Instability Mechanism And Stability Appraisal Theory Study On The Laminated Rock Foundation Pits In Guizhou Karst Region

In this article, the author envisages the unique geological environment condition of Guizhou, which is charactered by the Laminated rock mass and Karst environment, follows the overall approach from theoretical study to numerical simulation verification, systematically studies the Laminated rock foundation pits' types, influencing factor, deformation mechanism, failure model, stability appraisal theory and supporting design method, etc. The obtained achievements are listed as follow:1. According the different angle of foundation pit excavated wall, the strike and the dip relative to the foundation pit wall and bed, divides the Laminated rock foundation pits into different types.2. After analyzing the deformation and failure mechanical process of the Laminated rock foundation pits, not only divides the Laminated rock foundation pits into five kinds of deformation mechanism, but also summarizes the formation condition and application scope of every failure mechanism.3. Taking theoretic analysis and engineering examples into account, not only divide the Laminated rock foundation pits into six failure models and four foundation pit types in Karst region, but also summarize the possible failure models of every foundation pit.4. Using the limit equilibrium method and related mechanical acknowledge, studies the stability coefficient formulas of the Laminated rock foundation pit, when it occur planar sliding, arc sliding, wedge or block sliding, toppling failure, wall settlement and bottom uplift.5. Firstly applying Block Theory to the Laminated rock foundation pit, uses the stereo-analytic method to analyze and distinguish the blocks' finiteness, movability and stability of foundation pit walls and illustrates the concrete calculation steps.6. Using the FLAC program, simulates the rock mass stress, strain, and displace of foundation pit walls when rock mass occur planar sliding and arc sliding. 7. Aiming at rock mass failure character of the foundation pit walls, brings forward five active supporting constructions and elementarily suggests the design theory and methods about these supporting constructions.This article firstly roundly and systematically theoretical studies instability mechanism and stability appraisal method of the Laminated rock foundation pits in Guizhou Karst region. The research has significant theoretical meaning, practical meaning and wide application prospect for solving engineering problems, guiding engineering practice and developing foundation pit supporting theory.