Creep deformation and rupture under continuous loading lower the long-term durability of high-modulus polyethylene (HMPE) ropes in deepwater mooring systems. In this investigation, we develop a fractional viscoelastic damage model to describe deformation from the primary creep to rupture. The formulation is derived within an effective configuration framework using the Clausius–Duhem inequality and combines a generalized Almeida–Caputo fractional element with a Kachanov damage law. Effective stress drives both the instantaneous elastic response and the fractional memory integral, coupling damage accumulation with hereditary deformation. A sequential identification procedure determines the damage parameters from rupture lifetimes, the elastic parameter from initial strains, and the fractional parameters from strain–time records. Calibration against published HMPE strand data at 20–80
Reusing waste glass in concrete offers a route to reducing demand for natural aggregates and cement, but its effects on mechanical behaviour under different loading conditions require further investigation. In this paper, we examine concrete incorporating waste glass sand and powder as replacements for 20
To reveal the influence of the creep effects of bedded surrounding rock on the stability of long-span underground excavation stations, laboratory creep tests of slate with different bedding dip angles were carried out taking the Qingniwaqiao subsurface excavation station constructed by the arch cover method in Dalian Metro as the engineering background. Based on the Power-Ubiquitous model, a three dimensional numerical model of the station was established by FLAC3D. The time-dependent evolution characteristics of bedded surrounding rock displacement, structural stress and plastic zone after excavation were systematically analyzed, and targeted reinforcement measures for side wall rock mass under different bedding dip angles were put forward. The results indicate that bedding dip angles exert a dominant control on the mechanical and creep performances of bedded slate. By combining the ubiquitous-joint model with the power model, the Power-Ubiquitous model suitable for bedded slate was constructed. This model can represent the entire three-stage creep process of slate with different bedding dip angles. Without considering creep, the instantaneous settlement of the crown was 27.1 mm, and after 90 days of creep effect, it increased to 30.7 mm (an increase of 13.3
Models developed solely based on aggregate volume fraction cannot characterize the effects of variations in aggregate size proportions under a constant total aggregate content. This study investigates the elastic modulus and specific creep of hydraulic concrete with different proportions of two coarse aggregate size fractions. Four concrete mixtures were designed, with mass ratios of 5–20 mm to 20–40 mm coarse aggregates set as 5:0, 4:1, 2:3, and 0:5, while the coarse aggregate volume fraction was kept constant at approximately 47.5 με /MPa. The findings demonstrate that aggregate size proportions are critical for modelling the elastic modulus and creep of hydraulic concrete within the range of the present experimental conditions.
In order to explore the creep characteristics of sandstone, the step loading triaxial creep test is carried out. The deformation and long-term strength characteristics of sandstone were studied. By introducing the relationship between the internal friction angle and the effective internal friction angle, the damage variable considering the deterioration of the internal friction angle is established. And based on the test results, a damage creep model that can describe the viscoelastic-plastic deformation of sandstone is established. The results show that with the continuous increase of ( σ - σ _A ) t , both φ ^* / φ , c^* / c and tan φ ^* /tan φ shows a decreasing trend. Their change trends satisfy the negative exponential function. And the damage variable considering the deterioration of internal friction angle can better describe the creep damage process of rock. The theoretical value of the improved Nishihara model is in good agreement with the experimental results. It not only fully reflects the instantaneous elastic deformation after loading. It also reflects the primary creep of the first stage and the steady-stable creep of the second stage. The deformation in the accelerated creep stage was successfully fitted. The results are significantly better than the traditional Nishihara model. It shows that it has certain guiding significance for roadway surrounding rock collapse prediction.
