• Geomechanics and Engineering
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• v.23 no.4
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• pp.365-379
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• 2020

One of the leading causes for the damage of various underground structures during an earthquake is soil liquefaction, and among this liquefaction-induced uplift of these structures is a major concern. In this study, finite-difference modelling is carried out to study the liquefaction-induced uplift of an underground structure of 5 m diameter (D) with and without the replacement of the in-situ fine sand around the structure with the coarse sand. Soil replacements are carried out by three methods: replacement of soil above the structure, around the structure, and below the structure. The soil behaviour is represented using the elastic-perfectly plastic Mohr-Coulomb model, where the pore pressures were computed using Finn-Byrne formulation. The predicted pore pressure and uplift of the structure due to sinusoidal input motion were validated with the centrifuge tests reported in the literature. Based on numerical studies, an empirical equation is developed for the determination of liquefaction-induced maximum uplift of the underground structure without replacement of the in-situ sand. It is found that the replacement of soil around the structure with 2D width and spacing of D can reduce the maximum uplift by 50%.

• Journal of Ocean Engineering and Technology
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• v.14 no.3
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• pp.61-65
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• 2000

The estimation of soil stabilization is of great importance concerning the construction of structures on weak soil. A typical model of soil stabilization is considered as replacement, which is based on ground at failure due to direct loading on weak soil. The calculation of the line of predicting settlement was carried out using RPL and DIKE programs. The DIKE program is showing a tendency to excel totally about this embankment of the seadike. Hereafter, This program will be contributed widely to the construction of offshore structures on weak soil.

• Computers and Concrete
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• v.21 no.5
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• pp.531-538
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• 2018

The slag through sieve #4 replaced the natural fine aggregate in different proportions (0-50%) to make ready-mixed soil and slag (RMSAS). The fresh properties studied, and the concrete specimens were produced to test the hardened properties at different ages. Results showed that the workability of RMSAS decreases when the replacement increases. The unit weight increases with the replacement. The setting time extends when the replacement decreases and shortens when the replacement increases. The compressive strength, ultrasonic pulse velocity and hammer rebound value increase with the replacement. However, the high-replacement results decrease because of the expansion factor at late age. Resistivity is close and less than $20k{\Omega}-cm$. After the industrial of steelmaking by-products are processed properly, they can be used in civil engineering, not only as a substitute for natural resources and to reduce costs, but also to provide environmental protection.

• Journal of the Korean GEO-environmental Society
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• v.4 no.4
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• pp.61-71
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• 2003

On the soft soil consisted of silty clay, the compulsion replacement method is useful for revetment and its safety is very much affected by compulsion replacement depth. Usual method calculating the compulsion replacement depth on silty clay is considered the bearing capacity of soft soil with undrained shear strength increase from ground surface and weight of revetment. But according to soil deposit, there are some cases of soft soil with inter sand layer or clayed silt, which affect the compulsion replacement depth. In this paper, the compulsion replacement depth on soft soil with inter sand layer is analyzed by layered weighted average bearing capacity considering influence effect of Perloff et al.(1967) and compared with numerical method(FLAC). In the result, the calculated depth from numerical method is nearest to layered weighted average bearing capacity in case that contact width under revetment is $0.2B_o$(soft soil with inter sand layer), $0.5B_o$(only soft soil) and the effect of contact width under revetment is less than undrained shear strength, thickness and location of inter sand layer. Also the compulsion replacement depth is as much as the inter sand thickness($d_2/B_o$) is thinner, the inter sand layer location($d_1/B_o$) is farther, and undrained shear strength is less.

• Computers and Concrete
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• v.17 no.3
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• pp.423-433
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• 2016

After the industrial of steelmaking by-products are processed properly, they can be used in civil engineering, not only as a substitute for natural resources and to reduce costs, but also to provide environmental protection. This study used different amounts (10%, 20%, 30%, 40%,and 50%) of desulphurization slag to replace natural fine aggregates in ready-mixed soil materials, and tested the physical and fresh properties (slump, slump flow, tube flow, initial setting time, and bleeding) and hardened properties (compressive strength, ball drop, ultrasonic pulse velocity) of the materials. The variations between the performances of the materials with different mix proportions were discussed. When desulphurization slag is used in RMSM, the workability can be enhanced obviously significantly. When the replacement of desulphurization slag is 50%, the slump flow is increased by 110mm compared with the control group, and the initial setting time increases as the replacement increases, because of bleeding. When the replacement is 10% and 20%, the compressive strength at various ages is higher than that of the control group. When the replacement is 10%, the compressive strength at 7 days is higher than that of the control group by 60%, and the ultrasonic pulse velocity is proportional to the compressive strength, which increases with age and decrease as the replacement increases. An appropriate replacement can effectively accelerate construction, and allow projects to be finished ahead of schedule; therefore, an appropriate replacement, is applicable for ready-mixed soil materials.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.16 no.1
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• pp.18-26
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• 2004

In order to accelerate the rate of consolidation settlement, to reduce settlement, and to increase bearing capacity for soft ground under quay, sand compaction pile method (SCP) has usually been applied. SCP-reinforced ground is composite soil which consists of the sand pile and the surrounding soft soil. One of main important considerations in design and analysis for SCP-reinforced soils is stress concentration ratio according to area replacement ratio. In this paper, the numerical analysis was conducted to investigate characteristics of stress concentration ratio in composite ground. It was found that stress concentration ratio of composite ground is not constant as well as depends on several factors such as area replacement ratio, depth of soft soil, and consolidation process. The values of stress concentration ratio increase during loading stage due to stress transfer of composite soil, and reach up to 2.5∼12 according to area replacement ratio at the end of construction. After the end of consolidation, however, these values are converged to 2.5 to 6.0 irrespective of area replacement ratio due to increase in effective stress of soft soil during consolidation process.

• Journal of the Korean Geotechnical Society
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• v.19 no.3
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• pp.45-51
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• 2003

This study was undertaken to investigate behavior characteristics of soil-cement piles in composite foundations through computer analysis. The soil-cement piles with cushion subjected to the vertical central loading only were analyzed using the program - “ABAQUS”. The investigation was conducted for various conditions including soil property, pile dimension, replacement ratio, pile/soil modular ratio, and load intensity. The results of analysis provided not only the load transfer and settlement behaviors but also the effective pile length and load distribution between a pile and soil. It was concluded that in the design of composite foundations, the modular ratio and replacement ratio are two design parameters.

• Journal of Industrial Technology
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• v.23 no.A
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• pp.131-137
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• 2003

This thesis is results of centrifuge model experiments to investigate the behavior of replacement method in dredged and reclaimed ground. For experimental works, centrifuge model tests were carried out to investigate the behavior of replacement method in soft clay ground. Basic soil property tests were performed to find mechanical properties of clay soil sampled from the southern coast of Korea which was used for ground material in the centrifuge model tests. Reconstituted clay ground of model was prepared by applying preconsolidation pressure in 1g condition with specially built model container. Centrifuge model tests were carried out under the artificially accelerated gravitational level of 50g. Replacing material of leads having a certain degree of angularity was used and placed until the settlement of embankment of replacing material was reached to the equilibrium state. Vertical displacement of replacing material was monitored during tests. Depth and shape of replacement, especially the slope of penetrated replacing material and water contents of clay ground were measured after finishing tests. Model tests of investigating the stability of embankment after backfilling were also performed to simulate the behavior of the dike treated with replacement and backfilled with sandy material. As a result of centrifuge model test, the behavior of replacement, the mechanism of the replacing material being penetrated into clay ground and depth of replacement were evaluated.

• Journal of The Korean Society of Agricultural Engineers
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• v.47 no.1
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• pp.35-42
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• 2005

The research has been done to obtain a empirical equation for the depth of replacement by the analysis of data collected from 8 sea-dike construction sites of south coast of Korean peninsula. The correlation analysis results show that the depth of replacement was mainly dependent upon the height of embankment and the undrained shear strength of soft soil. The suggested regression equation was quite well predicted the depth of replacement and recommended to use under certain restrictions where the embankment height was less than 10m and under 0.2 kgf/cm^{2} of the undrained shear strength of soil.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.956-965
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• 2005

In this paper, the effect on the forced replacement depth of the revetment in soft soil with inter sand layer is analyzed by model test. In the result, the forced replacement occur in 60 second from filling the embankment material. The shape of the forced replacement depth is like to punching shape. Then, in case of thin inter sand layer and near the embankment, the forced replacement depth of inter sand layer case is more than only clayed soil case.