• Journal of Korean Society for Geospatial Information Science
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• v.22 no.3
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• pp.79-85
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• 2014

For the successful operation of unmanned ground vehicles(UGVs), optimal path planning should be considered with trafficability analysis, threat analysis, and so on. From among these, trafficability analysis is immensely important for safeness of UGVs especially in the case of driving the off-road such as unpaved road, grassland, and open fields. Geographical information has a pivotal role in extracting data and measuring cost for specified regions of interest. In this paper, we review possibilities to apply Land Cover Map(LCM) as a new, fundamental source and propose a new generation method of trafficability analysis map for optimal path planning of UGV. The simulation results show that the proposed method significantly improve the previous method by applying LCM either alone or in combination with the other GIS.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2002.10a
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• pp.224-228
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• 2002

To study the trafficability on soft and cohesive benthic terrain, a soil bin is designed and constructed. The information of shear strength of pacific seafloor and the results of dimensional analysis of vehicle-train system are used as basic datum for concept design of soil bin. Cohesive benthic terrain is modeled by means of bentonite-water mixture. The shear strength of the mixture is measured by motorized shear meter. Several facilities are constructed for mixing and evening modeled soil, transporting vehicle model. The shear strength in soil bin is investigated for depth, age and velocity. The result of this study is used as basic information to the experiment, study for development of crawler on benthic terrain.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.40 no.2
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• pp.217-223
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• 2020

As construction work on soft ground increases, many researchers have studied to secure the stability of trafficability with interest in construction safety accidents due to reinforcement work. Although the stability of soft ground is evaluated based on the allowable bearing capacity of theoretical equations proposed in the literature such as Yamanouchi and Meyerhof formulas, further numerical verification also requires comparison of the stress increase (Δσ_z) and deformation of the distributed contact pressure on the soft ground. In this study, the deformation of the soft ground is compared with the increasing the seam tensile strength of geotextile using the finite element analysis program, and the stress increase is investigated by variation of the distributed contact pressure by appling input data of case study.

• Proceedings of the Korean Geotechical Society Conference
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• 2003.03a
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• pp.521-528
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• 2003

In this study, a newly modified soil nailing technology called as the NDB(New Down and Board) soil nailing system is introduced. To improve the trafficability, workability, and economical efficiency, SMC(Sheet Molding Compound) board is adopted instead of using the concrete block facing. The SMC board has a distinct advantage of showing a fine view by directly coating with any kind of environmental photos. Composite material properties of the SMC board and cement grout are distinguished features of the NDB soil nailing system. In the present study, both laboratory tests(bending and punching failure tests) and field pull-out tests are carried out to analyze the behavior characteristics of the NDB soil nailing system, including the stress and strain distribution.

• Journal of the Korean Geotechnical Society
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• v.28 no.10
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• pp.41-54
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• 2012

This paper is to develop the method of surface soil improvement by electric heating equipment. For this purpose, the electric heating systems were invented to apply to the in-situ soil. Iaboratory tests were done to study the behaviors of sea clays by eletric heating. In lab tests, two different heating temperatures, $70^{\circ}C$ and $110^{\circ}C$, were applied to the saturated clays to examine the relationship between evaporation and compaction. In addition, trafficability was analyzed to the heated by applying cone penetrometer to the heated clays Furthermore, in-situ tests were conducted to analyze the range of soil improvement and strength variations. The temperature changes in field were measured and they were compared with those of the commercial program (Temp/W). Also, the bearing capacities of electrically heated field were tested by PBT (plate bearing test). Several conclusions were derived from the results of the numerical analysis and tests (lab and field). The improvement ranges and strength variations of electrically heated soil depended on the heating temperature and time. If the heating temperature is more than $100^{\circ}C$ evaporating the ground water, the bearing capacity and settlement increased rapidly. The bearing capacities of in-situ soil increased more than 3 times, and heated soil emitted a lot of vapors. The soil around electric heater was sintered completely, and its range was almost 20 cm.

• Journal of the Korean Geosynthetics Society
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• v.8 no.3
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• pp.9-16
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• 2009

In generally, ground surface strengthening such as using geotextile is needed to secure trafficability of construction equipment. Several calculation methods for bearing capacity for very soft ground improved by geotextile have been proposed already but they are not established yet. In this paper, elastoplastic finite element analysis is carried out to estimate bearing capacity improvement for very soft ground reinforced by geotextile. In conclusion, by reinforcing with geotextile the bearing capacity improvement of very soft ground is increased with the increase of the settlement after yielding. And it is enough that the length of geotextile is about 3~4 times of the loaded width for the effect to the bearing capacity improvement. Finally, the biggest tensile force of geotextile occurs at an edge of the uniform load.

• Journal of the Korean Geotechnical Society
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• v.19 no.4
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• pp.55-64
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• 2003

Desiccation of a soil is basically the removal of water by evaporation, which is controlled by evaporativity and evaporability. Surface evaporation improves the trafficability which is essential for the access of construction equipment in the area reclaimed with soft clay. The existing traditional methods for evaluating evaporation can not account for the deformation of reclaimed soft soils during evaporation. Therefore, a theoretical model for predicting the rate of evaporation from the surface of a deformable material is proposed. The model is based on a system of equations for coupled heat and mass transfer in unsaturated soils. The modified pressure plate extractor test and glass desiccator test were carried out to obtain the soil-water characteristic curve for a deformable soil. The column drying test was conducted to investigate one dimensional water flow, heat flow and evaporation in the surface. A finite difference program was developed to solve the coupled nonlinear partial differential equations, which permit the study of water, vapor and heat flows in the deformable soil. Comparison between measured and simulated values shows a reasonably good matching between the two.

• Journal of the Korean Geotechnical Society
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• v.21 no.8
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• pp.63-72
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• 2005

Rocks are dumped to soft marine ground in order to improve trafficability and construction conditions in the tideland reclamation construction sites. Though this rock layer under earth fill has caused in a serious seepage problems after construction, seepage behaviors of this embankment structure is not correctly investigated. Water flow through rock layers is, in general, known as Non-Darcy's flow. However, the embedded rock layer under earth fill is not known whether its flow is governed by Darcy's or Non-Darcy's law. Therefore, a numerical analysis, laboratory model test and filed investigations were performed for analyzing the those seepage characteristics in this research. Results show that there is significance of $95\%$ of confidence between observed heads and seepage rates, and the calculated ones by SAMTLE which is developed under the assumption that the water flows through the two-layer system obey the Darcy's flow. And after operating the hydraulic gradient(i) of $0.10\~0.55$ upon laboratory model, these seepage characteristics of the embedded rock layer show that Reynolds Numbers are less than 10 and the relationship between these velocities of rock layer(v) and hydraulic gradients(i) is linearly proportional with more than 0.79 of the coefficient of correlation $(R^2)$. And the Reynolds Number of the velocity calculated by the relation of v=ki in the embedded rock layer of OO sea dike is $1\~6$. It shows also laminar flow. Based on these results, it is concluded that the seepage characteristics of embedded rock layer under earth fill can be laminar and Darcy's flow.