Abstract: Freeze-thaw weathering of rock mass is mainly controlled by several factors, such as lithology, structure of rock mass, saturated water and temperature. In this study, the freezing and thawing strain tests were carried out on four kinds of fractured rock from the cold zone of Xinjiang. The strain processes of dry and saturated fractured rock were obtained under freezing and thawing conditions, respectively. It is found that the saturated fractured rock under eight strain stages, while the dry fractured rock experienced five strain stages. The swelling-shrinking ratio of saturated fractured rock was defined under the freezing and thawing action. Furthermore, the fitting relationships between the ratio of different lithology and freezing-thawing cycles were gained. At the same time, the variation law of strain in the process of cyclic freezing and thawing was analyzed, which revealed that the maximum micro-strain of fractured rock at the frost heave stage increased with the increase of the cycle number. Besides, the freeze-thaw strain tests on jointed rockmass were conducted under different constant temperatures, and the fitting relationships between strain and different constant temperatures were obtained as well. Testing results demonstrate that the ratio increased with increasing the freezing and thawing cycle. Moreover, the variation degree of swelling-shrinkage rate was related to rock porosity characteristics. In addition, saturated jointed rockmass was highly sensitive to the temperature during the freezing and thawing process, and the damage was reflected as the thermal and frost heaving damage.

Key words: fractured rockmass, freezing-thawing cycle, strain, swelling shrinking ratio , temperature damage effect