浅谈预制混凝土板渠道技术在新疆北疆地区的规划设计及应用

以新疆兵团第七师129团一支渠为例，通过查阅相关规范及文献资料，论述了预制混凝土板渠道的设计过程。并初步分析了渠道防渗改建的节水效益及增产效益。     

Fatigue Properties of Plain Concrete Under Triaxial Compressive Cyclic Loading

Experiments were made on plain concrete subjected to triaxial static loading and constant-amphtude compressive fatigue loading with a constant lateral pressure in two directions. The initial confining pressure was O, O. lfc, O. 25fc and O. 4fc, respectively, for the static test, and O. lfc and O. 25fc for the fatigue test. Based on the triaxial compressive constitutive behavior of concrete, the inflexion of confining pressure evolution was chosen to be the fatigue damage criterion during the test. The rule of evolution of longitudinal maximum and minimum strains, longitudinal cyclic modulus and damage were recorded and analyzed. According to the Fardis-Chen criterion model and the concept of equivalent fatigue life and equivalent stress level, a unified S-N curve for multi-axial compressive fatigue loading was proposed. Thus, the fatigue strength factors for different fatigue loading cases can be obtained. The present investigation provides information for the fatigue design of concrete structures.