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Excess pore water pressure generation in crushed and fine granular materials under cyclic traffic loads

By: Series: Doctoral thesis / Luleå University of TechnologyPublication details: Luleå : Luleå University of Technology, 2023Description: 194 sISBN:
  • 9789180483667
Subject(s): Online resources: Notes: Härtill 6 uppsatser Dissertation note: Diss. (sammanfattning) Luleå : Luleå tekniska universitet, 2023 Summary: Excess pore water pressure can develop in subgrades of railway and pavement substructures due to cyclic loading from heavy traffic, leading to the migration of fine particles into upper layers. This migration can clog pores and diminish the drainage capacity of upper layers, negatively impacting the long-term performance of sub-structures and service life, ultimately risking failure. Therefore, understanding the mechanisms behind the accumulation of excess pore water pressures and the migration of fine particles under cyclic loading is essential for efficient and cost-effective maintenance methods. The main objectives of this research include (1) investigating excess pore water pressure generation in crushed and fine granular materials under cyclic loading, (2) evaluating the migration of these materials into upper layers under cyclic loading, and (3) simulating a practical application using an advanced model to provide valuable insights into the operation of structures subjected to cyclic traffic loads while considering real-world factors from the field. A series of cyclic triaxial tests were conducted to investigate the generation of excess pore water pressure in fine granular materials. Two types of fine granular materials, tailings (a crushed material) and railway sand (a fine granular material) were selected for this investigation. The cyclic characteristics of these materials, including cyclic axial strain and excess pore water pressure, were evaluated in terms of number of cycles and applied cyclic stress ratios (CSR). As a result, the cyclic axial strain and excess pore water pressure were observed to accumulate over time due to cyclic loading. However, the extent of accumulation was found to be significantly dependent on CSR values and material types. In addition, a relationship between excess pore water pressure and cyclic axial strain of the fine granular materials was established and proposed based on the results from the undrained cyclic triaxial tests (including both tailings and railway sand samples).
Item type: Dissertation
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Härtill 6 uppsatser

Diss. (sammanfattning) Luleå : Luleå tekniska universitet, 2023

Excess pore water pressure can develop in subgrades of railway and pavement substructures due to cyclic loading from heavy traffic, leading to the migration of fine particles into upper layers. This migration can clog pores and diminish the drainage capacity of upper layers, negatively impacting the long-term performance of sub-structures and service life, ultimately risking failure. Therefore, understanding the mechanisms behind the accumulation of excess pore water pressures and the migration of fine particles under cyclic loading is essential for efficient and cost-effective maintenance methods. The main objectives of this research include (1) investigating excess pore water pressure generation in crushed and fine granular materials under cyclic loading, (2) evaluating the migration of these materials into upper layers under cyclic loading, and (3) simulating a practical application using an advanced model to provide valuable insights into the operation of structures subjected to cyclic traffic loads while considering real-world factors from the field. A series of cyclic triaxial tests were conducted to investigate the generation of excess pore water pressure in fine granular materials. Two types of fine granular materials, tailings (a crushed material) and railway sand (a fine granular material) were selected for this investigation. The cyclic characteristics of these materials, including cyclic axial strain and excess pore water pressure, were evaluated in terms of number of cycles and applied cyclic stress ratios (CSR). As a result, the cyclic axial strain and excess pore water pressure were observed to accumulate over time due to cyclic loading. However, the extent of accumulation was found to be significantly dependent on CSR values and material types. In addition, a relationship between excess pore water pressure and cyclic axial strain of the fine granular materials was established and proposed based on the results from the undrained cyclic triaxial tests (including both tailings and railway sand samples).