Study On The Size Effect Of The Slope Rock Mass Mechanical Parameters Determination Method

Rock mass is the synthesis of an intact rock and it’s joint. Mechanical Property of rock mass depends mainly on those of the intact rock and the joint, and it is never a simple overlap of the two. The presence of structural surface destruct the continuity and integrity of the rock mass. Although many methods of strength study on the jointed rock mass including theory deduce,experimental evaluation, in-out testing, similarity model testing and numerical simulating have been put forward at home and abroad, the strength of engineering rock mass can not be exactly obtained due to sophisticated geology characters of rock mass.Reasonable determination of mechanical Parameters of jointed rock is of great significance to the design and construction of rock mass engineering as well as the deformation and stability of rock mass.The presence of internal defects of the surface of rock mass and rock material make the existence of size effect in rock mass.But the fact in study of the size effect more concentrated in the standard test of different sizes, which is a big difference from the practical engineering rock mass,so the method of obtaining the results cannot be applied in engineering widely. In recent years, by combining of size effect in the rock mass with the fractal theory provide a good way for the mechanical parameters of rock mass. Through calculation of engineering scale, field geological investigation and the fractal characterization calculation to obtain presentative elementary volume,and then we can use damage mechanics and numerical testing to get parameters of rock mass. The core of this method is to determine the size of the representative elementary volume which get it reasonable will be more rapid and accurate to obtain parameters of slope rock mass.Researching in this paper mainly include the following aspects:(1) Firstly through summarizing on the rock mass parameters determination methods and geometrical parameters of structural plane of rock mass, according to the slope have two failure modes crack and slip sliding get how height influence on stability of slope, at the same time, based on the results obtained get a new formula of BQ take in account of slope height and the relationship between the correction of the the structural plane with slope;(2) According to test results of size effect and the relationship between REV, combined with the results of numerical simulation analysis of rock mass size effect mechanism;(3) According to the rock mass slope has the characteristics of fractal, combined the fractal self-similarity with size effect of rock mass to obtain the characterization of Presentative elementary volume expressions,and presents using numerical experiments and micro-mechanical damage mechanics method to get the rock mass parameters;(4). Basis the accurate survey on geometric parameters of the slope surface structure.then using Monte-Carlo method structure plane network simulation for slope rock mass; Using the acquired structural plane network to numerical testing of rock mass with different sizes. At last it get the relationship between strength parameters of rock mass and different sizes, at the same time, prove the correctness of the acquisition of Presentative elementary volume method. Finally, Using numerical testing and damage mechanics to obtained a practical engineering parameters of slope rock mass.