Stress-displacement Curves Research Articles

Effects of freeze–thaw cycles on the shear stress induced on the cemented sand–structure interface

Freeze–thaw alternation and freeze–thaw cycle erosion are the main reasons for the failure of the cemented soil–structure interface in cold regions. In this study, the direct shear and cyclic direct shear tests of cemented sand–structure interface were conducted in the frozen state (−10 °C) and thawed state (25 °C) at a 300 kPa normal stress under different freeze–thaw cycles (i.e., 0, 1, 5, 10, 15, 20, 25, 30). The experimental results for the shear stresses of the cemented sand–structure interface are presented, and the mechanism of shear stress formation and change was examined through mesoscopic analysis. Variations in shear stress with different freeze–thaw cycles were consistent. Typically, 10 was identified as the critical freeze–thaw cycle number for adfreeze strength, and the hyperbolic model of shear stress–displacement curve in the thawed state was obtained. The peak shear stresses of different freeze–thaw cycles gradually decreased as the shearing cycle number increased until entering a stable stage in frozen state and were close to each other in the thawed state. The internal damage of cemented sand and the formation of ice crystals on the surface increased with the increase in freeze–thaw cycle number. Hence, internal change in cemented sand under freeze–thaw cycles is the fundamental reason for alterations in shear stress. The results of this study shed light on shear stress complexity at the cemented sand–structure interface under freeze–thaw cycles and provide references for practical engineering.

Experimental and theoretical investigation on compression-shear properties of high-strength engineered cementitious composites (HS-ECC)

High-strength engineered cementitious composites (HS-ECC) has broad application prospects due to its excellent mechanical performance and durability. Construction materials in structural members are susceptible to combined compression-shear stress. Therefore, the mechanical properties of HS-ECC under the combined stress are experimentally investigated by a servo-controlled biaxial testing machine. The effects of normal stress ratio on the compression-shear properties are systematically studied, and mortar specimens serve as control group. The experimental results show that the shear stress versus shear displacement curves of HS-ECC are able to be divided into four stages, namely linear ascending, non-linear ascending, rapid descending and stable stages. Compared with mortar specimens, the shear strength and residual shear strength of HS-ECC increase by 5–21% and decrease by 33–42% respectively. HS-ECC has a friction coefficient of 0.53, which is smaller than that of mortar specimens and concrete. When the normal stress ratio increases, the dilation angle of HS-ECC decreases at first and then remains basically unchanged. The damage evolution of HS-ECC is delayed when compared with that of the mortar specimen. Finally, a damage constitutive model is proposed to describe the compression-shear properties of HS-ECC. It is found that the predicted results agree well with the experimental results. This study is of great significance to understand the compression-shear properties of HS-ECC and promote its structural applications.

Shear strength of soil-root system under different vegetation restoration modes on the Loess Plateau of China

The soil-root system shear strength (SRSS) is a useful dynamic parameter for evaluating soil detachment capacity by flowing water and slope stability. The changes in soil properties and root traits induced by vegetation restoration likely affect SRSS considerably. Nevertheless, few in-situ shear tests have been conducted to quantify the effects of restoration mode on SRSS in semi-arid region. This study was conducted to quantify the impact of restoration mode on SRSS of 0–50 cm soil layer at sites of one slope farmland (maize) and five vegetation restored lands (abandoned farmland, korshinsk peashrub, black locust, Chinese pine, and the mixed forest of amorpha and Chinese pine) and further to identify the related dominant contributing factors on the Loess Plateau. SRSS was reflected by the strain energy calibrated to 15% soil water content (SEc), peak shear stress (PSS) and the displacement of PSS (DPS) determined from the measured shear stress-displacement curves. The results showed that SEc decreased with soil depth (0–50 cm) for all vegetation restored lands. PSS increased with soil depth, except for slope farmland and abandoned farmland. DPS also decreased with soil depth as a whole. The mean SEc of 0–50 cm soil layer of different vegetation restored lands were 2.29–2.67 times greater than that of slope farmland. Chinese pine with a mean SEc of 138.3 J·m−2 was the best restoration mode to enhance soil erodibility. Soil water content significantly impacted SRSS and it decreased logarithmically with soil moisture. Plant roots could improve the ductility of soil, making shear failure with a great displacement. Root surface area density was the most sensitive parameter to reflect the effect of root system on soil strain energy. These results are helpful for understanding the mechanical mechanism of vegetation restored soils to mitigate erosion and to enhance slope stability in semi-arid region.

Investigation of intralayer and interlayer shear properties of stabilized rammed earth by direct shear tests

Rammed earth construction has attracted a lot of attention because of its unique advantages of energy saving, environmental protection, low cost, easy access to materials, and suitability for living. Due to the special layered segmental ramming process, the distribution of rammed earth is superimposed, which makes the rammed earth walls have many weak horizontal interfaces. The failure mode of many post-earthquake rammed earth buildings is mainly in the form of shear failure, and the slip failure at the interface of adjacent rammed layers is particularly serious. There is a lack of research on the cracking and slip phenomena between rammed earth layers and the shear parameters between and within rammed earth layers. In this study, the interlayer and intralayer shear behavior of rammed earth were compared in four aspects: failure phenomenon, shear stress-displacement curve, cohesion and internal friction angle, and shear modulus, using normal stress, additive type, and additive content as variables. The causes of slip failure easily occurring at the interlayer interface were investigated. The interlayer interface and intra-layer shear failure laws of unstabilized and stabilized rammed earth were explored. The compressive strength was used to predict the interlayer shear strength. The shear resistance parameters of unstabilized and stabilized rammed earth were determined to provide data for future measures to enhance the optimization of the interlayer interface. The results showed that the interlayer failure of rammed earth was mainly caused by the lack of cohesion of the soil at the interlayer interface, and the interlayer cohesion was 24%-45% of the intra-layer cohesion. The interlayer interface shear strength was about 35%-84% of the intra-layer shear strength.

Research on direct shear test of rock-like materials with two closed pre-existing cracks of different attitudes

To investigate the failure mode and strength characteristics of rock-like materials containing two non-coplanar closed discontinues, and the influence of crack attitude on the shear failure of rock mass, a series of direct shear tests are carried out on rock-like materials containing two pre-existing cracks of different attitudes, one of them is horizontal crack, and the other is inclined crack. The specimens containing pre-existing cracks of four inclinations (0°, 45°, 135°, and 180°) and three dip angles (30°, 60°, and 90°) are prepared, and the failure form and stress-displacement curve are recorded during the tests. The results show that the attitude of the crack has a significant effect on the failure form and strength characteristics. In positive shear, the shear stress increases slowly and the crack initiation of the crack occurs relatively late, and in negative shear, the shear stress increases rapidly and the crack initiation stage appears earlier. Under the normal stress of 1 MPa, the fracture surface fluctuates along the pre-existing cracks, and the difference in shear strength of each specimen is less than 1.0 MPa. Under the normal stress of 5 MPa, the fracture surface mostly distributes along the horizontal direction, and the difference in shear strength of each specimen is about 2.0 MPa. Under the same level of normal stress, the crack initiation and peak stress vary with the attitude of pre-existing crack, and the variation trend of peak stress is changed when the normal stress increased due to the difference in failure form. It is calculated that the ratio of crack initiation stress to peak stress ranges from 0.61 to 0.80.

Fracture characteristics of various concrete composites containing polypropylene fibers through five fracture mechanics methods

Abstract This paper investigates and compares the experimental results of fracture characteristics in various polypropylene fiber-reinforced concretes (high strength concrete, lightweight concrete, and engineered cementitious composite) on 90 three-point bend (notched and un-notched) beams. Five widely used fracture mechanics testing methods, such as work of fracture method, stress-displacement curve method, size effect method, J integral method, and ASTM E399, were used to investigate the fracture behavior. Results have demonstrated that fracture energy and fracture toughness improved as the dosage of polypropylene fibers increased in concretes. However, this improvement was different in concretes owing to various results of fracture mechanics testing methods and different properties of each concrete. Aggregates played significant role in the performance of polypropylene fibers on the fracture behavior of concretes. Among testing methods, the ASTM E399 showed the lowest values for the fracture toughness of concretes. Both work of fracture and stress-displacement curve methods exhibited appropriate results for the fracture energy of polypropylene fiber-reinforced concrete composites. The accuracy of size effect method was acceptable for determining size-independent fracture parameters of plain high strength and lightweight concretes. Furthermore, the J integral method showed more relevant results for the fracture toughness of polypropylene fiber-reinforced engineered cementitious composite.

ПРИМЕНЕНИЕ АРМОЭЛЕМЕНТОВ ИЗ ПЕРЕРАБОТАННОГО ДРОБЛЕНОГО БЕТОНА ДЛЯ СТАБИЛИЗАЦИИ ВОДОНАСЫЩЕННЫХ ИЛИСТО-ГЛИНИСТЫХ ГРУНТОВ

The improvement of fully saturated silty clay soil using columns of recycled crushed concrete is the subject of this paper's laboratory model studies. This study is being done to examine how recycled crushed concrete affects settlement control and bearing capacity. The research also examined the variation in subgrade modulus as well as the cause of a shallow circular footing's failure on soil where silt clay layer soil had been substituted with recycled broken concrete. The results demonstrated that combining both a partly replaced column of silty clay soil and a column of recycled crushed concrete significantly improves load bearing capability. The approach used may drastically alter the footing's stress displacement curve when it is resting on silty clay soil, reduce settlement, and make the replacement soil block within the container act as a deep foundation. Consequently, a foundation supported by silty clay may have its bearing capacity failure mechanism changed at the top of a column constructed of recycled crushed concrete, from exclusive settling to general bearing capacity failure. The use of fills with shattered concrete in them, whether natural or manmade, is growing. Hence, research into the bearing and deformation properties of this material is important for application areas such road construction, soil replenishment, and embankments.

Variation in shear strength of soil-root system under five typical land use types on the Loess Plateau of China

Shear strength of soil-root system (SRSS) is one of the most useful dynamic properties for evaluating soil erodibility and structural stability. The adjustment of land use may strongly affect SRSS by altering soil properties and plant root system. Few studies have been conducted to investigate the effect of land use on SRSS in semi-arid region. This study was performed to quantify the variation in SRSS with five typical land use types (cropland, orchard, grassland, shrub land and woodland) and identify the related dominant contributing factors on the Loess Plateau where land use has changed greatly in the past several decades. In-situ shear tests with large shear box (25 × 25 × 10 cm) were conducted to measure shear stress-displacement curves. The strain energy calibrated to 15 % soil water content (SEc), peak shear stress (PSS) and the displacement of peak shear stress (DPS) calculated from the curves were used to reflect SRSS. The results showed that woodland had the maximum SEc (124.4 J m−2) and PSS (1048.6 kPa), whereas cropland had the minimum SEc (65.6 J m−2) and DPS (7.2 mm). Woodland, especially coniferous species and its mixed forest, might be the most suitable land use type for vegetation restoration on the Loess Plateau to enhance soil erodibility or structural stability. The variation in SRSS with land use was closely related to the changes in soil properties and root traits. PSS increased with penetration resistance, while it decreased with soil water content. DPS was positive correlated to root biomass and morphological traits. SEc was mainly affected by the direct and indirect effects of root surface area density, penetration resistance, soil organic matter content and aggregate stability. The results are helpful for understanding the mechanical mechanism of vegetation restored soils to mitigate erosion and optimizing land use type in semi-arid region.

The development and application of an interfacial cohesive zone model of the pavement interlayer considering the characteristics of adhesive materials

The interlayer adhesive material is important to ensure the integrity of a pavement structure, but its influence on pavement performance as an actual material layer is usually ignored in pavement structure design and analysis. At present, the relationship between the shear stress and slip is usually expressed in the form of a coefficient. The interlayer adhesive material is a kind of heterogeneous composite material with rheological performance. Therefore, the relationship between a force and the displacement cannot be characterized by a simple linear relationship. In this paper, we develop a method for characterizing the properties of interlayer bonding materials using an interfacial cohesive zone model. First, we perform experimental tests, that is, a pull-out test and an oblique-shear test, to determine the optimal dosage of adhesive material, and then obtain the normal stress-displacement characteristic curve and shear stress-displacement characteristic curve for the optimal dosage of the adhesive material. Then, we divide the shear stress-displacement characteristic curve into four stages. Next, based on the characteristics of normal stress displacement curve and shear stress displacement curve, we develop a cohesive zone model based pavement interlayer simulation approach that can be used to characterize the stress displacement characteristics of interlayer adhesive materials. Finally, we present the performance of the interfacial cohesive zone model using finite element software to simulate the shear test and pull-out test, and find that the simulation results are basically consistent with the experimental results. Further, we apply the model to a special case, and the results are also consistent with the actual monitoring. It shows that the proposed method is reasonable.

Modeling Progressive Damage and Failure of Single-Lap Thin-Ply-Laminated Composite-Bolted Joint Using LaRC Failure Criterion.

Thin-ply composite failure modes also significantly differ from conventional ply composite failure modes, with the final failure mechanism switching from irregular progressive failure to direct fracture characterized by a uniform fracture with the reduction of the ply thickness. When open holes and bolt joints are involved, thin-ply-laminated composites exhibit more complex stress states, damage evolution, and failure modes. Compared to the experimental study of thin-ply-laminated composite-bolted joints, there are few reports about numerical analysis. In order to understand the damage evolution and failure mechanism of thin-ply-laminated composites jointed by single-lap bolt, a progressive damage model based on three-dimensional (3D) LaRC failure criterion combined with cohesive element is constructed. Through an energy-based damage evolution method, this model can capture some significant mechanical characteristics in thin-ply-laminated structures, such as the in situ effect, delamination inhibition, and fiber compressive kinking failure. The comparisons between the numerical predictions and experimental observations are made to verify the accuracy of the proposed model. It is found that the predicted stress-displacement curves, failure modes, damage morphologies, etc., are consistent with the experimental results, indicating that the presented progressive damage analysis method displays excellent accuracy. The predicted stress at the onset of delamination is 50% higher than that of the conventional thick materials, which is also consistent with experimental results. Moreover, the numerical model provides evidence that the microstructure of thin-ply-laminated composite performs better in uniformity, which is more conducive to inhibiting the intra-layer damage and the expansion of delamination damage between layers. This study on the damage inhibition mechanism of thin-ply provides a potential analytical tool for evaluating damage tolerance and bearing capabilities in thin-ply-laminated composite-bolted joints.

Bending and punching characteristics of aluminum sheets using the quasi-continuum method.

The nano-punching characteristics of single-crystalline aluminum are investigated using the quasi-continuum (QC) method. Four variables (i.e., crystal orientation, workpiece thickness, clearance between the punch and the substrate, and the taper angle of punch) are used to explore their effect during the nano-punching process. The shear stress distribution is used to express the punching effect on the punch and on both sides of the substrates. Besides, fracture strength, residual flash, and the atomic displacement vector are observed and discussed regarding the behaviors of the nano-punching process under various conditions. Based on the results, the Al workpiece with the X[111]Y[-110] orientation presents less lattice resistance during the punching process. Besides, the thickness of the workpiece has a significant effect on the punching quality. Workpieces with thickness values of 5 and 10 Å are more suitable for punching, due to stable loading and unloading stress-displacement curves and less residual flash on the cutting surfaces of these workpieces. In contrast, the effect of clearance has less impact on the punching behaviors of thinner workpieces. However, for thicker workpieces (i.e., 15 and 20 Å), a larger clearance will likely cause more residual flash. Furthermore, the taper angle of the punch should not be larger than 10°, otherwise, it might damage the workpiece and the substrate.

A New Shear Constitutive Model Characterized by the Pre-Peak Nonlinear Stage

The pre-peak shear stress-displacement curve is an important part of the study of the shear mechanical behavior of rock joints. Underpinned by the Haldane distribution, a new semi-analytical model for the pre-peak shear deformation of rock joints was established in this paper, the validity of which was verified by laboratory and in situ experimental data. Other existing models were employed to make comparisons. The comparison results show that the model has superior adaptability and is more suitable for convex-type shear constitutive curves than existing models. Besides, only one parameter was introduced to the model, which is more convenient for application. All of these imply that the proposed model is an effective tool to evaluate the pre-peak shear constitutive curves of different rock joints. The research results can provide a reference for further understanding of the shear fracture characteristics of rock materials.

Experimental and Numerical Simulation Study on Shear Strength and Secondary Particle Breakage of Coarse Sand with Different Dry Densities

In order to guarantee perpendicularity of rotary cast-in-place pile in Karst areas, filling, like sand, etc., is commonly used between the inner steel casing and the outer steel sleeve; while the outer steel sleeve is pulled out or a vertical load is applied on the top of the pile, the sand will move, contact, and push against each other, which leads to recrushing; therefore, shear characteristics and secondary breakage are a meaningful problem to study with regard to the influence of different sand densities. Through experimental direct shear tests, with different dry densities, shear stress versus shear displacement curves are obtained and internal friction angles are analyzed. The results show that internal friction angles increase along with increment of dry densities; more interesting is that the secondary breakage ratio also increases. A comparative numerical 2D model is set up using PFC2D, with lower porosity used to simulate a large dry density, and similar results are obtained, that is to say, with increase of dry densities, internal friction angles also increase.

Tensile mechanical properties and AE characteristics of shale in triaxial Brazilian splitting tests

Under the high temperature and high stress geological environment, how the physical and mechanical properties of deep shale reservoirs will change has become a hot research issue. Based on the Confined Brazilian Test, this paper improves a test method for the tensile strength of shale under triaxial conditions with a simple specimen fixture and convenient specimen preparation and performs a high confining pressure (0–60 MPa) Brazilian splitting test on Longmaxi Formation shales. The stress-displacement curve records the deformation and failure of shale. Acoustic emission technology (AET) detects the evolution process of fractures and further identifies failure modes. 3D optical scanning system reconstructs the fracture morphology. The results show that the maximum tensile strength of the shale specimens in the triaxial condition is increased by 58.5% relative to direct tensile strength. As the confining pressure gradually increases to 60 MPa, the specimen enters the stress state of compressed in three directions, the tensile failure mode gradually transitions to shear failure mode via tensile-shear composite failure mode, and the fracture angle gradually increases. The AE signal in triaxial conditions mainly shows a leap trend. The appearance of AE signal with high peak frequency can be used as a reference for micro-fracture initiation. The presence of shear fractures increases the roughness of the shale main fracture surface, and this effect diminishes as the confining pressure increases. This study can provide a reliable theoretical basis for the optimal design of hydraulic fracturing in deep shale gas reservoirs.

The effect of surface treatments on the interlaminar shear failure of GLARE laminate included AA6061-T6 layers by comparing failure characteristics

ABSTRACT The effect of surface treatments on hot-pressed GLARE 3/2 laminates included AA6061-T6 is evaluated in this paper. Sandpapering, degreasing and both degreasing and sandpapering are applied on AA6061-T6 sheets in order to contribute the improvement of the interlaminar shear strength (ILSS). The three-point bending tests are carried out by using two different span length-to-specimen thickness ratios (S/h) to examine also the effect of shear and bending on deformation and failure characteristics. Strength values and failure modes are obtained for both S/h ratios and all surface treatment types. Load-displacement and stress-displacement curves are evaluated. The results show that the maximum shear strength values for surface-treated laminates are increased by between 29% and 37% against untreated one. It is observed that the strength values and failure modes of all surface-treated GLARE laminates are influenced by an increase in the S/h ratio from 4.0 to 10.0 because of the increase in bending effect against shear.

Experimental study on interfacial damage characteristics of CRTS II slab track and CA mortar with AE and DIC techniques

Since the interface is often regarded as the weakest part of the ballastless track structure, there is a great need to investigate the interlayer bonding performance to ensure the safety of train operations for high-speed railways. In this study, the damage characteristics of the interface between China Railway Track System II (CRTS II) slab track and cement emulsified asphalt (CA) mortar (T-CA interface) under shear loading were thoroughly investigated. The interfacial deformation and damage development process during the direct shear experiments were recorded by a combination of acoustic emission (AE) and digital image correlation (DIC) techniques. Consequently, a bilinear cohesive zone model (CZM) of the T-CA interface was proposed. The results show that the AE activities are rare in the initial stage of loading, while they increase sharply when the shear loading approaches the interface bonding strength. The AE parameters can well characterize the entire process of interfacial failure. Through the DIC technique, the macroscopic deformation process was well captured and the shear stress versus relative displacement curves were derived. Subsequently, the relationship between the shear stress and relative displacement of the interface was well fitted by a bilinear CZM, of which parameters are calibrated through the experimental data. The effectiveness of the proposed bilinear CZM is validated by using a three-dimensional finite element model. This work provides a better understanding for the damage mechanism of the bond performance between CRTS II track slab and CA mortar.

Analysis of the Direct Shear Test and Microstructure of the Lunar Soil Simulant Solidified by Sodium Silicate

The lunar soil is an ideal building material for future lunar base construction. In order to improve the strength of lunar soil, basalt with similar composition to lunar soil was used to simulate lunar soil due to lack of real lunar soil, and the simulated lunar soil was reinforced with sodium silicate. In order to study the direct shear mechanical properties of the simulated lunar soil by sodium silicate solidification, a series of direct shear tests and SEM microstructure tests were carried out, and the shear stress-displacement whole process curve was obtained. Influence law of mechanical characteristic parameters such as shear strength, shear deformation modulus, peak deformation and energy dissipation was studied. The results of the direct shear test show that the shear stress-shear displacement curve of the sample changes from hardening to softening with the increase of sodium silicate content. The shear strength and shear deformation modulus of simulated lunar soil increased first and then decreased. When the sodium silicate content was 5%, the shear strength and shear deformation modulus reached the maximum, which were 560 kPa and 7224 kPa, respectively. The addition of 5% sodium silicate increases the energy dissipation coefficient of the simulated lunar soil by about 12%. The microscopic test results show that the N-A-S-H gel and AFt formed by the alkali excitation and adsorption of the sodium silicate will connect the lunar soil simulant particles into a whole network structure, thereby improving the shear strength.

Experimental analysis and mechanical model of interaction between warm frozen silt and pre-bored grouted planted nodular pile

To reveal interaction mechanism on the interface between the pre-bored grouted planted nodular pile (PGPN) and warm frozen ground, and to compare its bearing performance with that of cast-in-place pile, shear tests on the interface of the two types of pile were carried out at negative temperature under different influencing factors through self-designed test devices. Combined with the single factor method and response surface method, the influence laws of various factors and interaction on the adfreezing force of the interface were analyzed. The micro-deformation mechanism of the interface could be revealed by the binary medium model, and volume breakage rate and Weibull distribution function were introduced to establish the constitutive equation of the interface. The results showed that the cemented soil slurry could strengthen the frozen soil around the pile, The shear zone of the interface appeared on the frozen ground around the pile rich in ice film, and the shear stress-displacement curve showed a strain softening type and included four stages. Among all the influencing factors, temperature has the most significant effect on adfreezing force. The freezing strength has an exponential relationship with temperature, and the water content and normal stress have a linear relationship with freezing strength. Compared with the traditional cast-in-place pile, PGPN pile has higher bearing capacity and more stable deformation. The proposed interface constitutive model scientifically reveals the microscopic deformation mechanism of the shear zone. The model data fit well with the test results, which could provide valuable reference for the design and calculation of the bearing capacity of the pile foundation in warm frozen ground.

Study on the cohesive shear characteristics and intrinsic modelling of the root–tailing soil interface of Amorpha fruticosa

To study the soil consolidation effect of shrub plant roots on tailings soil and to explore the frictional characteristics of plant roots on tailings soil, three experimental conditions of the root–soil interface were established by using a modified indoor direct shear instrument with binders such as liquid sodium silicate and cyanoacrylate to conduct direct shear frictional tests at the root–soil interface using the roots of the typical slope protection plant Amorpha fruticosa. The Gompertz improved curve model was established by using the relationship between shear stress and shear displacement and the trend of the root–soil interface parameter index. The results were compared between the improved Gompertz curve model and the Clough–Duncan hyperbolic model, and a two-factor coupled improved Gompertz interfacial intrinsic structure model with normal stress and cohesive strength factor was established. The results showed that the interface shear stress and shear displacement showed strain hardening characteristics at different normal pressures for cohesive strength ratios of 1.5 and 1.7 at the root–tailing soil interface. At a cohesive strength ratio of 1.6, strain-softening was observed from 100 to 300 kPa and strain hardening was observed at 400 kPa. The improved Gompertz curve model predicts the shear stress and shear displacement curves at the root–soil interface with different cohesive strengths more reasonably than the Clough–Duncan hyperbolic model, and the maximum accuracy can be improved by nearly 40%. The two-factor coupled improved Gompertz curve model can fit the shear stress versus shear displacement relationship at the A. fruticosa root–tailing soil interface.

Effect of Cementation Degree on Shear Characteristic and Failure Mechanism of Bimrocks Containing Gravels of Different Sizes

Abstract To reveal the influence of cementation degree on the mechanical properties of bimrocks with different particle sizes under different types and contents of cement, indoor direct shear tests as well as numerical tests were conducted. The variation law of mechanical properties and the development law of internal force chain distribution of bimrocks under different conditions are fully studied. The specimens with three particle sizes, two cementing types (cement and gypsum), and three cementing contents were prepared for indoor shear tests under different normal stresses. The results show that the fluctuation of shear stress-displacement curve of bimrocks with round gravels of large particle size is relatively gentle, and the fluctuation of residual strength is relatively small. Under low normal stress, the peak shear strength of bimrocks with round gravels of large particle size can be increased by 115.2% under the action of cementation. Compared with the cohesion of samples without cementation, the maximum improvement of the cohesion of the samples containing large particle size, small particle size, and mixed particle size with different cementing materials is 143.2%, 149.0%, and 141.9%, respectively. The results show that, compared with the internal friction angle of samples without cementation, the maximum increases of the internal friction angle of the samples with large particle size, small particle size, and mixed particle size for adding different contents of cementing materials are 15.7%, 18.5%, and 21.2%, respectively. Numerical tests show that, with the increase of cementation degree, the gathering of force chain is more obvious and more concentrated near the shear surface.