Research On The Instruments And Measurement Methods For The Material And 3 Dimensional Model Test

As an important research method, Geo-mechanical model test is used to analyze the stability of the Rock Engineering. The model material is the principal part of the model, and its properties often determine the feasibility of the model test to a large extent. Being a new model material and mainly composed of natural iron ore and sand, the NIOS (Natural Iron Ore & Sand) material has been successfully used in a 3D geo-mechanical model test for a very large scaled underground powerhouse group caverns, but some of its properties and measurement methods in the model test still need to be studied and improved. The main works of the research are as the followings:1.The so-called Mini-multipoint-extensometer, which is used for the internal displacement measurement for 3D model test, is researched and designed. The methods of installation, orientation and debugging for the instruments are also studied.2. The improvement of the above instruments is presented in this paper. By using the concept of straight-curving and rigid-flexible combination, new displacement transfer patterns are worked out. The transfer distance is shortened, friction is reduced, and interferer between the installation of the instruments and the model making is also reduced obviously. An error analysis was made to the system by considering the additional deformation by tension stress. 3. An Axis-symmetric Tri-axial Mini-type Lever Creep Apparatus was designed and manufactured. Compressed air is used for the radial force instead of hydraulic medium. An independent redial loading system with a pressure cell connected with 70 liters compressed air tank was designed for each test sample, and it was proved to be stable. The system is efficient, easy manufactured, and without any bad aftereffect in the case of occasional accident. 4. With the apparatus mentioned above, the creep properties of the NIOS material under steady compressive stress were studied. It was shown that the results of creep properties of the NIOS material are reasonable. It is also proved that the device developed by author is available for the creep property test of model material..5.As an additional topic, the feasibility of using the Fiber-Sensor in the large scaled geo-mechanical model test is studied, and the way of protecting the fiber-sensor prevent from damage is discussed briefly.