• Journal of the Korean Geotechnical Society
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• v.16 no.1
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• pp.75-81
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• 2000

The anisotropy of soils has an important effect on stress-strain behavior. In this study, an attempt has been made to implement artificial neural network model for modeling the stress-strain relationship and predicting the undrained shear strength of normally consolidated clay with varying consolidation pressure ratios. The multi-layer neural network model, adopted in this study, utilizes the error back-propagation loaming algorithm. The artificial neural networks use the results of undrained triaxial test with various consolidation pressure ratios and different effective vertical consolidation pressure fur learning and testing data. After learning from a set of actual laboratory testing data, the neural network model predictions of the undrained shear strength of the normally consolidated clay are found to agree well with actual measurements. The predicted values by the artificial neural network model have a determination coefficient$(r^2)$ above 0.973 compared with the measured data. Therefore, this results show a positive potential for the applications of well-trained neural network model in predicting the undrained shear strength of cohesive soils.

• Journal of the Korean Geotechnical Society
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• v.20 no.6
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• pp.5-10
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• 2004

The earth pressure coefficient at rest for clayey soils in the one-dimensional state, $K_0$ obtained from the triaxial test is not correct in principle because the seepage flow is radial and the displacement of soil elements is three-dimensional. Measurements of the earth pressure and the pore water pressure during one-dimension consolidation in the consolidometer ring are presented. The earth pressure and pore water pressure are measured directly by a circular part of the consolidometer ring of a floating type at its mid height. A plastic clay showed $K_0$=0.5 irrespective of pressure in the consolidometer ring.

• Geomechanics and Engineering
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• v.30 no.5
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• pp.471-478
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• 2022

Creep of soils has a significant impact on mechanical properties. The one-dimensional consolidation creep test, thermal analysis test, scanning electron microscope (SEM) test, and mercury compression test were performed on Guilin red clay to study the changes in bound water and microstructure during the creep process of Guilin red clay. According to the results of the tests, only free and weakly bound water is discharged during the creep of Guilin red clay. When the consolidation pressure p is in the 12.5-400.0 kPa range, it is primarily the discharge of free water; when the consolidation pressure p is in the 800.0-1600.0 kPa range, the weakly bound water is converted to free water and discharged. After consolidation creep, the microstructure of soil changes from granular overhead contact structure to flat sheet-like stacking structure, with a decrease in the number of large and medium pores, an increase in the number of small and micro pores, and a decrease in the fractal dimension of pores. The creep process of red clay is the discharge of weakly bound water as well as the compression of large pores into small pores and the transition of soil particles from loose to dense.

• 한국방재학회:학술대회논문집
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• 2007.02a
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• pp.542-545
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• 2007

The vertical drain method generate the disturbed zone, because the drainage should be penetrated into the in-situ ground. The characteristics of the smear zone generated cause the problems that the coefficient of permeability decreases and the consolidation time anticipated in the design is not properly shortened. In this study, in order to understand such influence, the laboratory test were carried out so as to reasonably determine the coefficient of consolidation in silt. For that procedure, mandrel of a diversity were penetrated into the soil tube with silt, and then the variation of pore water pressure was measured with the pore pressure meter, Then, the range of smear effect on silt was estimated with monitoring data through the laboratory test, and also analyzed with inputting the coefficient of consolidation into the theoretical equation.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.11a
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• pp.33-40
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• 2000

The horizontal drain method is one of the soil improvement methods in reclamation works using dredged soils. In this method, plastic drain boards are installed horizontally in the ground, and a seepage pressure or negative pressure is applied through one end of these drains. In this study, a basic consolidation test using horizontal drains was conducted to investigate the effectiveness of this method. The configuration of soil box which was used in this test is 100cm(B)${\times}$100cm(L)${\times}$85cm(H). The drain board was reduced to 25mm${\times}$5mm. The variations in settlement and volume of drain water during the consolidation process were measured, and the distribution of water content and the transpormation of horizontal drain were investigated.

• Proceedings of the Korean Geotechical Society Conference
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• 2002.03a
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• pp.463-468
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• 2002

Based on the results obtain from the investigation of Nak-Dong River District, it was classified as very thick, soft soil deposit. Furthermore, during the construction of structures large settlements are expected. Since large settlement affects the structures life, it is very important to accurately determine the consolidation of soil based on the obtained results. In this study piezocone test and laboratory test were performed to determine the consoildtion properties of Nak-Dong River District Pusan, Gyeong-Nam province. Degree of consoildation and the coefficient of consoildation obtained from the data of piezocone test and the results of the Oedometer test were compared and analyzed. Using the results the porewater pressure coefficient($B_q$) was obtained and the relationship with the Plasticity Index was also determined. From the results of this study the effects of the degree of consolidation and consolidation coefficient, and the porewater pressure coefficient and the Plasticity Index was determined.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.1086-1093
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• 2005

In soft ground, consolidation settlement is mainly consider. The primary consolidation settlement which is the time when the excess pore water pressure is completely dispersed and the secondary consolidation settlement which follows. Recently as the depth of consolidation layer increases the consideration of not only the primary consolidation settlement but also of the secondary consolidation settlement becomes a very important element. But up to the present there were only a few in-depth study of the secondary consolidation settlement performed. At present there are a lot of methods available when it comes to the improvement of soft soil. In this study, Preloading Method which is the most commonly used soft soil improvement method locally was used in order to investigate the method for the reduction of secondary consolidation settlement. The objective of this study is to determine the amount of preloading required to reduce secondary consolidation settlement and to determine whether secondary consolidation settlement using standard consolidation test.

• Magazine of the Korean Society of Agricultural Engineers
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• v.31 no.1
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• pp.106-116
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• 1989

This study aims at scrutinizing the long4errn consolidation characteristics of peats sampled at three different regions of Chonbuk province. The standard consolidation test and the single load consolidation test were performed about these samples and especially in case of the latter the loading period was 350 days. The main condusions analyzed are as follows. 1. Void ratio showed much greater values than that of the general clay and was decresed greatly according to the increase of the load. 2. In case of the relationship between the sefflement and the long-term settlement time the rate of settlement increment became great according to the increase of the load step and the long4erm settlement became linely proportional to the logarithm of time alter 10 minutes. 3. The linear correlation was showed between the long4erm settlement time and the void ratio and therefore equations by regression analysis were derived in order to estimate the long-term settlement The slope of straight lines increased according th the increase of the load step and secondary consolidation coefficients ranged from 0.04-0.27. 4. The secondary consolidation coeffcient became linealy proportional to the compression index and the ratio of Ca to CC was 0.072. 5. The period required in ending the primary consolidation was about 10 minutes and alter that the secondary consolidation coefficient appeared to have constant value. Therefore the secondary consolidation coefficient was judged to be used as a significant factor in estimating the long4erm settlement. 6. In case of the single load consolidation test the secondary consolidation coefficient showed the tendancy increasing according to the increase of the consolidation pressure.

• Proceedings of the Korean Geotechical Society Conference
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• 1997.10a
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• pp.229-236
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• 1997

• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.5
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• pp.1243-1251
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• 1994

The implicit finite difference program was developed to evaluate the relationship between time and consolidation ratio within the zone of vertical drain effective radius. In the evaluation, the excess pore water pressure was considered to dissipate in two directions, namely, vertical and radial flow direction. To calculate subsoil stress increments in the soil due to multi-step embanking, the foundation soil was assumed to be an isotropic and homogeneous elastic medium and the initial excess pore water pressure was estimated by using Skempton's parameters whose condition is plane strain and elastic phase of pore pressure response within the soft ground. Regarding to the settlement estimation, immediate and primary consolidation settlements were calculated. The secondary or delayed consolidation settlement was not considered. Numerically calculated excess pore water pressure and settlements were similar to the measured data in situ. Thus, this method can be used to predict the time-consolidation ratio of each layer treated by vertical drain method.