Experimental Study On Fracture Damage Of Natural Freshwater Ice

Ice damage under natural conditions showed various forms of fracture model. In the hydraulic projects maximum static pressure of ice compression related to the slow rate of ice sheet limit damage. In order to confirm the applicability of fracture mechanics method in this research field, we need to understand corresponding progress of ice sheet destruction through On-site observation, dominated mechanical behavior of ice, critical information such as material properties. This requires systematic experimental research of natural freshwater ice in breaking destruction situation.The main task of this study is to measure the fracture toughness of freshwater ice, and the nominal bending strength. Identify the main factors, carry out ice sheet compression failure Simulation tests, confirmation the dominated failure mode and the changing conditions. The specific research Content as follows:Part I:Basic fracture toughness tests research. By using Standard size three-point bending specimen, determine the fracture toughness of S1-type lake ice. The test temperature are -2℃and-8℃. Strain rates are 6.25×10-5s-1,6.25×10-6s-1 and 6.25×10-7s-1. In the published literatures, it is rarely associated within such parameter scope. Total get 36 sets of test data. The results show that the fracture toughness of Kic increased with lower loading rate and higher test temperature and the incision depth has no significant impact on the test results.Part II:The research of fracture toughness Size effect. This is the hot and difficult point on the relative engineering research. Despite the sample size is limited, by using Proportional similar specimens we measured the data of size effect of fracture toughness, then Bazant fresh water ice type I fracture progressive size effect matching function is derived. As a group of on incision comparison specimen measurement, Measured the nominal flexural strength of water ice.Part III:Compression simulation failure test of ice specimens. Taking On-site ice sheet failure process as the simulation object, three different sizes of prototype compression ice specimen was used through a series of simulated failure tests. The experiments show that there existence several ice damage failure modes such as tensile fracture, compression fracture, and creep instability. The research confirmed how the loading rate, temperature, eccentricity, internal defects and pre-crack and other factors influence the failure mode and ultimate load. The test results of this article supply a gap in relative research, provide the experimental evidence and the necessary parameters for establishment the theoretical and numerical models of static ice force Analysis. These results fill gaps in related research, provided the experimental evidence and the necessary parameters for establishment the theoretical and numerical models of static ice force analysis...