Study On The Rock Deformation And Failure Based On Finite Deformation Theory

As the rapid development of large-scale water resources and hydroelectricprojects,the military underground defensive engineering and exploitation of deepunderground resources, the stability and control problems of rock engineering becomemore and more important, especially, the theories and numerical methods ofdiscontinuous and large deformation problems of rock have become the focus ofacademic circles. Based on finite deformation theory and discontinuous deformationanalysis (DDA), the deformation and failure problems of rock were studiedthoroughly by theoretical method, numerical method, and experiment. The mainprogresses are as follows:(1) The analytical/semi-analytical solution of stability of slope in open pitmining, displacement field and stability the surrounding rock of tunnels were studiedbased on finite deformation theory. The comparison of the result obtained based onsmall strain theory and the one based on finite deformation theory shows that themean rotation angle and the nonlinear characteristics of metric tensor are the maincause of the difference. And the difference increases with the mean rotation angle anddeformation.(2) The improvement of the present DDA was carried out based on finitedeformation geometric theory. The improved DDA code can separate the rotation anddeformation correctly and can handle the large displacement, large deformation andlarge rotation problems exactly. The universality and accuracy of the improved codewere validated by examples. Two typical problems of mining engineering:(i)"slotted-drilling" induced pressure relief and permeability improvement in coal seamgas extraction technology;(ii) movement and load distribution of overburden rockstratum during long wall mining; were also analyzed by employing the improved code.The numerical results provide basis for engineering.(3) The characteristics of rock deformation and failure under the effects ofmulti-factors (temperature, water and confining pressure) were studied based onorthogonal design experiment. It can be concluded that the mean rotation angle canreflect the localization deformation and failure of rock well. With the consideration ofmean rotation angle, a constitutive equation was presented. It can be found that thisconstitutive model coincides with the experimental data and can describe the compaction stage, linear enhancement stage and the plastic yield stage well.(4) The Burgers model was used to describe the creep behavior of rock; theevolution law equation of steady-state creep rate under the effects of temperature,saturated time and confining pressure was obtained. A DDA code that can computethe rheology problem was developed. The numerical analysis of dry-roomtemperature and high temperature, high humidity rock surrounding a tunnel was alsomade. It shows that the rheology behavior and the pressure relief process can be wellmodeled by using the developed DDA code.The dissertation incudes77figures,22tables and cites303references.