• Title/Summary/Keyword: Extremely soft soil

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A Study on the Steering Characteristics of Tandem Tracked Vehicle on Extremely Cohesive Soft Soil (연약지반 직렬 무한궤도 주행차량의 선회특성 연구)

  • Kim, Hyung-Woo;Lee, Chang-Ho;Hong, Sup;Choi, Jong-Su;Yeu, Tae-Kyeong;Kim, Sea-Moon
    • Ocean and Polar Research
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    • v.32 no.4
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    • pp.361-367
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    • 2010
  • The principal objective of this paper was to evaluate the steering characteristics of a tandem tracked vehicle, each side of which features two tandem tracks, when crawling on extremely cohesive soft soil. The tandem tracked vehicle is assumed to be a rigid-body with 6-dof. The dynamic analysis program of the tandem tracked vehicle was developed via Newmark's method and the incremental-iterative method. A terra-mechanics model of extremely cohesive soft soil was implemented according to the relationships of normal pressure to sinkage, of shear resistance to shear displacement, and of dynamic sinkage to shear displacement. In order to simplify the characteristics of contact interaction between track segments and cohesive soft soil, the characteristics of soil are equated to the properties of intact soil. In an effort to evaluate the steering characteristics of a tandem tracked vehicle crawling on extremely cohesive soft soil, a series of dynamic simulations were conducted for a tandem tracked vehicle model with respect to the front and rear steering angle, the steering ratio, and the initial velocity.

Dynamic Analysis of Underwater Tracked Vehicle on Extremely Soft Soil by Using Euler Parameters (오일러 매개변수를 이용한 해저연약지반 무한궤도 차량의 동적거동 해석)

  • Kim, Hyung-Woo;Hong, Sup;Choi, Jong-Su;Yeu, Tae-Kyeong
    • Journal of Ocean Engineering and Technology
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    • v.20 no.6 s.73
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    • pp.93-100
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    • 2006
  • This paper is concerned with the dynamic analysis of an underwater tracked vehicle, operating on extremely soft soil of the deep-seafloor. The vehicle is assumed as a rigid-body with 6-dof. The orientation of the vehicle is defined by four Euler parameters. To solve the motion equations of the vehicle, the Newmark numerical integrator is used in the incremental-iterative algorithm. The normalization constraint of Euler parameters is satisfied by using of a sequential updating method. The hydrodynamic force and moment are included in the tracked vehicle's dynamics. The hydrodynamic effects on the performance of tracked vehicles are investigated through numerical simulations.

Dynamic Analysis of Tracked Vehicle by Buoy Characteristics (부이 특성에 따른 궤도 차량 동적 거동)

  • Kim, Hyung-Woo;Min, Cheon-Hong;Lee, Chang-Ho;Hong, Sup;Bae, Dae-Sung;Oh, Jae-Won
    • Ocean and Polar Research
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    • v.36 no.4
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    • pp.495-503
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    • 2014
  • This paper focuses on the dynamic responses of a tracked vehicle crawling on extremely cohesive soft soil, each side of which is composed of two parallel tracks. The tracked vehicle consisted of 2 bodies. One body is the tracked vehicle body, which is assumed to be a rigid body with 6 DOFs. The other body is the buoy body. The two bodies are connected by a revolute joint. In order to evaluate the travelling performance of a 7 DOFs vehicle, a dynamic analysis program for the tracked vehicle was developed using Newmark's method and the incremental-iterative method. The effects of road wheels on the track and soil are not taken into account. A terra-mechanics model of extremely cohesive soft soil is implemented in form of relationships: normal pressure to sinkage, shear resistance to shear displacement, and dynamic sinkage to shear displacement. Pressure-sinkage relationship and shear displacement-stress relationship should represent the non-linear characteristics of extremely soft soil. Especially, since the shear resistance of soft soil is very sensitive to shear displacement, spatial distribution of shear displacement occurring at the contact area of the tracks should be calculated precisely. The proposed program is developed in FORTRAN.

Study on Steering Ratio of Four-Row Rigid Tracked Vehicle on Extremely Cohesive Soft Soil Using Numerical Simulation (수치해석을 이용한 연약지반 4열 강체 무한궤도 차량의 최적 선회비 연구)

  • Kim, Hyung-Woo;Lee, Chang-Ho;Hong, Sup;Choi, Jong-Su;Yeu, Tae-Kyeong;Min, Cheon-Hong
    • Journal of Ocean Engineering and Technology
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    • v.27 no.6
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    • pp.81-89
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    • 2013
  • This paper considers the steering characteristics of a four-row tracked vehicle crawling on extremely cohesive soft soil, where each side is composed of two parallel tracks. The four-row tracked vehicle (FRTV) is assumed to be a rigid body with 6-DOF. A dynamic analysis program for the tracked vehicle is developed using the Newmark-${\beta}$ method based on an incremental-iterative scheme. A terra-mechanics model of an extremely cohesive soft soil is implemented in the form of the relationships of the normal pressure to the sinkage, the shear resistance to the shear displacement, and the dynamic sinkage to the shear displacement. In order to investigate the steering characteristics of the four-row tracked vehicle, a series of dynamic simulations is conducted with respect to the distance between the left and right tracks (pitch), steering ratios, driving velocity, reference track velocity, lengths of the tracks, and properties of the cohesive soft soil. Through these numerical simulations, the possibility of using a kinematic steering ratio is explored.

Dynamic Analysis of Underwater Test Collector on Extremely Soft Soil (해저연약지반 시험집광기의 동적거동 해석)

  • Kim, Hyung-Woo;Hong, Sup;Choi, Jong-Su;Yeu, Tae-Yeong
    • The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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    • v.13 no.3
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    • pp.222-228
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    • 2008
  • We conducted a dynamic analysis of an underwater test collector, which operates on extremely soft soil of deep-seafloor. The underwater test collector consists of nodule pick-up device, vehicle tracks, nodule crusher, loading frame and electric-electronic system. The weight of underwater test collector is about 8600 kg. The average normal pressure, that the underwater test collector supports, is about 6.0 kPa. The dynamic analysis model of underwater test collector is developed using commercial software RecurDyn-LM and Visual Fortran 90. A terramechanics model of extremely soft soil is implemented to the software based on user-written subroutine and applied to the dynamic analysis of the underwater test collector model. The dynamic responses of test collector are studied with respect to track velocities, terrain conditions, and coefficients of added mass and drag.

Comparative study on the behavior of lime-soil columns and other types of stone columns

  • Malekpoor, Mohammadreza;Poorebrahim, Gholamreza
    • Geomechanics and Engineering
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    • v.7 no.2
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    • pp.133-148
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    • 2014
  • An experimental study is carried out to evaluate the performance of Lime mortar-Well graded Soil (Lime-WS) columns for the improvement of soft soils. Tests are conducted on a column of 100 mm diameter and 600 mm length surrounded by soft soil in different area ratios. Experiments are performed either with the entire area loading to evaluate the load - settlement behavior of treated grounds and only a column area loading to find the limiting axial stress of the column. A series of tests are carried out in soaking condition to investigate the influence of moisture content on the load - settlement behavior of specimens. In order to compare the behavior of Lime-WS columns with Conventional Stone (CS) columns as well as Geogrid Encased Stone (GES) columns, the behavior of these columns have been also considered in the present study. Remarkable improvement in the behavior of soft soil is observed due to the installation of Lime-WS columns and the performance of these columns is significantly enhanced by increasing the area ratio. The results show that CS columns are not suitable as a soil improvement technique for extremely soft soils and should be enhanced by encasing the column or replaced by rigid stone columns.

A Study on Dynamic Responses of Tracked Vehicle on Extremely Soft Cohesive Soil (점착성 연약지반 주행차량의 동적거동 연구)

  • Kim, Hyung-Woo;Hong, Sup;Choi, Jong-Su
    • Ocean and Polar Research
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    • v.26 no.2
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    • pp.323-332
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    • 2004
  • This paper concerns about a study on dynamic responses of tracked vehicle on soft cohesive soil. For dynamic analyses of tracked vehicle, two different models were adopted, i.e. a single-body model and a multi-body model. The single-body vehicle model was assumed as a rigid body with 6-dof. The multi-body vehicle was modeled by using a commercial software, RecurDyn-LM. For the both models properties of cohesive soft soil were modeled by means of three relationships: pressure to sinkage, shear displacement to shear stress, and shear displacement to dynamic sinkage. Traveling performances of the two tracked vehicle models were compared through dynamic analyses in time domain.

Reclamation and Soil Improvement on Ultra Soft Soil (II) - Soil Improvement (초연약지반의 매립 및 지반개량 사례 연구 (II) - 지반개량)

  • Na, Yung-Mook;Kim, Hee-Hong;Kwon, Duk-Woo
    • Journal of the Korean GEO-environmental Society
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    • v.6 no.1
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    • pp.33-44
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    • 2005
  • The 'Silt Pond' is 180 hectares in size and contained ultra soft slurry-like soil varying between 3 to 20 meters in thickness. Soil improvement work in the Silt Pond commenced by installing vertical drains in the mid of 1996, following completion of sand spreading up to +4.0m CD. Prior to soil improvement work in the main area of Silt Pond, experimental tests including laboratory tests with a large diameter consolidation cell and pilot tests were carried out to investigate the deformation behavior of an extremely soft soil. Due to its high compressibility, large strain usually occurred in the initial stage of deformation does not comply with Terzaghi's one dimensional consolidation theory. Taking into consideration experimental test results, the soil improvement works were carried out in main area of Silt Pond containing ultra soft soil. This paper presents the case study on improvement of ultra-soft soil.

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Study of Deepsea Mining Robot "MineRo" Using Table of Orthogonal Arrays (직교 배열표를 이용한 심해저 채광로봇 미내로의 주행 특성 연구)

  • Lee, Chang-Ho;Kim, Hyung-Woo;Choi, Jong-Su;Yeu, Tae-Kyeong;Lee, Min-Uk;Oh, Jae-Won;Hong, Sup
    • Journal of Ocean Engineering and Technology
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    • v.28 no.2
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    • pp.152-159
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    • 2014
  • KRISO(Korea Research Institute of Ships & Ocean Engineering) designed and manufactured a pilot mining robot called "MineRo" in 2012. MineRo is composed of four track modules. In general, much time and money are needed for deep-sea tests. Therefore, a numerical analysis to predict the dynamic behaviors has to be performed before a deep-sea test. In the numerical analysis, the information about the mining robot and soil properties are the most important factors to analyze the driving performance and dynamic response of MineRo. A terra-mechanics model of extremely cohesive soft soil is implemented in the form of the relationships between the normal pressure and sinkage, and between the shear stress and shear displacement. It is possible to acquire information about MineRo from the CAD model in the design phase. The Wong model is applied to the terra-mechanics model. This model is necessary to acquire many soil coefficients for a numerical analysis. However, in soil testing, the amount of soil property data obtained is limited. Moreover, it is difficult to analyze all of the cases for the many soil coefficients. In this paper, the dynamic behaviors of MineRo are analyzed according to the driving velocity, steering ratio, and variable extremely cohesive soft soil properties using a table of orthogonal arrays. The dynamic responses of MineRo are the turning radius, sinkage, and slip ratio. The relationships between the dynamic responses and variable soil properties are derived for MineRo.

Effects of Dye Bath Soil Type on Quality of Mat Rush (Juncus decipiens Nakai) (서로 다른 니염토가 골풀의 품질에 미치는 영향)

  • Lim, June-Taeg;Kwon, Byung-Sun;Jung, Dong-Soo;Kae, Bong-Myung;Hyun, Kyu-Hwan;Shin, Dong-Young
    • KOREAN JOURNAL OF CROP SCIENCE
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    • v.51 no.spc1
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    • pp.229-232
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    • 2006
  • This study was conducted to select the most suitable dye bath soil of mat rush for good quality. Dry stem weight ranged from 102.5 to 107.0 g, dry stem ratio ranged from 34 to 36%, color of stem ranged from soft gray to heavy gray, degree of softness ranged from high to low and degree of floating ranged from extremely high to low. All the good quality components, such as dry stem weight, dry stem ratio, color of stem, degree of softness and degree of floating showed large variations. Hadong white ceramic soil, the superior dye bath soil of mat rush, showed relatively superior values for all the good quality components with 102.5 g in light dry stem weight, 34% in high dry stem ratio, good color of soft gray in color stem, high in degree of softness and extremely high id degree of floating. The results indicate that dye bath soils shows different adaptabilities to a particular dye bath and Hadong white ceramic soil seems to be the most suitable dye bath soil of mat rush for good quality.