Mohr-Coulomb Failure Research Articles

Multiphysics Simulations of Microwave Induced Damage Applied to Rock Samples of Varying Strength and Absorptivity

AbstractIn this work, we show the development of a numerical model to investigate the 3D interactions between microwave radiation and basalt, granite, and sandstone rock samples. In particular, we assign sample heterogeneity based on the Weibull statistical distribution, and invoke a damage model for elemental tensile and compressive stresses based on the maximum tensile stress and the Mohr–Coulomb theories, respectively. Model implementation is facilitated by the use of comsol for use in coupling the electromagnetic, thermal, and solid displacement relations. Various parametric studies are conducted related to variable input power and waveguide port alignment, with model validation conducted with respect to damage resulting from a uniaxial compression test. The results indicate that relatively high induced temperatures will promote damage potential, but its impact must be placed within the context of the sample strength to quantify the true potential damage evolution of a given rock mass. As observed herein, a mechanically weaker rock may be prone to mechanical damage; however, it may also possess a relatively large relative permittivity, enabling it to absorb the least amount of microwave radiation thus yielding comparatively low overall damage profiles compared to a more mechanically competent rock mass.

The temperature-dependent shear strength of ice-filled joints in rock mass considering the effect of joint roughness, opening and shear rates

Abstract. Global warming causes many rockfall activities in alpine mountains, especially when ice-filled joints in the rock mass become thawed. The warming and thawing of frozen soils and intact rocks have been widely studied in the past several decades; however, the variation of shear strengths of ice-filled joints is not fully understood. In this study, a series of compression–shear experiments were conducted to investigate the shear strength of ice-filled rock joints by considering the effects of joint roughness, temperature, opening, shear rates and normal stress. The joint roughness can improve the shear strength of ice-filled joints. However, the contribution of joint roughness is controlled by some noticeable bulges instead of the joint roughness coefficient (JRC) index. The peak shear strength of the ice-filled joint linearly increases with the increasing aggregation of rupture ice area before these noticeable bulges. As the joint opening increases, the effect of joint roughness decreases, and the shear strength of ice-filled joints tends to be equal to the shear strength of pure ice. In addition, the shear strength quickly reduces with increasing temperature from −15 to −0.5 ∘C. The shear failure mode changes from shear cracking of joint ice to the shear debonding of the ice–rock interface above −1 ∘C. Increasing shear rate decreases the shear strength of ice-filled joints because the joint ice displays the brittle failure phenomenon at a high shear rate. The peak shear strength of the ice-filled joint linearly increases with the increase in normal stress. Moreover, it is also proved that the Mohr–Coulomb criterion can be used to characterize the shear strength of ice-filled joints under different normal stresses. This research can provide a better understanding of the warming degradation mechanism of ice-filled joints by considering the abovementioned important influencing factors.

Numerical study on cracking behavior and fracture failure mechanism of flawed rock materials under uniaxial compression

AbstractThe numerical approach is a vital means for evaluating the stability of flawed rocks. In this paper, the extended non‐ordinary state‐based peridynamics (NOSB‐PD) theory is employed to simulate the fracture process of rocks containing two pre‐existing flaws. Two stress criteria, including the maximum tensile stress criterion and the Mohr–Coulomb criterion, are implemented into the NOSB‐PD numerical method to respectively judge the tensile and shear failure of rock materials. The effects of inclination angles and ligament angles on the crack initiation and coalescence modes for flawed rocks are investigated based on the numerical results. The numerical results are in good agreement with the previous experimental results. The fracture mechanism of flawed rocks is revealed based on the evolutionary distribution characteristics of the maximum principal stress field and shear stress field obtained by the extended NOSB‐PD theory.

Prediction of Seismic Bearing Capacity Considering Nonlinearity and Dilatancy by Sequential Quadratic Programming

Most of the published literature regarding bearing capacity are often focused on linear and associative soils. Concerning the intrinsic strength nonlinearity in dilatancy soils, this study investigates the problem of the seismic bearing capacity in the framework of the kinematic theorem of limit analysis. The conventional linear Mohr–Coulomb criterion is substituted with a nonlinear power law criterion to depict the nonlinearity of the soil strength. The non-associative feature of soil materials is considered by defining a nonlinear dilatancy coefficient. A generalized tangential technique is accordingly introduced to linearize the strength envelope for making the nonlinear criterion tractable in the analysis. A non-symmetrical translational failure mechanism that is comprised of several rigid wedges is used to characterize the failure of the foundation at the limit state. Moreover, the seismic action is considered by the classic pseudo-static method. Based upon the energy equilibrium theory of the upper-bound limit analysis, new analytical solutions are derived from the work-balanced equation with nonlinearity and dilatancy. This rigorous upper-bound solution is formulated as a multivariate optimization problem and is readily addressed by sequential quadratic programming (SQP). To verify the reliability of the new expressions, the present results are compared with already posted solutions and the original pseudo-dynamic solutions. The comparative results show a good agreement with previous works, and the correctness and rationality of the new analytical solutions are validated. The detailed parametric study reveals that, in the non-associative flow soils, the ultimate bearing capacity is significantly decreased with a reduction in the dilatancy coefficient. Particularly in the linear condition, namely m = 1, the larger the internal friction angle is, the more obvious the influence of the non-associative feature on the bearing capacity is.

A Volume Averaging FEM-Based Fracture Model for Damage Process in Cohesive-Frictional Solids

In this study, a mesh-independent fracture model is implemented in the standard finite-element (FE) framework by leveraging a volume averaging approach. For the tension regime, a cohesive crack model is adopted for the onset and propagation of the crack, in which the direction of a new crack is defined as the eigenvector of the maximum principal stress. For the compression regime, the Coulomb criterion is considered for the onset and propagation of the crack, and the new crack direction is obtained based on the Mohr–Coulomb criterion by employing the residual friction angle. In addition, a new return mapping algorithm, i.e., the general return mapping, is developed for both compression and tension loading conditions to improve the numerical robustness, convergence, and accuracy. Finally, in order to validate the constitutive behavior, a stress-point calculation is performed, followed by boundary value problems to illustrate the robustness of the suggested return mapping algorithms and the mesh-independence effects of the volume averaging methodology.

A Method for Computing Slip-Line Fields with Stress Discontinuity in Cohesionless Backfills

A method for computing slip-line fields in the case of cohesionless backfills with stress discontinuity was proposed. The potential failure zone is divided into the Rankine zone and the transition zone, and the Rankine zone is rigorously determined using the theory of plastic mechanics. The potential failure zone and the Rankine zone are then further divided into a series of triangular slices. On the basis of the force and moment equilibrium conditions of a typical triangular slice, the recurrence equation of the lateral force is established. Furthermore, the relationship between the failure surface inclination angle and the interslice force inclination angle is established by satisfying the Mohr–Coulomb criterion. An iterative procedure for calculating the lateral force of the triangular slices by changing the failure surface inclination in the transition zone is performed until the interslice force satisfies the stress condition of the transition zone boundary, resulting in a stress discontinuity line if the Rankine zone and the transition zone intersect and the intersection line satisfies the stress characteristics of stress discontinuity. Example studies are performed to verify the present method, which shows that the soil–wall interface friction has the most significant effect on stress discontinuity, and the location of the stress discontinuity line gradually approaches the backfill surface with an increase in retaining wall inclination.

Study on mechanical properties and wellbore stability of deep sandstone rock based on variable parameter M-C criterion

With the depletion of shallow oil and gas resources and the increase in fossil energy consumption, deep oil and gas resources have become the main driving force of economic development. However, the physical and chemical properties and rock mechanics characteristics of the deep sandstone stratum are remarkable, and there is little research on the rock failure law of the deep sandstone stratum. Therefore, a batch of sandstone with similar homogeneity was selected, and several triaxial mechanical experiments with variable confining pressure were conducted for such sandstone. The mechanical constitutive model of rock samples under different confining pressures, the macroscopic failure characteristics of rock samples, and the evolution law of wave velocity and internal energy of rock samples during mechanical loading were analyzed. According to the experimental results of triaxial mechanics, a calculation model of wellbore collapse pressure in deep sandstone formation was established based on the variable parameter Mohr–Coulomb criterion. The results show that the crack propagation process of rock samples under mechanical loading can be divided into four stages. The characteristic strength, peak strain, elastic modulus, and deformation modulus of rock samples were positively correlated with confining pressure and showed obvious nonlinearity in high confining pressure areas. The failure mode of the rock sample changed from brittle failure to plastic brittle failure with the increase in confining pressure. According to the characteristics of the stress-strain curve, the variation of acoustic wave velocity during triaxial mechanical loading can be divided into three different types. The variation trend of acoustic wave amplitude of rock samples is consistent with the stress-strain curve. With the loading of axial stress, the elastic energy curve was a concave function, the curve of dissipated energy started increasing at the cracking stress of rock samples. After destroying the rock sample, the decline slope of the dissipated energy curve decreased with the increase in confining pressure. Considering the limited failure of the borehole wall, an evaluation model of borehole wall stability in deep sandstone formation based on variable parameter M–C criterion was established. The equivalent density of borehole collapse pressure predicted using the M–C strength criterion method with variable parameters was smaller than that predicted with traditional methods. The research results provide a theoretical basis for safe and efficient drilling in a deep sandstone formation.

Dynamic failure characteristics of surrounding rocks under different lateral pressure coefficients in deep tunnel transient excavation

A novel transient unloading testing system was adopted to simulate the transient excavation of tunnels under different lateral pressure coefficients (k0). The results show that the transient excavation of a tunnel induces significant stress redistributions and concentrations, particle displacements and vibrations to the surrounding rocks. The decrease of k0 enhances the dynamic disturbance of transient tunnel excavation, and especially when k0 = 0.4 and 0.2, the tensile stress can be observed on the top of the tunnel. The peak particle velocity (PPV) of the measuring points on the top of the tunnel decreases with the increasing distance between the tunnel boundary and measuring point. The transient unloading wave is generally concentrated on lower frequencies in the amplitude-frequency spectrum under the same unloading conditions, especially for lower k0 values. In addition, the dynamic Mohr–Coulomb criterion was used to reveal the failure mechanism of a transient excavated tunnel by involving the loading rate effect. It is found that the excavation damaged zone (EDZ) of the tunnel is dominated by the shear failure, and the number of the shear failure zones increases with the decrease of k0. The EDZ of tunnels after transient excavations varies from ring-shape to egg-shape and X-type shear with the decrease of k0. The evolution of the EDZ induced by the transient unloading is associated with k0, i.e., the shear failure of surrounding rocks mainly occurs in the stress redistribution stage under high k0 (1.0–0.7), while the dramatic destruction of surrounding rocks is more prone to occur after the transient unloading process when k0 ≤ 0.6.

A Strain Hardening and Softening Constitutive Model for Hard Brittle Rocks

To study the strain hardening and softening mechanism for hard brittle rocks, a strain hardening and softening constitutive model for hard brittle rocks is developed. First, the normalised hardening and softening factors are defined, which characterise the yield state of rock at the stages of pre-peak hardening and post-peak softening, respectively. Then, a unified strength parameter evolution model is established that can describe the nonlinear characteristics of cohesion and the internal friction angle under different confining pressures. Based on the Mohr–Coulomb criterion, a strain hardening and softening constitutive model is proposed. Finally, the proposed model was implemented in FLAC3D, and triaxial compression numerical tests of granite and diabase were conducted. The results show that the constitutive model can characterise the nonlinear mechanical behaviour of the pre-peak hardening stage and post-peak softening stage of hard brittle rock. The model was also able to satisfactorily capture the transition from brittle failure to plastic failure for hard brittle rock under high confining pressures.

Experimental investigations on effects of gas pressure on mechanical behaviors and failure characteristic of coals

The mechanical behavior of coal is the key factor affecting underground coal mining and coalbed methane extraction. In this study, triaxial compression and seepage tests were carried out on coal at different gas pressures. The mechanical properties and failure process of coal were studied, as well as the acoustic emission (AE) and strain energy. The influence of gas pressure on the mechanical parameters of this coal was analyzed. Based on the conventional energy calculation formula, the pore pressure was introduced through the effective stress formula, and each energy component of coal containing gas was refined innovatively. The contribution of gas pressure to the total energy input and dissipation during loading was quantitatively described. Finally, the influence of gas pressure on coal strength was theoretically analyzed from the perspectives of Mohr–Coulomb criterion and fracture mechanics. The results show that the total absorbed energy comprises the absorbed energy in the axial pressure direction (positive) and in the confining pressure direction (negative), as well as that induced by the pore pressure (initially negative and then positive). The absorbed energy in the axial pressure direction accounts for the main proportion of the total energy absorbed by coal. The quiet period of AE in the initial stage shortens, and AE activity increases during the pre-peak stage under high gas pressure. The fractal characteristics of AE in three stages are studied using the correlation dimension. The AE process has different forms of self-similarity in various deformation stages.

Statically Admissible Stress Fields in Conical Sand Valleys and Heaps: A Validation of Haar–von Kármán Hypothesis

The usage of the Haar–von Kármán hypothesis for circumferential stress in axisymmetric problems is still questionable. This study aims to reveal statically admissible stress fields in conical sand valleys and heaps by applying the Haar–von Kármán hypothesis to rigid-plastic material obeying the Mohr–Coulomb criterion. The original boundary-value problem reduces to a pair of ordinary differential equations by employing the self-similarity assumption in conjunction with the condition of incipient failure everywhere. The pair of governing equations are numerically integrated with the fifth-order adaptive Runge–Kutta method. The shooting method is employed to numerically convert the boundary-value problem to the initial-value problem. Moreover, the singularities that occurred in the integrations are coped with by numerical perturbation of the initial boundary conditions. A line of stress discontinuity together with the stress jump condition is imposed to link the stress solution between the rigid and plastic regions. Admissible stress fields in various axisymmetric geometries are successfully achieved whereby the load transfer mechanisms in the conical sand heaps and valleys are elucidated. The arch action that occurred in bulk solid is observed. The effect of the circumferential stress hypotheses, that is, Haar–von Kármán hypothesis and Lévy’s flow rule, on the results of rigid-plastic solution is demonstrated; therefore, the advantages and disadvantages of both the hypotheses are elucidated. This study rigorously justifies the validity of the Haar–von Kármán hypothesis, thus a guideline on determining the value of hoop stress using the Haar–von Kármán hypothesis is proposed.

Fracture analysis-based mode-I stress intensity factors of crack under fracture grouting in elastic–plastic soils

For the interaction of crack on the soil–grout interface under fracture grouting, an approximate method to determine the stress intensity factor (SIF) of crack on the soil–grout interface was proposed based on the conservation J2-integral. With this method, the energy release rate of crack propagation under fracture grouting can be defined by the parameters of elastic–plastic soils and the grouting pressure. In order to study the change of strain energy near the crack of elastic–plastic soil under fracture grouting, a mechanical model of elastic–plastic soil with crack was established based on non-associated Mohr–Coulomb criterion model, and the SIF of crack with spring boundary was investigated. The influence of the crack depth ratio and crack aspect ratio on the SIF of cracks under the spring boundary were analyzed, and revealed the rule of crack growth under fracture grouting in elastic–plastic soils. The results showed that the variation of the crack depth ratio and crack aspect ratio had an effect on the change of the SIF of cracks. Increasing the crack depth ratio and crack aspect ratio caused an increase in the SIF of the crack. The results can provide the reference for foundation reinforcement in elastic–plastic soils.

Experimental and Numerical Investigation on the Triaxial Compressive Behavior of Steamed Recycled Aggregate Concrete

The use of recycled aggregates to produce precast concrete products is conductive to the green development of construction industrialization. This paper aimed to study the effects of curing regimes and confining pressures on the triaxial compression behavior of recycled aggregate concrete (RAC). Triaxial compression tests were carried out on RAC under different curing regimes (standard curing, 60 °C—12 h and 80 °C—9 h), and the designed confining pressures were 0 MPa, 2.5 MPa, 5 MPa, and 10 MPa. The results show that the increase of confining pressure limits the expansion of cracks, causing the failure mode to change from vertical splitting to oblique shearing, and the triaxial compressive strength is doubled at most. Compared with standard curing, steam curing significantly weakened the triaxial compressive strength of RAC, which was related to the reduction of RAC cohesion, and the cohesion of RAC steam cured at 80 °C was reduced by 30%. The triaxial compression failure of RAC closely follows the Mohr–Coulomb criterion. Based on the discrete element method and test results, an RAC triaxial compression numerical model considering the shape of the actual coarse aggregate was established, and the propagation of cracks was discussed at the mesoscopic level.

Strengthening effect of sulphoaluminate cementitious grouting material for water-bearing broken rocky stratum

A rapid-hardening sulphoaluminate cementitious grouting material (SCGM) is improved for water-bearing broken rocky stratum. Hydroxy propyl methyl cellulose (HPMC) and polycarboxylate-based superplasticizer (PCE) are used to improve fresh-state performance. Main diffusion ability, fresh-state properties, basic mechanical strengths, microstructure, etc., are investigated. A novel grouting simulation apparatus is designed to assess grouting effectiveness, the holistic reinforcement effect, compressive strength and anti-permeability of grouted specimen, typical failure mode, influence of key parameter and bonding characteristic of grout-rock interface are studied. The combination of 0.4 % PCE and 0.02 % HPMC can be applied at water-binder ratio (w/b) of 0.65–1.0. The maximal 3 d and 28 d unconfined compressive strength (UCS) of SCGM are 15.87 and 18.60 MPa, its 28 d UCS of grouted specimen can attain 14.98 MPa. The SCGM is eligible for rapid water blocking and effective reinforcement especially in water-rich and broken rocky strata. Based on the Coulomb failure criterion, relationships among UCS, internal friction coefficient and cohesion of reinforced rock were derived. Based on the linear relationship between internal friction angle (φ) or cohesion (C) and volumetric block proportion (VBP), the quantitative expression with UCS and VBP was established. In comparision with experimental data, feasibility of the quantitative formula in predicting UCS of reinforced rock is proved.

Development of unified p–y curve model for clays using finite element analysis of laterally loaded piles

In this study, a unified p–y curve model is developed for clays in undrained conditions using the results of 3D finite element (FE) modeling. The p–y curves are primarily used in the analysis of laterally loaded piles. Formulas for the ultimate lateral bearing capacity factor ( Np), and the reference deflection in the p–y curve ( y50), were obtained using the results of parametric studies and regression analysis. The tangent hyperbolic function was used to model the p–y curve shape. In the FE models, the clay soil material was modeled as elastic-perfectly plastic material using Mohr–Coulomb criteria, and the pile material was modeled as elastic only. The parametric study results show that Np varies nonlinearly with depth. The proposed model for Np is composed of two regions: a nonlinear zone and a linear zone. The model for Np used the undrained shear strength ( su), effective unit weight of soil ( γ′), and pile width ( D) as parameters. Further, the proposed model for y50 was found to be dependent on the soil stiffness ( Es), D, and Np. The dependency of y50 on Np was often overlooked in previous studies. Finally, the proposed model was imported in LPILE program and the results from previous case studies were compared with the proposed model predictions.

Analysis and countermeasures of large deformation of deep-buried tunnel excavated in layered rock strata:A case study

Large deformation has been a common engineering problem during the construction of tunnels in areas with high geo-stress, the large deformation of layered surrounding rock tunnels is closed related to the rock’s structural characteristics. In this paper, taking the Jiaoding tunnel as an example, large deformation of the tunnel excavated in the layered surrounding rock strata was analyzed. First, the main disaster-causing factors were analyzed through the in-situ tests, uniaxial compression tests, and immersion tests. Subsequently, the failure models of composite strata and weak interlayer were established respectively based on the geometric method and Mohr-Coulomb theory, the large deformation mechanism of layered rock tunnels under the coupling actions of multiple factors was discussed. Finally, the construction timing of the second primary lining was studied based on field tests and theoretical analysis. The results showed that the high geo-stress and special rock mass structure were the main factors leading to the large deformation of the surrounding rock. And the weak interlayers, the rheological properties of rocks, and the softening effect of groundwater on rocks were important factors that aggravate the deformation of surrounding rock. Three large deformation mechanisms of the Jiaoding tunnel were summarized: bending deformation of layered rock, deformation caused by weak interlayers, and rock rheological deformation. The second primary lining in the Jiaoding tunnel shall be constructed in time after the excavation of the middle bench, and the distance between the second primary lining and the working face of the middle bench must be less than 6 m. The research results can provide a theoretical basis and practical reference for the large deformation control of similar layered surrounding rock tunnels.

Application of adaptive grid-based multi-objective particle swarm optimization algorithm for directional drilling trajectory design

The parameters optimization is the key issue for directional drilling trajectory design in oil and gas fields development, and there are three main challenges in multi-objective and multi-constraint optimization: (1) how to establish a multi-objective optimization model based on geological constraints; (2) how to design an appropriate optimization algorithm and solve the optimization model effectively; (3) how to select the desired result from the obtained Pareto solution and meet the engineering requirements. To build a safe and cost-efficient directional drilling trajectory, a new multi-objective optimization model is established in this paper. The effective objective functions to evaluate the drilling trajectory are summarized as the minimum trajectory length, torque, and strain energy. Moreover, the new model takes the wellbore stability based on Mohr–Coulomb criterion as constraint to prevent the borehole from collapsing. A novel adaptive grid-based multi-objective particle swarm optimization(AGMOPSO) is presented to achieve a set of Pareto optimal solutions of the established optimization model. In this algorithm, a new particle flight mode based on arcsine function of inertia weight and Gaussian mutation strategy are introduced to further improve the global searching ability and obtain more non-inferior solutions. To ensure the uniformity of non-inferior solutions, the adaptive grid based on density control factor is designed to map the space of objective functions to the grid space and adaptively adjust the density of non-inferior solutions in the external archive. Besides, a linear weighted summation function is developed to realize leader selection and archive maintenance of non-inferior solutions. The optimization results on the Pareto front indicate that AGMOPSO has better convergence and uniformity than the unmodified algorithm and reported results. To be concluded, AGMOPSO achieves a better optimization performance and obtain a better trajectory for drilling trajectory optimization model with geological constraints, which has good practical and theoretical significance for directional drilling trajectory optimization.

Experimental Study on the Shear Properties of Soil around Piles with Permeation Grouting

While post-grouting is frequently reported to improve the engineering performance of piles, the shear strength of the soil around piles is not well understood. To investigate the strengthening mechanism of soil around piles with permeation grouting, laboratory tests were carried out on homemade cement soil from the aspects of shear strength and microstructure characteristics. The evolution rule of the shear stress–shear displacement curve of grouting soil with different cement contents was analyzed, and the influence of grouting parameters on shear strength was explained. A composite exponential model describing the shear stress and shear displacement of permeation grouting silty clay was established. Furthermore, the influence of different cement content on changes in the microstructural characteristic parameters of the soil around piles was studied. The results show that penetration grouting has a positive effect on improving the shear strength of the soil around piles, and the failure mode of silty clay changed from elastic–plastic failure to brittle failure after grouting. Permeation grouting makes the particle structure denser, which limits the changes in pore arrangement and distribution. The shear failure of the soil around piles under permeation grouting obeys the Mohr–Coulomb criterion of failure. It is recommended to increase the grout diffusion radius during construction, considering the reinforcement effect of permeation grouting on the soil around piles.

Analytical method for calculation of the strength of cylindrical rock specimens during their longitudinal stress

The goal of this research is to develop a method for calculating the strength of cylindrical rock specimens under axial failure. This will allow for the management of the stress-strain state of rock masses, which is an important issue for many mining companies. To achieve this goal, analytical modeling of the process of failure of cylindrical rock specimens under axial failure was carried out. This was done using experimental values of four indicators of rock properties: shear strength, coefficients of internal and external friction, and elasticity modulus. The results of this research allow for the determination of the ultimate strength and residual strength of cylindrical rock specimens using the four property indicators. These indicators can be experimentally determined using simple methods in laboratory conditions of mining companies. The scientific novelty of this research lies in the fact that analytical modeling of the process of failure of cylindrical rock specimens under axial failure was conducted for the first time, taking into account internal and external friction. This allowed for new results to be obtained and provided a basis for the development of new methods for managing the state of rock masses. The practical significance of this research lies in the fact that the proposed method allows for the determination of the ultimate and residual strength of rock specimens using four property indicators. These indicators can be experimentally determined in mining company laboratories, making the calculation results applicable for the management of the state of rock masses and the efficient destruction of rocks during disintegration. Thus, this method has significant practical significance for the mining industry. A method for calculating the strength of cylindrical specimens under longitudinal failure mode has been developed. The average convergence of calculated strength values with fс = 0.5 to experimental data is 83.4%, which corresponds to a good level of reliability for rock materials. It has been shown that the self-organization of longitudinal failure mode in cylindrical rock specimens occurs in accordance with Coulomb's criterion of maximum effective shear stress, which has been improved to account for contact friction.

Mechanical Properties of Self-Compacting Rubberized Concrete with Different Rubber Types under Triaxial Compression

Different rubber aggregates lead to changes in the effect of stress conditions on the mechanical behavior of concrete, and studies on the triaxial properties of self-compacting rubber concrete (SCRC) are rare. In this study, 35 cylindrical specimens taking lateral stress and rubber type as variables were prepared to study the fresh properties and mechanical behaviors of SCRC under triaxial compression, where the rubber contains two types, i.e., 380 μm rubber powder and 1–4 mm rubber particles, and four contents, i.e., 10%, 20% and 30%. The test results demonstrated that SCRC exhibited a typical oblique shear failure mode under triaxial compression and had a more moderate descending branch compared with self-compacting concrete (SCC). The presence of lateral stress can significantly improve the compression properties, including initial elastic modulus, peak stress and peak strain, with an improvement range of 3%–73% for peak stress. While rubber aggregates mainly targeted the deformation abilities and toughness for improvement, and the peak strain improvement ranges were 0.1–3.1 times and 0.1–1.0 times for SCRC containing rubber powder and SCRC containing rubber particles, respectively, relative to SCC. At a high lateral stress of at least 12 MPa, the loss of strength due to the addition of rubber can be controlled within 10%, in which case the content of rubber powder and rubber particles was recommended to be at most 20% and 30%, respectively. Based on the Mohr-Coulomb theory, the failure criteria of SCRC with different rubber types were established. For analysis and design purposes, an empirical model was proposed to predict the stress-strain behavior under triaxial compression, considering the influence of different rubber content and lateral stress. The results obtained in this study can provide a valuable reference for the design and application of self-compacting rubberized concrete in practical projects, especially those involving three-way compression states and requiring high-quality deformation and energy dissipation.