• Journal of the Korean Geotechnical Society
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• v.22 no.10
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• pp.121-129
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• 2006

Stone column is one of the ground improvement systems which is being used for accelerating consolidation and increasing bearing capacity for settlement sensitive structures like load embankments, bridge abutments, oil storage tanks etc. The effects of this method are enhancement of ground bearing capacity, reduction of settlement, prevention of liquefaction and prevention of lateral ground movement. Recently, geosynthetic reinforced (encased) stone column approach has been developed to improve its load carrying capacity through increasing confinement effect. Although such a concept has successfully been applied in practice, fundamentals of the method have not been fully explored. This paper presents the results of an investigation on the bearing capacity and failure mechanism of geogrid-encased stone column by model tests. The results of the analyses indicated improved bearing capacity of the geogrid reinforced stone column method over the conventional strone column method with no encasing.

• Journal of Conservation Science
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• v.21
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• pp.21-32
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• 2007

Low-viscosity alkoxysilanes that polymerize into the porous network of decayed stone by a sol-gel process are widely used as stone consolidants. During drying, the gel network contracts due to capillary pressure generated by solvent evaporation. We have prepared tetraethoxysilane mixed solution containing methyltrisilane, ethyl trisilane and (3-glycidyloxypropyl)trimethoxysilane having epoxy ring in order to reduce the shrinkage happened inside the stone porous structure during the gel formation. Mixed solutions were applied into sandstone and granites and characterized by FT-IR, SEM. The gelation time, water uptake, contact angles were measured and compared with those of the commercial stone conservation materials.

• Journal of the Korean Geotechnical Society
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• v.24 no.11
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• pp.35-41
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• 2008

Stone columns, one of the soft ground improvement techniques, are being used for not only accelerating consolidation but also increasing bearing capacity of soft grounds. In this study, in order to observe the stress distribution characteristics which are one of the important factors to estimate the settlement reduction of the soft ground, lab-scale experiments were performed in stone column reinforced clay ground. The stress distribution ratio of stone column decreased with the lapse of time after surcharge loading but increased as the stiffness of clay deposit increases. It shows that the modified Baumann and Bauer's solution, which is able to easily predict the stress distribution ratio of stone column reinforced soft ground, exhibits reasonable agreement with the measured data.

• 한국문화재보존과학회:학술대회논문집
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• 2005.11a
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• pp.88-99
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• 2005

• Proceedings of the Korean Geotechical Society Conference
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• 1992.10a
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• pp.75-86
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• 1992

The elevation of reclamation work in the coastal area for the industrial complex is determined through the investigation and review of marine conditions, drainage plan and fill materials. The embankment to be constructed with crushed stone on the soft soil should be safe against the wave force, immediate and long term consolidation settlement, overturning and sliding due to self-weight and other forces. Because of lack of fill material from the borrow pit, the soft marine clay to be dredged shall be used as the reclamation material. And Paper Drain Board is used as the improvement method for the deep soft clay strata.

• Journal of the Korean GEO-environmental Society
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• v.2 no.4
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• pp.63-72
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• 2001

As construction cases on soft ground are increasing, the necessity of ground improvement is also increasing. Granular pile is one of the methods for soft clay and for loose sandy soil. In our country, SCP(Sand Compaction Pile) method using sand material has been mainly used to improve soft ground, but Granular pile with crushed-stone was not used much. However, alternative material such that crushed-stone is needed to substitute for sand due to the environmental and economical problems. In this study, staged load test and consolidation test were performed in the laboratory to observe the behavior of soft ground improved by Granular pile. In order to evaluate the characteristics such as bearing capacity, drainage, and settlement, sand and crushed-stone were applied as each pile material. The test results show that crushed-stone has higher bearing capacity and less settlement than those of sand under similar pore water pressure condition. Therefore, crushed-stone is determined to be appropriate as substitute for sand.

• Journal of the Korean Geosynthetics Society
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• v.6 no.1
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• pp.17-25
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• 2007

This study presents a modeling approach for geogrid-encased stone column(GESC) method which is widely used in Europe as an alternative to conventional pile foundations. Several benefits of using the stone column method include sound performance, low cost, expediency of construction, and liquefaction resistance, among others. Recently, geosynthetic-encased stone column approach has been developed to improve load carrying capacity through increasing confinement effect. The aim of this research is to establish a systematic approach for modeling of GESC and to form a database for the fundamentals of GESC. This paper presents details of 3D modeling of GESC together with the general behavior of GESC.

• Journal of the Korean Geotechnical Society
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• v.18 no.5
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• pp.43-54
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• 2002

As construction cases of structure are increasing in the soft ground, the necessity of ground improvement is also increasing. Granular pile is one of the improvement methods for soft ground and for loose sandy soil. In domestic, SCP(Sand Compaction Pile) method using sand material has been mainly used to improve soft ground, but Granular pile with crushed-stone was not used much. However, alternative material such as crushed-stone is needed to substitute for sand due to the environmental and economical problems. In this study, staged load test and consolidation test were performed in the laboratory to observe the behavior of soft ground improved by Granular pile. In order to evaluate the characteristics such as bearing capacity, drainage, md settlement, sand and crushed-stone were applied as each pile material. The test results show that crushed-stone has higher bearing capacity and less settlement than those of sand under similar fore water pressure condition. Therefore, crushed-stone is determined to be appropriate as the substitute for sand.

• Journal of the Mineralogical Society of Korea
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• v.30 no.2
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• pp.71-81
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• 2017

Rock properties and the effects of chemicals that were used for conservation were studied for effective conservation treatment of Seated Buddha rock carving, which is composed of grayish white tuff, at Golguram Hermitage, Gyeongju. The rocks contain 3-5% montmorillonite, a swelling mineral and reacting with water, the d spacing of swelling minerals was increased (1.54-2.69%). On the one hand, the physical properties of the rock samples, such as surface hardness, water absorption rate, and porosity improved after the application of ethyl silicate-based stone strengthener. On the other, the interlayer of swelling minerals decreased and greater the of swelling mineral content, the greater is the extent of swelling (4.23-12.12%). When the ethyl silicate-based stone strengthener was applied after pretreatment with a swelling inhibitor, the physical properties were similar to those of the stone strengthener alone. There was no interlayer spacing change of swelling minerals due to swelling inhibition treatment; however, when the stone strengthener was applied after the swelling inhibitor, interlayer changes were similar to those when only the stone strengthener was treated (4.10-11.85%). Though the peak intensity of swelling minerals in X-ray diffraction pattern decreased, the effect of the swelling inhibitor was almost negligible. Therefore, it is not appropriate to use ethyl silicate-based stone strengthener for Golgulam rock containing swelling minerals and supplementing them with a swelling inhibition system is not effective. Because weathering rapidly progresses when swelling minerals contact moisture, for now, measures to prevent water contact, such as expansion of the canopy, are needed in the lower and side parts of the carving.

• Journal of Conservation Science
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• v.27 no.2
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• pp.201-209
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• 2011

While consolidants based on tetraethoxysilane (TEOS) have been widely used for the consolidation of decaying stone heritages, TEOS-based consolidants suffer from practical drawbacks, such as crack formation of the gel during the drying phase due to the developed capillary force. We have prepared new TEOS-based consolidants containing flexible (3-glycidoxypropyl) trimethoxysilane (GPTMS) in order to reduce capillary force development during gel drying. In this study, we have prepared TEOS/GPTMS-based consolidants containing ETEOS in order to improve the surface hydrophobisity. The physical properties of the TEOS/GPTMS/ETEOS solution with different hydrolysis were compared with those of the commercial products Wacker OH$^{(R)}$. The contact angle of the surface increased with the addition of the ETEOS, which is higher than that of Wacker OH$^{(R)}$. The sol-gel mechanism was manipulated by the degree of hydrolysis as well as the amount of ETEOS. The properties and the applicability of the developed consolidants for the decayed Korean granites are also investigated.