• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.05a
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• pp.528-530
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• 2008

The effect of consolidation temperature on the microstructure, density and mechanical properties (especially, wear property) of $Al_{92.5}-Fe_{2.5}-Cr_{2.5}-Ti_{2.5}$ alloy fabricated by gas atomization and magnetic pulsed compaction was investigated. All consolidated alloys consisted of homogeneously distributed fine-grained fcc-Al matrix and intermetallic compounds. Relative higher mechanical properties in the MPCed specimen were attributed to the retention of the nanostructure in consolidated bulk without cracks. The as consolidated bulk by magnetic pulsed compaction showed the enhanced wear properties than that of a general consolidation process. In addition, the wear mechanism and fracture mode of MPCed bulk was discussed.

• Geotechnical Engineering
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• v.12 no.4
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• pp.131-144
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• 1996

In order to accelerate the rate of consolidation settlement and to gain a required shear strength for a given soft clay deposit, the preloadina technique combined with a vertical drainage system has been widely applied. Even if a sophisticated numerical analysis technique is applied to solve the consolidation behavior of drainage-installed soft deposits, the actual field behavior is often different from the behavior predicted in the design state due to several uncertainties involved in soil properties, numerical modelling, and measuring system. In this paper, two back-analysis schemes such hs simplex and BFGS methods have been implemented in an a Bisymmetric consolidation program, AXICON which considers the variation of compressibility and permeability during the consolidation process. Utilizing the program, one might be able to appropriately predict the subsequent consolidation behavior from the measured data in an early stage of consolidation of drainage-installed soft deposits.

• Journal of the Korean GEO-environmental Society
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• v.8 no.6
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• pp.37-43
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• 2007

The interface layer having different consolidation properties and nonlinear material function with permeability needs to be considered to predict consolidation behavior. In this study, interface equation between different layers has been derived and then applied to existing finite difference scheme for conducting consolidation analysis. These results have been compared with those by conventional method in which different layers are converted to single layer having conversion value of properties. Also, although the conventional consoilidation analysis is used to consider non-linearity of the permeability with effective stress, an approximated nonlinear method as a function of consoilidation coefficient with effective stress have been developed and applied to the consoilidation analysis for various cases.

• Journal of the Korea institute for structural maintenance and inspection
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• v.11 no.4
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• pp.138-146
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• 2007

Geotechnical performance at the soft ground is strongly dependent on the properties of the soil beneath and adjacent to the structure of interest. These soil properties can be described using deterministic and/or probabilistic models. Deterministic models typically use a single discrete descriptor for the parameter of interest. Probabilistic models describe parameters by using discrete statistical descriptors or probability distribution density functions. The consolidation process depends on several uncertain parameters including the coefficients of consolidation and coefficients of permeability in vertical and horizontal directions. The implication of this uncertain parameter in the design of prefabricated vertical drains for soil improvement is discussed. A sensitivity analysis of the degree of consolidation and calculation of settlements to these uncertain parameters is presented for clayey deposits.

• Geomechanics and Engineering
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• v.8 no.2
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• pp.187-220
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• 2015

Soil disturbance induced by installation of mandrel driven vertical drains decreases the in situ horizontal hydraulic conductivity of the soil in the vicinity of the drains, decelerating the consolidation rate. According to available literature, several different profiles for the hydraulic conductivity variation with the radial distance from the vertical drain, influencing the excess pore water pressure dissipation rate, have been identified. In addition, it is well known that the visco-plastic properties of the soil also influence the excess pore water pressure dissipation rate and consequently the settlement rate. In this study, a numerical solution adopting an elastic visco-plastic model with nonlinear creep function incorporated in the consolidation equations has been developed to investigate the effects of disturbed zone properties on the time dependent behaviour of soft soil deposits improved with vertical drains and preloading. The employed elastic visco-plastic model is based on the framework of the modified Cam-Clay model capturing soil creep during excess pore water pressure dissipation. Besides, nonlinear variations of creep coefficient with stress and time and permeability variations during the consolidation process are considered. The predicted results have been compared with V$\ddot{a}$sby test fill measurements. According to the results, different variations of the hydraulic conductivity profile in the disturbed zone result in varying excess pore water pressure dissipation rate and consequently varying the effective vertical stresses in the soil profile. Thus, the creep coefficient and the creep strain limit are notably influenced resulting in significant changes in the predicted settlement rate.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.4C
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• pp.229-238
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• 2006

Observed field behaviors are frequently different from the behaviors predicted in the design state due to several uncertainties involved in soil properties, numerical modeling, and error of measuring system even though a sophisticated numerical analysis technique is applied to solve the consolidation behavior of drainage-installed soft deposits. In this study, genetic algorithms are applied to back-analyze the soil properties using the observed behavior of soft clay deposit composed of multi layers that shows complex consolidation characteristics. Utilizing the program, one might be able to appropriately predict the subsequent consolidation behavior from the measured data in an early stage of consolidation of multi layered soft deposits. Example analyses for drainage-installed multi-layered soft deposits are performed to examine the applicability of proposed back-analysis method.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.4
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• pp.953-963
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• 1994

Treatment techniques of soft clay layers is needed sophisticated technology in civil engineering. Especially, dredged and reclaimed clay has high liquid limit and water content, so it is difficult to use. Now it comes to the applicability as good construction materials by predicting the behaviors. This paper is to evaluate the characteristics of sedimentation and self-weight consolidation of extremely soft clay, and is to find the way of applying model test result of reconstructing the in-situ condition to design. The consolidation properties of soft clay layers changing the size of the cell are investigated by large-scale consolidation test apparatus and the behaviors of self-weight consolidation are predicted by numerical analysis.

• Geomechanics and Engineering
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• v.19 no.5
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• pp.447-462
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• 2019

The vacuum preloading method has been used in many countries for ground improvement and land reclamation works. A sand cushion is required as a horizontal drainage channel for conventional vacuum preloading. In terms of the dredged-fill foundation soil, the treatment effect of the conventional vacuum preloading method is poor, particularly in Tianjin, China, where a shortage of sand exists. To solve this problem, straight-line vacuum preloading without sand is widely adopted in engineering practice to improve the foundation soil. Based on the engineering properties of dredged fill in Lingang City, Tianjin, this paper presents field instrumentation in five sections and analyzes the effect of a prefabricated vertical drain (PVD) layout and a vacuum pumping method on the soft soil ground treatment. Through the arrangement of pore water pressure gauges, settlement marks and vane shear tests, the settlement, pore water pressure and subsoil bearing capacity are analyzed to evaluate the effect of the ground treatment. This study demonstrates that straight-line vacuum preloading without sand can be suitable for areas with a high water content. Furthermore, the consolidation settlement and consolidation degree system is developed based on the grey model to predict the consolidation settlement and consolidation degree under vacuum preloading; the validity of the system is also verified.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.03b
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• pp.677-684
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• 2000

Piezocone test as well as Dilatometer tests are used worldwide to evaluate the engineering properties of clay soils. The common strong point of the two tests is that they can estimate, by the identical test equipment, various properties of soils, which are the unit weight of soils of OCR, K$\sub$o/, undrained shear strength(s$\sub$u/), coefficient of consolidation(c$\sub$h/) and soil classification etc,. A series of the two types of field tests are performed in this study on marine clays with low plasticity at Inchon International Airport construction site to estimate various properties of the soils such as s$\sub$u/, OCR, and c$\sub$h/, which are then compared each other as well as with the results of reference tests. The comparisons show that the way of interpretation is the most critical factor in obtaining confidential results for a certain engineering property for both tests.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.30 no.3
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• pp.63-72
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• 1998

This research was intended to evaluate the effect of carboxymethylcellulose(CMC) on the coating structure and surface strength of coated paper prepared with amphoteric latex based coating color. Printability and optical properties of coated papers were compared. The influence of the consolidation behavior of coating color on the coating structure and the surface strength of coated paper was investigated. Compared with the conventional anionic latex, amphoteric latex formed bulkyer, smoother and more porous coating layer, which in turn, restricted binder migration in the coating layers, and facilitated immobilization of coating colors. However, dry pick strength of coated paper was decreased. The addition of CMC to these systems had strongly influenced on. the consolidation behavior and porosity in the dry state, through forming the network structure of coating layers by the interaction with amphoteric latex particles. Thus, printability and optical properties of coated papers were improved. Results indicated that amphoteric latex could be practically applied to the paper coating to improve printability and optical properties of coated papers.