• Journal of the Korean GEO-environmental Society
• /
• v.20 no.8
• /
• pp.13-20
• /
• 2019

In order to ground reinforcement, the chemical grouting, the anchor, the soil nailing system, the micropile, etc. can be mentioned by the methods widely used in domestic. The above ground reinforcement methods are developed by various methods depending on the type of reinforcement, installation method, presence of prestress, grouting method, etc. However, in common, the strength of reinforcement, the friction force of grout and reinforcement and the friction force of grout and ground are the main design variables. Therefore, the optimized ground reinforcement is a material with a high tensile strength of the reinforcement itself, the friction force between the reinforcement and the grout is high, and the application of an optimal grouting method is necessary to improve the friction force between the grout and the ground. In this study, a total of 20 model tests were conducted to analyze the reinforcement effects according to the shape of the reinforcement and the grouting method. As a result of the test, As a result of the experiment, it is judged that the reinforcing effect is superior to the perforated + wing type reinforcement and post grouting method.

• Journal of the Korean Geotechnical Society
• /
• v.38 no.9
• /
• pp.53-67
• /
• 2022

Micropiles are cast-in-place-type piles with small diameters. They are widely used for the foundation reinforcement of existing buildings and structures because this technique is easy to construct and economic. A base expansion structure is developed following the mechanism of radial expansion at the pile tip under compression. Numerical analysis, durability tests, and centrifuge tests have been conducted using the base expansion structure. In this study, three-dimensional numerical modeling was performed to describe the behavioral mechanism of the base expansion structure using steel bar penetration under compressive loading, and numerical analyses using centrifuge test conditions were performed for the comparative studies. Additionally, the base structure was modified based on the results of lab-scale analyses, and the bearing capacities of micropiles were compared using field-scale numerical analyses under various ground conditions.

• Proceedings of the KSR Conference
• /
• 2010.06a
• /
• pp.880-894
• /
• 2010

The Grout injected precast pile is widely used in rapid-transit railway bridge recently. The existing portland cement of well used filling at injected precast method that with low strength and environmental pollution, unstable in which ground water contamination by cement flow out, ground relaxation by water down, decrease of horizontality resistance and durability and load transfer divide etc. In particular, as in rapid-transit railway bridge need to secure safety from different angle with vibration of high speed train, horizontal force when train stop and earthquake. Works of foundation construction consider to requirements of the times to coal yard green growth. Together, new green foundation method for possible economics and securing of reduce the term of works are material to developments. Therefore, we carried out study that it is using and development new concept environment - friendly filling include durability and earthquake resistance, for secure safety and minimize environment pollution. To achieve this, we carried out difference tests that new green fillings of underwater concrete, high liquidity, high viscosity, early stiffness as compared to existing portland cement fillings. As results, new green filling have outstanding application at precast pile method and micropile construction method with vertical bearing capacity, horizontal bearing capacity and many case. From now on we will be looking forward to development of new environment-friendly foundation method from various further studies.

• Journal of the Korean Geotechnical Society
• /
• v.39 no.3
• /
• pp.29-40
• /
• 2023

In this study, we investigated the reinforcing effects of waveform micropiles in a stratigraphic setting comprising buried soil, weathered soil, and weathered rock. We conducted a series of field load tests and determined that waveform micropiles exhibited sufficient bearing capacity through frictional resistance in the soil layer and demonstrated favorable constructability in conditions with deep bedrock layers. Moreover, the vertical stiffness of waveform micropiles was approximately 2.2 times higher than that of conventional micropiles when subjected to the same design load. Pile group load tests comprising conventional and waveform micropiles showed that micropiles with higher stiffness carried a greater proportion of the load. Although there was no significant difference in the bearing capacity between conventional and waveform micropiles under the same design load, waveform micropiles with higher stiffness showed a load-carrying capacity 1.7 to 3.2 times greater than that of conventional micropiles. These findings suggest that waveform micropiles can be effectively used for foundation reinforcement and reduce the risk of foundation failure when increased loads due to modifications such as expansion remodeling are expected.