Analysis Method For Stability Of Karst Roof Under Foundation Pile Based On Info-gap Theory

Stability Analysis and evaluation of karst roof under pile foundation is one of the key issues for the design and construction of foundation of buildings in karst areas. Karst roof, as a deep underground structure, has the characteristic of more complexed uncertain variables. Owing to the inability to obtain a wealth of uncertain information, there are shortcomings of the traditional probabilistic procedure and the present non-probabilistic approach employed to underground structures. From this point, this paper studies the robust reliability method based on the Information-Gap theory which is abbreviated as Info-Gap theory.Firstly, according to the existing limit equilibrium analysis method on safety factor of karst roof under foundation pile under different failure modes, a response output model to the stabilization and security function of karst roof is set up and the general evaluation criteria is established based on the response output model. Also based on the research about the method to determine the allowable change range of these uncertain variables on the condition that the structural performance can satisfy the intended function, robust reliability model is established.Then the Info-gap theory is introduced and the process of the development and the main contents of such theory are elaborated, thereby establishing the measurement method of the degree of uncertainty of uncertain variables as well as the robustness function to evaluate the robustness of structures. Then the calculation method of the robust reliability index is brought forward by interval combination algorithm, so a new uncertainty analysis method for the stability of karst roof under foundation pile based on Info-Gap theory is put forward.This method not only has lower requirement for the message amount of engineering data but also can not know the random distribution shape of uncertain variables, and it is a supplement and improvement for the existing relative research, What’s more, because these uncertain variables are divided into design variables and design parameters in this method to achieve the dynamic analysis of allowable uncertain degree of design parameters under different design variables, thus, the method proposed in this paper has the function of not only passive reply but also active disposal. Finally, in the analysis of practical engineering example, the operating process and application process of the method proposed in this paper are presented and the rationality and feasibility of this method is verified.