• Title/Summary/Keyword: geotechnical parameters

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Experimental evaluation of the effects of cutting ring shape on cutter acting forces in a hard rock (커터 링의 형상에 따른 디스크커터 작용력의 실험적 평가)

  • Chang, Soo-Ho;Choi, Soon-Wook;Park, Young-Taek;Lee, Gyu-Phil;Bae, Gyu-Jin
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.15 no.3
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    • pp.225-235
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    • 2013
  • Cutter forces acting on a disc cutter in TBM are the key parameters for TBM design and its performance prediction. This study aimed to experimentally evaluate cutter forces with different ring shapes in a hard rock. The stiffness of a cutter ring was indirectly estimated from a series of full-scale linear cutting tests. From the experiments, it was verified that the rolling stress acting on a V-shape disc cutter was much higher than on a CCS disc cutter even though the penetration depth by a V-shape disc cutter could be increased in the same cutting condition. Finally, it is suggested that a prediction model considering the shape parameters of a disc cutter should be used for its better prediction.

Impact of spatial variability of geotechnical properties on uncertain settlement of frozen soil foundation around an oil pipeline

  • Wang, Tao;Zhou, Guoqing;Wang, Jianzhou;Wang, Di
    • Geomechanics and Engineering
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    • v.20 no.1
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    • pp.19-28
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    • 2020
  • The spatial variability of geotechnical properties can lead to the uncertainty of settlement for frozen soil foundation around the oil pipeline, and it can affect the stability of permafrost foundation. In this paper, the elastic modulus, cohesion, angle of internal friction and poisson ratio are taken as four independent random fields. A stochastic analysis model for the uncertain settlement characteristic of frozen soil foundation around an oil pipeline is presented. The accuracy of the stochastic analysis model is verified by measured data. Considering the different combinations for the coefficient of variation and scale of fluctuation, the influences of spatial variability of geotechnical properties on uncertain settlement are estimated. The results show that the stochastic effects between elastic modulus, cohesion, angle of internal friction and poisson ratio are obviously different. The deformation parameters have a greater influence on stochastic settlement than the strength parameters. The overall variability of settlement reduces with the increase of horizontal scale of fluctuation and vertical scale of fluctuation. These results can improve our understanding of the influences of spatial variability of geotechnical properties on uncertain settlement and provide a theoretical basis for the reliability analysis of pipeline engineering in permafrost regions.

Probabilistic Analysis of Vertical Drains Using Spreadsheet (Spreadsheet를 이용한 연직배수공법의 확률론적 해석)

  • Kim, Seong-Pil;Heo, Joon;Yoon, Chang-Jin
    • Proceedings of the Korean Geotechical Society Conference
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    • 2010.09a
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    • pp.1024-1029
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    • 2010
  • The conventional factor of safety as used in geotechnical engineering does not reflect the degree of uncertainty of the relevant parameters. Then in the geotechnical engineering, there have been efforts to reflect the uncertainties of the geotechnical properties through probabilistic analysis. In this study, a practical method for calculation the second moment reliability index using the optimization tool of a spreadsheet software is introduced. And this methodology was proposed by Low, B. K.(1996). The method is based on the perspective of an ellipsoid that just touches the failure surface in the original space of the variables. The method is applied to vertical drains(PVD) and compared with th result of Monte Carlo Simulation method.

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Evaluation of Frost Heave Prediction and Frost Susceptibility in Sample using JGS Test Method (일본 동상성판정기준을 적용한 시료의 동상예측 및 동상성 평가)

  • Kim, Young-Chin;Hong, Seung-Seo
    • Proceedings of the Korean Geotechical Society Conference
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    • 2008.03a
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    • pp.926-931
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    • 2008
  • This paper show two different standardized test methods(Japanese Geotechnical Society; JGS 2003). One test is a "Test Method for Frost Heave Prediction Test, JGS 0171-2003", and the other test is a "Test Method for Frost Susceptibility, JGS 0172-2003". The purpose of this test is to obtain the freezing rate(freezing speed), frost heave ratio(heave to sample height), frost heave rate(heaving speed), and other parameters to be used for frost heave prediction and determine the frost susceptibility by freezing test with water intake. This method shall be used to predict the frost heave in frozen ground and evaluate the frost susceptibility of natural and replacement materials.

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International Research on Geotechnical Risk & Landslide Hazards (지반공학적 재해 및 산사태 위험도 분석에 관한 연구)

  • Yoon, Gil-Lim;Yoon, Yeo-Won;Kim, Hong-Yeon
    • Proceedings of the Korean Geotechical Society Conference
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    • 2009.03a
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    • pp.444-455
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    • 2009
  • Great concerns on geotechnical risk & hazard assessment have been increased due to human and economic damage by natural disasters with recent global climate changes. In this paper, geotechnical problems in particular, landslides which is interested in European countries and North America, were mainly discussed. For these, 18 key topics on geotechnical risk and hazards which had been discussed at the LARAM 2008 workshop in Italy were analyzed after grouping by subjects. Main topic contents consisted of applications such as field measurement, early warning systems, uncertainty analysis of parameters using radar, optical data and statistical theory and so on. And the problems related to analysis of vulnerability and deformation due to earthquakes, investigation of gas zone using seismic reflection data in a landslide area, risk quantification and hazard assessment of landslide movements and multi-dimensional analysis for stability of complex slopes were attracted. Also, there were studies on risk matters of cultural heritage, the blockglide of clayey ground, simulations of debris flows based on GIS, quantification of the failure processes of rock slopes, a meshless method for 3D crack modelling, and finally risk assessment for cryological processes due to global warming.

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Remote monitoring technique for geotechnical structures using acoustic emission (미소파괴음을 이용한 지반구조물 원격계측기술)

  • Cheon, Dae-Sung;Jung, Yong-Bok;Park, Eui-Seob;Park, Chan;Jang, Hyun-Ick
    • Proceedings of the Korean Geotechical Society Conference
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    • 2008.10a
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    • pp.946-956
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    • 2008
  • Acoustic emission(AE) is low-energy seismic event associated with a sudden inelastic deformation such as the sudden movement of existing fractures, the generation of new fractures or the propagation of fractures. These events rapidly increase before major failure and happen within a given rock volume and radiate detectable seismic waves. Rock slopes are usually large in scale and there are many discontinuities in rock mass. AE waves are strongly attenuated when they propagate through joints. Thus we should resolve the attenuation problem to monitor large volume. In this study, we developed waveguide which is composed of two different materials, cement mortar and stainless steel rod. And several laboratory tests on developed waveguide are performed to obtain generalized AE parameters to predict the failure stage in rock slope. Comparing field data with experimental data in laboratory tests, failure stage of rock slope can be evaluated. To verify and optimize the developed monitoring method, we are now carrying out the field application at a rock slope.

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Determination of Critical State Parameters in Sandy Soils from Standard Triaxial Testing (II) : Experiment and Recommendation (표준삼축시험으로부터 사질토에서의 한계상태정수 결정에 관한 연구 (II) : 실험 및 추천)

  • 조계춘
    • Journal of the Korean Geotechnical Society
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    • v.19 no.1
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    • pp.77-92
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    • 2003
  • A set of standard triaxial testing was performed to identify underlying physical processes and inherent limitations in the determination of critical state parameters in sandy soils. The experimental test results showed that the critical state friction angle for a given soil is constant regardless of drainage condition while the critical state line on the e-log p'space is significantly affected by drainage condition mainly because of insufficient strain attained in standard triaxial tests and strain localization effects in udrained tests. It appeared that the best method to determine critical state parameters in laboratory testing is to use homogeneous loose specimens under drained shear condition. In addition, a reference state parameter was suggested to design tests that will avoid dilatancy or strain localization effects in drained tests.

A Simple Approach of Estimating the Shear Strength Parameters for Unsaturated Soil-Aggregate Systems (불포화 지반재료의 전단강도정수 추정을 위한 간편법)

  • Park, Seong-Wan;Kim, Yong-Rak
    • Journal of the Korean Geotechnical Society
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    • v.19 no.3
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    • pp.75-82
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    • 2003
  • This paper presents the results of a study that was performed to evaluate fronds of shear strength parameters in stabilization of unbound soil-aggregate systems based on the theory of unsaturated soil mechanics. Two important shear strength parameters, effective cohesion and effective angle of internal friction were estimated by the proposed approach using the results from suction measurements and unconfined compressive strength test. In addition, the effect of different addition rates of stabilizing agent was compared. Due to the stabilization process, an increase in suction potential on engineering properties of geomaterials was observed by using dielectric constant measurements. In conclusion, the results from this study show that the proposed approach can be simply used for predicting shear strength parameters of the stabilized geomaterials.

Correlation of elastic input energy equivalent velocity spectral values

  • Cheng, Yin;Lucchini, Andrea;Mollaioli, Fabrizio
    • Earthquakes and Structures
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    • v.8 no.5
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    • pp.957-976
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    • 2015
  • Recently, two energy-based response parameters, i.e., the absolute and the relative elastic input energy equivalent velocity, have been receiving a lot of research attention. Several studies, in fact, have demonstrated the potential of these intensity measures in the prediction of the seismic structural response. Although some ground motion prediction equations have been developed for these parameters, they only provide marginal distributions without information about the joint occurrence of the spectral values at different periods. In order to build new prediction models for the two equivalent velocities, a large set of ground motion records is used to calculate the correlation coefficients between the response spectral values corresponding to different periods and components of the ground motion. Then, functional forms adopted in models from the literature are calibrated to fit the obtained data. A new functional form is proposed to improve the predictions of the considered models from the literature. The components of the ground motion considered in this study are the two horizontal ones only. Potential uses of the proposed equations in addition to the prediction of the correlation coefficients of the equivalent velocity spectral values are shown, such as the prediction of derived intensity measures and the development of conditional mean spectra.