• Journal of the Korean Geotechnical Society
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• v.33 no.10
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• pp.49-58
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• 2017

Grouting for soil improvement has generally been applied to the depth over water table. Recently, it is needed to develop the grouting technique for soils under greater static water pressure or greater overburden pressure in constructions such as deep excavation or harbour deepening. In this study, a laboratory apparatus was developed to control the injection pressure, load pressure, and hydrostatic pressure. A series of experiments were performed with various degrees of hydrostatic pressure using the developed equipment. As a result, injected volume increase as injection pressure increase, while the volume significantly decreased under hydrostatic pressure. Larger volume of grout bulb was shown in soils with larger granular and pore size based on the comparison result of volume changes with respect to the amount of grouting injection.

• Journal of the Korean Geotechnical Society
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• v.39 no.2
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• pp.19-30
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• 2023

Underground structures, such as compacted sand piles applied as soft ground countermeasures, are analyzed for settlement and stability by the composite ground design method. The basic principle of the composite ground design method is the arching effect. The reinforcing effect of the pile is evaluated as the stress-distribution ratio. When applying grouting piles with elastic properties using the ground reinforcement method, the existing stress-distribution ratio was only considered when the pile was installed. This study shows that the method of applying the stress-distribution ratio applied in previous studies should be changed when the ground reinforcement pile is installed at an arbitrary location in the ground without raising it to the ground surface. When high strength jet routing is applied, the stress-distribution ratio (n) to the in-situ ground generally ranges from 30 to 50. However, if the pile is located far from the surface and the depth goes down to the boundary depth of the stress sphere, the stress-distribution effect rapidly decreases, and the stress-distribution ratio converges to 1.5.

• Journal of the Korean GEO-environmental Society
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• v.22 no.12
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• pp.59-63
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• 2021

This study presented the characteristics and additive effects of the grout with mixing ratio for developing of high-efficiency grouting technology under high depth conditions. The laboratory investigation were conducted with Portland cement (OPC) and micro cement (S8000-E) including viscosity experiments, particle size analysis experiments, Gel-Time experiments and uniaxial compressive strength experiments. As a result of the viscosity experiment, it was shown that OPC is advantageous in terms of viscosity, but S8000-E is suitable when considering the passage of rock joint intervals through particle size analysis. The Gel-Time experiment shows that it is not that difficult with injection as a grout material even when silica fume (SF) was applied. The strength of the cured material is improved as increase in the content of silica fium (SF). Within the range of the study, the optimal mixing ratio obtained through various experiments is S8000-E, w/c=70%, silica fium (SF)=6%, and 7 days.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2102-2107
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• 2007

GSHP systems are used for air-conditioning systems in commercial buildings, schools, and factories because of low operating and maintenance costs. These systems use the earth as a heat source in heating and a heat sink in cooling mode. Ground heat exchangers are classified by a horizontal and vertical type according to the installation method. Vertical type is usually constructed by placing small diameter high density polyethylene tube in a vertical borehole. Vertical tube sizes range from 20 to 40 mm nominal diameter. Borehole depth range between 100 and 200 m depending on local drilling conditions and available equipment. In this study, to evaluate the performance of single u-tube with bentonite grouting, single u-tube with broken stone grouting and double u-tube bentonite grouting of vertical ground heat exchangers, test sections are buried on the earth and experimental apparatus is installed. Therefore the heat transfer performance and pressure loss of these are estimated.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09a
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• pp.29-39
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• 2010

By understanding the construction process of sea dikes and the current state of the thickness and speed of fluid in the bottom layer protection work of final closure gaps, a construction method applicable for the blocking of bottom layer work will be selected. The three construction methods selected will be tested in site through various methods, and the reinforcement of bottom layer protection and impervious effect will be verified. The verification results are as follows: 1) The overall riprap layer were 0.5~1.0m thicker than planned so that the grouting depth and grout input amount increased 2) The applied construction methods permeability of riprap layers were improved from $\alpha{\times}10^{-2}cm/s$ before the construction to $\alpha{\times}10^{-4}cm/s$ after construction. 3) The results of core extraction in order to grossly verify the hardening time and durability allowed the identification of grout injection effect. The amount of filling of the injection was difficult to judge because the slime in many areas made the reading of borehole photography difficult.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.267-278
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• 2010

To improve the grout penetration characteristics, vibration method was adopted in this study. The grout material perturbed by cyclic vibration is injected into the ground. By applying the vibrating flow system, cement particles will become less adhesive and the clogging tendency will be decreased. A series of pilot-scale chamber tests were performed to verify the enhancement of the groutability by applying the vibratory grout injection; assessment on change of the lumped parameter $\theta$ which represents a barometer of clogging phenomenon was made. Moreover, the effect of vibratory grout injection through the joint was also investigated using artificially made rock joints. Experimental results as well as analytical results show that the grout penetration depth can be substantially improved by vibration grouting. Moreover, it was found that enhancement of the permeation grouting due to vibratory injection is more dominant at low grouting pressure of less than 400kPa.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.11 no.2
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• pp.7-11
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• 2015

Recently, as the demand for sustainable energy sources is increasing, ground-source heat pump (GSHP) systems are receiving growing attention. However, the initial cost of GSHP system is higher than it of the conventional systems, especially, in small-size buildings. Therefore, for the application to the small-size building, it is necessary to develop small-size ground heat exchanger with small-size buildings. In this study, analysis of unit-type heat exchanger due to grouting materials. As a result, 1492.14 W of heat exchange rate was acquired in the condition of cement-silica sand-graphite materials.

• Economic and Environmental Geology
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• v.32 no.6
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• pp.661-667
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• 1999

Estimation of inflow rates into subsection of a tunnel is establishing the proposed grouting part, measuring the degree of grouting, and settling the dispute over deplrtion of groundwater which may be resulted from tunneling. A current meter was used to calculate inflow rates of groundwater to each subsection of the tunnel. The study area is composed of section 1 and 2 of Imha-Youngchun waterway trnnel which has 32.976km length, with each section having 3,745m and 4,079m, respectively. The depth from groung surface to tunnel ranges from 122.45m to 358.3m. Total inflow rates of groundwater into each section measured three times by the current meter, together with bottle and eye measurement, were compared with groundwater inflow rates of each section measured by datalogger. The calcuated inflow rates of the sections by bottle and eye measurement were 8.8%∼54.7% of inflow rate (averaging 27,4%), whwewas those by the current meter were 76.9%∼110.6%(averaging 92.9%). Therfore, the current meter is regarded as useful method to calculate groundwater inflow rates into subsections of a tunnel.

• Journal of the Korean Geotechnical Society
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• v.26 no.7
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• pp.37-47
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• 2010

To improve the grout penetration characteristics, a vibratory grout injection technique was adopted in this study. It is a technique of grout injection in which an oscillating pressure is added to the steady-state pressure as an injection pressure. By applying the vibration during grout injection, cement particles will become less adhesive and the clogging tendency will be decreased. A series of pilot-scale chamber tests were performed to verify the enhancement of the groutability by applying the vibratory grout injection; assessment on the change of the lumped parameter $\theta$ which represents a barometer of clogging phenomenon was made. Moreover, the effect of vibratory grout injection through the joint was also investigated using artificially made rock joints. Experimental results as well as analytical results show that the grout penetration depth can be substantially improved by vibratory grouting. Moreover, it was found that enhancement of the permeation grouting due to vibratory injection is more dominant at grouting pressure less than 400 kPa.

• Tunnel and Underground Space
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• v.28 no.6
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• pp.528-546
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• 2018

Cases of TBM tunnelling have been consistently increasing worldwide. In many recent subsea and urban tunnelling projects, TBM excavation has been preferably considered due to its advantages over drill and blast tunnelling. Difficult ground conditions are highly probable to appear in subsea and urban tunnels because of the shallow working depth and alluvial characteristics. Under the difficult ground conditions, ground reinforcement measures should be considered including grouting, while it is of great importance to select the optimal grout material and injection method to cope with the ground condition. The benefits from TBM excavation, such as fast excavation, increased safety, and reduced environmental impact, can be achieved by applying appropriate ground reinforcement with the minimum overrun of cost and time. In this report, various grouting methods were reviewed so that they can be applied in difficult ground conditions. In addition, domestic and international cases of successful ground reinforcement for difficult grounds were introduced for future reference.