Rheological Analysis of Soft Rock Unloading Combined with Finite Element Analysis Based on H-K Constitutive Model

The rheological and mechanical features of soft rock in the unloading environment differ in terms of the timeliness under the conditions of loaded rock. For the purpose of analyzing the stability of soft rock in the rheological process accurately, the finite element analysis algorithm based on the H-K constitutive model is used to analyze its nonlinear rheological features and adjust the changes in the surrounding rock stress in a timely manner during the excavation of soft rock. In accordance with the rheological acceleration features of soft rock at the rheological stage, the damage produced at the rheological acceleration stage of soft rock is modified by using the finite element analysis (FEA) method. Through fitting the algorithm to the analysis, it can be concluded that the application of the finite element analysis method based on the H-K constitutive model can present the image of the rheological nonlinearity of soft rock accurately. Finally, the results of the experimental research indicate that through the application of the finite element analysis algorithm based on the H-K constitutive model in the process of rheological analysis of soft rock, the advantageous performance of the rheological and mechanical properties of soft rock can be presented more evidently. However, with the decrease in the surrounding air pressure, the deviatoric stress of the soft rock will become increasingly larger. In the case of an axial change, the corresponding rate of deformation will increase in the range of 12%–35%. The rate of deformation in the lateral soft rock will fluctuate in the range of 9%–28% in accordance with the corresponding growth rate. This suggests that soft rock unloading can reduce the constraint of particles sliding inside the soft rock, which will further increase the rate of deformation change.