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<p>As one of the most sensitive components in the mechanical behavior of engineering structures, damage to rock-concrete interface in high-temperature environments is significant and has a profound impact on the load-bearing capacity of engineering structures. In this paper, a discrete element numerical model (DEM) is established based on the theory of particle thermal expansion. With the aid of rock-concrete bi-material Notched Semi-Circular Bend (NSCB) sample, the damage and failure characteristics of concrete-rock interface at an early age under different loading rates, temperatures and heat transfer modes are simulated. The influence of temperature and loading rate on the fracture mechanical properties of bi-material specimens was discussed from a microscopic perspective. The compressive strength and elastic modulus of the rock are 71.76&#xa0;MPa and 10.77&#xa0;MPa respectively. The 7d concrete has a strength of 22.6&#xa0;MPa and an elastic modulus of 3.02&#xa0;MPa, while the 14d concrete has a strength of 29.85&#xa0;MPa and an elastic modulus of 3.17&#xa0;MPa. The findings suggest that with the add in loading rate, the interface fracture opening angle shows a tendency to rise; however, there exists a specific threshold for the opening angle. As the temperature keeps rising, the particle radius in the sample keeps increasing and the distribution of the contact force chain becomes significantly looser, reducing the sample’s resistance to deformation. The degree of deterioration of sandstone-concrete NSCB specimens at high temperatures can be divided into three phases: slight deterioration, rapid deterioration and stable deterioration. 200&#xa0;°C is the temperature threshold for sandstone-concrete interface. When the temperature reaches 300&#xa0;°C, the degree of internal deterioration of sandstone and concrete is the most intense. The number of thermal cracks in the samples increased by 295% and 696% respectively at 7d and 14d. The tensile strengths of both sandstone and concrete materials, as well as the bond strength of their adhesive interfaces, exhibit a significantly higher sensitivity to temperature than to loading rate, suggesting that the damage mode of sandstone-concrete bi-material samples is primarily governed by thermal effects. Moreover, the deterioration of sandstone-concrete bi-material samples under different heat transfer modes is significantly different, and the degree of deterioration is highly correlated with the age of the concrete. The research results provide theoretical basis and technical support for the development of disaster air defense in high-temperature tunnels and the construction of durability of deep structures.</p>

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Numerical investigation of temperature-dependency fracture behavior of early-age concrete-sandstone interfaces

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年1月18日

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  • Jianyou Lu,
  • Xiaonan Chen,
  • Xinhai Min,
  • Chengsen Wu,
  • Yichao Rui,
  • Tengfei Guo

摘要

As one of the most sensitive components in the mechanical behavior of engineering structures, damage to rock-concrete interface in high-temperature environments is significant and has a profound impact on the load-bearing capacity of engineering structures. In this paper, a discrete element numerical model (DEM) is established based on the theory of particle thermal expansion. With the aid of rock-concrete bi-material Notched Semi-Circular Bend (NSCB) sample, the damage and failure characteristics of concrete-rock interface at an early age under different loading rates, temperatures and heat transfer modes are simulated. The influence of temperature and loading rate on the fracture mechanical properties of bi-material specimens was discussed from a microscopic perspective. The compressive strength and elastic modulus of the rock are 71.76 MPa and 10.77 MPa respectively. The 7d concrete has a strength of 22.6 MPa and an elastic modulus of 3.02 MPa, while the 14d concrete has a strength of 29.85 MPa and an elastic modulus of 3.17 MPa. The findings suggest that with the add in loading rate, the interface fracture opening angle shows a tendency to rise; however, there exists a specific threshold for the opening angle. As the temperature keeps rising, the particle radius in the sample keeps increasing and the distribution of the contact force chain becomes significantly looser, reducing the sample’s resistance to deformation. The degree of deterioration of sandstone-concrete NSCB specimens at high temperatures can be divided into three phases: slight deterioration, rapid deterioration and stable deterioration. 200 °C is the temperature threshold for sandstone-concrete interface. When the temperature reaches 300 °C, the degree of internal deterioration of sandstone and concrete is the most intense. The number of thermal cracks in the samples increased by 295% and 696% respectively at 7d and 14d. The tensile strengths of both sandstone and concrete materials, as well as the bond strength of their adhesive interfaces, exhibit a significantly higher sensitivity to temperature than to loading rate, suggesting that the damage mode of sandstone-concrete bi-material samples is primarily governed by thermal effects. Moreover, the deterioration of sandstone-concrete bi-material samples under different heat transfer modes is significantly different, and the degree of deterioration is highly correlated with the age of the concrete. The research results provide theoretical basis and technical support for the development of disaster air defense in high-temperature tunnels and the construction of durability of deep structures.