• Geomechanics and Engineering
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• v.8 no.1
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• pp.113-132
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• 2015

In this study, lime (L), silica fume (SF), and lime-silica fume (L-SF) mix have been used for stabilizing and considering their effects on the soft clay soil. The improvement technique adopted in this study includes improving the behaviour, of a square footing over soft clay through grouting the clay with a slurry of lime-silica fume before and after installation of the footing. A grey-colored densified silica fume is used. Three percentages are used for lime (2%, 4% and 6%) and three percentages are used for silica fume (2.5%, 5%, 10%) and the optimum percentage of silica fume is mixed with the percentages of lime. Several tests are made to investigate the soil behaviour after adding the limeand silica fume. For grouting the soft clay underneath and around the footing, a 60 ml needle was used as a liquid tank of the lime-silica fume mix. Slurried silica fume typically contains 40 to 60% silica fume by mass. Four categories were studied to stabilize soft clay before and after footing construction and for each category, the effectiveness of grouting was investigated; the effect of injection hole spacing and depth of grout was investigated too. It was found that when the soft clay underneath or around a footing is injected by a slurry of lime-silica fume, an increase in the bearing capacity in the range of (6.58-88)% is obtained. The footing bearing capacity increases with increase of depth of grouting holes around the footing area due to increase in L-SF grout. The grouting near the footing to a distance of 0.5 B is more effective than grouting at a distance of 1.0 B due to shape of shear failure of soft clay around the footing.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.04a
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• pp.98-101
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• 2002

Numerical experiments were performed to investigate horizontal barrier formation in unsaturated soils by permeation grouting through multiple vertical injection pipes. The results were compared with the horizontal barrier formation achieved by using multiple horizontal injection pipes. It was observed that tile point injection of the vertical pipe system generates a gel barrier that has a less lateral area than the injection through the horizontal pipe.

• Geomechanics and Engineering
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• v.10 no.4
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• pp.527-546
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• 2016

This paper discusses improvements of compressibility, permeability, static and liquefaction strengths of in-situ soils by grouting. Both field testing and laboratory evaluation of the on-site samples were conducted. The improvement of soils was influenced by two main factors, i.e., the grout materials and the injection mechanisms introduced by the field grouting. On-site grout mapping revealed the major mechanism was fracturing accompanied with some permeation at deeper zones of sandy soils, where long-gel time suspension grout and solution grout were applied. The study found the compressibility and swelling potential of CL soils at a 0.5 m distance to grout hole could be reduced by 25% and 50%, respectively, due to the grouting. The effect on hydraulic conductivity of the CL soils appeared insignificant. The grouting slightly improved the cohesion of the CL soils by 10~15 kPa, and the friction angle appeared unaffected. The grouting had also improved the cohesion of the on-site SM soils by 10~90 kPa, while influences on the friction angle of soils were uncertain. Liquefaction resistances could be enhanced for the sandy soils within a 2~3 m extent to the grout hole. Average improvements of 40% and 20% on the liquefaction resistance were achievable for the sandy soils for earthquake magnitudes of 6 and ${\geq}7.5$, respectively, by the grouting.

• Journal of the Korea Institute of Building Construction
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• v.16 no.1
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• pp.45-52
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• 2016

In this research, characteristic properties of gel time and homo gel strength of liquid chemical grouting material for soil grouting using non-cement binder(NCB) were measured according to kinds of liquid B's Binders, W/B of liquid B's Binders and the volume ratio between liquid A and liquid B in order to examine on the applicability of soil grouting material using non-cement binder. The test was performed using NCB-1, NCB-2, NCB-3 which are environment-friendly inorganic binders developed by means of collaboration by our research team and which are different from chemical composition ratio each other. In conclusion, it was found that NCB could be applied to liquid soil grouting material using non-cement binder and replace ordinary portland cement, because NCB had the most excellent performance in certain section of gel time and homo gel strength in condition of this experiment.

• Journal of the Korean GEO-environmental Society
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• v.11 no.10
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• pp.25-31
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• 2010

Anchor, soil nail, micropile have been widely used for slope reinforcement and foundation. These all methods need grouting work after placing reinforcing member. In domestic case, gravity fill techniques and pressure grouting techniques are mainly used. In contrast the pressure re-injection grouting method is not commonly used because grouting equipment and lack of practical application example is short and the verification of reinforcing effect is difficult. Pressure re-injection grouting is a kind of post grouting which technique increases the radial stresses acting on the grout body and causes irregular surface to be developed around bond length that tends to interlock the grout and the ground. In this study, the field test was performed to evaluate the reinforcing effect with the variation of grouting methods and pullout characteristics of reinforcing member placed by pressure re-injection grouting method. The test results showed that the post-grouting methods were useful to increase the pullout capacity.

• Geomechanics and Engineering
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• v.23 no.6
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• pp.513-521
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• 2020

In this paper, due to the need for cutting cement-soil group pile composite foundation under the 7-story masonry structure of Zhenghe District and the shield tunnel of Zhengzhou Metro Line 5, a field test was conducted to directly cut cement-soil single pile composite foundation with diameter Ф=500 mm. Research results showed that the load transfer mechanism of composite foundation was not changed before and after shield tunnel cut the pile, and pile body and the soil between piles was still responsible for overburden load. The construction disturbance of shield cutting pile is a complicated mechanical process. The load carried by the original pile body was affected by the disturbance effect of pile cutting construction. Also, the fraction of the load carried by the original pile body was transferred to the soil between the piles and therefore, the bearing capacity of composite foundation was not decreased. Only the fractions of the load carried by pile and the soil between piles were distributed. On-site monitoring results showed that the settlement of pressure-bearing plates produced during shield cutting stage accounted for about 7% of total settlement. After the completion of pile cutting, the settlements of bearing plates generated by shield machine during residual pile composite foundation stage and shield machine tail were far away from residual pile composite foundation stage which accounted for about 15% and 74% of total settlement, respectively. In order to reduce the impact of shield cutting pile construction on the settlement of upper composite foundation, it was recommended to take measures such as optimization of shield construction parameters, radial grouting reinforcement and "clay shock" grouting within the disturbance range of shield cutting pile construction. Before pile cutting, the pile-soil stress ratio n of composite foundation was 2.437. After the shield cut pile is completed, the soil around the lining structure is gradually consolidated and reshaped, and residual pile composite foundation reaches a new state of force balance. This was because the condensation of grouting layer could increase the resistance of remaining pile end and friction resistance of the side of the pile.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.04a
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• pp.110-113
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• 2002

Statistical- based, principal component analysis (PCA) was applied to chemical data from two underground storage systems containing LPG to assess the usefulness of such technique at the initial stage (Pyeongtaek) or middle stage (Ulsan) of hydrochemical studies. For the first case, both natural and anthropogenic contamination characterize regional groundwater. Saline water buffered by Namyang lake affects as a natural factor, whereas cement grouting influence as an artificial factor. For the second study area, contaminations due to operation of LPG caverns, such as disinfection activity and cement grouting effect, deteriorate groundwater quality. This study indicates that principal component analysis would be particularly useful for summarizing large data set for the purpose of subsurface characterization, assessing their vulnerability to contamination and protecting recharge zones.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.11a
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• pp.71-76
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• 2000

In generally, grouting consists of injecting a suspension or solution into the voids of soils. The low slump mortar grout has been used in America since 1950's. The Compaction Grouting, the injection of a very stiff under relatively high pressure, form a cylinderical grout support pile. The grout generally does not enter soil pores but remains in homogeneous mass that gives controlled displacement either to compact loose soils, or for lifting of structures, or both. In this paper, on the case of the reinforcement construction of 00 plant that the foundation's bearing capacity is insufficient and is to reinforce the foundation, a study has been peformed to analyze the effectiveness of the ground improvement. The bearing capacity of the Compaction Pile has been verified by the S.P.T and the settlement of the improved ground has been monitored rising the magnetic extensometer.

• Journal of Korean Tunnelling and Underground Space Association
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• v.10 no.4
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• pp.383-395
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• 2008

The grouting is one of the improved techniques which is aim to decrease the permeability and to strengthen the soft ground. But The grouting method has many problems about a suitability of grouting procedure and an effectiveness of grouting after grouting work because of a technical characteristic operated inside the soil. The grouting $p{\sim}q{\sim}t$ chart of a typical index about grouting rate and time alteration of grouting pressure is one method to estimate the suitability of grouting factor with monitoring during grouting procedure. This study is automatic grouting system (AGS) which can control the testing and grouting procedures. It can make the detailed $p{\sim}q{\sim}t$ chart and analyze the grouting characters of the ground by comparing the detailed pattern of $p{\sim}q{\sim}t$ chart with standard pattern. If using the $p{\sim}q{\sim}t$ chart derived from AGS in the grouting work, it is an objective standard estimating the suitability of grouting factor with grouting materials, grouting method, grouting rate and grouting pressure, as results it expects successfully to improve reliability of the grouting work.

• Journal of the Korean Geotechnical Society
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• v.24 no.4
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• pp.101-114
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• 2008

Pressurized grouting is a common technique in geotechnical engineering applications to increase the stiffness and strength of the ground mass and to fill boreholes or void space in a tunnel lining and so on. Recently, the pressurized grouting has been applied to a soil-nailing system which is widely used to improve slope stability. Because interaction between pressurized grouting paste and adjacent ground mass is complicated and difficult to analyze, the soil-nailing design has been empirically performed in most geotechnical applications. The purpose of this study is to analyze the ground behavior induced by pressurized grouting paste with the aid of laboratory model tests. The laboratory tests are carried out for four kinds of granitic residual soils. When injecting pressure is applied to grout, the pressure measured in the adjacent ground initially increases for a while, which behaves in the way of the membrane model. With the lapse of time, the pressure in the adjacent ground decreases down to a value of residual stress because a portion of water in the grouting paste seeps into the adjacent ground. The seepage can be indicated by the fact that the ratio of water/cement in the grouting paste has decreased from a initial value of 50% to around 30% during the test. The reduction of the W/C ratio should cause to harden the grouting paste and increase the stiffness of it, which restricts the rebound of out-moved ground into the original position, and thus increase the in-situ stress by approximately 20% of the injecting pressures. The measured radial deformation of the ground under pressure is in good agreement with the expansion of a cylindrical cavity estimated by the cavity expansion theory. In-situ test revealed that the pullout resistance of a soil nailing with pressurized grouting is about 36% larger than that with regular grouting, caused by grout radius increase, residual stress effect, and/or roughness increase.