关键词: 时变特性, 时变断裂, 裂缝口张开位移, 裂缝口张开速率, 裂缝尖端张开位移, 裂缝扩展长度

Abstract: Time-dependent fracture behaviors in mass concrete closely relate to the safety of concrete structures in service. To investigate these behaviors of concrete under sustained loads, this study conducts wedge-splitting tests under a long-term constant load at 85% of the maximum load, using compact tension specimens in three different sizes. The test results indicate three development stages occur in time-dependent crack mouth and crack tip opening displacements and time variations in crack mouth opening rate: deceleration, stable development, and accelerated failure. Compared with the static fracture test on the same specimen size, a larger critical crack mouth opening displacement occurs in the present long-term constant load test. And a highly linear correlation can be observed between the displacements at the crack mouth and the tip. In addition, the geometry relation between the opening displacement and propagation length of cracks fits in well with the hinge model.

Key words: time-dependent characteristics, time-dependent fracture, crack mouth opening displacement, crack mouth opening rate, crack tip opening displacement, crack propagation length