunnel face was stabilized by means of UAM and ALC injection. And the settlement was restored using L.W grouting method.

• The Journal of Engineering Geology
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• v.33 no.4
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• pp.599-609
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• 2023

In the seismic retrofitting of harbor breakwaters in Korea, the recovery rate is often uncertain due to site conditions and site conditions, and problems continue to arise. Therefore, in this study, we analyzed the recovery rate and compressive strength of the improved material through drilling survey by grouting confirmation method after applying low-fluidity mortar injection method, and furthermore, we checked the elastic modulus by downhole test and tomography to confirm the reinforcement effect of soft ground after ground improvement. The experimental results showed that the average shear wave velocity of the ground increased from 229 m/s to 288 m/s in BH-1 and BH-3 boreholes to a depth of 28.0 m, and the average shear wave velocity of the ground to a depth of 30.0 m tended to increase from 224 m/s to 282 m/s in the downhole test. This is believed to be a result of the increased stiffness of the ground after reinforcement. The results of the tomographic survey showed that the Vs of the soft ground of the sample at Site 1 increased from 113 m/s to 214 m/s, and the Vs of the sample at Site 2 increased from 120 m/s to 224 m/s. This shows that the stiffness of the ground after seismic reinforcement is reinforced with hard soil, as the Vs value satisfies 180 m/s to 360 m/s in the classification of rock quality according to shear wave velocity.

• Journal of the Korean Geosynthetics Society
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• v.14 no.2
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• pp.95-103
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• 2015

In this study, the causes and countermeasures for the leakage of a sea dyke under construction are analyzed. In general, the seabed ground is clearly divided from the embankment but a lot of parts show abnormal zones with low resistivity from the results of electric resistivity survey. Hence the causes of the leakage are considered as following: three-dimensional shear strain behavior, irregular compulsory replacement of the soft seabed ground with low strength and quality deterioration of the waterproof sheets during the closing process. The improvement method is determined by considering the constructability in the seawater and its velocity condition, durability, economic feasibility, similar application cases and so on. Consequently, a combination of low slump mortar and slurry grouting and injection method is selected as an optimum combination. Mixing ratio and improvement pattern are determined after drilling investigation and pilot test. The improvement boundary is separated into general and intense leakage area. The construction is performed with each pattern and the improvement effects are confirmed. The confirmed effects with various tests after completion show tolerable ranges for all of the established standards. Finally, various issues such as prediction of length of the waterproof sheet, installation of it against seawater velocity, etc. should be considered when sea dykes are designed or executed around the western sea which has high tide difference.