Abstract: The holes caused by dissolution in red-bed soft rock are well developed in Chengdu. Submerging test, leaching test and dissolution test are performed with the samples of red-bed soft rock form different depth of Bandao City in Chengdu. Then the influencing on the environmental water and the erosion degree of soluble components in red bed soft rock containing saline deposit under different processes are analyzed after observing the dissolution characters and behaviors of rock sample under different environmental waters. The results show that the content of gypsum in red-bed soft rock rises with the depth increase. The causticity of rock and environmental water is significantly enhanced; the soluble components of red-bed soft rock dissolve and drain gradually under water, so as to turn to pore enlargement, permeability enhancement, strength reduction and lost of integrity; the acid environmental water makes the calcium carbonate cement drains faster and does great damage to the connection of structure, so as to influence the strength of red-bed soft rock obviously. The compressive strength, wave velocity of the rock are tested after submerging test, leaching test and dissolution test. The test results show that the uniaxial compressive strength of the soft rock reduces obviously after corroded by sulfuric acid. The uniaxial compressive strength reduces for 76% from 8.5 MPa to 2 MPa. The wave velocity in the rock also reduces for 40% from 2 204 m/s to 1 355 m/s. Meanwhile, the pH value of the rock reduces from 8.77 to 7.29 and its conductivity increases from 55 μs/cm to 1 100 μs/cm.

Key words: red-bed soft rock of containing saline deposit, environmental water, dissolution