A Study Of Physical Model-Test Technology And Application In Geotechnical Engineering

Physical model test is intuitionistic and can qualitatively or quantitatively reflect the mechanics trait of crude rock-mass and interaction among complex engineering structures in underground engineering. Furthermore, it can simulate complex engineering structure, geologic conformation, stratum combination and so on of the underground engineering. Model test is more and more of real engineering significance with more and more great underground engineering being constructed and more and more complex problem appearing and more and more study content needing to be solved. Based on the similarity theory, proceeding with model-test technology, plane stress model test on deformation and subsidence of ground surface and surrounding rock caused by exploiting inclining mine near surface and plane strain model test studying the stress distribution and transmogrification and breakage of rigid brittle surrounding rock under the condition of high-stress are done. In addition, the result of physical model test has been contrasted that of numerical analysis. The main studying content is listed below:(1) The model material, which density is over 27KN/ m3, is made from powdery Fe3O4, powdery quartz grit, gesso, water and so on. The content of gesso being adjusted in this kind of model material,the tensile strength of standard sample with it can range between 0.0018～0.0180 MPa, the cohesion strength can range between 0.0013～0.0700MPa MPa. Therefore, the material adapts to simulating rock-mass considering gravity field.(2) Rigid and brittle rock trends to rockburst,which is generalized by uniaxial compressive strength(σc), brittleness coefficient (K) and exponential of strike energy (WB). When developing the similar material of rigid and brittle rock, some ingredient such as quartz grit, gypsum, cement, water, et al is blended by different proportion. From the results of the proportioning test, it is found out that the different proportion of these ingredient influencesσc, K and WB differently. In physical simulating test,σc, K and WB are checked in general and the directions for the material generalization are confirmed. The mechanical parameters of materials by the selected direction not only meet with requests for rockburst, but also are convenient for making large physical models.(3) The servo-control program of the triaxial model-test large machine in geotechnical engineering is redeveloped, so that the program can control different stress conditions and stress paths. The machine has been debugged repeatedly until it meets the demand of physical model test.(4) Based on the antetype of the representative geological section of a copper mine, the physical general model test is done and the deformation law of surrounding rock and the subsidence law of ground surface caused by exploiting inclining mine near surface are discovered.(5) In order to apply the triaxial model-test large machine better in geotechnical engineering, a series of model-test technologies, such as casting technology of physical model, plane strain control technology, the strain measure technology and full inner-spy photography technology in breakage process, are developed. Moreover, applying these technologies, several cavern models of different section shapes simulating rigid brittle surrounding rock are made and tested under different load conditions so that deformation and breakage mechanism and the stress distribution character of surrounding rock are analyzed efficaciously.(6) Contrasting analysis of physical and numerical simulation has carried out on the basis of the results of physical model test.