Direct Shear Research Articles

Experimental study on root-reinforced soils (R2S) and soil root (S-R) interaction in nature

ABSTRACT Biotechnical stabilization, involving vegetation such as trees and shrubs, is commonly employed to reinforce/stabilize soil masses. This research aimed to examine the interaction between soil and roots, focusing on two grass species readily found locally in Kashmir valley: a standard turf grass and a flood channel grass known for its extensive root system. Variables included root length, vegetation type, and root percentage, while strength assessments such as Unconfined Compressive Strength (UCS) tests and Direct Shear Tests (DST) were conducted. Three soils, including two naturally occurring and one artificially prepared in the laboratory, were examined for studies on S-R interaction. UCS values increased considerably for different soil types with the maximum enhancement seen in artificial soil wherein the UCS increased from 65 kPa to almost 400 kPa. Cohesion (c) also showed enhancement from 21 kPa in the control sample to 29 kPa for 1.0% root content and 25 mm root length. Micro-structural analysis was performed and the micrographs clearly showed signs of root surface roughness, adherence of soil particles and interlocking between the grains and root fibers. By stabilizing soil masses, roots can play an important role in slope stability, soil conservation, and other geotechnical applications.

Investigation of damage and crack characteristics of epoxy modified recycled asphalt mixtures based on a three-dimensional meso-heterogeneous model

Epoxy asphalt has excellent fatigue resistance, making it a valuable addition to recycled asphalt mixtures. However, the lack of sufficient understanding of the cracking mechanism in epoxy-modified recycled asphalt mixtures (EMRAM) hinders its widespread application. The purpose of this paper was to investigate the damage and crack characteristics of EMRAM based on a three-dimensional meso-heterogeneous model. The coarse aggregates were first randomly generated using the secondary Delaunay algorithm. Meanwhile, the fracture parameters of each component material and asphalt-aggregate interface in EMRAM were tested through three-point bending tests and direct shear tests, respectively. Cohesive zone model elements were then inserted at the aggregates, asphalt mastic, and interfaces between different materials to establish a three-dimensional meso-heterogeneous model of EMRAM. Finally, based on the established model, the damage degree of each composition material in EMRAM was quantitatively analyzed to identify the vulnerable aspects of EMRAM during the crack propagation stage. Optimization strategies were proposed accordingly. The results demonstrated that the model established in this study can accurately represent the meso-heterogeneous of EMRAM and effectively simulate its cracking behavior. EMRAM was more susceptible to developing internal damage within the aggregates, followed by relatively noticeable damage at the interface and the internal regions epoxy-modified fine aggregate mastic. The cracking resistance of EMRAM showed a trend of initially increasing and then decreasing with an increase in the volume fraction of coarse aggregates with a size above 4.75 mm. The optimal range for the volume fraction of coarse aggregates in EMRAM was within 35–44 %. The fracture energy of EMRAM was improved by more than 30 % after gradation optimization compared to EMRAM with gradation at the median value of AC20. Within the designed service life, EMRAM durable pavement can save at least 30 % more in economic costs compared to ordinary asphalt concrete pavement.

Numerical study on dynamic shear properties of concrete under high loading rates

Under high dynamic loads, the destruction of concrete structures is significantly influenced by the dynamic shear properties of concrete, especially when local failure occurs. Previous experimental studies have demonstrated that the shear behaviors of concrete exhibit a considerable strain rate effect. This study aims to numerically investigate the influence of the material parameters and the stress states on the shear properties and to further explore the mechanism of the shear strain rate effect. A mesoscale concrete model with the consideration of randomly distributed coarse aggregates, mortar matrix, and interfacial transition zone (ITZ) is developed to simulate the responses of concrete specimens subjected to shear loads at various loading rates. The model was validated by comparing numerical results with experimental data. Parametric studies were conducted to examine the influence of concrete parameters and confining pressures on its dynamic direct shear strength. The results indicate that the rate effect on the direct shear strength of concrete is substantial. The main reason is that more aggregates are damaged under high loading rates. Larger coarse aggregate size, smaller shear section size and high strength of ITZ could increase the rate sensitivity of the concrete in varying degrees. Additionally, confining pressure significantly enhances the direct shear strength of concrete but mitigates the influence of loading rates.

Bonding characteristics between existing concrete substrate and high ductility geopolymer overlays under direct shear loading

High ductility geopolymer (HDG) looks promising as an exceptional repair material due to the faultless mechanical properties and environmental benefits. The interfacial bonding characteristics between existing normal concrete (NC) substrate and HDG overlay are the vital impact on the overall performance of repaired structures. This study presented the NC-HDG bonding behavior under the direct shear tests, and totally 45 specimens were designed with various concrete strength grades, interface roughness and elongations of HDG. To capture the fracture characteristics, the digital image correlation (DIC) technique was employed. Test results showed that the direct shear bonding strength (τu) had an increasing trend as the NC strength dropped or the interface roughness and elongations of HDG were increased, among the interface roughness affected the τu mostly, with the improvement amount of 185.07 %∼343.28 %. The direct shear strength ratio (defined as the ratio of τu to the inherent shear strength of NC) was ranged as 0.110∼0.489, i.e., at least half of shear strength of NC was lost during repairing. Based on the DIC measured results, the improvement of NC strength, interface roughness and elongations of HDG all delayed the interfacial crack initiation under direct shear loading. Moreover, the upper-bound limit analysis was adopted, a simplified method for predicting the direct shear bonding strength of NC-HDG interface was proposed and showed a sufficient precision.

A Novel Method for Estimating the Undrained Shear Strength of Marine Soil Based on CPTU Tests

The undrained shear strength is an essential parameter in the foundation design of marine structures. Due to the complex marine environment and technical limitations, it is difficult and costly to obtain offshore samples. Piezocone penetration tests (CPTU) are relatively low-cost compared to drilling and sampling methods. Therefore, based on the soil behavior type index (Ic) derived from CPTU results, a model for estimating cone factors (Nkt, Nke) is proposed to improve the accuracy of estimation of undrained shear strength. The result shows that the soil behavior type index (Ic) and cone factors take on a negatively correlated exponential relation. Incorporating a cone factor that varies with the soil behavior type index (Ic) significantly enhances the accuracy of undrained shear strength predictions compared to the conventional method of using a constant cone factor. This approach reduces the root mean square error (RMSE) for Nkt (Nke) from 0.124 (0.126) MPa to 0.056 (0.06) MPa, and the mean absolute error (MAE) from 0.0154 (0.016) MPa to 0.0032 (0.0036) MPa. The method was validated at an additional location and the predictions were in high agreement with the results of the consolidated quick direct shear test. The developed method can serve as an effective tool used in the design of foundations of marine structures.

Combined Effect of the Microstructure and Mechanical Behavior of Lateritic Soils in the Instability of a Road Cut Slope in Rwanda

A very common hazard in Rwanda is represented by the instability of steep road cut slopes in lateritic soil. In its natural state, this material appears as a fine-grained weak and altered rock, generally in unsaturated conditions. Steep cut slopes made by this material could remain stable for a long time unless weathering weakens its mechanical behavior and heavy rainfall provokes a rapid landslide. This paper presents the results of an experimental investigation on the microstructural, petrophysical, and geotechnical properties of lateritic soil from a road cut slope located in Kabaya (Ngororero District—Rwanda), which was recently subjected to a landslide. The mechanical properties of the material are strictly related to the geological origin and history of the deposits, their formation environment, and weathering processes. These characteristics were revealed by peculiar microstructural features (micro-texture, porosity, and degree of alteration of original mineral paragenesis). The experimental investigations included identification and classification tests, direct shear tests on saturated samples, and swelling tests. This multidisciplinary approach provided insights into the relationship between geotechnical properties and the microstructural, petrophysical, and chemical characteristics of the altered rocks. This study showed how different levels of chemical alteration operated by weathering processes, in conjunction with brittle deformation related to the tectonic history, formed in the same site two shallow rock layers with similar macro-scale features and mechanical behaviors but markedly different microstructural and chemical properties. The innovative aspect of this research suggests an integrated multidisciplinary approach to considering microstructural aspects in addition to mechanical behavior in the slope stability analyses in lateritic soil. In particular, this study demonstrates the importance of such an approach since the failure mechanism is better explained if it is based on microstructural observations instead of considering the soil shear strength parameters only. This research helped to explain the formation of the landslide failure mechanism in a specific road cut slope, which could be assumed as representative of many other similar slopes subjected to landslides in Rwanda.

Effect of shear rate and saturation on shear strength of mineral and anthropogenic soil

The aim of the study was to determine the shear strength of mineral and anthropogenic soil of similar grain size as a function of the applied shear rate and water saturation. Stability calculations using the finite element method of the road embankment model were also carried out to demonstrate the variation in factor of safety values depending on the adopted values of the angle of internal friction and cohesion. The tests were carried out in a direct shear apparatus in a 100 x 100 mm box with a sample height of 20.5 mm. The samples were formed directly in the apparatus box at optimum moisture content until a compaction index of IS = 1.00 was obtained. Tests were carried out under conditions without and with water saturation at shear rates of 0.01, 0.05, 0.1, 0.5 and 1.0 mm•min–1 until 18% horizontal displacement was achieved. The results showed that the effect of shear rate on the strength parameters was not unequivocal and was much smaller than the changes caused by saturation of samples. An increase in shear rate resulted in small changes in the angle of internal friction with a tendency towards a decrease. In contrast, cohesion varied over a much larger range with increasing shear rate, with an apparent initial decrease and subsequent increase. The saturation of the samples resulted in a decrease in the angle of internal friction of the cohesive soil and an increase for the ash-slag mixture. The cohesion of both soils decreased. The results obtained from the road embankment model stability calculations confirmed that soil saturation had a greater influence on the factor of safety values obtained than the shear rate.

Experimental and DEM analysis for the shear characteristics of interface between sand and irregular concrete under dynamic normal loading

To explore the dynamic shear property of sand–irregular concrete interface, a series of direct shear tests were conducted under dynamic normal loading. These tests were designed with various joint roughness coefficients (JRC), amplitudes and frequencies of dynamic normal loading. DEM models were established to analyze the microscopic mechanical behavior. The research results indicate that a larger amplitude and frequency of the dynamic normal loading would lead to a decrease in the interface shear stress and dilation. As the JRC increased, the interface shear strength first increased and then decreased, and the dilation increased. A rougher surface would reduce the phase shift between peak shear and normal stress. The phase shift between normal stress and friction coefficient was always half a normal loading cycle. A greater JRC would activate a more violent particle motion and a thicker shear band. The increase in effective roughness would lead to an increase in the deviation angle of the anisotropic direction. The evolution of force chains was observed in three-dimensional space. Weak force chains were screened out during the shearing process. As the shearing developed, the number of force chains decreased, the average length and strength of force chains continued to increase.

Effect of loading frequency and cyclic stress ratio on undrained cyclic behaviors of clay-structure interface with various overconsolidation ratios

The widely used suction caissons in offshore engineering are commonly subject to cyclic loads including the wind, wave, and current. For proper design and sustainable maintenance of the suction caisson foundations, it is essential to investigate the dynamic response of the clay-structure interface. This research conducted a series of clay-structure interface cyclic shear tests under constant volume equivalent undrained state using a modified direct simple shear device to fully investigate the effects of cyclic stress ratio (CSR), loading frequency, and overconsolidation ratio (OCR) on the dynamic response of the interface. The interface shear strength, relative shear displacement, the number of cycles to failure (Nf), and interface pore water pressure were analyzed. Results show that the Nf is strongly affected by CSR and loading frequency. A model is proposed to describe the decrease in the Nf with increasing CSR under a given loading frequency and OCR. The Nf increases approximately linearly with loading frequency on a double-logarithmic scale. Additionally, the contour diagrams, defining the Nf as a function of interface average and cyclic shear stress under various OCRs, are proposed to predict the failure behaviors of clay-structure interface subjected to various loading combinations. Besides, the development models are established respectively to describe the evolutions of accumulated interface pore pressure (Uia) against the number of cycles (N) and cyclic relative shear displacement (Wcy), presenting better capability to describe the development of Uia. The findings in this study hold potential implications for determining whether the failure occurs under corresponding loading conditions and predicting interface pore pressure development.

An interface constitutive model of plastic tensile–compressive damage under impact loading based on continuous–discontinuous framework

Bullet penetration test is a classic impact loading test, which involves complex dynamic elastic–plastic response. Conventionally, this process was often described using a single high-strain-rate constitutive model, which could only capture a specific type of failure during the impact damage process. Furthermore, these constitutive models were mostly defined on element and posed the risk of computational divergence(element distortion). In this work, a novel constitutive model for combined tensile–compressive damage in interface element was developed within a Continuous–Discontinuous Element Method(CDEM) framework. This model successfully captures the processes of pit formation and target collapse during projectile penetration. The tension and compression damage parts of the developed interface constitutive model were validated through Brazilian splitting test and interface direct shear test. Subsequently, bullet penetration test is simulated and the post-penetration velocity is compared with published results from other studies, with computational errors found to be within 2.56%, thus validating the accuracy of the developed interface constitutive model.

Study of the mechanical properties and propagation mechanisms of non-coplanar and discontinuous joints via numerical simulation experiments

Non-coplanar and discontinuously jointed rock masses are more complex than coplanar and discontinuously jointed rock masses. The mechanical properties and propagation mechanisms of non-coplanar and discontinuous joints were studied via direct shear tests with microscopic numerical simulation experiments. The numerical simulation tests were performed under different normal stresses, joint inclination angles, and shear rates. The numerical experimental results show that the microscale failure of non-coplanar and discontinuously jointed rock masses is mainly caused by tensile cracks. Additionally, when the peak shear stress is reached, the growth rate of cracks increases rapidly, and the number of cracks increases with increasing normal stress. The shear strength of non-coplanar and discontinuously jointed rock masses increases with increasing normal stress. Under the same normal stress, the variation curves of the shear strength of non-coplanar and discontinuously jointed rock masses with respect to the dip angle exhibit an “S”-shaped nonlinear pattern. Rock masses with joint inclination angles of approximately 15° and 65° have minimum and maximum shear strengths, respectively. The joint dip angle has a significant impact on the final failure mode of rock bridges in the rock mass. As the joint dip angle increases, the final failure modes of rock bridges change from “end-to-end” connection to a combination of “head-to-head” and “tail-to-tail” connections. The shear rate has a certain impact on the peak shear stress, but the impact is not significant. The spatial distribution of the tensile force chains changes as shearing progresses, and stress concentration occurs at the tips of the original joints, which is the reason for the development of long tensile cracks in the deeper parts.

Cyclic behavior of port-said soft clay in cyclic direct simple shear tests

A thick deposit of soft clay, known as “Port-Said Clay” (PSC), is commonly encountered in the northern formations close to the Mediterranean shores of Egypt. The growing level of development, including transportation corridors like highways and tunnels, in areas rich with PSC necessitated an in-depth study to characterize its dynamic behavior. This study presents a first comprehensive experimental investigation of the dynamic behavior of the soft PSC using Cyclic Direct Simple Shear Tests. The effects of plasticity index (PI), loading frequency (f), and cyclic stress ratio on the cyclic resistance, shear modulus, shear modulus reduction ratio, pore water pressure generation, and damping ratio was investigated. The results showed that all the investigated behavior parameters are primarily sensitive to PI and f. The conclusions drawn from this study on PSC open the way to further laboratory-based investigations of the dynamic behavior of PSC, in addition to numerical modelling of the seismic interaction between PSC and different types of structures.

ANALISIS STABILISASI TANAH LEMPUNG MENGGUNAKAN CAMPURAN ABU SEKAM PADI TERHADAP NILAI KUAT GESER TANAH

The main aim of stabilization is to change the technical properties of the soil itself, such as the compressibility and bearing capacity of the soil. Based on the results of testing the physical and mechanical properties of the original soil of Sambirejo Village, Puhpelem, Wonogiri according to the ASSHTO method, the original soil is included in group A-7-6, which is medium to poor clayey soil material. Meanwhile, according to the USCS method, it is included in the CH group, namely organic clay with high plasticity, fat clays. After conducting further research with variations in the rice husk ash mixture of 0%, 5%, 10%, 15%, and 20%, the results showed that the soil physical test showed the values of water content (W), liquid limit (LL), plasticity index (PI ), and the percentage passing filter No. 200 experienced a decrease with increasing percentage of addition of rice husk ash with yield figures on original soil of 53.00%, 52.00%, 15.32%, 62.00% while on original soil with a mixture of 20% rice husk ash obtained results of 50.11%, 41.10%, 1.65%, 51.00 %. Meanwhile, the specific gravity (Gs), plasticity limit (PL), and shrinkage limit (LL) increased with increasing percentage of rice husk ash addition with the yield figures on the original soil being 5.409%, 36.68%, 12.65%, while on the original soil with a mixture of rice husk ash 20% rice obtained yields of 6.071%, 39.45%, 26.89%. Based on the results of the Direct Shear Test, the soil experienced an increase with each addition of rice husk ash. The highest Direct Shear Test value occurred in 20% mixed soil, namely 0.583 kg/cm2 and the lowest Direct Shear Test value occurred in original soil, namely 0.394 kg/cm2.

A new large-scale shear apparatus for testing geosynthetics-soil interfaces incorporating thermal condition

Geosynthetics-soil interfaces are exposed to varying temperatures coupled with complex stress states. Quantifying the mechanical response of the interface considering this combined influence of temperature and complex stress is always a huge challenge. This study proposes a new displacement and stress-loading static and dynamic shear apparatus that is capable of testing the geosynthetics-soil interfaces with high and low-temperature controlling function. The apparatus satisfactorily simulates monotonic and cyclic direct shear tests, and creep shear tests on geosynthetics-soil interfaces at temperatures ranging from −30 °C to 200 °C. To validate the functionality of this device, a series of temperature-controlled experiments were conducted on different types of interfaces (sand-geogrid interfaces, sand-textured geomembrane interfaces, sand-smooth geomembrane interfaces). The experimental results indicate that the apparatus can simulate static, dynamic, and creep shear loading on geosynthetics-soil interfaces in high and low temperature environments, and these can be measured reliably. It also manifests that temperature has a non-negligible influence on all mechanical interface responses. These findings highlight the significance and potential of the proposed apparatus and its practical implications.

Study on shear surface morphology and failure mechanism of soil-rock mixture under wet-dry cycle action

The present study investigates the failure modes and formation mechanisms of shear surfaces in soil-rock mixtures from various perspectives. Firstly, through in-situ direct shear tests, two main shear failure modes, namely planar and non-planar, are identified. Subsequently, using PFC 2D numerical simulation, an in-depth exploration of the characteristics and causes of these two typical failure modes is conducted. The findings reveal that in the natural state, the material is relatively dry, and the matrix suction within the soil-rock mixture is significant. During shearing, the inter-particle force chains are prone to rupture, exhibiting characteristics akin to brittle failure. This leads to nearly planar shear surfaces, with force chain ruptures primarily localized near the planar regions adjacent to the shear surface. However, after multiple dry-wet cycles, the plastic enhancement of the soil-rock mixture reduces the matrix suction to almost zero. The continuous rupture and reorganization of force chains deepen the shear band under their influence, resulting in non-planar shear surfaces. It is noteworthy that the characteristic point fitting curve of non-planar shear surfaces exhibits a nonlinear trend. In summary, our study elucidates the evolution process and causes of shear surface morphology in soil-rock mixtures, which holds significant implications for understanding their mechanical properties and engineering behavior.

Estimating Shear Strength of Marine Soft Clay Sediment: Experimental Research and Hybrid Ensemble Artificial Intelligence Modeling

In the design of offshore engineering foundations, a critical consideration involves determining the peak shear strength of marine soft clay sediment. To enhance the accuracy of estimating this value, a database containing 729 direct shear tests on marine soft clay sediment was established. Employing a machine learning approach, the Particle Swarm Optimization algorithm (PSO) was integrated with the Adaptive Boosting Algorithm (ADA) and Back Propagation Artificial Neural Network (BPANN). This novel methodology represents the initial effort to employ such a model for predicting the peak shear strength of the soil. To validate the proposed approach, four conventional machine learning algorithms were also developed as references, including PSO-optimized BPANN, Support Vector Machine (SVM), BPANN, and ADA-BPANN. The study results show that the PSO-BPANN model, which has undergone optimization via Particle Swarm Optimization (PSO), has prediction accuracy and efficiency in determining the peak shear performance of marine soft clay sediments that surpass that offered by traditional machine learning models. Additionally, a sensitivity analysis conducted with this innovative model highlights the notable impact of factors such as normal stress, initial soil density, the number of drying–wetting cycles, and average soil particle size on the peak shear strength of this type of sediment, while the impact of initial soil moisture content and temperature is comparatively minor. Finally, an analytical formula derived from the novel algorithm allows for precise estimation of the peak shear strength of marine soft clay sediment, catering to individuals lacking a background in machine learning.

Performance of industrial fly ash based stabilized mine haul roads under seasonal moisture changes

Mine haul roads play an important role in the mining industry. They are often designed as unsealed roads, which are frequently damaged due to seasonal moisture variation, especially when the subgrade soil is expansive clay. In this study, the performance of mine haul roads built on expansive clay soil is investigated for seasonal moisture variation using experimental and numerical investigations. Shrinkage, swelling, soil water characteristics curve (SWCC) tests, and direct shear testing were first performed to assess the hydraulic and shear performance of the control and municipal solid waste incineration (MSWI) fly ash-treated soils. The swelling reduced from 1.95 to 1.02, while the shrinkage reduced from 3.4% to 1.84% after the addition of 20% MSWI fly ash. SWCC results showed that the MSWI fly ash addition reduces the void spaces and increases residual saturation. The consolidation settlement reduced by 50% after adding 20% MSWI fly ash. The cohesion of both soil and MSWI fly ash-treated samples exhibited a bell-shaped trend with moisture increase, in contrast to friction angles which decreased with increasing saturation levels. 3D numerical models were used to predict the performance of control soil and MSWI stabilized mining haul roads using the experimental test data. The control pavement experienced increased settlement and rutting as saturation levels increased. The behaviour of the stabilized pavement differed, with the model having a 20% degree of saturation showing the least deformation due to increased stiffness from high suction. Overall, this study highlights the benefits of MSWI fly ash-based soil stabilization in improving the performance of mine haul roads under seasonal moisture changes. The findings emphasize the importance of considering the degree of saturation and stabilization techniques in pavement design to mitigate settlement and enhance overall performance.

Study on the microstructure and strength characteristics of marine soft soil under wet-dry cycle condition

For marine soft soil under the periodic wave loading, the pore water content in soil suffering dry-wet cycle for a long time, which affects its microstructure and macroscopic mechanical strength, resulting in insufficient bearing capacity and excessive deformation of soft soil. To reveal the microstructural characteristics and strength attenuation law of marine soft soil under dry-wet cycle condition, electron microscopy scanning and direct shear tests under different times of dry-wet cycles were carried out, and the mathematical equations of pore structure and strength parameters were established based on fractal theory. The research results showed that: (1) The pore structure changed considerably after the first dry-wet cycle, and then changed gently with the increase of dry-wet cycle times, which was reflected by the fractal dimension D value decreases to a constant value gradually. (2) The shear strength of the soil diminishes with an increase in the number of dry-wet cycle times, and the maximum attenuation occurs after the first dry-wet cycle. (3) The relationship between cohesion (c), internal friction angle (φ), and fractal dimension (D) is exponential, with the curve shapes being concave and convex, respectively.

Experimental investigation on fractal mechanism and shear failure characteristics of cement mortar at different curing ages

In this paper, the NMR and direct shear tests were conducted successively on cement mortar specimens with different curing ages (7 days, 14 days and 28 days). The porosity, shear strength, shear stiffness and shear energy of cement mortar are measured and analyzed through interpreting the pore distribution patterns and their corresponding fractal dimensions. The cross-sections of shear surface were characterized into point cloud data via 3D laser scanning and quantified by three dimensionless parameters (the root mean square value of the first derivative, root mean square value and joint roughness coefficient). The grey relation analysis (GRA) method and principal component analysis (PCA) is employed to analyze the relationship between the pore structures (i.e., gel pores, transition pores, capillary pores and pores or cracks) and distribution and the fractal dimensions. The results indicate that the shear peak strength is linearly correlated with the joint roughness coefficient. Compared to the fractal characteristics of pore size (T2 spectra) and pore distribution (MRI), we demonstrated that there is a strong correlation between the peak shear strength and the fractal dimension of shear fracture surface, which suggests that the quantitative characterization of internal pores and shear strength variations in cement mortar specimens can be achieved through the numerical values of fractal dimensions.

Mechanical properties of steel fiber reinforced recycled concrete under compression-shear stress state

The continuous urbanization of construction has led to an increasing demand for concrete, resulting in large-scale gravel and river sand mining, which seriously affect the sustainable development of the environment. The waste concrete produced by the demolition of old buildings is processed into recycled aggregate to replace natural aggregate, and then the preparation of recycled concrete can effectively alleviate this problem. This paper investigates the mechanical properties of steel fiber reinforced recycled concrete (SFRRAC) under compression shear conditions, a compression shear test with 99 cubic specimens was designed, with the variation parameters being recycled aggregate concrete replacement rate, compressive stress, and steel fiber content. The failure mode of SFRRAC under compression-shear stress was observed, and the shear force-displacement curve was calculated. Furthermore, a thorough examination was performed to assess the mechanical characteristics of SFRRAC specimens under compression-shear stress. The findings of this study suggest that as the compressive stress increases, the failure characteristics of the specimens shift from exhibiting brittle failure to displaying ductile failure. The shear strength is most sensitive to the change in compressive stress. When the compressive stress reaches 6 MPa, the shear strength can reach 3.41 times that of the direct shear specimen. The shear strength of SFRRAC specimens is composed of the bond strength of concrete, shear expansion strength, and friction shear strength. The incorporation of steel fibers can modify the distribution of shear strength among the individual components. The adverse effect of the recycled aggregate replacement rate on the toughness index of the specimen is mainly concentrated after the peak point. Nevertheless, an elevation in compressive stress and the inclusion of steel fibers can counterbalance this detrimental influence. The shear strength calculation formula of SFRRAC in shear state is put forward, which has a reference value. This study provides an experimental reference and a theoretical basis for further examination of SFRRAC.