• Title, Summary, Keyword: Very soft ground

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The Reality and Problem of Soft Ground Improvement Construction (연약지반 개량 시공의 실제와 문제점)

  • Choi, Gwi-Bong;Hwang, Soung-Won;Kim, Jong-Ryeol
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.672-679
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    • 2008
  • During recent years, the large soft ground improvements very rapidly increase with industrial development and it is the types and scales of structure that is enlarged by degree. Then, we must enter construct equipment to improve soft ground and we fulfilled works by carrying out soft clay soil to gain trafficability for them. For improving the soft ground, we lay geotextile on soft clay ground and fill the filter sand that can drain the pore water. Then, we landfill cover soil for come by trafficability of construction tools. Ater that we penetrate vertical drain for dehydration through soft ground. there are very complicated works. For these reason we suggest the methods of soft ground improvement constructions.

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Analysis of the effect factors on behavior of the surface reinforced very soft ground (표층처리된 초연약지반 거동에 대한 영향인자 분석)

  • You, Seung-Kyong;Lee, Jong-Sun;Yang, Kee-Sok;Cho, Sam-Deok;Ham, Tae-Gew;Choi, Hang-Seok
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.475-483
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    • 2008
  • It is necessary to develop a national design method for surface reinforcement of very soft ground because most current design works rely on crude empirical correlations. In this paper, the mechanical behavior of very soft ground that is surficially reinforced was investigated with the aid of a sents of numerical analysis. Several material properties of each dredged soft ground, reinforcement and backfill sand mat have been exercised the numerical analysis in order to compare the result of numerical analysis with those of the laboratory model test. Through the matching process between the numerical and experimental result, it is possible to find the appropriate material properties of the dredged soft ground, reinforcements and backfill sand mat. These verified material properties permit to show the effect of the stiffness of reinforcement and the thickness of sand mat on the overall deformation.

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Numerical Analysis on Behaviors of Very Soft Ground Improved by Geotextile (토목섬유로 개량된 초연약지반의 거동에 관한 수치해석)

  • Ahn, Dong-Han;You, Seung-Kyong
    • 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.

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Evaluation of Influencing Factors on Settlement Behavior of Very Soft Ground with Reinforced Surface (표층처리공법으로 개량된 초연약지반의 침하거동에 미치는 영향인자 분석)

  • You, Seung-Kyong;Lee, Jong-Sun;Ham, Tae-Gew;Yang, Kee-Suk;Cho, Sam-Deok;Choi, Hang-Seok
    • Journal of the Korean Geotechnical Society
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    • v.24 no.12
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    • pp.85-92
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    • 2008
  • It is necessary to develop a rational design method for surface reinforcement of very soft ground because most current design works rely on merely crude empirical correlations. In this paper, the mechanical behavior of very soft ground that is surficially reinforced was investigated with the aid of a series of numerical analyses. Several material properties of each dredged soft ground, reinforcement and backfill sand mat have been exercised in the numerical analysis. The result of numerical analysis was compared with those of the laboratory model test. Through the matching process between the numerical and experimental result, it is possible to determine representative material properties of the dredged soft ground, reinforcements and backfill sand mat. These verified material properties permit to evaluate the effect of the stiffness of reinforcement and the thickness of sand mat on the overall deformation of the reinforced soft ground.

An Analytical Study on Bearing Mechanism of Very Soft Ground Covered with Geotextile by Effects of Friction between Ground and Geotextile (토목섬유로 표층 처리된 초연약지반의 지지 메커니즘에 미치는 토목섬유와 지반의 마찰 영향)

  • Ahn, Dong-Han;You, Seung-Kyong
    • Journal of the Korean Geosynthetics Society
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    • v.9 no.4
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    • pp.47-55
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    • 2010
  • In general, ground surface strengthening such as using geotextile is needed to secure trafficability of construction equipment. There are many researches for mechanical beha-vior of very soft ground covered with geotextile, however, most of them are under the condition to fix geotextile completely. In this study, numerical analyses were carried out to figure out the effects of restricting conditions of geotextile on bearing mechanism of very soft ground covered with geotextile. In numerical analyses, joint elements were used to figure out the friction properties between ground and geotextile. The results of numerical analyses were compared with the results of model test. In conclusion, the effects of restricting conditions of geotextile on bearing mechanism of very soft ground covered with geotextile became clear.

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Development of Prediction Method for Behavior of Reinforced Very Soft Clay (표층보강 초연약지반 거동의 예측 방법 개발)

  • Lee, Jong-Sun;Lee, Chul-Ho;You, Seung-Kyong;Choi, Hang-Seok
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.482-491
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    • 2009
  • In this study, the mechanical behavior of very soft ground that is reinforced on the surface has been investigated with the aid of a series of numerical analyses. Key material properties of each dredged soft ground, reinforcement and backfill sand mat have been parametrically estimated in the numerical analysis. Along with the result of the study previously performed, a series of in-situ loading conditions and settlement exerted by surface reinforcing operation by construction vehicles has been numerically simulated. These result have been used to evaluate the limit bearing capacity for the unreinforced and reinforced soft ground. Also, the results of the numerical analysis obtained in this research were compared with Yamanouchi's empirical correlation for the limit bearing capacity. Engineering charts listed in this paper for estimating the limit bearing capacity provide field engineers with preliminary design tool for surface reinforcement of very soft ground.

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A Study on the Application of SCS for the Surface Stabilization of Ultra-soft Ground (초연약지반 표층처리를 위한 SCS의 적용성 조사 연구)

  • Chun, Byung-Sik;Yang, Hyung-Chil;Yoo, Young-Nam
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.425-428
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    • 2005
  • To resolve land demand by the development of various industries and the cityward tendency of population, the construction of ultra-soft ground that is unused in the past has been progressing with activity. The ultra-soft ground has very small shear strength and large deformation, so leads to many problems in ground improvement in construction. In order to dispose of these problems, it is necessary to develope the chemical materials that can be applied to the surface stabilization of ultra-soft ground. In this study, the new ground treatment that is using cement and SCS is compared, analyzed with existing ground treatment. In addition, through the laboratory tests that check the characteristic of congealment and strength, the application of SCS in field is affirmed.

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Analysis of seepage in trenching for surface desiccation of dredged soft ground (준설매립지반 표층건조처리를 위한 트렌치 굴착시 간극수의 침투해석)

  • 정하익;오인규;이용길;이승원;이영남
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.529-536
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    • 2002
  • The purpose of this paper os to present and discuss some of flow and drain observed in modelling results. Because dredged fill ground of Yul-Chon located in the south coast of Korea is very soft, this ground should be improved after operation of surface stabilization. There are surface stabilization method such as chemical stabilization, desiccation, horizontally vacuum drain, replacement, and geosynthetics. In Yul-Chon, PTM(Progressive Trenching Method) is adopted to provide the necessity condition of surface desiccation. In the case trench in the dredged soft ground is formed by PTM equipment, pore water in the ground is drained through trench. There, drain and desiccation of surface ground increase, and bearing capacity is improved. In this research, when trench in the dredged soft ground is formed by PTM equipment, permeable characteristics and drain efficiency of pore-water are analyzed using SEEP/W software package. Results show variation of total head, pressure head, flux, hydraulic gradient, and flow quantity.

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Stable Walking of a Humanoid Robot under Soft Terrains (부드러운 지면에서의 휴머노이드 로봇의 안정보행)

  • Yoo, Young-Kuk;Kim, Jin-Geol
    • Journal of the Korean Society for Precision Engineering
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    • v.26 no.4
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    • pp.72-81
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    • 2009
  • The purpose of this paper is to accomplish the stable humanoid robot walking on the soft terrains. The goal of the humanoid robot development is to make the robotic system perform some tasks in human living environment. However, human dwelling environments are very different from those of laboratories, where varied experiments are performed by the robot. In many cases, the ground is soft or elastic unlike the floor of a laboratory. When a robot walks on the soft ground, the sole of robot contacts the uneven ground. This results in unstable walking or walking may be impossible according to the degree of softness. Therefore, the algorithm that facilitates stable walking on the soft ground surface is required. In this paper, we suggest an algorithm that controls the ankle to help the robot walk stably on the soft ground using the humanoid robot (ISHURO-II) as a real model. A humanoid robot walking on the soft ground was simulated to verify that the proposed algorithm results in stable walking.

Comparisons of methods determining preconsolidation pressure for western marine clay of korea (서해점토에 대한 선행압밀하중 선정기법 비교)

  • Im, Eun-Sang
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.960-963
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    • 2010
  • In recent days, the development project for industry or housing complex at west coast of Korea is on an increasing trend. the design of soft ground is necessarily required. So, the evaluation of consolidation characteristics for soft ground is very important in design and construction. Especially, the correct evaluation of preconsolidation pressure or OCR for given soft ground is essential at the west coast that has a large tidal range, since it affects the settlement of soft ground. In this study, various methods determining preconsolidation pressure were carried out to investigate the application of each method. The preconsolidation pressure that evaluated from the results of conventional consolidation tests on the songsan clay were compared.

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