The Techniques Of Complex Block Geometric Modeling With Tunnel Surrounding Rock And Analysis Of The Block’s Stability

The terrain conditions are quite complicated in our state and there are manymountains, especially in the southwest region of our country. with the rapiddevelopment of railway in recent years, tunnel through these complex areas hasbecome the first choice.the change of the natural stress state in rock masses leads tounloading and stress redistribution in the course of the construction of tunnel. Whenthe surrounding rock masses can’t bear the rebound-stress and the redistribution stress,some blocks will lose stability to slide along structural plane, furthermore, causing thestability-losing failure of engineering rock masses.Therefore, the stability of surrounding rock in tunnel construction has become one ofthe most important problems. In the surrounding rock developped structure plane,structure plane cut each other may form all kinds of complex blocks, how to buildthese blocks geometric model and evaluating stability has become the key problem ofsurvey and design. Combining with the Hetaowan Tunnel, this paper made thefollowing findings and basic understanding:(1) The paper studied the basic content of block theory, and summed up theadvantages and the existing problems on the stability analysis of surrounding rock.(2) This paper built the space equation of structure plane. Basing on geometryelements of the block body, the method of determining the topology relationshipsbetween points of intersection, lines of intersection and the plane is produced, andthen a basic method to distinguish the vertexes of block is put forward.(3) Building the geometric model of a tetrahedron、five-faces block body andsix-faces block body, the parameters such as the areas, volumes, barycenter and so onof the block body with a curved surface is evaluated by the multiple integral method.(4) Now many large finite element software can conduct Boolean operation suchas autocad、ansys software. Using the software Boolean function build block model,and directly read these block basic parameters, compared with multiple intergral ofgeometrical parameters.