Due to reasons such as the reservoir water level fluctuation and rainfall preliminarily

alternate wetting and drying usually occurred in the rock

which is fairly harmful for long term safety of rock. Taking argillaceous sandstone in Three Gorges Reservoir area as the research object

the conventional uniaxial and triaxial compression tests after the action of wet and dry cycle in acid environment

have been conducted to obtain the relevant mechanical parameters of the argillaceous sandstone in wet and dry cycle of acid environment. Relative to the dry specimen without dry-wet cycle

there are different degrees of reduction in elastic modulus

uniaxial compressive strength

cohesion and internal friction angle of argillaceous sandstone with different times of dry-wet cycle. Overall trends of substantial decrease of various mechanical in dices appears

at which saturated with water for the first time

then the decrease of amplitude reduces with the increase in wet and dry cycles. Meanwhile

the pH value of acid environment has a great influence on the mechanical properties; there is a critical pH value influencing the mechanical properties of argillaceous sandstone. The influence of acid environment on mechanical properties of argillaceous sandstone significantly increase in the case below this critical value

there is smaller influence on its mechanical properties when the pH value is higher than the critical pH value.