• Title/Summary/Keyword: Rowe

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Compressibility behaviour of peat reinforced with precast stabilized peat columns and FEM analysis

  • Kalantari, Behzad;Rezazade, Reza K.
    • Geomechanics and Engineering
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    • v.9 no.4
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    • pp.415-426
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    • 2015
  • Researches have been done to discover ways to strengthen peat soil deposits. In this model study, fibrous peat that is the most compressible types of peat has been reinforced with precast peat columns stabilized with ordinary Portland cement and polypropylene fibres. Rowe cell consolidation tests as well as plate load tests (PLTs) were conducted on various types of test samples to evaluate the strength and deformation of untreated peat and peat reinforced by various types of columns. PLTs were conducted in a specially designed and fabricated circular steel test tank. The compression index ($C_c$) and recompression index ($C_r$) of fibrous peat samples reduced considerably upon use of precast columns. Also, PLT results confirmed the results obtained from Rowe cell tests. Use of polypropylene fibres added to cement further decreased ($C_c$) and ($C_r$) and increased load bearing capacity of untreated peat. Finite element method (FEM) using Plaxis 3D was carried out to evaluate the stress distributions along various types of tested samples and also, to compare the deformations obtained from FEM analysis with the actual maximum deformations found from PLTs. FEM results indicate that most of the induced stresses are taken on the upper portion of tested samples and reach their maximum values below the loading plate. Also, a close agreement was found between actual deformation values obtained from PLTs and values resulted from FEM analysis for various types of tested samples.

Comparison of Coefficient of Consolidation and Prediction of Excess Pore Water Pressure of Agricultural Reservoir under Embankment on Soft Ground (연약지반상에 축조된 농업용저수지의 과잉공극수압 예측과 압밀계수의 비교)

  • Lee, Dal-Won;Kim, Eun-Ho
    • Journal of The Korean Society of Agricultural Engineers
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    • v.52 no.2
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    • pp.1-9
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    • 2010
  • This study was carried out to comparison of coefficient of consolidation and the prediction of excess pore water pressure in agricultural reservoir on soft clay ground. For the purpose of verification of the proposed equation, laboratory model tests and field tests were performed and excess pore water pressure was compared to those predicted with the Terzaghi's method. The predicted excess pore water pressure according to ponding was very applicable to practice because it was close to the observed data. Also, for the comparison of coefficient of consolidation, the oedometer, constant rate of strain (CRS), and Rowe cell tests were performed. The coefficient of consolidation at the Rowe cell and CRS tests showed a greate increase than in the oedometer test. The ratio of the vertical and horizontal coefficient of consolidation showed a large difference according to various tests method and mixing ratio. Therefore, it is recommended that careful attention should be paid to predicting the required consolidation period in agricultural reservoir.

Experimental Study on Consolidation Characteristics of Soft Marine Deposit by Piezocone Dissipation Test (피에조콘 소산시험을 통한 해성연악지반의 압밀특성에 대한 실험적 연구)

  • 박찬국;송정락;김수일
    • Journal of the Korean Geotechnical Society
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    • v.18 no.2
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    • pp.137-146
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    • 2002
  • Field piezocone dissipation tests are performed, and the results are compared to the Rowe cell consolidation tests results to investigate the consolidation characteristics of soft marine deposit at the same location in Korea. From these results, statistical formula fur the relation between the coefficients of horizontal consolidation$(c_r)$ from Rowe cell consolidation tests and $t_{50}$ from pore pressure dissipation tests by Piezocone is suggested through the regression analysis. The results are also compared to the existing theoretical formula. It is also shown that suggested formula is similar to Torstensson's(1977) formula based on cylindrical cavity expansion theory and Houlsby and Teh's(1988) formula based on strain path method.

Small Strain Measurements of Sands in Plane Strain Compression (평면 변형률 압축상태에서의 모래의 미소 변형률 측정)

  • 박춘식;장정욱
    • Geotechnical Engineering
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    • v.10 no.1
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    • pp.27-46
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    • 1994
  • It has been demonstrated in plane strain compression tests performed on dense Toyoura sand and Silver Leighton Buzzard sand, that the newly developed instrumentation for small strain measurements was capable of measuring the altering stiffness of sands for a wide range of shear strain from ($10^{-6}$to $10^{-2}$. It was found that for the range of shear strain($\gamma$) from $10^{-5}$ to those at peak, the Rowe's stressiilatancy relation seemed to be a good approximation for Toyoura sand and Silver Leighton Buzzard sand. However, the value of K and Poisson's ratio(at elastic range:${\nu}_{psc}^e$) varied with sand types. It was also found that the value of ${\nu}_{psc}^e$ and stress -dilatancy relation was irrespective of overconsolidation ratio(OCR).

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Constant Rate of Strain Consolidation Test with Rowe Cell on the Clay with Sand Seam (샌드심이 존재하는 점토에 Rowe Cell를 이용한 일정변형률 압밀시험)

  • Kim, Jae-Hong;Kim, Chan-Kee;Kim, Tae-Hyung
    • Journal of the Korean Geotechnical Society
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    • v.33 no.5
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    • pp.5-13
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    • 2017
  • The sand layer deposited in clay is called a sand seam, which is formed by inflow of sands due to river flooding or slope failure in the middle of sinking and sediment of clay. When the sand seam exists in clay layer, the drainage direction changes from one way to both ways, and the time of consolidation may be reduced. However, it is not clearly proved due to lack of studies of sand seam and currently is not reflected in the design of soft soil improvement. As a fundamental study about sand seam, the oedometer tests and constant rate of strain tests with Rowe cell were conducted on clay specimens with sand seam. For tests, a frozen method was specially designed for making the sand seam. It was concluded that the test results showed the sand seam affects the coefficient of consolidation of clay. If the thickness of sand seam exceeds 0.05 times of specimen height, the sand seam works as drainage layer of pore water horizontally as well as vertically, and consequently the consolidation is accelerated.

Consolidation Characteristics of Dredged Soil with High Water Content (고함수비를 가진 준설토의 압밀특성)

  • 주재우;정규향;김영규
    • Magazine of the Korean Society of Agricultural Engineers
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    • v.45 no.5
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    • pp.133-139
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    • 2003
  • Dredged soil from sea has much higher water content than liquid limit of clay and even if small loads apply, it will suffer a great settlement. Therefore it is very difficult to perform a consolidation test with general consolidation apparatus because of high water content. In this study Rowe Cell Apparatus consolidation tests have been performed with 1 remolding clay of water content 56% and 4 slurry clays of a water content of 100%, 120%, 133% and 150%. From the test results the consolidation characteristics such as compression index, secondary compression index and consolidation coefficient have been investigated with a variation of water content of dredged soil. The equations to get consolidation constants such as a compression index, a consolidation coefficient have been proposed with the field water content.

Evaluation of the Degree of Disturbance on Oedometer Test (압밀시험의 교란정도 추정)

  • 전남수;최명진;김팔규
    • Proceedings of the Korean Geotechical Society Conference
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    • 2000.11a
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    • pp.369-376
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    • 2000
  • Parameters that represent the characteristic of consolidation have been determined by the oedometer tests. They are varied by the process of sampling and transportation, accuracy of apparatus, process of sample trimming and the skill of engineers. Also, it is difficult to grasp what factor exert a influence on the parameters. In this study, Slurry Rowe Cell Tests were peformed to evaluate the disturbance. Using the plot of e - log p which obtained from Rowe Cell test results, we compared the swelling indexes at the stress relief and the last loading stage. With that result, we tried to presume the disturbance of the 330 oedometer tests. The plot of compression-swelling index at the stress relief considerably scattered but at the last step of load shows a correlations between them. And the plot of depth-p$\sub$c/ shows a correlation with the different swelling indexes, but not in the LL-p$\sub$c/. Consequently, it is considered that the disturbance of the consolidation tests can be presumed by the comparison of the difference of swelling index.

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A Study on the Flexibility of Anchored Sheet Piles (앵커로 지지(支持)된 널말뚝의 유연성(柔軟性)에 관한 연구(研究))

  • Chun, Byung Sik;Kang, In Sung
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.8 no.2
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    • pp.197-204
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    • 1988
  • This thesis studied the flexibility of anchored sheet piles and the behavior of it according to the levels of excavation. The results showed that the bending moment of sheet piles was reduced due to the displacement of walls and the load of anchor and also that Rowe's moment reduction curve was rational. It concluded that the displacement of anchored sheet piles and the soil settlement behind the walls can be reduce by suitable choice of anchor load and wall flexibility.

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Significance of nonlinear permeability in the coupled-numerical analysis of tunnelling

  • Kim, Kang-Hyun;Kim, Ho-Jong;Jeong, Jae-Ho;Shin, Jong-Ho
    • Geomechanics and Engineering
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    • v.21 no.2
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    • pp.103-109
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    • 2020
  • The inflow rate is of interest in the design of underground structures such as tunnels and buried pipes below the groundwater table. Soil permeability governing the inflow rate significantly affects the hydro-geological behavior of soils but is difficult to estimate due to its wide range of distribution, nonlinearity and anisotropy. Volume changes induced by stress can cause nonlinear stress-strain behavior, resulting in corresponding permeability changes. In this paper, the nonlinearity and anisotropy of permeability are investigated by conducting Rowe cell tests, and a nonlinear permeability model considering anisotropy was proposed. Model modification and parameter evaluation for field application were also addressed. Significance of nonlinear permeability was illustrated by carrying out numerical analysis of a tunnel. It is highlighted that the effect of nonlinear permeability is significant in soils of which volume change is considerable, and particularly appears in the short-term flow behavior.