| The permafrost area, glacier area, stable snow accumulated land and seasonal frozen ground consist43.5%of the total area of China. This area contains great amount of natural resources and it is inevitable to confront the problem lead by freezing and thawing action. Freeze-thaw cycle is an invisible killer to the stability, security and durability of rock construction in cold region, it will lead to a series of disasters which can cause great damage and economy loses. So, it is of significant importance to study about the degradation mechanism and stability analysis in freezing and thawing condition. This paper conducted a freeze-thaw cycle experiment on granite rock, and detected the rock’s damage by advanced nuclear magnetic resonance (NMR) technology. Finally obtained the strength of samples by conducting an uni-axial compress experiment. The main content are as follow:(1) Introduce the main theory of NMR and its application in rock and soil engineering based on the analysis of current research situation on the rock properties and rock construction in cold region and put forward some suggestions on the frozen rock research.(2) Choosing granite rock which comes from a certain mine of Heilongjiang as samples, a freeze-thaw cycle experiment was conducted to get the physical changes of granite rock. The cycle index ranges from0to100.NMR technology was used to detect the T2spectrums and NMR images of these samples. Finally, conducted an uni-axial compress experiment to obtain the mechanics change of all samples.(3) Based on the data of experiment, theory of damage mechanics were used to analyze the degradation mechanism of granite rock in the condition of freeze-thaw cycle. The relationship among rock porosity, strength, elastic modulus and cycle index were obtained and came up with an experimental equation between effective strength and porosity.(4) This paper discussed the type of slope failure mode and its failure mechanism and related factors. Combined all these researches, this paper presented an accumulation method concerning freeze-thaw affection of security index. Fault tree analysis (FAT) was used here to analyze slope failure factors. |
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