Abstract：According to the feature of geomechanical model test of rock mass，a new type combination 3D model test rack apparatus which is composed of rack body and rack bottom plate，is researched and manufactured. The rack body of the apparatus consists of various box type steel structure members connected by screw bolts with high strength；the rack bottom plate consists of shape steel plates with screw bolt grooves. The 3D combined geomechanical model test rack apparatus is formed by fixing rack body and rack bottom plate in the screw bolt groove through high strength screw bolts. Application of the apparatus to a large-scale offspur tunnel model test indicates that it possesses some remarkable technical superiorities such as original structure，great stiffness，good stability，flexible assembly and free regulation for its size.
