Robust Experiment Design Of Deep Tunnel And Robust Analysis For Surrounding Rock And Support

Recently, with the rapid development of China's national economy and national defense construction, the development and utilization of underground space have become a necessary trend. The stability of the underground cavern excavation and supporting has great influence on engineering safety during the construction period and operation period. It is one of the most important research content in engineering field. However, because of its special geological environment occurrence in deep tunnel and under the influence of the “three high and one disturbance”, the mechanical properties of rock mass shows a high degree of dispersion and anisotropy.More uncertain factors should be considered during designing, it brings a lot of difficulty to the evaluation of the stability in surrounding rock of tunnel.Aiming at the uncertainty characteristics of underground structure, the paper introduced the robust design method of uncertain structures, including robust experiment design and robust reliability. The main contents are as follows:Firstly, the paper introduced concept of robust design, Taguchi mitsuji design method was introduced. Based on the principle of similarity, it chose reasonable experiment materials and selected rational orthogonal table for experiment. Taking uniaxial compressive strength of standard test block as a quality indicator. Quality indicator was transformed into signal-noise ratio based on “larger the better” SNR function. The signal-noise ratio reflects the influence parameters of standard test block uniaxial compressive strength.Secondly, the Information-gap theory was introduced for the robust analysis of shotcrete support. Using Info-gap model to describe the fluctuation of actual value nearing nominal value of uncertain parameters, the greatest horizon of the fluctuation of uncertain variables that the structural performance can suffer is further defined as the robust reliability index which will be consistent with no-failure to measure the structural reliability. Further, the robust optimization model was studied based on Info-gap model. The info-gap function was using to measure the robustness of constraint conditions. By moving the constraint function method, the uncertain variables is transformed into a set of deterministic optimization. In this condition, the structure satisfied optimization condition and robust requirement at the Same time.At last, The paper analyzed the strength failure and instability failure of surrounding rock. Based on the slip-line field theory and combined arch theory, itobtained the homogeneous elastic-plastic surrounding's ultimate bearing capacity of surrounding rock. And then The supporting structure response function was build, the process of robust analysis was further established. Examples of tunnel engineering was taken to show the concrete operation procedures of the method. It analyzed the relationship between parameters and structure robust ability. Meanwhile, the paper explored the important degree of cohesion and friction angle on structure. The robust reliability method has low requirement for information of parameters and only to know the boundary value. It has advantage to deal with uncertain problems of underground structure.