Study on Dynamic Constitutive Model of Weakly Consolidated Soft Rock in Western China

Abstract

To obtain the impact mechanical response and establish the dynamic damage constitutive relationship of frozen sandstone at low temperature conditions, the impact test of Cretaceous red sandstone under different temperatures was conducted using a split Hopkinson pressure bar (SHPB) device. According to the characteristics of the stress-strain curves obtained by the test, a constitutive model considering the damage effect, temperature effect, and strain rate effect was established, which was improved by Zhu–Wang–Tang (Z–W–T) constitutive model. It was proved that the fitting curves of constitutive equation were in good agreement with the test curves. The fluctuation amplitude of fitting error was controlled within ±4 MPa. The physical meaning of each parameter of the constitutive model is clear, and most of them are fixed values. The selection range of variable parameters and the related change rules are confirmed, which improves the practicability of constitutive model. The constitutive equation can well describe the nonlinear features of this kind of frozen sandstone under impact loading. It was also found that the constitutive equation was applicable to express the dynamic mechanical properties of rock-like materials such as hard rock, soft rock, frozen soil, raw coal, and concrete. It can be referred to the parameter determination method in this paper to study and determine the parameters, reduce the difficulty of parameter selection, and improve the practicability of the constitutive model and parameters, so as to guide the engineering practice better.

Dynamic Splitting Behavior and the Constitutive Relationship of Frozen Sandstone Containing a Single Fissure

“…Yang et al [19] considered Cretaceous red sandstone and conducted the SHPB dynamic impact test to study its deformation, failure, and energy transfer laws under low-temperature conditions. e dynamic mechanical properties of weakly consolidated soft rock under different freezing temperatures were studied using the split Hopkinson pressure bar system, and a dynamic constitutive model considering the temperature effects was established [20,21]. Weng et al [22] studied the effects of strain rate on the dynamic mechanical properties of dry siltstone and saturated siltstone at low temperatures, and the associated mechanism of water/ice weakening and strengthening of the dynamic mechanical properties of siltstone was discussed.…”