| Rock creep is an inherent property of rock,which affects the stability and safety of geotechnical engineering;Existing studies have shown that the presence of water may lead to the instability of surrounding rock in the engineering which was in a stable state.In this paper,uniaxial compression and uniaxial loading creep tests of similar soft rock under different water-cut conditions are carried out,and the instantaneous and creep mechanical properties of similar soft rock under different water-cut conditions are explored;based on nonlinear function and damage mechanics,a nonlinear creep model for soft rock is established.It is necessary to study the rock creep characteristics in different water-cut states.The main research contents are as follows:(1)The basic mechanical parameters of similar soft rock in different water cut states were obtained by uniaxial compression test.The test results showed that the presence of water significantly affected the compressive strength,elastic modulus and deformation of similar soft rock;a damage constitutive model was established based on Harris function and assumption that the rock failure criterion obeyed the maximum positive stress failure criterion,and the results showed that this model had a better simulation effect on the rock compression curve;the energy evolution during uniaxial compression of rock was analyzed,and the results showed that the presence of water reduced the rock storage limit and strain energy limit.(2)The uniaxial creep test of similar soft rock under different water cut states was carried out,and the creep characteristics of similar soft rock under different water cut states together with the effects of water on the creep amount and long-term strength of rock were obtained.The results showed that similar soft rock creep was mainly manifested as attenuation creep and isokinetic creep under lower loading stress,and accelerated creep will occur in similar soft rock under higher loading stress;when the loading stress was the same,the creep of saturated rock samples was 2?3 times of that of dry rock samples,and the time for saturated rock samples to transition from the attenuation creep stage to the steady-state creep stage was longer than that of dry rock samples;water increased the rock creep ratio while decreased the long-term strength of rocks.(3)The characteristics and scope of application of the element combination model were introduced.To solve the shortcomings that the element combination model failed to accurately simulate the accelerated creep stage of rocks,a nonlinear creep model was constructed based on the change rule of mechanical parameters during rock creep and the introduction of nonlinear viscous elements on the basis of the generalized Kelvin model;the constitutive equation and one-dimensional and three-dimensional creep equations of the creep model were given;the creep test data were used to verify the model and identify the parameters.The results showed that the model could accurately simulate the rock creep curve.(4)Based on the damage mechanics theory and Harris function,the nonlinear function and the damage viscous element were introduced into the Bingham model to establish the creep damage model,futhermore,the curve fitting and parameter identification of the model were carried out.The results showed that the model can simulate the whole process of rock creep well,and all the correlation coefficients were above 0.98.Figure[62]Table[13]Reference[82]... |
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