Slip Failure Research Articles

Detection and Theoretical Numerical Simulation of the Failure Depth of the Bottom Plate in Belt Pressure Mining

Aiming at the problems of safety production cost caused by the increase of mining face width and pressure mining in Xizhuo Coal Mine in Chenghe Mining area, a mechanical model of floor plastic slip failure is established based on the theory of plastic slip line, and the difference between it and the traditional floor failure model is analyzed. The damaged contour line of the support stress and lateral support stress on the bottom plate through the advancing direction of the working face is the intersection line of a straight line and an arc line. The failure of the floor caused by lateral supporting stress is the failure of the floor again on the basis of the failure of the floor in the advancing direction of the working face, and there is a superimposed failure area. The analysis of the failure form of the stope floor by this mechanical model is closer to the engineering practice. By using “ultrasonic detection method + stress monitoring inverse analysis method,” the measured data such as disturbance failure depth and distribution law of large mining width working face were obtained. The test method used in this paper is relatively rare in the monitoring of the depth of floor disturbance failure at home and abroad. Considering that the traditional pressure water test method has disadvantages such as easy collapse hole, long period, and large error in monitoring the failure rule of deep floor rock mass, the embedded stress monitoring and reverse analysis method and ultrasonic detection method are used to successfully collect and real‐time monitor the data of rock floor before, during and after mining in the lower part of wide mining face of Xizhuo Coal Mine for the first time, and several effective data are obtained, which solves the three‐part “spatial‐time” all‐round floor disturbance and failure law field measurement which cannot be realized by traditional testing technology. By comparing the results of theoretical analysis, field measurement, and numerical simulation, the law and depth of floor disturbance failure of a 240‐m wide mining face in the Chenghe mining area are obtained for the first time, which provides scientific guidance for floor water disaster induced by coal seam mining under similar conditions in the future and has an important reference role for the prevention and control of Ordovician ash water disaster in coal mining. It provides important technical parameters for the safe setting of the effective water barrier layer and the selection and timing of the grouting layer of the floor, which can bring considerable economic and social benefits. The research results have important popularization value.

Experimental study of uniaxial compressive mechanical properties of rough jointed rock masses based on 3D printing

Abstract Roughness and inclination are important factors affecting the strength and deformation properties of jointed rock masses. Serrated joint specimens with varying joint roughness coefficient (JRC) and inclination angle were manufactured by 3D printing technique and cement mortar material. Then, uniaxial compression tests were performed for serrated joint specimens. The results show that when inclination angle equals 0° or 90°, the stress–strain curves of serrated joint specimens with various JRC values are basically the same and display a similar variation trend as that of the complete specimen, hence JRC presents a very little impact. When inclination angle varies from 30° to 60°, the stress–strain curves display a significant difference for various JRC values. Both the compressive strength and peak strain increase with the JRC value. With the increase in JRC value, the stress–strain curve exhibits a stress drop point, and with the further increase in JRC value, the stress drop point obviously delays or disappears directly. Variation in uniaxial compressive strength and deformation modulus with inclination angle is approximately U-shape for serrated joint specimens and displays typical anisotropic characteristics. Due to the variation in inclination angles and JRC values, failure modes of serrated joint specimens under uniaxial compression varies from splitting tensile or shear slip failure to compound tensile and shear failure. Rough serrated joint has a strengthening effect on the resistance ability to vertical load, and large roughness can effectively slow down the shear slip failure of jointed rock masses.

Economical Measures against Soft Ground at High Embankment on Peaty Ground

Peat, which is considered a special soil, is widely distributed over approximately 2,000 km2 in Hokkaido, Japan. In terms of engineering properties, peat is extremely high in water content, ignition loss, and void ratio and extremely in low shear strength. Ground improvement methods using cement are effective for the rapid construction of embankments on peaty ground. However, to avoid differential settlement and lateral flow, most of such construction is carried out with an improvement ratio of ap=50%. In this case, the improvement can certainly be expected to be effective. However, it is less economical than other soft ground improvement methods. The challenge is to reduce the cost of improving the ground. Our institution (the Civil Engineering Research Institute for Cold Region, PWRI) has developed an economical measure against soft ground that uses cement with a reduced improvement ratio in combination with a crushed-stone mat (gravel foundation reinforcement), and we conducted the test construction of a 16-meter-high embankment to verify effectiveness of the method. The crushed-stone mat consists of a 50-cm layer of crushed stone covered with a geo-synthetic material. The test construction achieved the following results. (1) Settlement of the embankment was significantly reduced. (2) Slip failure did not occur. (3) Displacement to the surrounding ground did not occur. (4) The geotextile in the crushed-stone mat exhibited less strain than that which would cause the geo-synthetic to exceed its design strength. These results show that this economical measure against soft ground was effective at stabilizing the high embankment constructed on peaty ground.

Mechanical performance of a bond-type anchorage system for CFRP cable exposed to elevated temperature

Both high-temperature pullout tests without and with pre-tension load were conducted on the bond-type anchorage system specimens with bonding medium of UHPC (Ultra-high Performance Concrete) for Carbon fiber reinforced polymer (CFRP) cable in order to fully understand the bonding behavior of CFRP cable-UHPC interface under high temperature. The variation laws of ultimate pullout load, average bond strength of CFRP cable-UHPC interface and slippage corresponding to ultimate pullout load were uncovered in two types of high-temperature pullout tests. Then, the bond performances of CFRP cable-UHPC interface in high-temperature pullout tests with pre-tension load ratio from 0.2 to 0.6 and target temperature in the range of 100–210 ℃ were compared to these in high-temperature pullout tests without pre-tension load in order to identify the effect of temperature-load path. Finally, theoretical models for determining average bond strength of CFRP cable-UHPC interface and critical bond length of CFRP cable for the bond-type anchorage system under high temperature were developed by incorporating effects of high temperature and pre-tension load ratio. The obtained results demonstrate that the dominant failure mode of the bond-type anchorage system in high-temperature pullout tests is slip failure of CFRP cable-UHPC interface, and shear failure morphologies of embossed rid for CFRP tendon are closely correlated with target temperature. In high-temperature pullout tests without pre-tension load, the average bond strength of CFRP tendon-UHPC interface gradually decreased as the increasing target temperature, the corresponding attenuation ratios in temperature ranges of 25–300 ℃ and 300–400 ℃ are 84% and 47%, respectively. In high-temperature pullout tests with pre-tension load, the average bond strength of CFRP tendon-UHPC interface approximately linearly decreased as the increasing target temperature or pre-tension load ratio. The presence of pre-tension load results in acceleration of damage of CFRP cable-UHPC interface, and the damage degree is proportional to pre-tension load. The developed theoretical models of mechanical properties for the bond-type anchorage system exposed to high temperature can accurately predict average bond strength of CFRP cable-UHPC interface and critical bond length of CFRP cable.

Influence of lithology and bedding orientation on failure behavior of “D” shaped tunnel

To explore the influence of lithology on the failure behavior of layered tunnel, true triaxial compression experiments were undertaken on cubical phyllite and yellow sandstone samples containing a “D” shaped hole. The failure progress of the hole sidewalls was monitored and captured using a miniature camera. The results reveal that the initial vertical failure stress of the phyllite samples presents a “U” shaped change as the bedding angle increases. At the bedding angle of 45°, compared with the initial vertical failure stress of the yellow sandstone tunnel, that of the phyllite tunnel is lower, resulting in larger rock fragments and deeper V-shaped grooves. The failure pattern of the phyllite tunnel is primarily manifested as extensive shear sliding failure, and the failure is more severe. The failure of the yellow sandstone tunnel is primarily characterized by the sequential laminar fracturing along the maximum principal stress direction, predominantly manifesting as tensile failure. The primary factors influencing the failure of two types of layered rocks are the significant variations in the clay mineral content within the rocks. For the phyllite, it contains nearly one-third of montmorillonite (a clay mineral). This results in the formation of weak bedding planes within surrounding rocks, which induces shear slip failures along these bedding planes. In contrast, the yellow sandstone has a lower clay mineral content, leading to the absence of distinct weak bedding planes within the surrounding rock. In this case, bedding planes present ignorable effect on the surrounding rock.

Interface space-time slip behavior of prefabricated composite beams under fatigue loading

This study investigates interface slip behavior within prefabricated composite beams subjected to cyclic fatigue loading. Static and fatigue tests on five beams were performed to analyze their interface slip characteristics and failure modes. The study investigates the growth and distribution of interface slip over time and space using fatigue cycles as a temporal parameter and beam length as a spatial parameter. Correlations between slip behavior and overall structural characteristics, including maximum mid-span displacement and ultimate bearing capacity, were established. To model this phenomenon, a fatigue accumulation slip calculation model was introduced in the temporal domain, while a slip differential equation considered material fatigue damage in the spatial domain. By combining temporal and spatial slip data, a time-space slip model for the interface of composite beams was developed and validated by experiments. The study identifies a three-stage nonlinear growth trend in interface slip over time at each measuring point of the composite beam. Spatially, the slip increases nonlinearly from the mid-span towards the beam's end. Significantly, space slip accounts for a substantial proportion, ranging from 71% to 87% of the total slip, while time slip contributes 13% to 29%. Moreover, the research demonstrates a robust positive Pearson correlation (correlation coefficient > 0.89) between space-time slip at the end of a composite beam and both maximum mid-span displacement and ultimate bearing capacity, highlighting the profound influence of space-time slip on the composite beam's mechanical properties. The developed slip model effectively predicts interface space-time slip in composite beams exposed to different fatigue cycles.

Numerical Analysis of Interbedded Anti-Dip Rock Slopes Based on Discrete Element Modeling: A Case Study

Varying geological conditions and different rock types lead to complex failure modes and instability of interbedded anti-dip rock slopes. To study the characteristics of failure evolution of interbedded anti-dip slopes, a two-dimensional particle flow code (PFC2D) based on the discrete element method (DEM) was utilized to establish an interbedded anti-dip rock slope numerical model for the Fushun West Open-pit Mine based on the true geological conditions and field investigations. The slope model with an irregular surface consists of interbedded mudstone and brown shale as two different rock layers, and a number of small-scale rock joints are randomly distributed in the rock layers. The influence of different inclination angles (20° and 70°) of the rock layer and slope angles (60° and 80°) on the stability of interbedded anti-dip rock slopes was considered. The evolution of the failure progress was monitored by the displacement field and force field. The simulation results showed that the rock joints in the rock stratum promoted crack initiation and increased the crack density but did not change its shear-slip failure mode. A large inclination angle of the rock layers and slope angle can lead to topping slip failure along the slip zone. However, shear-slip instability generally occurs in interbedded anti-dip rock slopes with small inclination angles of the rock layer and small slope angles. These results can contribute to a better understanding of the failure mechanism of interbedded anti-dip rock slopes under different geological conditions and provide a reference for disaster prevention.

Failure Behavior and Surrounding Soil Stress Responses of Suction Anchor in Low-Strength Muddy Clay

Anchorage failure of a suction anchor is more likely to occur in low-strength muddy clay. This paper focuses on the failure behaviors of suction anchors and muddy clay stress responses. The centrifugal model test was used to study the loading processes of suction anchors with various pulling angles. Firstly, the multi-stage developing process of anchoring force was analyzed according to the test results. Numerical modeling was used to validate the test results. The displacement of the suction anchor and muddy clay soil were analyzed using the numerical results. Then, the numerical and testing results were compared to analyze the horizontal soil pressure responses around the suction anchors. It was found that the change in loading direction affected the distribution and development of soil stress. The horizontal soil resistance played a crucial role in improving the bearing capacity. The soil stress variation and anchor displacement revealed that the suction anchors exhibited multi-attitude coupling movement during the inclined pulling. The vertical pulling suction anchor showed shear–slip failure behaviors, while the inclined pulling suction anchors showed compression–shear–slip coupling failure behaviors. The results of this study provide insight into the interaction mechanism between suction anchors and muddy clay, serving as a reference for the design and application of suction anchors.

In-Situ Test and Numerical Simulation of Anchoring Performance of Embedded Rock GFRP Anchor

Compared to traditional steel reinforcement, GFRP anchors demonstrate outstanding mechanical performance and corrosion resistance, and so they are an ideal substitute for steel reinforcement in anti-floating projects. Based on finite element software, a 3D axisymmetric calculation model of GFRP anti-floating anchors in medium-weathered granite was established in this paper. Combined with the in-situ ultimate pull-out tests, the bonding anchoring performance and bearing characteristics between the anchor body, anchoring mortar, and rock–soil mass were analyzed. The research findings indicated that the cohesive bonding elements exhibited a high degree of conformity in defining the interface contact relationship of the GFRP anti-floating anchor anchoring system. The axial force of the GFRP anti-floating anchor body is “attenuated” along the depth direction, and there was a critical value of anchoring length; under the same conditions, the reasonable anchoring length should be 3.5~5.0 m. All the anchors in the in-situ tests exhibited interfacial shear slip failure between the anchor body and the anchor mortar, with an average maximum load of 450 kN, which is consistent with the maximum failure load of the simulated anchors. Compared to a load of 50 kN, the maximum stress of the anchor mortar increased by 50% under a load of 450 kN. The displacement variation of the surrounding rock–soil mass showed a decreasing trend from the inside to the outside and from the top to the bottom. The research results provided valuable references for the optimization design of GFRP anti-floating anchors.

An investigation of bond behavior between composite materials (CFRP, GWMM, KPGC) and substrates (Brick and Concrete) for strengthening existing masonry structures

The use of novel composite materials to repair and upgrade existing masonry structures is a major research topic. The Rilem Technical Committee 250-CSM (Composites for the Sustainable Strengthening of Masonry) and Assocompositi (Italian Industry Association for Composite Materials) conducted a round robin test to study the properties of up to 25 types of composite materials in terms of direct tension and bonding behavior. These research results provide a more comprehensive understanding of the mechanical properties of fabric reinforced cementitious matrix (FRCM) reinforcement systems and further improve the standardization of testing procedures. However, owing to the diversity of composite materials and substrates, these results cannot be directly applied to strengthening existing masonry structures in China.In this study, we aimed to comprehensively investigate the bonding behavior between various commonly used composite materials and substrates. Three brick types commonly used in rural areas of China were selected as substrates, namely clay solid brick, shale perforated brick, and concrete hollow block, and three mainstream composite materials were selected as reinforcement materials, namely carbon fiber-reinforced polymer (CFRP), galvanized wire mesh mortar matrix (GWMM), and knitted polyester geogrid cementitious matrix (KPGC). It should be noted that both GWMM and KPGC can be viewed as FRCMs, because they comprise both a fabric and matrix. First, the mechanical properties of the composites were determined by unidirectional tensile tests. Second, single- and double-lap tests were conducted using a specially designed test setup. A comprehensive analysis of the experimental results was conducted, including failure modes, load-global slip curves, failure loads, peak stresses, and exploitation ratios. Finally, the prediction formula for the bonding load capacity of the composite materials mentioned above was explored using the experimental results recorded in this study and relevant literature. The results not only explain the bonding behavior among CFRP, GWMM, PGCM and different substrates, but also broaden the material selection scopes in the repair process of existing masonry structures in a large number of villages and towns in China.

Study on the relationship between the maximum anchoring force and anchoring length of resin-anchored bolts of hard surrounding rocks based on the main slip interface

The critical anchoring length of the hard rock bolt anchoring system is relatively short, which is prone to problems such as the designed anchoring length being too short to achieve the expected anchoring force, or the excessive anchoring length, which causes waste of resin cartridges. Therefore, predicting the maximum anchoring force for a specific anchoring length is of substantial significance for the design of bolt support parameters design and surrounding stability control. Herein, laboratory experiments, theoretical analysis, and in-situ test are implemented to explore the relationship between the maximum anchoring force and the anchoring length for the bolt anchoring system. The achieved results reveal that the slip failure of the bolt-resin interface (B-R interface) is the main failure mode of the hard rock anchoring system. In the presence of the main slip interface condition (i.e., assuming that the anchoring system fails only at the B-R interface) and for specific values of bolt diameter and elastic modulus, the maximum anchoring force does not depend on the strength of the surrounding rock, but only the anchoring length. The proposed relational model based on the main slip interface of the maximum anchoring force and anchoring length can successfully break the strength limit or surrounding rock type to utilize more experimental data acted upon by various surrounding rock conditions. According to the relational model, the relational curve and function for the maximum anchoring force in terms of the anchoring length of the Φ20 mm rebar bolt are obtained. It is found that the obtained relational curves have high accuracy through in-situ verification and comparison with the curves proposed by other researchers. The research results could provide solid theoretical references for the maximum anchoring forces prediction and bolt support parameters design.

Simulasi Model Sambungan Mekanis dengan Menggunakan Coupler Untuk Beton Pracetak

The use of mechanical joints can improve the performance of the connection and make the time more efficient. The purpose of this study was to determine the maximum tensile force, failure pattern and effect of epoxy thickness on the maximum tensile force, epoxy-bar bonding stress, and epoxy-coupler bonding stress of each splice type Grouted Coupler Connector. The research specimens were 6 pieces with varying thicknesses of epoxy and diameter of reinforcing steel. Software that supports the pullout test simulation is ANSYS and the research data processing method uses Simple Linear Regression Analysis. The output from the pullout test simulation is the maximum tensile force with a thickness of 25mm epoxy on the reinforcing steel D16, D22, and D25 of 91.156 kN; 148,090 kN, and 203,295 kN. All the test specimens have an epoxy coupler slip failure pattern. And the concluded from the simple linear regression analysis is a significant effect between the thickness of the epoxy on the maximum tensile force and bond stress, with a negative regression coefficient value. The optimum value of using thick epoxy with a varying diameter of reinforcing bars is 25mm.

Numerical Study on the Damage Characteristics of Layered Shale Using 3D DEM

Layered shale is a kind of rock with obvious anisotropy, which is significantly influenced by the inclination angle of the rock. In this study, the influence of bedding dip on the strength characteristics, failure mode, and internal fracture evolution of layered shale was investigated through laboratory triaxial compression tests and three-dimensional discrete element numerical simulations. Results show that the numerical model of layered shale constructed using the bonded block model can simulate the layered shale in terms of U-shaped strength variation and failure modes very well. Based on the distribution of cracks and failure characteristics of layered rocks, the failure modes of layered rocks are classified as follows: Shear failure across the bedding plane, slip failure along bedding planes, combined tensile splitting and shear failure. The development of microcracks damage in the slip failure model is controlled by interlayer joints, while in other failure modes, it is jointly controlled by the rock matrix and interlayer joints. The relationship between microscopic joint parameters and the variations of Young's modulus and peak strength has been proposed.

Structure stability and shear failure behaviors of asphalt mixtures from the perspective of aggregate particle migration

Shear deformation of asphalt mixtures is the macroscale accumulation of aggregate migration, addressing excessive aggregate slip and rotational migrations can reduce shear failure. In this research, the slip failure and torsional failure tests were introduced to achieve targeted investigations using developed instruments. Deformation resistance of the asphalt mixture was analyzed from the granular properties. The results indicate that shear energy is dissipated by structural self-organization induced by aggregate migration. Coarse gradation and complex aggregate morphology enhance the structure stability. The shear failure threshold resulting from aggregate slip exceeds that of rotation over fourfold. The packing coefficient (PC) and the critical moment of inertia (IC) were proposed to evaluate the slip and rotation resistances of asphalt mixtures, the indicators show good parabolic and linear relationships with the peak forces of slip and rotation as gradation changes, which can be illustrated by the interfacial friction and the spatial hindrance provided by the aggregate morphologies of texture and form. Finally, the findings were validated by the discrete element method.

Engineering Geology and Slope Stability Analysis in Kendari-Andoolo Road Section, Wolasi District, South Konawe Regency, Southeast Sulawesi

This research presents the engineering geological features of the Kendari-Andoolo road section, Wolasi Sub-district, South Konawe Regency, Southeast Sulawesi, a vulnerable area for landslides. The slope factor of safety (FoS) was also determined using the limit equilibrium method on a single and overall slope. Hand auger drilling and Wenner-Schlumberger configuration geoelectric surveys were conducted to estimate the slope failure plane. The study area is composed of phyllite, mudstone, and sandstone. Discontinuities at the face of the slope are N45ºE and N105ºE shear fractures, N280ºE foliation, and N310ºE fault brecciation. The overburden is low plasticity organic silt (OL) with a density range of 16.92 kN/m3-18.01kN/m3 and a plasticity index of 8.64-10.57 (medium). The FoS values of the slopes assumed rotational and nonrotational slip failures. On a single slope assuming rotational failures, the FoS value was lower than the nonrotational plane but still above the threshold value. The critical FoS is on the rotational sliding plane on the overall slope model. The slope's landslide failure plane is the clay's boundary layers and weathered phyllite.

Stability evaluation of fault in hydrocarbon reservoir-based underground gas storage: A case study of W gas storage

Fault stability evaluation is crucial for ensuring safety of underground gas storage (UGS) reconstructed from depleted oil and gas reservoirs. To make assessment result more reasonable, a novel fault stability evaluation method is proposed, and four major faults in W gas storage are studied as a case to detailly describe this method. This method considers both shear rupture failure and frictional slip failure of fault based on Mohr-Coulomb criterion and Amonton’s law. In addition, dynamic variation in rock shear strength parameters under cyclic stress is understood and taken into account in fault stability evaluation by rock mechanics experiments. Meanwhile, specificity of fault friction coefficient in different UGSs is also considered in this method, and fault friction coefficient of W gas storage is determined by an empirical model. Fault stability evaluation results are quite disparate when different fault failure types are considered. For W gas storage, max operation pressure leading to fault failure is 62.10 MPa when shear rupture is regarded as fault failure type, and it reduce to 35.91 MPa when frictional slip is considered as fault failure type. Therefore, it is necessary to consider both two failure types, and further determine the key failure type in fault stability evaluation. Rock shear strength parameters vary with stress cycle, but the variation range is not significant in W gas storage. Rock cohesion shows a tendency that it fast declines first with stress cycles, then slow declines, and eventually tends to a constant. And variation in internal friction angle is contrary. Above both parameters orderly decrease by 3.08% and 8.75% after 53 cyclic stress cycles. The specificity of fault friction coefficient cannot be neglected in different UGSs. Otherwise, it could result in significant misestimate on fault stability of UGS. For W gas storage, fault friction coefficient is determined of 0.71 by empirical model, which is significant disparate to previous works. This work proposes an effective method which can help scholars and engineers to accurately evaluate fault stability in UGS.

Experimental Study on Pore Pressure Variation and Erosion Stability of Sandy Slope Model under Microbially Induced Carbonate Precipitation

With the development of a free trade port on Hainan Island, the construction of tourist roads around the island is currently underway. However, the weather conditions on Hainan Island, which include strong typhoons and rainstorms, pose challenges for the construction of highway-cutting slopes on the coastal weak sandy terraces. These slopes are susceptible to sand loss and erosion from rainfall. To address this issue, MICP green spray irrigation solidification technology is used to strengthen the sandy cutting, and pore water pressure monitoring is carried out on the slope model during MICP solidification and rainfall scour. Combined with the model pore water pressure and flow slip failure pattern, a dynamic analysis was conducted. The results show that MICP sprinkler irrigation technology can solidify the surface of the slope model in a short time, and after three sets of rotation reinforcement, the model achieved a cementation depth of 4 cm, with a well-reinforced surface and closely connected sand samples. Under the erosion effect of simulated rainfall intensity, the sand loss of the slope was weakened, without damage to the sand binding, and the integrity was enhanced. The cementation between the sand grains facilitated the conversion of most of the rainfall into runoff. However, despite these efforts, the slope eventually slid after 150 s. During the sliding process, the leading edge of the slope model lost sand and became unloaded, and the failure mode was graded a creep slip failure. Finally, the slope was divided into several blocks due to the continuous expansion of cracks following the slope failure. The erosion stability of the sandy slope under heavy rains was optimized and the sand loss was prevented effectively. This study proposes a new method of MICP remediation techniques that serve as a new test basis for the practical application of MICP technology in engineering projects.

Structural behavior of stainless steel anchor channels embedded in concrete under perpendicular and longitudinal shear

Stainless steel anchor channels with channel bolts (SSAC-CBs) have been chosen as alternatives to conventional carbon steel anchor channels to enhance corrosion resistance, ductility, and load-bearing capacity. This study evaluated the shear performance of SSAC-CBs embedded in concrete members under perpendicular and longitudinal shear loads using static monotonic tests. The failure modes and shear capacities of the specimens were compared with those obtained by finite element analysis (FEA) models established using ABAQUS. Concrete edge breakout failure accompanying the channel flexural yielding and channel bolt fracture dominated in the SSAC-CBs under perpendicular shear. The load–displacement curves for perpendicular shear exhibited four salient stages: initial linear elasticity, slippage, strain hardening, and damage and failure. Under longitudinal shear, the SSAC-CB specimens exhibited a failure of the serrations in the contact area between the serrated channel bolt head and channel lips and slip failure between the hook-type channel bolt and channel lips. In addition, the numerical analysis results indicated that the load-bearing capacities, initial elastic stiffnesses, and failure modes obtained through the FEA models were consistent with the test results. Furthermore, theoretical formulas were proposed for the shear capacity for SSAC-CBs under perpendicular and longitudinal shear. The research outcomes provide valuable guidance for the design and application of SSAC-CBs in engineering.

Dynamic Mechanical Behavior of Rock Specimens with Varying Joint Roughness and Inclination under Impact Load

The influence of joint roughness and inclination on the dynamic mechanical properties of rocks is a prominent research area. In order to investigate the effects of joint roughness and inclination on the dynamic mechanical properties of jointed rocks, impact tests were conducted using a spilt Hopkinson pressure bar (SHPB) apparatus for prefabricated serrated joint cement mortar specimens with varying joint roughness and inclination. The failure mode, stress wave propagation characteristics, peak stress, and stress wave energy transfer law under impact load were analyzed. The results indicate that both joint inclinations and joint roughness coefficients (JRC) have a strong influence on the failure mode, peak stress, and stress wave energy transfer of jointed specimens. The jointed specimens exhibit three distinct failure modes under impact load, namely splitting tensile failure, shear slip failure, and compound failure of splitting tensile and shear. The peak stress initially decreases then increases with the increase in joint inclination angle, namely a V-shape variation, while it gradually increases with JRC increasing from 0 to 20. Jointed specimens exhibit the lowest peak stress at an inclination angle of 45° and JRC of 0. The variation of transmitted energy coefficient is similar to the peak stress, while the variation of reflected energy coefficient is opposite to the peak stress. At joint inclination angles of 0° or 90°, the reflected energy coefficient increases with the increase of JRC from 0 to 20, while the transmitted energy decreases. However, when the joint inclination angle is in the range of 30° to 60°, the reflected energy coefficient gradually decreases with JRC increasing, while the transmitted energy coefficient gradually increases.

Experimental investigation on the friction behavior of CFRP plate in contact with sandblasted steel plate

The coefficient of static friction (COSF) between the steel plate and carbon fiber-reinforced polymer (CFRP) plate is a significant impact parameter for the design of mechanical anchors. In this study, the friction behavior and wear mechanism between the sandblasted steel plate and CFRP plate with different surface treatment methods under various normal pressures and anchor lengths were investigated through the planar clamping anchor. In order to improve the surface roughness level, the surface of CFRP plate was treated by galling or sand coating. The results indicate that the COSF of the galling surface ranged of 0.28–0.30 corresponding to various parameters, while that of the sand coating surface changed between 0.27 and 0.35. Although the COSF could be obviously enhanced by the surface sand coating, the discreteness of COSF was large and the relaxation of bolt preload was severe. Moreover, the COSF presented a decreasing trend when the normal pressure exceeded 33 MPa, whereas that kept almost constant with the increase of anchor length. The failure mode changed from slip failure to incomplete or complete burst failure with increasing normal pressure and anchor length. The friction failure process of CFRP plate was dominated by ploughing and wear, which caused changes of the tensile load and bolt preload at different stages. The research in this paper contributes to providing guidance for the design of mechanical clamping anchors, especially for the clamping anchor with constant or variable curvature waveform.