Based on uniaxial compression test of sandstone under the different drying-wetting cycles

the laws of drying-wetting effect on mechanical behaviors of sandstone

such as deformation behavior

intensity behavior and failure characteristic

were analyzed. The results show that the elastic modulus and the peak strength of sandstone trend to decrease with the increase of drying-wetting cycles

and its reduction range is changed from large to small; moreover

the decrease of above data can not develop limitlessly but there is a constant value as critical value; in this test

the constant values of elastic modulus and the peak strength are experiment data of 20th drying-wetting cycles. The failure characteristic of sandstone is also affected by drying-wetting cycles

the less drying-wetting cycles are

the more obvious brittle damage is; that are

with the strengthen of drying-wetting effect

the damage law of sandstone present a transformation from brittleness to ductility. On the basis of these tests

taking the strain and drying-wetting cycles as input layer and the stress as output layer

the three layers neural network constitutive model

whose structure is 2-12-1

was proposed. Through the massive samples learned and inspected

the model can well describe the mechanical properties of sandstone under the cyclic drying-wetting effect

which also confirms that it is feasible and reliable for the neural network method to establish the rock constitutive model. At last

the intact function relations between the mechanical behavior and the cyclic drying-wetting effect were built.