Abstract
Considering the influence of confining pressure in the actual service environment of concrete in underground projects, the damage characteristics of fiber-reinforced concrete under the action of confining pressure are evaluated according to the variation of measured permeability values by means of a triaxial ultralow permeability damage test system. The tests were carried out according to the stress loading and unloading paths of 1⟶5⟶10⟶15⟶20⟶10⟶5⟶1 MPa for an axial pressure when the confining pressure value was 1 MPa and kept constant. Firstly, the damage permeability of the fiber-reinforced concrete specimens was verified to be significantly lower than that of the ordinary concrete under the same confining pressure. Secondly, by conducting single loading and unloading tests at different loading rates (0.5, 1.0, 1.5, and 3.0 MPa/s), it was confirmed that the loading rate had a significant effect on the damage cracking of the specimens, with the faster the loading rate, the more pronounced the damage characteristics. Finally, a triaxial cyclic dynamic load test with a confining pressure value of 1 MPa and an axial loading speed of 1.5 MPa/s was carried out, revealing that the damage characteristics of the test blocks changed from elastic deformation to obvious plastic deformation damage as the number of loading times increased.
Highlights
IntroductionAs a new type of building material, fiber-reinforced concrete has good crack resistance and corresponding durability, enjoying a wide application prospect in the development of urban underground space [1]
Under the conditions of high-speed loading and cyclic dynamic loading, the loading speed has a great influence on the degree of damage and cracking. erefore, it is necessary to discuss the dynamic mechanical damage performance of fiberreinforced concrete materials [4–7]
According to the GB500812002 Test Method for Mechanical Properties of Concrete, when the strength grade of concrete is between C30 and C60, the static loading speed should be controlled at 0.5∼0.8 MPa/s. is section focuses on the evaluation of damage characteristics of test blocks under static confining pressure, and the loading speed is controlled at 0.5 MPa/s
Summary
As a new type of building material, fiber-reinforced concrete has good crack resistance and corresponding durability, enjoying a wide application prospect in the development of urban underground space [1]. 2. Principle of Ultralow Permeability Damage Test under Confining Pressure e appearance of internal cracks of fiber-reinforced concrete structures after loading damage will reduce impermeability. E permeability change rule obtained from triaxial loading stress measurement can more truly reflect the actual situation of internal loading damage and cracking of fiber-reinforced concrete [22–25]. Erefore, with the help of ultralow permeability damage testing system, the research on dynamic loading damage mechanism of fiber-reinforced concrete test blocks under confining pressure is conducted. The loading stress state of the test block is changed; the state information and flow rate information of the test block are collected and recorded; and the damage permeability of the fiber-reinforced concrete test block is calculated
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
