The load-bearing capacity of screw piles in silty soils based on mechanical, piezocone and seismic soundings

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Journal Title
Journal ISSN
Volume Title
School of Engineering | Doctoral thesis (article-based) | Defence date: 2024-10-18
Date
2024
Major/Subject
Mcode
Degree programme
Language
en
Pages
144 + app. 74
Series
Aalto University publication series DOCTORAL THESES, 192/2024, Tallinn University of Technology. Doctoral thesis, 56/2024
Abstract
To accurately determine how piles behave in a particular situation, a static pile loading test is considered the most reliable method, although its implementation is restricted to special cases due to its high cost. In Estonia, the estimation of pile capacity is commonly based on dynamic probing data, specifically collected using the DPSH-A method. Furthermore, certain Estonian investigation companies have started to adopt static-dynamic probing tests. Cone penetration testing and piezocone penetration testing have been used in a limited number of site investigations in Estonia. The direct application of sounding outcomes for the determination of pile load-bearing capacity has emerged as a preferred approach. These methods are called direct methods. Such methods may encounter a drawback when relying on cone penetration testing or standard penetration testing data, as they may provide limited support in identifying the connections between load and settlement relation of the pile. When evaluating the load capacity of piles, it is essential to consider the relationship between load and settlement. Researchers have extensively studied analytical soil models based on stress, strain, and strength data obtained from practical experiments to better understand this connection. The small strain shear modulus is a key parameter in these models, and its determination is often done through the seismic cone penetration test. The load-bearing capacity of screw piles in silty soils has been assessed using mechanical, piezocone, and seismic soundings. The findings indicated that there was a significant reduction in the variability of the computed outcomes when the sounding was carried out at a depth greater than several meters below the pile base. In terms of the direct methods relying on the cone penetration test, it was discovered that the LCPC method produced the most satisfactory outcomes for Fundex piles. The Briaud and Tucker (1988) method is distinguished among the different standard penetration test methods for its remarkable ability to accurately predict outcomes for Fundex piles. Comparing values from the cone penetration test and static-dynamic probing test for displacement piles and full displacement piles, it was found that the Eurocode 7 method demonstrated the most favorable performance. These studies provide evidence that the three direct methods (Briaud and Tucker (1988), LCPC, and Eurocode 7) all incorporate the s/B=10% failure criterion and have shown satisfactory outcomes. A comprehensive analysis was conducted to investigate the relationship between normalized operative shear stiffness and normalized pseudo-strain for screw piles in silty soil, leading to a highly significant correlation. The load-bearing capacity of screw piles in silty soils exceeds that of other types of piles, particularly in situations with low strain.
Description
Supervising professor
Korkiala-Tanttu, Leena, Prof., Aalto University, Department of Civil Engineering, Finland
Thesis advisor
Kurnitski, Jarek, Prof., Tallinn University of Technology, Estonia
Keywords
cone penetration test (CPT) pile load–displacement, static-dynamic probing test (SDT), dynamic probing super heavy (DPSH-A), piezocone penetration test (CPTu), seismic piezocone penetration test (SCPTu), shear wave velocity, bearing capacity, pile, static load test
Other note
Parts
  • [Publication 1]: Leetsaar, Lehar; Korkiala-Tanttu, Leena; Kurnitski, Jarek. 2022. CPT, CPTu and DCPT Methods for Predicting the Ultimate Bearing Capacity of Cast In Situ Displacement Piles in Silty Soils. Springer. Geotechnical and Geological Engineering.
    DOI: 10.1007/s10706-022-02292-6 View at publisher
  • [Publication 2]: Leetsaar, Lehar; Korkiala-Tanttu, Leena. 2023. Deterministic and Probabilistic Analyses of the Bearing Capacity of Screw Cast in Situ Displacement Piles in Silty Soils as Measured by CPT and SDT. The Baltic Journal of Road and Bridge Engineering.
    DOI: 10.7250/bjrbe.2023-18.600 View at publisher
  • [Publication 3]: Leetsaar, Lehar; Korkiala-Tanttu, Leena. 2024. Advantages of using a seismic piezocone penetration test for analysis of a single screw in situ displacement pile in silty soils. Indian Geotechnical Journal.
    DOI: 10.1007/s40098-024-00942-5 View at publisher
Citation