• Title/Summary/Keyword: Vertical stress increment

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Characteristic of Vertical Stress in Sandy Soil according to Loading Types (재하방법에 따른 사질토 지반의 연직응력 특성)

  • Nam, Hyo-Seok;Lee, Sang-Ho;Kwon, Moo-Nam
    • Journal of The Korean Society of Agricultural Engineers
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    • v.51 no.6
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    • pp.83-90
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    • 2009
  • This study was carried out to evaluate the vertical stress properties in sandy soil according to changes of loading type in soil bin compacted three layers. The following conclusions and comparisons have been made based on careful analysis from theoretical and experimental methods. : When sandy soil subjected to cycle-loading, compression of foundation and diffusion of vertical stress increment(${\Delta}{\sigma}_2$) were influenced by magnitude of loading plate. When sandy soil subjected to reloading after removing of pre-loading, the distribution of ${\Delta}{\sigma}_2$ depth at one time of loading plate width was different from its distribution at more deep point cause of load hysteresis, so in case of design of structure, the effect of ${\Delta}{\sigma}_2$ as depth must be considered. The increment of vertical stress will be different as loading condition and foundation depth, the loading condition must be considered in case of structure design.

Study on the Method of Determination of Vertical Stress Due to Extension of Embankment Width (성토폭의 확장에 의한 지중응력 결정법 연구)

  • Lee, Seung-Hyun;Kim, Eung-Seok
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.16 no.10
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    • pp.6846-6851
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    • 2015
  • In this study, equation of calculating vertical stress increment developing in underneath of the embankment due to the extension of embankment width was derived through the use of theory of elasticity. Concept of the origin of plane was adopted to simplify derivation procedure for obtaining the equation. Comparing the results of the equation for calculating vertical stress increment with those of the numerical analyses, differences in the magnitudes of vertical stress increments decrease as the depths below embankment increase. Comparing the vertical stress increments with horizontal distances which correspond to certain depth, vertical stress increments obtained from the derived equation were slightly greater than those of numerical analyses.

An Experimental Study for Soil Pressure Increment Ratios according to Strip Load in Sandy Soil (사질토 지반의 띠하중 재하에 따른 지중응력증가비의 실험적 고찰)

  • Bong, Tae-Ho;Kim, Seong-Pil;Heo, Joon;Son, Young-Hwan
    • Journal of The Korean Society of Agricultural Engineers
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    • v.53 no.4
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    • pp.21-27
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    • 2011
  • Soil stress distribution under loading is one of the important problems in civil engineering. Many models have been proposed to interpret the stress distribution in soil and most models assume that the soil is homogeneous and isotropic. Therefore, the actual stress distribution may be different. In addition, With the increase of the top load, soil stress does not increase linearly. In this study, vertical stress changes in sandy soil according to top load increase were measured through experiments. Experimental results, vertical soil stress due to top load increase showed an initial nonlinear behavior and when the load increases to some extent, vertical soil stress showed a linear behavior. ${\alpha}$ value obtained by existing theories always 1.00. But, ${\alpha}$ value by experiment was observed from 0.91 to 1.22 and ${\alpha}$ value was increased with increasing distance from the loading plate.

An Experimental Investigation of Boussinesq's Theoretical Value of Vertical Stress Increment in Sandy Soil Mass Caused by Surface Strip Loading (지표면 띠하중 재하에 따른 사질토지반 지중연직응력 증가량의 Boussinesq 이론값에 대한 실험적 고찰)

  • Lim Jong-Seok
    • Journal of the Korean Geotechnical Society
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    • v.20 no.9
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    • pp.5-15
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    • 2004
  • It is worthwhile to verify the vertical stress distribution in soil mass for rigorous design of foundation. A series of laboratory model tests were performed to investigate the Boussinesq's theory on vertical stress increment in sandy soil mass caused by surface loading. The test results were also compared with Boussinesq's theoretical values. The Boussinesq's theoretical values were always smaller than test results under the footing regardless of depth. Outside of the footing the values were larger than the measured stress at the depth of just footing width. The theory and the test showed similar results when the depth reached two and three times the footing width. The vertical stress decreased as the applied load increased. These trends were confirmed to be valid for the considered range of the relative density of sand and/or the width of footing. More accurate values can be acquired by correcting the theoretical values using these results when Boussinesq's theory is used.

The Effects of Principal Stress Rotation in K0-Consolidated Clay (K0-압밀점토(壓密粘土)의 주응력회전(主應力回轉) 효과(効果))

  • Hong, Won Pyo
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.8 no.1
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    • pp.159-164
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    • 1988
  • The directions of the principal strain increment, stress, and stress increment during rotation of the principal stress axes at any stress level was studied for $K_0$-consolidated clay using torsion shear apparatus with individual control of the vertical stress, the confining pressure, and the shear stress on hollow cylinder specimens under undrained and drained condition. The torsion shear tests were performed according to predetermined stress-paths, which were chosen to cover over the full range of rotation of principal stress axes. The test results indicated that the strain increment vectors at failure coincided with the stress vectors. That is, the direction of strain increment coincided with the direction of stress increment at small stress levels and with the direction of stress at higher stress levels, which indicated that the behavior of clay was transfered from elastic to plastic as the stress level was increased. The applicability of the elastoplastic theory for modeling of the behavior of clay during rotation of the principal stress axes was given.

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Characteristics of Vertical Stress Distribution in Sandy Soil According to the Relative Compaction and Composition of the Soil Layer (사질토 지반의 상대다짐도 및 토층에 따른 연직지중응력 분포 특성)

  • Nam, Hyo-Seok;Lee, Sang-Ho
    • Journal of The Korean Society of Agricultural Engineers
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    • v.52 no.2
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    • pp.43-50
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    • 2010
  • This study was carried out to evaluate the vertical stress properties in sandy soil according to changes of foundation condition in soil bin compacted three layers. The following conclusions and comparisons have been made based on careful analysis from theoretical and experimental methods. : When sandy soil subjected to circular uniform load, the vertical stress increments ($\Delta\sigma_z$) was increased as load increasing, the maximum values of $\Delta\sigma_z$ was achieved at the point loading axis, and $\Delta\sigma_z$ was not shown over at a distance of three times of loading plate width (B). The vertical stress increments were achieved largely at 80 % relative compaction (Rc) compared to 95 % relative compaction due to stress concentration in sandy soil. When sandy soil subjected to circular uniform load, the $\Delta\sigma_z$ differences between theoretical and experimental values as load increased were more increased and its maximum differences were achieved at stress axis. When gravel surface macadamized over sandy soil subjected to load, the $\Delta\sigma_z$ was concentrated to load axis as load increasing, so that macadamization will be decreased load transmission.

A PHOTOELASTIC STUDY OF THE STRESS DISTRIBUTION IN BONE BY THE TRANSPALATAL LINGUAL ARCH (TRANSPALATAL LINGUAL ARCH에 의한 골내 응력 분포에 관한 광탄성적 연구)

  • Ko, Ki-Young;Tae, Ki-Chul;Kook, Yoon-Ah;Kim, Sang-Cheol
    • The korean journal of orthodontics
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    • v.27 no.5 s.64
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    • pp.711-721
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    • 1997
  • The purpose of this study was to investigate the stress distribution and intensity derived from the transpalatal lingual arch in the investing bone composed of photoelastic material(PL-3). The transpalatal lingual arch wire was deflected in the horizontal and vertical direction to give the various conditions. The two-dimensional photoelastic stress analysis was performed, and the stress distrebution was recored by photography The results were as follows: 1. In bilateral expansion, as horizontal deflection was singly applied, the stress was more concentrated on the root apex in square free end than round. In square free end, as vertical deflection was increased gradually, the black line meaning center of rotation moved inferiorly together with the increment of whole fringes. 2. In application of vertical deflection on anchorage side for unilateral expansion, the stress distribution that expansive force leaned to expansion side was observed. As vortical deflection increased, the extruding stress was observed on molar of expansion side. And as horizontal deflection increased, the tipping stress on the molar of anchorage side was observed. 3. In unilateral rotation with the asymmetric toe-in, the fringe appeared on the distal aspect of root apex.

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Vertical Load Transfer Mechanism of Bucket Foundation in Sand (사질토 지반에 설치된 버킷기초의 수직 하중전이 특성)

  • Park, Jeong-Seon;Park, Duhee;Yoon, Se-Woong;Jang, Hwa-Sup
    • Journal of the Korean Geotechnical Society
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    • v.31 no.7
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    • pp.29-39
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    • 2015
  • The vertical load imposed on the bucket foundation is transferred from the soil inside the bucket to the bottom of the foundation, and also to the outer surface of the skirt. For the design of a bucket foundation installed in sand, the vertical load transfer characteristics have to be clearly identified. However, the response of bucket foundations in sand subjected to a vertical load has not been investigated. In this study, we performed two-dimensional axisymmetric finite element analyses and investigated the vertical load transfer mechanism of bucket foundation installed in sand. The end bearing capacity of bucket foundation is shown to be larger than that of the shallow foundation, whereas the frictional resistance is smaller than that for a pile. The end bearing capacity of the bucket foundation is larger than the shallow foundation because the shear stress acting on the skirt pushes down and enlarges the failure surface. The skin friction is smaller than the pile because the settlement induces horizontal movement of the soil below the tip of the foundation and reduces the normal stress acting at the bottom part of the skirt. The calculated bearing capacity of the bucket foundation is larger than the sum of end bearing capacity of shallow foundation and skin friction of pile. This is because the increment of the end bearing capacity is larger than the reduction in the skin friction.

Experimental Study on Recycled-Aggregate Porous Concrete Pile Method (순환골재 다공질 콘크리트말뚝 공법에 대한 실내모형실험)

  • You, Seung-Kyong;Lee, Chang-Min;Kim, Se-Won;Choi, Hang-Seok
    • Journal of the Korean Geosynthetics Society
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    • v.7 no.2
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    • pp.23-29
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    • 2008
  • The purpose of this research is to assess the application of recycled-aggregate that is gained from construction wastes as the material of compaction pile method. At the same time, the development of the new technique rectifies defects of the existing compaction pile method for soft ground improvement. In this research, laboratory chamber tests were carried out analyzing the effect of the soft ground improvement by porous concrete pile using recycled aggregate. Through the results of the laboratory chamber tests, the variations of settlement, excess pore pressure, and increment of the vertical stress with time and the behavior of the composite ground were elucidated.

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Inverse analysis of erection process for prismatic tensegrity structures with redundant cables

  • Pei Zhang;Huiting Xiong;Jingjing Yang;Jiayan Liu
    • Steel and Composite Structures
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    • v.49 no.2
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    • pp.125-141
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    • 2023
  • Firstly, a new kind of prismatic tensegrity structures with redundant cables is defined, the topology, geometry and forming conditions of which are introduced further. The development of its mechanical properties including self-stress states and structural stiffness with the increment of the twist angle is also investigated carefully. Combined with the topology of this kind of structures, a reasonable erection scheme is proposed, in which some temporary lifting points need to be set and two groups of vertical cables are tensioned in batches. Then, a simplified dynamic relaxation method is employed to track the erection process inversely, which aims to predict each intermediate equilibrium state during the construction, and give the key structural parameters that can effectively guide the construction. The removal of the active cables, the relaxation or tension of the passive cables are simulated by controlling their axial stiffness, so that the structural composition as well as the serial numbers of the elements always keep invariant regardless of the withdrawal of the slack cables. The whole analysis process is clear in concept, simple to implement and easy to popularize. Finally, several examples are given to verify the practicability and effectiveness of the proposed method further.