渗透溶蚀对西域砾岩强度及破坏模式影响研究OA

Aiming at seepage-mechanical instability caused by the weakening of Xiyu conglomerate when it meets water,we conduct seepage dissolution tests and mechanical tests on the conglomerate under different seepage pressures-for the Momoke water control project in Kashgar,Xinjiang-focusing on the influence of seepage pressures and loading paths on the seepage characteristics and strength evolution of rock mass.The results show time variations in permeability coefficients feature two stages:In initial stage,the water absorption and expansion of clay minerals lead to a sudden drop in the rock mass's permeability(41%-52%within 48 h at 0.05 MPa);in later stage,dissolution of its calcium cement leads to significant adjustment in its pore structure with permeability approaching a stable value(2.40-6.45 mD).Variations in calcium ion concentration confirms the characteristics of water-rock reaction in the two stages.Direct loading causes a sudden drop in the conglomerate's permeability and a continuous damage to its structure,while step-by-step loading promotes its dynamic pore erosion-siltation balance,resulting in a smaller attenuation range of its mechanical parameters.The coupling effect of infiltration and dissolution generates nonlinear deterioration in the conglomerate's mechanical properties,and an increase in infiltration pressure causes a nonlinear decrease in a number of its parameters-such as compressive strength,elastic modulus,residual strength,and tensile strength.Damage to its microstructure makes the failure mode shift from brittle splitting to tensile-shear composite failure.This study lays a basis of multi-field coupling analysis for stability prediction of Xiyu conglomerate strata.