Study On Rock Time-varying Strength And Slope Dynamic Stability Based On Creep Properties Of Water-bearing Soft Rock

Progressive failure of rock creep caused by aging in the long-term loads, especially the soft rock under the condition of water often control the damage in rock engineering. Therefore, grasping the rock rheological properties and its time-varying rock mass strength parameters in groundwater environment correctly has important practical significance. Research was carried out by a combination method including testing research, theoretical analysis and numerical simulation in this paper. According to uniaxial creep tests of sandy mudstone under different moisture conditions and the non-linear rheology theory and damage theory, the creep properties of sandy mudstone under different moisture conditions is analyzed. Based on the theoretical study results, researches on the effectiveness of soft rock slope stability under different moisture conditions are carried out. The main contents in this paper are as follows:1. According to the mechanics and deformation tests of the sandy mudstone in different moisture conditions, which is collected freshly from the Beishan mine in XinJiang, the stress-strain curves under4kinds of moisture conditions are obtained. Based on the creep tests of sandy mudstone under different moisture conditions, uniaxial strain-time curves are obtained under different moisture conditions, and the variation law of creep curves with the change of stress and moisture content is analyzed.2. According to the basic nonlinear rheology theory of rock and the relevant researches on stress-strain relationship of sandy mudstone, a revised Kelvin model is put forward, and the rheological constructive equation of it is present. it is indicated that the revised Kelvin model has many special characteristics and has a better adaptability in describing the rheological properties of rocks.3. In order to describe the whole rock creep curves, the nonlinear creep model is established by installing a swath model with the generalized kelvin model In parallel According to the nonlinear least squares theory and uniaxial creep test results of sandy mudstone, the parameters of the new model are obtained by inversion caculation and the results show that the model can well describe uniaxial creep the properties of sandy mudstone.4. According to the rock creep properties under different water contains, on the basis of the sandy mudstone water absorption test and aging theory, introduces water instantaneous injury D(w) and long-term creep damage factor Ds (w) are established.5. Through the limit strain of rock accelerated creep, time varying uniaxial compressive strength of sandy mudstone are calculated, Combined with Hoek-brown experience strength criterion, rock time varying compressive strength, time varying tensile strength and time-varying rock mass strength parameters c,φ are calculated.6. Based on FLAC3D and Geo-slope software, numerical calculation of stability is carried out on Beishan mine non-working slope under different water condition. The early warning fixed number of year, slope protection measures are put forward to ensure the production safety of mine in its service life.