Experimental Study On Fracture Of Roller Compacted Concrete Under The Combined Effects Of Water Pressure And External Force

With the rapid development of water resources and hydropower in China, more and more large water conservancy facilities to be built. The roller compacted concrete dam rapid development in recent years, for its advantages of simple construction, rapid, safe and can shorten the construction period, reduce cost. The roller compacted concrete must layered casting which made roller compacted concrete different with ordinary concrete about structural characteristics. Layered crush made a large number of horizontal layers existed in the dams, which made lots of weak side between the layers. Different construction conditions make different layer cementation, which impact integrity and stability of dams. So, study on roller compacted concrete layer between the stress state is the key to evaluate and analysis related performance about roller compacted concrete dam.In this paper, the experimental study on fracture of roller compacted concrete considered the combined action of stress and water pressure, combined the actual working state of dam and the existing research inadequacy. This article did the following:(1) Two batches of specimens were made with different time intervals: one simulate roller compacted concrete, another one is 24 h time intervals which simulate cold seam in engineering. All the specimens with the same dimension: 375mm×360mm×200mm and total 46 specimens.(2) This paper did fracture experimental study on roller compacted concrete and 24 h time intervals specimens under pure mechanical load then get initial crack toughness and unsteady crack toughness. The results show that the level of intermittent time affect the values of the fracture toughness of roller compacted concrete specimens significantly. The roller compacted concrete specimens higher than the layer interval time is 24 h about initial load, unsteady load, initial crack toughness and unsteady crack toughness.(3) The experiment use mixed loading way: maintained water pressure at 0.1MPa, 0.15 MPa, 0.2MPa to impose mechanical load until the specimen cracks. Analysis specimen fracture condition under two different load and found the water pressure affect the fracture toughness significantly.(4) Combined with the experiment data, the fracture criterion for concrete under water pressure and external force was established based on the double K fracture criterion, then found that the new fracture criterion has certain applicability under water pressure and external force through analysis experiment data.