Initial damage is a significant factor leading to alterations in the mechanical properties of discarded tire materials. With reinforced soil being at its serviceability limit state, the one-dimensional tensile stress state predominates within the reinforcement material. The tensile properties of tire-derived geotechnical reinforcement material(TGRM) with initial damage directly determine whether the reinforcement effect can stably exist within the reinforced soil. To investigate the tensile properties, damage mechanisms, and the relationship between the failure mode of TGRM and its absorptive capacity for strain energy under initial damage conditions, static tensile tests were conducted to obtain the stress-strain relationships, post-fracture elongation rates and fracture morphologies of both strip-shaped and ring-shaped TGRM. During the tensile process, research indicates that the non-zero-degree steel fibers within TGRM undergo a symmetrical interlaminar relative displacement. This ensures that the cross- remains macroscopically planar throughout, ultimately leading to a interlayer cracking in the belt layers. Prior to the cracking, a reliable anchoring relationship constantly exists between the steel fibers and the rubber matrix. Initial damage determines the integrity of zero-degree belt layer and the depth of non-zero-degree steel fibers embedded into the rubber matrix, which in turn affects the strain energy storage capacity and the failure mode of TGRM. The results may provide references for the establishment of the constitutive relationship and strength theory of TGRM under initial damage conditions.

Research investigating the complex mechanical properties and energy evolution mechanisms of frozen calcareous clay under the influence of multiple factors is crucial for optimizing the artificial ground freezing method in shaft sinking, thereby enhancing construction quality and safety. In this study, a four-factor, four-level orthogonal test was devised, taking into account temperature, confining pressure, dry density, and water content. The complex nonlinear curvilinear relationship between deviatoric stress, volume strain, and axial strain of frozen calcareous clay under different interaction levels was analyzed. The sensitivity of each factor to the peak volume strain was explored, and the energy evolution mechanism of frozen calcareous clay during the triaxial compression process was analyzed. The findings are summarized as follows: (1) The deviatoric stress-axial strain curves demonstrate the strain-hardening characteristics of frozen calcareous clay specimens. Furthermore, as temperature decreases, the hardening degree increases. (2) Sensitivity analysis indicates that the factors' influence on peak volumetric strain ranks as follows: dry density > confining pressure > temperature > water content. Under the various interactions, specimens exhibit significant volumetric shrinkage. When the temperature remains constant, peak volumetric strain is negatively correlated with dry density but positively correlated with confining pressure. (3) Input energy density, elastic strain energy density, and dissipated energy density of frozen calcareous clay all increase with axial strain. (4) When temperature is held constant, both peak input energy density and peak dissipated energy density rise with increasing confining pressure. Meanwhile, peak elastic strain energy density shows a linear increase with higher confining pressure and lower temperatures.

In this research, a soil reinforcement approach was explored by introducing a polyvinyl acetate polymer treatment along with sisal fiber material, considering two mean particle sizes (D50 = 0.63 and 2.00 mm). The sand specimens were mixed with varying sisal fiber contents (Fs = 0 to 0.8%) and polyvinyl acetate polymer contents (PVAc = 6%, 9%, and 12%). A series of unconfined compression tests were performed to evaluate the compressive strength of the tested materials. The experimental findings indicate a positive correlation between the concentration of polyvinyl acetate polymer and the unconfined compressive strength within the tested range. The shear strength and of the sand initially increases with rising sisal fiber contents and then decreases with further increments in sisal fiber, peaking at a maximum value when the fiber content reaches a threshold of 0.6%. The findings validate the significance of the strain energy parameter as a reliable indicator for elucidating and forecasting the mechanical characteristics of soil reinforcement. New correlations have been developed to predict variations in unconfined compressive strength and peak strain energy based on the studied parameters (Fs, PVAc, and D50). The agreement between predicted and measured characteristics validates the effectiveness of these established relationships in accurately predicting UCS and strain energy factors.

The natural property of rock material, whether impact occurs, is the key influencing factor of the occurrence of rock burst disaster. To accurately assess rock burst proneness, this study focuses on typical sandstone as the research object. Uniaxial cyclic loading and unloading tests were conducted to measure the elastic strain energy accumulated in sandstone under different stress levels and a relationship between elastic strain energy and stress level was established. The results show that: (1) The peak stress under cyclic loading and unloading conditions is slightly lower than the uniaxial compressive strength. With an increase in the number of cycles, the internal damage of sandstone continues to accumulate, and the mechanical properties such as compressive strength continue to deteriorate; (2) With an increase in stress, the input strain energy, elastic strain energy, and dissipated strain energy also increase; (3) When the stress is low, the increase in elastic strain energy is large and shows a steady growth; with an increase in stress, the increase of elastic strain energy decreases; (4) The square of stress at any time has a good linear relationship with elastic strain energy. According to the relationship obtained from the test, the elastic strain energy at the peak stress time can be obtained; (5) A new criterion for assessing rock burst proneness is proposed: residual energy release rate index W-T, which characterizes the energy release per unit time when the rock burst occurs. The intervals for evaluating the rock burst proneness of the residual energy release rate index W-T are as follows: W-T 2, indicating strong rock burst proneness; and (6) The rationality of the proposed residual energy release rate index W-T is verified by the multi-index method and the multi-sample method, and the proposed residual energy release rate index is used to determine the rock burst proneness of 10 kinds of rock samples. The evaluation accuracy is shown to be high, and it can reflect the actual rock burst proneness (c) 2024 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/ 4.0/).

Urbanized oil-rich regions, such as Ahvaz, Iran, face significant geotechnical challenges due to widespread oil contamination in soils. This contamination poses a major problem for construction projects, particularly with the increasing installation of oil pipelines within city limits, which exacerbates soil pollution risks. Addressing this challenge, the present study explores an innovative solution using pumice powder (PP), a natural silica-based stabilizer, to improve the longterm geotechnical properties of oil-contaminated fine-grained soils. This research fills a critical knowledge gap by evaluating the effectiveness of PP in stabilizing soils contaminated with varying oil concentrations (4 %, 7 %, and 10 %) and treated with different percentages of PP (5 %, 10 %, and 15 %). The comprehensive investigations in this study included assessments of mechanical properties, durability, microstructural changes through field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and chemical properties using Fourier transform infrared analysis (FTIR). The findings revealed that 10 % PP significantly increased the soil's long-term unconfined compressive strength by up to 370 %, enhanced durability, and reduced susceptibility to cracking, marking a sustainable alternative to environmentally costly traditional stabilizers. This novel use of PP not only fills a crucial knowledge gap concerning the long-term structural integrity and resilience of such soils but also advances the field towards more sustainable and ecologically responsible soil stabilization practices, contributing broadly to environmentally friendly construction methodologies in the oil-rich regions.

Liquefaction, which typically occurs in saturated sandy soil deposits, is one of the destructive phenomena that can occur during an earthquake. When the soil reaches liquefied state, it loses a significant amount of resistance and stiffness, which often results in widespread catastrophic damages. Therefore, accurate evaluating the potential of soil liquefaction occurrence is of great importance in earthquake geotechnical designs in regions prone to this phenomenon. The strain energy-based approach is a novel robustness technique to evaluate liquefaction potential. In the current research, 165 laboratory data sets from cyclic experiments were collected and analyzed. A predictive model using gene expression programming (GEP) was proposed to assess strain energy needed for occurrence of soil liquefaction. Assessing physical behavior of developed GEP-based model was conducted through sensitivity analysis. Performance of GEP-based was validated by comparing with a series of centrifuge experiments and cyclic triaxial tests results. Subsequently, after experimental verification of numerical modeling, the strain energy required for soil liquefaction under cyclic loading at different conditions were numerically evaluated and compared with the strain energy calculated by proposed model. Finally, the developed GEP-based model was compared with established strain energy-based relationships. The results indicated high precision of proposed GEP-based model in determination of strain energy required for soil liquefaction triggering.

Mixing discrete flexible fibres into sand may improve its liquefaction resistance during cyclic loading. Here, the benefits are demonstrated by performing undrained cyclic triaxial tests on fibre-reinforced samples in very loose and loose states. The development of a liquified state may be delayed when fibres are present. Here, the strain energy dissipation during loading, and liquefaction development, is focused on. The results show that strain energy continuously dissipates as undrained cyclic loading proceeds. The capacity energy, which coincides with a double amplitude axial strain of 5% or the unity of excess pore pressure ratio (ru\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${r}_{u}$$\end{document}), whichever occurs first, is increased by the inclusion of fibres. Under the two-way symmetrical cyclic loading, with a cyclic stress ratio of 0.2, the inclusion of fibres with a fibre content of 0.5% leads to the capacity energies of the samples in very loose and loose states increasing by 86.8 and 158.8%, respectively. The generation of pore pressure is closely related to the dissipated energy. The fibres alter the liquefaction responses of a sand skeleton in ways that depend on the applied loading conditions, and this depends on the extent to which the fibres are mobilized in tension during loading. When unities of ru\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${r}_{u}$$\end{document} are attained for fibre-reinforced sand samples, their states may vary greatly and remain far from liquefaction. A newly defined pore pressure ratio (ru & lowast;)\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$({{r}_{u}}{*})$$\end{document} proves to be a better indicator of liquefaction in fibre-reinforced sand. A possible energy-based method, intended for practical use to assess liquefaction resistance of fibre-reinforced sand, and the margin of safety against liquefaction, is also presented.

Accurate prediction of rockburst proneness is one of challenges for assessing the rockburst risk and selecting effective control measures. This study aims to assess rockburst proneness by considering the energy characteristics and qualitative information during rock failure. Several representative rock types in cylindrical and cuboidal sample shapes were tested under uniaxial compression conditions and the failure progress was detected by a high-speed camera. The far-field ejection mass ratio (FEMR) was determined considering the qualitative failure information of the rock samples. The peak-strength energy impact index and the residual elastic energy index were used to quantitatively evaluate the rockburst proneness of both cylindrical and cuboidal samples. Further, the performance of these two indices was analyzed by comparing their estimates with the FEMR. The results show that the accuracy of the residual elastic energy index is significantly higher than that of the peak-strength energy impact index. The residual elastic energy index and the FEMR are in good agreement for both cylindrical and cuboidal rock materials. This is because these two indices can essentially reflect the common energy release mechanism characterized by the mass, ejection velocity, and ejection distance of rock fragments. It suggests that both the FEMR and the residual elastic energy index can be used to accurately measure the rockburst proneness of cylindrical and cuboidal samples based on uniaxial compression test. (c) 2024 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/ licenses/by-nc-nd/4.0/).

Mining Exploration, excavation, and construction are considered as mining activities which are recently growing dramatically. Therefore, utilizing the mining wastes with the least environmental damage is a significant concern. Tailings dams are one of the conventional solutions that store the extracted hazardous substances safely for water resources management and environmental protection. This reseach deals with the effects of monotonic and seismic loadings on silt-sized copper wastes existed in a tailings dam at Northwest Iran as a case study. Various values of initial static shear stress are performed using an automated cyclic triaxial system. Monotonic undrained compressive tests were performed with a relatively constant density and considering three values of 50, 100, and 150 kPa for mean effective stress. Depending on the first density of samples, applying a mean effective confining pressure of 100 kPa, increased the initial densities by 25 to 30% as compared to the initial condition.Moreover, the effect of initial shear stress ratio with three values of 0, 0.2, and 0.4 was evaluated. No peak point was observed for samples under alpha = 0, whereas, samples with alpha = 0.4 encountered a peak point before reaching to the phase transformation point. The results of cyclic experiments were used to evaluate capacity energy and residual pore pressure based on the strain energy approach. Cyclic tests on the samples were performed considering the shear amplitude of 0.75% and frequency of 0.3 Hz. It is shown that the most energy dissipation occurs at the first cycle possessing the highest stiffness. For alpha = 0, energy density increased from 474 J/m(3) to 1147.4 J/m(3); however, a more intense increase was measured from 682 J/m(3) to 5839 J/m(3) when alpha = 0.4. It is also found that applying initial shear stress has a pretty considerable influence on monotonic strength and the liquefaction resistance of silts. The increase of alpha from 0 to 0.4 yielded a linear increase in the shear strength of samples in the range of 20 kPa to 70 kPa. The results of this paper were then validated accurately through some previous studies.