Experiments On Stress Relaxation Characteristics Of Siltstone And Stability Control Of Chamber Underground

The problems of soft rock have been put forward as a worldwide difficulty since1960s,and have been one of the major problems that influence the production and construction. Thestudy on rheological property of the soft rock has been the research emphasis. As an importantpart of the rheological property of the soft rock, stress relaxation attracts the domestic andforeign scholars more and more. However, the difficulty of experiment for stress relaxation isvery great, the studies on it has mostly been on the theory. At the same time, the study on rockrheology is insufficient, there still needs much basic work to form a mature method for thesoft rock supporting.Through the general mechanics experiment and the uniaxial stress relaxation experimentto the specimens made by the rocks from the Xin’an coal mine of Huaning Group, this papermakes researches to the result of the experiment and explores the stress relaxationcharacteristics of the argillaceous siltstone. Using the finite element analysis software namedANSYS, this paper simulates the stress relaxation characteristics under axial ant triaxialpressures, and compares the results with the experiment. On the basis of the field testing, thestress relaxation characteristics for soft surrounding rock are analyzed in this paper. By theexperiment of stress relaxation, this paper can supplies some fundamental works for thesupporting of the underground project, enriches the theories of soft rock and promotes thedevelopment of technology for supporting of the underground project.General mechanics experiment and uniaxial stress relaxation experiment about soft rockroadway and grouting specimens of flexible pore cushion were executed on SAW-2000Electro-hydraulic Servo-controlled Rock Mechanics Testing System manufactured in Kexintesting instrument corporation．Parameters of general mechanical properties for tunnels wereobtained. Besides, uniaxial stress relaxation experiments are held under two different ways ofloads, one is staged loading and the other is stepped loading. On the basis of Xi Yuan model,the stress relaxation characteristics of the specimens which are under different strain levels isanalyzed.Similar models which are put under different constraining conditions are created byANSYS, and the corresponding data is analyzed. By giving the models uniaxial pressureunder different strain levels, the uniaxial stress relaxation characteristics are concluded.Besides, the triaxial conditions are simulated. The results are analyzed and compared to theexperiments, making up the shortage of experiment.The data for the field experiment are recorded after making some monitoring points on different places, as a result, the stress relaxation characteristics for real tunnels are concluded.A new supporting method which using the theory of stress relaxation is investigated. Thetunnel is supported mainly by given a fixed deformation, and is analyzed the effects caused bystress relaxation. With the Hope that this can help form a mature method for the soft rocksupporting, and enriches the basic work for stress relaxation.