Study of the mechanical properties and constitutive model of the roadbed rehabilitation polyurethane grouting materials under uniaxial compression

Abstract

AbstractPolyurethane grouting materials are increasingly used in the non‐excavation rehabilitation of roadbeds. The compressive strength of roadbed rehabilitation polyurethane (RHPU) grouting materials is the key to achieving the desirable repair effect, whereas the constitutive model of RHPU grouting materials is not yet understood. Here, the mechanical properties of RHPU grouting materials under compression were experimentally investigated, followed by establishing the hyperfoam constitutive model. The variation laws of the critical parameters in the model with density were function fitted, and then the constitutive model was simplified as an equation of density as the single independent variable. The comparisons between the theoretical and experimental mechanical behavior of RHPU grouting materials were discussed to illustrate the applicability of the hyperfoam constitutive model. Results show that with the increasing density, both the yield strength (σ1), elastic modulus (E1), and secant modulus (Es) increases exponentially, and the Poisson's ratio (v) increases logarithmically. The maximum increase in σ1, E1, Es, and v are about 750%, 720%, 940%, and 50%, respectively. Compared to the effects of density on the mechanical properties, the effect of loading rate is much smaller, and the side length has no effect. For RHPU samples with a density not exceeding 0.35 g/cm3, the hyperfoam model can well describe the uniaxial compression mechanical behavior, but for those whose density exceeds 0.35 g/cm3, the model can only describe the mechanical behavior before yielding. The theoretical yield strength of the RHPU samples obtained from the model is close to the experimental value (with differences of about 0.1%–14.4%). This study provides a base to evaluate the compressive strength of the practically used RHPU grouting materials based on the density.