• Geotechnical Engineering
• /
• v.12 no.2
• /
• pp.9-18
• /
• 1996

The results of a series of triaxial compression tests on remolded normally consolidated clay are compared with the predictions .by the isotropic single -hardening constitutive model, which incorporates eleven parameters. The parameters can be determined from undrained triaxial compression tests on isotropically consolidated specimens of remolded clay. The model with the determined parameters is applied to predict the stress-strain and pore pressure behaviors for untrained triaxial compresion tests on anisotropically consolidated specimens. Also the model is utilized to predict the stress strain and voltmetric strain behavior for drained triaxial compression tests on both isotropic and anisotropic specimens. The predicted response agrees well with the measured behavior for undrained triaxial compression tests on not only isotropically but also anisotroically but also anisotropically consolidated specimens. The initial volumetric strain is, however, predicted to be less than the measured value from drained triaxial compression tests, while the predicted volumetric strain close to failure is greater than the measured value. Nevertheless, it may be stated generally that overall acceptable predictions are produced. Therefore, the results of this study indicate that the applicability of the model on prediction of the behavior of normally consolidated clay is achieved sufficiently.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.28 no.1C
• /
• pp.9-17
• /
• 2008

In this research, an analytical solution for the coefficient of permeability of soils during consolidation is suggested. The pore pressure and the flow rate measurements at different locations during consolidation are utilized. The void ratio and volume compressibility of soils under consolidation are also estimated. A large consolidation testing device, possible in both vertical and radial drainage is designed and manufactured. And consolidation test with kaolinite soils were performed under radially inward drainage direction. Pore pressures in varying radial distances and flow rate with time were measured as well as vertical deformations. From the test results, the changes of permeability, volume compressibility and void ratio under consolidation and their spatial variations are estimated. Thus the proposed solution is verified by comparing with the experimentally estimated test results. In addition, it is confirmed that permeability, void ratio and volume compressibility decrease as consolidation and loading steps progress. Also, these soil characteristics increase with radial distant from drainage boundary, where lowest values observed, and slightly decrease as approaching undrained boundary.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
• /
• 2006.04a
• /
• pp.203-206
• /
• 2006

본 논문에서는 폐타이어를 지반보강재로 재활용하는 경우 배수조건에 따른 용출특성을 알아보기 위하여 실내실험을 실시하였다 배수조건과 비배수조건으로 연속식 용출시험을 수행하여. 유출수의 pH, 탁도, TOC, Zn 농도를 분석하였다. 실험결과 배수조건인 경우 시간이 경과할수록 용출 농도가 감소하여 주변 환경에 큰 영향을 미치지 않을 것으로 판단되나, 비배수 조건인 경우 용출 농도가 증가하는 현상을 발견할 수 있었다. 배수조건은 폐타이어가 지하수위 위에 존재하는 경우이며, 비배수조건은 폐타이어가 지하수위 아래에 존재하는 경우에 해당한다. 특히, 폐타이어가 지하수위 아래에 위치하는 경우 지오텍스타일의 클로깅 등으로 인하여 배수가 원활히 되지 않을 경우에는 주변환경에 큰 영향을 미칠 것으로 예상되며 이에 대한 각별한 주의가 필요할 것이다.

• Journal of the Korean Geotechnical Society
• /
• v.20 no.5
• /
• pp.17-25
• /
• 2004

The flat dilatometer test (DMT) is a geotechnical tool to estimate in-situ properties of various types of ground materials. The undrained shear strength is known to be the most reliable and useful parameter obtained by DMT. However, the existing relationships which were established for other local deposits depend on the regional geotechnical characteristics. In addition, the flat dilatometer test results have been interpreted using three intermediate indices - material index $(I_D)$, horizontal stress index $(K_D)$, and dilatometer modulus (E$_{D}$) and the undrained shear strength has been estimated merely using the horizontal stress index $(K_D)$. In this paper, the applicability of the flat dilatometer to Korean soft clay deposit has been investigated. Then an artificial neural network was developed to evaluate the undrained shear strength by DMT and the ANN, based on the $p_0, p_1, p_2, {\sigma '}_v$ and porewater pressure. The ANN which adopts the back-propagation algorithm was trained based on the DMT data obtained from Korean soft clay. To investigate the feasibility of ANN model, the prediction results obtained from data which were not used to train the ANN and those obtained from existing relationships were compared.

• Journal of the Korean Geotechnical Society
• /
• v.32 no.8
• /
• pp.15-25
• /
• 2016

In order to analyze undrained shear strength for clayey silt with low plasticity from Hwaseong site, a series of laboratory and in-situ tests were performed. The Unconfined Compressive (UC) test and Simple Consolidated-Undrained Triaxial (SCU) test were examined in order to assess their applicability to the measurement of the undrained strength of this soil. In the case of clayey silt with low plasticity, although the samples were properly taken by undisturbed sampling method, the residual effective stress and the unconfined compressive strength were reduced considerably. Therefore, an effective confining pressure that corresponds to the typical marine clay should be applied to the soil specimen before shearing in order to compensate for the loss of residual effective stress. By evaluating the shear strengths of clayey silt with low plasticity as 75% of $s_{u(scu)}$, the in-situ shear strength of this kind of soil can be duplicated.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.13 no.2
• /
• pp.243-252
• /
• 1993

Undrained cyclic simple shear tests and undrained cyclic triaxial tests were performed on silt containing sand in order to investigate the effects of silt contents on the liquefaction strength and shear characteristics of the sand. From the view that the difference of liquefaction strength for different content of silt stems from dilatancy characteristics of the sand, stress-dilatancy relation of the sand was obtained from drained triaxial test in which the mean stress was kept constant. Considerations on liquefaction behaviors were made by comparing the drained and undrained behaviors of sands during static shear test. It is concluded that ${\lambda}$-value of the stress-dilatancy relation will be closely related to the liquefaction strength.

• Journal of the Korean Geotechnical Society
• /
• v.21 no.8
• /
• pp.73-84
• /
• 2005

A three layered neural network model was developed using back propagation algorithm to estimate the UU undrained shear strength of Korean soft soil based on the database of actual undrained shear strengths and piezocone measurements compiled from 8 sites over the Korea. The developed model was validated by comparing model predictions with measured values about new piezocone data, which were not previously employed during development of model. Performance of the neural network model was also compared with conventional empirical methods. It was found that the number of neuron in hidden layer is different for the different combination of transfer functions of neural network models. However, all piezocone neural network models are successful in inferring a complex relationship between piezocone measurements and the undrained shear strength of Korean soft soils, which give relatively high coefficients of determination ranging from 0.69 to 0.72. Since neural network model has been generalized by self-learning from database of piezocone measurements and undrained shear strength over the various sites, the developed neural network models give more precise and generally reliable undrained shear strengths than empirical approaches which still need site specific calibration.

• Proceedings of the Korean Geotechical Society Conference
• /
• 1996.10a
• /
• pp.285-294
• /
• 1996

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.7 no.3
• /
• pp.183-193
• /
• 1987

After clay particles have been sedimented isotropically, the clay deposits have been consolidated under $K_0$-stress system. Therefore, in order to predict the behavior in-situ of normally consolidated clays, the effect of $K_0$-consolidation should be considered. A series of undrained and drained triaxial compression tests was performed on remolded specimens of clay consolidated under both $K_0$-and isotropic stress systems and the effect of $K_0$-consolidation was investigated. $K_0$-consolidation has much effect on the deviator stress, especially at initial deformation stage of consolidated-undrained tests, but has little effect on the principal effective stress ratio. Thus, the undrained strength behavior of $K_0$-consolidated samples can not be predicted from isotropically consolidated test data. However, the failure envelop, provided by the maximum principal effective stress ratio failure criterion, is unique and curved.

• Geotechnical Engineering
• /
• v.10 no.3
• /
• pp.41-54
• /
• 1994

This study aims at investigating the mechanism and operation of cubical triaxial test developed by Lade in order to obtain analysis on the clayey foundation deformation. A comparison on deviator stress, pore water pressure and stress path is made between test results of clay using the cubical consolidated undrained test as well as plane strain test.