Abstract:  To investigate the water inrush disaster mechanism of tunnel excavation in marlite and the information evolution law, a case study is conducted on the Qinyu tunnel of the LanzhouHaikou National Expressway, and similar material of marlite tunnel surrounding rock is developed. Then, a largescale tunnel water inrush threedimensional geomechanical model test system is developed to achieve lowfrequency periodic loading and unloading, automatic data collection, and stable water pressure loading.  Furthermore, an early warning system for tunnel water inrush disaster is developed using the Python programming language, based on which the model test of the evolution process of water inrush disaster in marlite tunnel is performed. The research results show the following: (1) The tunnel excavation disturbance will destroy the balance between the pressure of the surrounding rock and that of seepage water, causing microfissures in the surrounding rock to expand and penetrate, and the water inrush phenomenon is caused further. (2) When water inrush occurs, the pressure, seepage water pressure, and displacement of the waterresisting surrounding rock will show an obvious sudden change; the maximum release rates of surrounding rock pressure and seepage water pressure are 18.6% and 73.35%, respectively, and the maximum displacement is 0.18 mm. (3) The similar materials of marlite can better meet the test requirements, as well as the stability and reliability of the threedimensional geomechanical model test system for tunnel water inrush. 

Key words: tunnel, marlite, model test, similar material, water inrush mechanism, disaster early warning, geomechanical model test system