• Journal of the Korean Geosynthetics Society
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• v.19 no.4
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• pp.65-74
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• 2020

In earth pressure balance (EPB) shield TBM tunnelling, the application of soil conditioning which improves properties of the excavated muck by additives injection, is generally used for enhancing the performance of TBM. Therefore it is important to apply the soil conditioning in the numerical model which simulates excavation performance of TBM equipment, but related studies on a method that simulates soil conditioning are insufficient to date. Accordingly, in this study, an laboratory pressurized vane test apparatus was devised to evaluate the characteristics of conditioned soil. Using the apparatus, the vane shear tests were performed on foam-conditioned soil with different shear rates, and the test was numerically simulated with discrete element method (DEM). Finally, the contact properties of particles in DEM were determined by comparing the results of test and analysis, and it indicates that the applicability of pressurized vane test and DEM model for reproducing soil conditioning in TBM excavation model with DEM.

• Asian Journal of Turfgrass Science
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• v.7 no.1
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• pp.13-18
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• 1993

Much attention has been given recently to solve the environmental contamination in golf courses Changing to culture practice rather than chemical practice that depends on pesticides and fertilizers is a hot issue in golf courses or grasslands. Organic soil conditioners improve soil-plant envirormental conditions rich in physical properties. In this study, measuring systems to evaluate soil conditioning effects were set up for on-site purpose. After establishing the methodology for evaluating soil conditioner effects, 2 kinds of organic conditioners were rested for examination. The systems for the methodology included a set of simulating equipment for field capacity, an impact type soil column compactor, and an infiltration-percolation system. Test results using the systems showed bulk density and infiltration rate of mixed soil were decreased at highter rates of conditioner, but total porocities were increased. Increased porocities were most capillary pore space which has a positive effect on soil water potential. The systems and methodology in this study seem to have an efficiency to measure the effects of soil conditioner on site purpose.

• Journal of Korean Tunnelling and Underground Space Association
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• v.25 no.2
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• pp.65-85
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• 2023

The use of TBM (Tunnel boring machine) has increased worldwide due to its performance together with the benefit of being safely and environmentally friendly compared to conventional tunneling. In particular, EPB (Earth Pressure Balanced) TBM is widely used because it can be applied to various grounds compared to Open TBM. Also EPB TBM has a simple mechanical structure and advantages in cost, requires less ground area than Slurry TBM. EPB TBM has advantages in soft ground, and more importantly, can extend its applicability by use of appropriate soil conditioning, which improves mechanical and hydrological properties of excavated soil and increases the excavation performance of EPB TBM. Various studies suggested the proper mixing ratio and injection ratio, but almost they are limited to laboratory test under atmospheric pressure such as slump test. Actual field conditions may differ depending on the ground and mechanical condition. In this study, first the amount of used soil conditioning used in the field with various grounds from hard rock to soft ground was estimated through laboratory tests and compared with the estimate in design stage. And also it was compared with the amount used during actual excavation. In addition, experience of soil conditioning for the problems of cutter head clogging and groundwater inrush that occurred during excavation is discussed. Finally, lesson learned for the use of soil conditioning in difficult ground condition such as mixed ground are reviewed.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.21 no.3
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• pp.99-110
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• 2018

Compared to yellow dust coming from China or particulate matter created naturally in spring due to Total Suspended Particulate(TSP), particulate matter in winter season have much more serious effect on human body as they penetrate cell membranes. Although such particulate matter are becoming a social issue, there are no concrete plans on how to reduce them. Air-purifying plants are limited in maintaining the indoor air quality of large area because it is usually difficult to quantify their performance. In order to improve this, a bio-filter that can be connected to air conditioner is suggested as an option. This study seeks to improve air conditioning model-based monitoring method for bio-filters from prior studies and objectify correlations between applied vegetation and growing environment into quantitative indicators. By doing so, this study seeks to provide criteria on plants applied to artificial soil-based vegetation bio-filters and basic information to set air-conditioning features. The study results confirmed significant tendency on the growing stability of each purifying plant in mechanical air-conditioning environment. Among three models selected for bio-filter vegetation models, epipremnum aureum showed high performance in quantitative indicators, including soil moisture, EC, and leaf temperature, etc., indicating that it would assure the highest growing stability in this test air-conditioning environment.

• Korean Journal of Soil Science and Fertilizer
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• v.25 no.4
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• pp.311-324
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• 1992

Polymeric substances in organic matter of soils aggregate soil particles into a crumb structure which greatly influences such properties as water movement, aeration and heat transfer. Poorly-structured soils may be improved by the incorporation of synthetic polymers where the main objects are : promoting germination or establishing crops, improving drainage, combating wind and water erosion, and reducing evaporation from the surface of soil under arid condition.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.23 no.5
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• pp.356-364
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• 2011

Storage and transfer heat in soils is governed by the soil thermal properties and these properties are therefore needed in many engineering applications, including horizontal ground heat exchanger for ground-coupled heat pumps. This paper presents the evaluation results of the thermal diffusivity of soils (silica, quartzite, limestone, sandstone, granite, and two masonry soils used for the trench backfilling materials of the horizontal ground heat exchanger. To assess this thermal property, we (i) measure the soil thermal conductivities using single-probe method and (ii) use the de Vries method of summing the heat capacities of the soil constituents. The results show that the thermal diffusivity tends to increase as dry soil begins to wet, but it approaches a constant value or even decreases as the soil continues to wet. Combined algorithm with and improved model for the thermal conductivity of soils and the constituent equation provides accurate estimates of the soil thermal diffusivity.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.18 no.10
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• pp.783-790
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• 2006

A one-dimensional numerical model coupled with parameter estimation is used to predict the effective thermal conductivities of soil formations and borehole resistances from in situ field test data. In this application a new method of using initial ignoring time (IIT) obtained from error estimation is tried and turned out to be successful in determining soil thermal conductivities. This method is used for single-U and double-U borehole system. The results of this method are compared and agreed well with those of existing software (GPM) in the analysis of single-U borehole data. In the analysis of double-U borehole data this method seems to be better in predicting soil and borehole properties.

• Journal of Korean Tunnelling and Underground Space Association
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• v.24 no.5
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• pp.355-374
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• 2022

Soil conditioning improves the performance of EPB (earth pressure balance) shield TBMs (tunnel boring machines) by reducing shear strength, enhancing workability of the excavated soil, and supporting the tunnel face during EPB tunnelling. The mechanical and rheological behavior of the excavated muck mixed with additives should be properly evaluated to determine the optimal additive injection condition corresponding to each ground type. In this study, the laboratory pressurized vane test apparatus equipped with a vane-shaped rheometer was developed to reproduce the pressurized condition in the TBM chamber and quantitively evaluate rheological properties of the soil specimens. A series of the pressurized vane tests were performed for an artificial sand soil by changing foam injection ratio (FIR) and polymer injection ratio (PIR), which are the injection parameters of the foam and the polymer, respectively. In addition, the workability of the conditioned soil was evaluated through the slump test. The peak and yield stresses of the conditioned soil with respect to the injection parameters were evaluated through the rheogram, which was derived from the measured torque data in the pressurized vane test. As FIR increased or PIR decreased, the workability of the conditioned soil increased, and the maximum torque, peak stress, and yield stress decreased. The peak stress and yield stress of the specimen from the laboratory pressurized vane test correspond to the workability evaluated by the slump tests, which implies the applicability of the proposed test for evaluating the rheological properties of excavated soil.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.23 no.5
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• pp.321-326
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• 2011

Recently, ground source heat pump (GSHP) systems have been introduced in many modem buildings which use the annually stable characteristic of underground temperature as one of the renewable energy uses. However, all of GSHP systems cannot achieve high level of energy efficiency and energy-saving, because their performance significantly depends on thermal properties of soil, the condition of groundwater, building loads, etc. In this research, the effect of thermal properties of soil on the performance of GSHP systems has been estimated by a numerical simulation which is coupled with ground heat and water transfer model, ground heat exchanger model and surface heat balance model. The thermal conductivity of soil, the type of soil and the velocity of groundwater flow were used as the calculation parameter in the simulation. A numerical model with a ground heat exchanger was used in the calculation and, their effect on the system performance was estimated through the sensitivity analysis with the developed simulation tool. In the result of simulation, it founds that the faster groundwater flow and the higher heat conductivity the ground has, the more heat exchange rate the system in the site can achieve.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.2
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• pp.173-182
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• 2005

The Performance of U-tube ground heat exchanger for geothermal heat Pump systems depends on the thermal properties of the soil, as well as grout or backfill materials in the borehole. In-situ tests provide a means of estimating some of these properties. In this study, in-situ thermal response tests were completed on two vertical boreholes, 130 m deep with 62 mm diameter high density polyethylene U-tubes. The tests were conducted by adding a monitored amount of heat to water over a $17\~18$ hour period for each vertical boreholes. By monitoring the water temperatures entering and exiting the loop and heat load, overall thermal conductivity values of grout/soil formation were determined. Two parameter estimation models for evaluation of thermal response test data were compared when applied on the same temperature response data. One model is based on line-source theory and the other is a numerical one-dimensional finite difference model. The average thermal conductivity deviation between measured data and these models is of the magnitude $1\%$ to $5\%$.