A true triaxial geomechanical model test apparatus for studying the precursory information of water inrush from impermeable rock mass failure

To study the precursory information of water inrush from impermeable rock mass failure, a true triaxial geo-mechanical model test apparatus was developed. The test apparatus designed is 5.5 m in length, 4.0 m in width and 2.5 m in height. It is mainly composed of a steel frame system, a hydraulic control system, a water pressure loading system and a data monitoring system. The main feature of the true triaxial model test apparatus is its ability to apply high, uniform compressive loads in all three principal directions to perform tests under true triaxial static loading conditions. The apparatus can also be used to study the solid-fluid interaction of the surrounding rock mass and water. A test sample can be placed into and removed from the apparatus automatically and conveniently by hydraulic control software. A model test of the water inrush in the Xiema Tunnel, which is located in Chongqing, China, was carried out by using this apparatus. The size of the experimental sample was 1500 x 1000 x 1000 mm. The variations in displacement, stress and seepage pressure were investigated. The test results indicate that the apparatus is stable and reliable.