• Proceedings of the Korean Geotechical Society Conference
• /
• 2002.10a
• /
• pp.334-341
• /
• 2002

Nowadays, owing to the development of analysis techniques for PDA test, we can evaluate the serious damage of pile during driving in site. In this study, we checked the damage of pile by pulling it out after evaluation of the pile damage during driving by PDA testing. After that, almost damaged pile was checked and the outline depth of damage could be verified. To increase the quality of driven pile, we have to increase the number of PDA testing for drivability analysis with checking the damage especially for preliminary pile driving and dynamic load test for checking the bearing capacity and consider the application of driving by energy monitoring.

• Proceedings of the Korean Geotechical Society Conference
• /
• 1998.10a
• /
• pp.129-136
• /
• 1998

• Geomechanics and Engineering
• /
• v.33 no.1
• /
• pp.91-99
• /
• 2023

To test the effect of various pile tip shape series of model scale loading tests were carried out on test piles with special pile tips. Special pile tips were made using the 3D printer and were attached to the bottom end of the test pile for loading tests. The pile tips were made to have 30°, 45°, 60° inclined tips, as well as a rounded tip. The main objective of the test was to observe the effect of various pile tip shapes on settlement and penetrability of the pile. Moreover, a numerical model simulating the pile loading test carried out in this study was established and verified based on the loading test results. From this, the stress concentration around the pile tip was investigated. This will allow us to analyze the decrease of stress concentration around the pile tip which is the main cause of the pile tip damage during pile installation. However, modifying the pile tip shape will eventually increase the settlement of the pile. By estimating the degree of increase in pile settlement, the viability and the efficiency of the pile shape modification was judged. In addition, case studies on the effect of different pile tip shape and ground conditions on pile settlement and stress dispersion was conducted.

• International Journal of High-Rise Buildings
• /
• v.9 no.4
• /
• pp.369-376
• /
• 2020

Given the importance of quickly recovering livelihoods and economic activity after an earthquake, the seismic performance of the pile foundation is becoming more critical than before. In order to promote seismic retrofit of the pile foundations, it is necessary to develop a method for evaluating the seismic performance of the pile foundation based on the experimental data. In this paper, we focus on the building that was suffered severe damage to the pile foundation, conduct simulation analyses of the building, and report the results of evaluating the dynamic characteristics when piles are damaged using a system identification method. As a result, an analysis model that can accurately simulate the behavior of the damaged building during an earthquake was constructed, and it was shown that the system identification method could extract dynamic characteristics that may damage piles.

• Journal of the Korean Geotechnical Society
• /
• v.39 no.1
• /
• pp.27-38
• /
• 2023

In this study, the impact of pile tip geometry, including shape, size, and angle, on the drivability and stress concentration during pile driving was investigated using 3D printing technology and finite element numerical analysis. A series of field loading tests were conducted on a test pile with various pile tip conditions, including width, angle, and shape. The changes in settlement were quantified as a ratio to the settlement of a conventional pile tip case and large deformation finite element analysis was used to investigate the maximum stress on a pile tip and the location of possible damage during pile driving. The results showed that by modifying the shape, size, and angle of the pile tip, the drivability of the pile could be improved and the maximum stress concentration around the pile tip could be significantly reduced, thereby ensuring the structural integrity of the pile during pile driving.

• Structural Monitoring and Maintenance
• /
• v.10 no.2
• /
• pp.107-116
• /
• 2023

The health condition of of deep water high pile foundation is vital to the safe operation of bridges. However, pier foundations are vulnerable to damage in deep water due to exposure to sea torrents and corrosive environments over an extended period. In this paper, combined with aninvestigation and analysis of the typical damage characteristics of main pier group pile foundations, we study the safety monitoring and real-time early warning technology of the deep water high pile foundations, we propose an early warning index item and early warning threshold of deep water high pile foundation by utilizing a numerical simulation analysis and referring to domestic and foreign standards and literature. First, we combine the characteristics of structures and draw on more mature evaluation theories and experience in civil engineering-related fields such as dam and bridge engineering. Then, we establish a scheme consisting of a Early Warning Index Systemand evaluation model based on the analytic hierarchy process and constant weight evaluation method and apply the research results to a project based on the Jiashao bridge in Zhejiang province, China. Finally, we verify the rationality and reliability of the Early Warning Index Systemof the Deep Water High Pile Foundations.

• Geomechanics and Engineering
• /
• v.33 no.5
• /
• pp.463-475
• /
• 2023

Tunnel construction activity, conducted mainly in mountains and within urban centres, causes soil settlement, thus requiring the relevant management of slopes and structures as well as evaluations of risk and stability. Accordingly, in this study we performed a three-dimensional finite element analysis to examine the behaviour of piles and pile cap stability when a tunnel passes near the bottom of the foundation of a pile group connected by a pile cap. We examined the results via numerical analysis considering different conditions for reinforcement of the ground between the tunnel and the pile foundation. The numerical analysis assessed the angular distortion of the pile cap, pile settlement, axial force, shear stress, relative displacement, and volume loss due to tunnel excavation, and pile cap stability was evaluated based on Son and Cording's evaluation criterion for damage to adjacent structures. The pile located closest to the tunnel under the condition of no ground reinforcement exhibited pile head settlement approximately 70% greater than that of the pile located farthest from the tunnel under the condition of greatest ground reinforcement. Additionally, pile head settlement was greatest when the largest volume loss occurred, being approximately 18% greater than pile head settlement under the condition having the smallest volume loss. This paper closely examines the main factors influencing the behaviour of a pile group connected by a pile cap for three ground reinforcement conditions and presents an evaluation of pile cap stability.

• Proceedings of the Earthquake Engineering Society of Korea Conference
• /
• 2006.03a
• /
• pp.105-112
• /
• 2006

Liquefaction-induced lateral spreading has been the most extensive damage to pile foundations during earthquakes. However, a case of pile failure was reported despite the fact that a large margin of safety factor was employed in their design. This means that the current seismic design method of pile is not agreeable with the actual failure mechanism of pile. Newly proposed failure mechanism of pile is a pile failure based on buckling instability. In this study, failure behavior of pile embedded in liquefied soil deposits was analyzed considering lateral spreading and buckling instability performing 1g shaking table test. As a result, it can be concluded that the pile subjected to excessive axial loads ($near\;P_{cr}$) can fail by buckling instability during liquefaction. When lateral spreading took place in sloping grounds, lateral spreading increased lateral deflection of pile and reduced the buckling load, promoting more rapid collapse. In addition, buckling shape of pile was observed. In the ease of pile buckling, hinge formed at the middle of the pile, not at the bottom. And in sloping grounds, location of hinge got loiter compared with level ground because of the effects of lateral spreading.

• Geomechanics and Engineering
• /
• v.32 no.5
• /
• pp.523-540
• /
• 2023

The failure of slope can cause remarkable damage to either human life or infrastructures. Stabilizing piles are widely utilized to reinforce slope as a slip-resistance structure. The workability of pile-stabilized slopes is affected by various parameters. In this study, the performance of earth slope reinforced with piles and the behavior of piles under static load, by shear reduction strength method using the finite difference software (FLAC^3D) has been investigated. Parametric studies were conducted to investigate the role of pile length (L), different pile distances from each other (S/D), pile head conditions (free and fixed head condition), the effect of sand density (loose, medium, and high-density soil) on the pile behavior, and the performance of pile-stabilized slopes. The performance of the stabilized slopes was analyzed by evaluating the factor of safety, lateral displacement and bending moment of piles, and critical slip mechanism. The results depict that as L increased and S/D reduced, the performance of slopes stabilized with pile gets better by raising the soil density. The greater the amount of bending moment at the shallow depths of the pile in the fixed pile head indicates the effect of the inertial force due to the structure on the pile performance.

• Journal of Biosystems Engineering
• /
• v.16 no.3
• /
• pp.281-289
• /
• 1991

During the storage and transport of fruits in the bulk state, significant damage by dead load may occur. To reduce such damage, the prediction model of allowable pile depth, duration and optimum thickness of packaging cushion for fruits was developed in this study. From the preliminary experiment and some assumptions, the derived equations were verified to be a good prediction of the above three parameters.