Load Transfer Model Based on Similitude Principle and Numerical Analysis of Reinforcement Effect of Pile Side Compaction Grouting
ObjectiveBridges play a vital role in the development of transportation infrastructure. The pile foundation is the main load-bearing structure of a bridge and plays a vital role in ensuring its structural safety. As the economy and society continue to advance, many highways experience severe traffic...
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| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Editorial Department of Journal of Sichuan University (Engineering Science Edition)
2025-05-01
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| Series: | 工程科学与技术 |
| Subjects: | |
| Online Access: | http://jsuese.scu.edu.cn/thesisDetails#10.12454/j.jsuese.202301044 |
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| Summary: | ObjectiveBridges play a vital role in the development of transportation infrastructure. The pile foundation is the main load-bearing structure of a bridge and plays a vital role in ensuring its structural safety. As the economy and society continue to advance, many highways experience severe traffic congestion and frequent safety accidents due to a significant increase in traffic volume and limited traffic capacity, necessitating the implementation of expansion projects. However, numerous existing bridge pile foundations fail to meet the load-bearing requirements of these expansion projects. Grouting technology, recognized for its efficiency, cost-effectiveness, and convenience, is widely applied to enhance the load-bearing capacity of pile foundations. Despite its extensive application, the mechanism by which grouting reinforces in-service pile foundations remains unclear, and quantitatively evaluating the grouting effect proves challenging. The design of grouting parameters along the pile side and the evaluation of the reinforcement effect on pile foundations remain key research difficulties. Therefore, it is of substantial scientific and engineering value to systematically and comprehensively investigate the reinforcement mechanism of grouting in existing bridge pile foundations.MethodsFocusing on the reinforcement project of friction piles on silty clay-fine sand formations, this study employed model experiments, finite element simulations, and field tests to clarify the mechanisms by which lateral densification grouting enhanced the load-bearing capacity of existing friction piles. It proposed design methods for lateral grouting parameters and conducted load-bearing capacity analysis for silty clay-fine sand formations, achieving reinforcement through grouting in pile foundations within such formations.The main research contents and achievements were as followsConclusionsWhen the length of the reinforced segment is 4 m, the optimal reinforcement effect is achieved when the reinforcement is positioned at a depth ranging from 40% to 90% of the pile length, resulting in a 10.7% to 13.7% increase in bearing capacity. When the reinforcement length exceeds 16 m (approximately 70% of the pile length), it significantly improves the ultimate lateral friction resistance in the lower part of the pile, leading to a noticeable reduction in settlement under the same load level.;Results and Discussionsa lateral densification grouting model device was developed, assuming the grouting reinforcement body to be cylindrical along the pile's length, using the lateral expansion of cylindrical airbags to simulate the lateral densification grouting reinforcement method. The study investigated the effects of grouting pressure and the distance between grouting holes and the pile's side on the effectiveness of grouting reinforcement. Based on the ultimate bearing capacity and lateral friction resistance of the pile foundation, a design method for grouting parameters in silty clay-fine sand composite formations was proposed. For every 0.25 MPa increase in grouting pressure, the ultimate bearing capacity of the pile foundation increased by approximately 20% to 40%. Compared to unreinforced pile foundations, when the grouting pressure reached 1.25 MPa, the maximum increase in the pile foundation's bearing capacity was 167.27%. The relative position of the grouting holes to the pile significantly affects the pile foundation's bearing capacity. For every 5 cm increase in the distance between the grouting hole and the pile's side, the decrease in bearing capacity was 12% to 25%. The distance between the grouting hole and the pile's side must be less than 15 cm to ensure the effectiveness of pile foundation grouting reinforcement. Based on the theory of physical similarity, an index-based load transfer model for pile side loads in silty clay and fine sand formations was established using simulated test data from indoor lateral densification grouting experiments. A load transfer index model for the pile-soil contact surface was developed using FORTRAN language and embedded into ABAQUS to conduct numerical calculations of lateral grouting on an engineering scale in existing pile foundations. The reliability of the model was verified by comparing the numerical simulation results with the measured values of pile bearing capacity in the field. The measured ultimate bearing capacity of the pile foundation on-site was 6 000 N, while the numerical simulation produced a value of 5 850 N, demonstrating good agreement in settlement under ultimate loads. Therefore, this load transfer model accurately predicted the effectiveness of lateral grouting reinforcement in existing pile foundations. The study also analyzed the effects of reinforcement position and length on lateral friction resistance and pile bearing capacity. |
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| ISSN: | 2096-3246 |