Abstract：Several newly developed techniques and methods for 3 dimensional geo-mechanics model test are introduced，such as new model material NIOS with high density and low cost，so-called discretized finite principal stress surface loading and monitoring system for the generation of the modeled initial stress field of the test，the special technique and apparatuses for modeling the excavation of houses located deep inside the model material，inner peep technology and so on. By adopting those new techniques and methods mentioned above，a very large 3D model test with high comparability for a newly designed underground powerhouse has been fulfilled. The excavation sequence and the supporting reinforcements were also modeled in the test. The model test was successful and the results were fairly satisfactory. Those techniques and methods can be used for other large geo-mechanics model test.
