Study on deterioration mechanism of granite with a natural single weak surface after freeze-thaw treatment

Abstract

Natural weak plane of rock is a great threat to the stability of the rock project in cold areas due to the freeze-thaw environment. However, the effect of both weak plane and freeze-thaw cycles is rarely considered. This paper investigated the deterioration mechanism of granite with a natural single weak surface after 0, 20, 40, and 60freezing-thawing cycles. Experimental results show that as the number of freeze-thaw cycles increased, the peak strength of samples decreased while the axial strain gradually increased. The weak plane angle has a significant impact on the sample strength. The strength and elastic modulus changed in a ‘U' shape with the increase of weak plane angle. The samples exhibited a shift from brittle failure to ductile failure with the increase of freeze-thaw cycles. A theoretical model for predicting rock strength is proposed with consideration of weak plane and freeze-thaw effects by combining the single weak plane theory with the decay function. The proposed model is verified by experimental data. The predicted values based on the proposed model match well with experimental data. Samples with lower porosity but higher tensile strength and elastic modulus have larger frost resistance. The research results can provide a scientific basis for the safety assessment of geotechnical engineering in cold regions.