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In order to study the effect of rainfall infiltration on the stability of root-soil complex slopes in cold and arid environments, based on the indoor root-soil complex straight shear test, the root system was simplified into a two-dimensional symmetric model consisting of the main root and one level of lateral roots with different inclinations to simulate the root-soil complex straight shear test, and the tensile force of lateral roots with different inclinations was obtained along with shear strength indexes of the specimens, and the stability of the slopes with different inclinations was analyzed based on the infinite slopes and the rainfall I-D model for the different inclination of the lateral roots through the based on the infinite slope and rainfall I-D model, the stability analysis of slopes with different inclination of lateral roots across the potential slip surface was carried out. The results show that with the increase of lateral root inclination angle, the tension of front lateral root increases, the main root and back lateral root tension changes insignificantly, and the tension of front lateral root gradually decreases when it is greater than 37.5°. Under different vertical pressures, the contribution of root configuration to the shear strength of the soil body is the front lateral root. The main root, and the back lateral root in the order of the front lateral root. The factor of safety of the vegetative soil and root-soil composite slopes decrease sharply with the increase of the depth of the slope potential slip surface, and compared with the the maximum increase in the slope safety factor of root-soil composite is about 27.01% compared with that of the vegetative soil. The research results can provide some data for the study of vegetation ecological slope protection and soil conservation in cold and arid environments. [ABSTRACT FROM AUTHOR]

[Objective] The aims of this study are to explore the influence of vegetation on the soil consolidation effect of slope, and to provide data support for preventing soil erosion and reducing soil erosion in the dry-hot valley of Jinsha River. [Method Four typical vegetations (Acacia confusa, Quercus franchetii, Phyllantthus emblica, Pinus yunnanensis) in Yongren County of Yunnan Province were taken as the research objects. Indoor single root tensile test and direct shear test were carried out to study the difference of soil shear performance of different vegetation types and the influence of various factors on it. [Results] (1) The average single root tensile resistance of the four plants decreased in the order: Quercus franchetii Phyllantthus emblica Pinus yunnanensis > Acacia confusa. The average tensile strength of single root decreased in the order: Phyllanthus emblica > Acacia confusa Pinus yunnanensis Quercus franchetii. The tensile resistance of a single root had an exponential function relationship with the root diameter, and the tensile strength of a single root had a significant negative correlation with the root diameter. (2) Under the four vertical pressures, the shear strength of the four vegetation root-soil composites was greater than that of the plain soil, and the shear strength index varied with the depth of the soil layer. The soil cohesion of the Pinus yunnanensis vegetation had the largest variation with the depth of the soil layer (51.47%), and the internal friction angle of the Quercus franchetii vegetation had the largest variation with the depth of the soil layer (37.96%). (3) The grey correlation method was used to comprehensively analyze the correlation between root tensile properties, soil physical and chemical properties and soil cohesion and internal friction angle. The correlation between cohesion and root tensile strength was the strongest, followed by root tensile resistance, and the water content was the weakest. The correlation between internal friction angle and soil bulk density was the strongest, followed by organic matter, and total potassium was the weakest. [Conclusion] The tensile properties of plant roots and the physical and chemical properties of soil can significantly affect the shear properties of soil. among which the tensile properties of roots have a greater impact on soil cohesion, and have no significant effect on soil internal friction angle. [ABSTRACT FROM AUTHOR]

In order to improve the water hole blasting effect in the water rich rock area of a certain open pit mine, a study was conducted on rock debris filling materials through theoretical analysis and on site experiments. The influence of radial water uncoupling charge coefficient, filling length, and delayed detonation on the blasting effect was analyzed through numerical simulation. The results show that as the particle size of rock debris increases, the shear strength of the filling structure also increases, and the effect of filling is also enhanced; The filling effect is most significant when the ratio of <5 mm with $5 mm rock debris particles is 3 5 7 in the filling structure; When the radial water uncoupled charge coefficient Kd is 1. 33, perfect blasting effects can be achieved to save explosive costs;Delayed detonation can provide more free surfaces to reduce the fragmentation of rock masses. [ABSTRACT FROM AUTHOR]

Research on the stability of tailings dam is often achieved through the finite element method with strength reduction. The influence of shear strength parameters(c) of tailings dam stability varies. In this paper, the theory of shortest path strength reduction is introduced to conduct a stability analysis of a large tailings dam in Northeast China. The main conclusions are as follows: 1) Approximating the actual unit weight of tailings using Optum G2, stability analysis of tailings dam with shortest path strength reduction under seepage conditions is conducted to obtain the minimum safety factor of the slope and potential failure surfaces. 2) During unequal strength reduction, as the reduction ratio increases, the length of the reduction path first decreases and then increases, indicating that the minimum safety factor obtained by the shortest reduction path corresponds to the most unfavorable limit state of the tailings dam. 3) The minimum safety factor obtained through the limit analysis of shortest path strength reduction is slightly lower than the results of the Swedish slip circle method and simplified Bishop method, but overall, it is in good agreement. 4)With the increase in height of the tailings dam, the minimum safety factor continues to decrease, and the range of potential sliding bodies of the tailings dam increases, with the corresponding sliding surface expanding towards the reservoir. [ABSTRACT FROM AUTHOR]

Copyright of Fly Ash Comprehensive Utilization is the property of Hebei Fly Ash Comprehensive Utilization Magazine Co., Ltd. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chinese Journal of Applied Mechanics is the property of Chinese Journal of Applied Mechanics Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to study the variation of shear strength of unsaturated sandy soils and establish an effective prediction model, taking sandy soils in Nanchang area as the representative, the mechanism of the influence of water content and dry density on the shear strength of unsaturated sandy soils was investigated. The results show that under different water content and dry density conditions, the shear stress-shear displacement curves of unsaturated sandy soils are all of softening type, showing a fourstage nonlinear law of change, which presented a decreasing variability with the change of water content and dry density. The shear strength of unsaturated sandy soils decreases with increasing water content and saturation, which increases with increasing dry density. The cohesion of unsaturated sandy soils decreases and then increases with increasing water content, increasing approximately linearly with increasing dry density. The angle of internal friction increases and then decreases with increasing moisture content, and the change in the coefficient of internal friction resulting from the change in dry density is small, within about 25% . Based on the Moir-Coulomb strength criterion, regarding water content and dry density, a nonlinear regression model of shear strength of unsaturated sandy soils was constructed, which could provide a reference for the selection and prediction of engineering geological parameters. [ABSTRACT FROM AUTHOR]

To study the crack propagation, local buckling and vertical shear strength of partially filled narrow steel box-UHPC composite beam in negative moment zone, reverse forward loadings were taken to five composite beams with different UHPC layer thicknesses and infilled HSC heights, and the failure process, load-crack width curve, load-midspan deflection curve, midspan strain distribution, and web stress-strain curves were obtained and analyzed. The results show that compared to the specimens with NC flange, the shear bearing capacity of the specimens with half-UHPC flange and full-UHPC flange has not been significantly increased, only increased by 8. 3% and 11. 6%. Compared to the unfilled specimens, the shear bearing capacity of the half-infilled and fullinfilled specimens has been increased by 61. 7% and 87. 2%, respectively. After replacing part NC with UHPC of the flange, the specimens can effectively control crack development, and infilled HSC in the steel box can effectively reduce local buckling of the web. The calculation method for the shear bearing capacity of composite beams was established with the subitem superposition method, considering the contribution of flange, steel girder, and infilled HSC to the shear bearing capacity, and it can accurately predict the shear bearing capacity of count beams. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Dalian University of Technology / Dalian Ligong Daxue Xuebao is the property of Journal of Dalian University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The laminate was manufactured with T800 grade high toughness carbon cloth and carbon ribbon prepreg, T800 grade glass fiber prepreg, aramidon and quartz hybrid prepreg. The influence of high temperature and high pressure multiple curing on the mechanical properties of laminates was investigated. After five times of high temperature and high pressure curing, the laminate pore defects, bending strength and shear strength were tested. The results show that the internal quality of four different prepreg laminates is qualified. With the increase of curing times, the bending strength of T800 grade high toughness carbon cloth laminate decreases most obviously, and the shear strength of T800 grade glass fiber prepreg laminate decreases most obviously. However, the bending strength and shear strength of the four kinds of prepreg laminates decrease by less than 10%. The minimum shear strength of aramid and quartz hybrid prepreg after curing for five times is 1.64% lower than the theoretical index, and the shear strength of other materials is higher than the property requirements of each laminate. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Shanghai Jiao Tong University (1006-2467) is the property of Journal of Shanghai Jiao Tong University Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Coal Science & Technology (0253-2336) is the property of Coal Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The shear mechanical parameters of coal are important parameters for analyzing the deformation and stability of coal. In order to study the shear characteristics of straight joints of coal under different normal stress and shear rate conditions, the shear numerical simulation and laboratory test were carried out to study the influence of normal stress and shear rate on the shear characteristics of straight joints of coal. The results show that the shear strength of joints decreases with the increase of shear rate, and increases with the increase of normal stress. The higher the normal stress, the greater the influence of shear rate on the shear strength of joints. Shear stiffness is positively correlated with normal stress and negatively correlated with shear rate. When the shear rate reaches a certain value, the influence of shear stiffness is not obvious. The increase of shear rate makes the simulated joints more prone to shear slip, which is easy to cause coal and rock dynamic disasters. This phenomenon is more serious in high normal stress.

[Objective] The aims of this study are to explore the characteristics and disparities in shear strength of root-soil complexes in different forest stands, and to provide a theoretical basis for addressing local soil erosion issues more effectively. [Methods] This study focuses on Beichuan County, Sichuan Province. Direct shear tests were conducted on intact root-soil complexes of several typical forest stands in the area, measuring relevant indicators such as shear strength, soil properties, and root characteristics. Principal component analysis was utilized to analyze the influencing factors of shear strength. [Results] (1) There were significant differences in shear strength among root-soil composites of different forest stands. The shear strength of 30-year-old Magnolia liliiflora forest (XY) was the highest, followed by Spotted bamboo Phyllostachys bambusoides forest (BZ), while the shear strength of 5-year-old Cryptomeria forest was the lowest. (2) The plant root system significantly contributed to soil stabilization, with an increase in shear strength of root-soil composites ranging from 0.13 kPa to 0.99 kPa, with an average increase of 350.0%. Additionally, the peak displacement, softening segment length, and residual shear strength of root-soil composites were enhanced, with average increases of 75.0%, 66.7%, and 262.5%, respectively. The total energy consumption of root-soil composites varied among different forest types but generally correlated with their shear strength. (3) Comprehensive analysis through principal component analysis revealed that, apart from soil bulk density and the dry and wet weights of 5~8 mm roots, all other indicators were closely related to shear strength. [Conclusion] Plant roots play a significant role in soil stabilization. The notable differences in shear strength of root-soil complexes were observed among different forest stands. [ABSTRACT FROM AUTHOR]

To study the flow and strength characteristics of coal slime based backfill materials, orthogonal tests were used to design one cemented backfill material combining coal slime, high-water-content materials, cement, and fly ash. By using range, analysis of variance, and multi-variate regression analysis, influences of four key factors on the initial setting time, bleeding ratio, diffusivity, compressive strength, and shear strength of the backfill material were studied. These four factors include coal slurry water mass per cent concentration (A), high water material mass / slurry water mass (B), cement mass / slurry water mass (C) and fly ash mass / slurry water mass (D). Results show that initial setting time, diffusivity, compressive strength, and shear strength of the backfill material are 52−67 min, 42.0−76.5 cm, 0.076−0.247 MPa, and 0.033−0.139 MPa, respectively, all distributed in wide ranges. For initial setting time, the four factors are listed in a descending order as B>C>A>D according to their influences; for the compressive strength, the four factors are ranked as D>C>A>B; for the shear strength, the four factors are listed in an order as C>D>A>B. Mathematical equations between A, B, C, D and initial setting time, diffusivity, compressive strength, and shear strength were gotten, initial setting time and A, B presents quadratic function relation, and C, D present exponential relation; diffusivity and A, B, C presents quadratic function relation, and D presents trigonometric relation; compressive strength and A, D presents exponential relation, and B, C presents quadratic function relation; shear strength and A, B presents quadratic function relation, and C, D presents exponential relation.One prediction model for characteristic parameters, namely, fluidity and strength, of the coal slime based backfill material under action of various factors was established and calibrated.

The borehole shear test is an important method to quickly measure the shear strength of rock in the field, but its application is limited due to its large measurement error. By analyzing the principle of borehole shear and the research results, it is found that incomplete shear is the reason for the large error of rock borehole shear test, and a correction method of borehole shear method based on the unequal area of pressure and shear was proposed. Experimental equipment was designed to carry out the simulated borehole shear test, and the characterization rules of sandstone shear mechanical parameters under different shear plate parameters were studied, which proved the effectiveness and correction effect of the proposed method. Finally, the applicability of the method was verified by literature data. Specific results are as follows: ① The root cause of large error in rock borehore shear test is that the selection of compression area and shear area is distorted and unequal, the actual shear failure area is less than the area between shear teeth, and the corrected compression area and shear area increase linearly with the increase of normal force under different shear tooth lengths. Based on the relationship between the parameters of shear tooth, compression area and shear area, a correction method of borehole shear test is proposed. ② The shear stress-shear displacement curve of rock borehole shear can be divided into compaction stage, elastic deformation stage, plastic deformation stage and post-peak stage. With the increase of normal force, the positive stress, shear stress and shear stiffness increase under different shear plate parameters, and the displacement decreases when the peak point of shear stress is reached. There are obvious rules between borehole shear parameters and the characteristic value of shear mechanical parameters. With the increase of the shear tooth length, the cohesion increases linearly, and the internal friction angle increases as a quadratic function. With the increase of the shear plate area, the cohesion increases linearly and the internal friction angle decreases as a quadratic function. ③ The increase of the shear tooth length and the shear plate area can reduce part of the measurement deviation. The shear tooth length increases from 1.0 mm to 2.5 mm, the total deviation of cohesion and internal friction angle decreases from 62.96% to 19.91%, the total improvement increases from 30.8% to 74.1%. The shear plate area increases from 400 mm2 to 520 mm2, the total deviation of cohesion and internal friction angle decreases from 64.07% to 37.69%, and the total improvement increases from 39.56% to 56.05%. Both experimental and literature data validation show that the correction method improves the accuracy of cohesion and internal friction angle by about 50% and 6%, respectively.

Objective Rainfall disasters are one of the most common disasters on loess slopes in northern Shaanxi, and revealing the effects of rainfall on loess slope stability is beneficial for preventing and controlling such disasters. Methods This research studied the mechanical properties of Q2 loess in northern Shaanxi under rainfall conditions through a series of tests. Combined with numerical simulation technology, the influence of these changes on the stability of loess slopes in northern Shaanxi was analyzed.Firstly, the drying-wetting cycles test (cyclic path and the number of cycles) was designed to simulate rainfall conditions (such as intensity, frequency, etc.).Secondly, a triaxial shear test was performed to obtain the variation law of the mechanical properties of the Q2 loess in northern Shaanxi.Finally, taking a loess slope in northern Shaanxi region as an example, finite element calculations were carried out, by which the change characteristics of the slope safety coefficients and plasticity zones under different rainfall conditions were analyzed. Results The results show that (1) the shear strength of Q2 loess after the action of drying-wetting cycles has nonlinear deterioration characteristics. When the number of drying-wetting cycles exceeds a specific range, the marginal effect of the deterioration of the physical and mechanical property parameters of loess is weakened and tends to stabilize. (2) The stability of loess slopes decreases under the effect of rainfall, and it decreases with the increase of rainfall frequency or intensity. (3) The plastic zone of Q2 loess slopes in northern Shaanxi increases with the continuous deterioration of the mechanical properties of the Q2 loess, which reveals a nonlinear characteristic of the influence of rainfall on the stability of the loess slopes. Conclusion The research results can provide a reference for preventing rainfall-induced landslide.

To study the engineering properties of red clay modified by sodium polyacrylate, the Liuzhou remodeled red clay cured by sodium polyacrylate was selected for the permeability test with variable head and triaxial shear test to analyze the permeability and mechanical properties of the modified red clay and to determine the optimum amount of sodium polyacrylate. The disintegration resistance and microscopic mechanism of the modified red clay were determined by the disintegration test and scanning electron microscope test, respectively. The results show that the permeability coefficient of the modified soil decreases gradually with the increase of sodium polyacrylate, and gradually stabilizes after reaching 3% with the permeability coefficient of 8.1379×10−7 cm/s, 90.78% lower than that of the plain soil. In contrast, the shear strength of the modified red clay shows an increasing trend firstly, then decreases, and then keeps stable at at 2%, which is 394.21% higher than that of the plain soil. The optimal dosage is 3%, and in such situation, the anti-disintegration performance of the modified soil is improved by 42.86%. The pores between the soil particles filled by polymer chains lead to the continuous fragmented granular red clay . The arrangement structure and denseness are better than those of the plain red clay. The impermeability, mechanical properties, and disintegration resistance of the red clay modified by sodium polyacrylate are significantly improved. This study can provide theoretical information for the practical engineering.

To improve the interfacial properties of poly-p-phenylenebenzobisoxazole(PBO) fiber/epoxy resin (EP)composites, the surfaces of acidified PBO fibers were coated with the sizing agents of waterborne polyurethane modified using γ-aminopropyltriethoxysilane(KH550). The surface chemical composition of PBO fibers was characterized by X-ray photoelectron spectroscopy (XPS) and energy dispersive spectroscopy (EDS). Scanning electron microscopy (SEM)was employed to characterize the surface morphology of PBO fibers and the tear surface morphology of PBO/EP composites. Furthermore, the mechanical properties of single PBO fibers and PBO/EP composites were analyzed. The results show that the active groups on the surfaces of PBO fibers increase significantly with the values of O/C(atomic ratio)from 0.16 to 0.25 after being coated with the sizing agents, and the defects on the surfaces of PBO fibers can be repaired effectively. By adjusting the contents and structure of the sizing agents on the fibers, the interlaminar shear strength and tensile strength of PBO/EP unidirectional composites reach 41.3 MPa and 1.70 GPa, respectively. In contrast to the untreated ones, the interlaminar shear strength and tensile strength of modified composites increase by 44.9% and 15.6%, respectively.

In order to explore the enhancement effect of palm fiber on the mechanical property of quartz sand, the reduced triaxial extension test was carried out to test the shear property of palm fiber reinforced quartz sand under saturated condition. The stress-strain curves, initial elastic modulus and secant modulus of saturated quartz sand reinforced with different fiber lengths and contents were calculated. The varying law of the shear strength of palm fiber reinforced quartz sand with the fiber content was analyzed based on the Mohr-Coulomb criterion. Furthermore, the strengthening effect of palm fiber on the mechanical properties of quartz sand was obtained through comparing the volume strain and porosity of contrast plain sand and reinforced sand during shear process. The results show as followed. Palm fibers can enhance the stress-strain strength of quartz sand during tensile failure, while the optimal fiber content and length for improving the peak stress and residual stress of quartz sand are 0. 9% and 12 mm. The initial elastic modulus and peak secant modulus of palm fiber reinforced quartz sand increase with the rise of effective confining pressure, and the overall stiffness is positively correlated with the effective confining pressure. The strengthening effect of palm fibers on the shear strength of quartz sand only appears in the low confining pressure state. The critical porosity and shear dilating of quartz sand are reduced by the addition of palm fibers. The research results are helpful to promote the applications of palm fiber reinforced sand and provide the corresponding theoretical basis. [ABSTRACT FROM AUTHOR]

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Copyright of Experimental Technology & Management is the property of Experimental Technology & Management Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

At present, ultra-high performance concrete (UHPC) is widely used for reinforcement of composite members and normal concrete (NC) structures. After reinforcement, the interface between UHPC and NC becomes the most vulnerable part due to the combined effect of interface normal tensile stress and interface tangential shear stress. Reinforcement planting treatment is a common method to connect the interface between old concrete and new concrete. In this study, the shear strength of UHPC-NC specimens with and without reinforcement planting and the effect of reinforcement rate on shear performance were comprehensively analyzed by straight shear test and finite element simulation. The results show that the shear strength of specimens without reinforcement planting is only 20% of that of integrally cast specimens, while the shear strength of the reinforcement planting specimens could reach 40% to 80%. In specimens without reinforcement planting, the damage form is brittle damage. In reinforcement planting specimens, the development of interface cracks is controlled, the interface shear strength is improved, the slip of interface slip is increased, and the interface is ductile failure. [ABSTRACT FROM AUTHOR]

To investigate the strength degradation and microstructure characteristics of Ili loess under wetting-drying cycling, triaxial shear tests and scanning electron microscopy tests were conducted under five wetting-drying cycling paths. The effects of different dry densities, wetting-drying cycling amplitudes, and cycles on the shear strength of Ili loess and the evolution of micro pore distribution were analyzed. The relationship between macro strength and micro pore loss mechanisms was also explored. The results show that the greater the wetting-drying cycle amplitude and the number of cycles, the faster the attenuation rate of the shear strength of Ili loess, the greater the attenuation amplitude, and the triaxial shear strength of undisturbed soil after five wetting-drying cycles is close to remolded loess. The cohesive force of Ili loess with the same dry density decreases with the increase of cycles. When the dry density is 1.55 g/cm³ under the same wetting-drying cycle path, the cohesive force of Ili loess deteriorates most significantly, while the effect of dry wet cycles on internal friction angle is slightly significant. In addition, the deterioration of cohesion is related to changes in pore area ratio and pore characteristic parameters. The greater the increase rate of pore area ratio and pore characteristic parameters after wetting-drying cycling, the more obvious the degradation of cohesion. The change trend of internal friction angle is similar to that of pore fractal dimension, but the change is not significant. [ABSTRACT FROM AUTHOR]

The study investigated the strain fatigue properties of 4 types of silane-modified polyether (MS) sealants under different conditions. The results indicate that the shear strain frequency will not change the service life of MS sealant, but it will significantly change the duration. It is advisable to select a shear strain frequency of 10 Hz. The greater the average strain, the shorter the service life of MS sealant. With a fixed strain ratio of 0.1, MS sealants show no damage after 10 million cycles of strain when the average strain is not exceed 1.25 mm. After D4 curve environmental aging according to ISO standard 9142:2003, 4 types of MS sealant has the service life of exceed 10 million cycles, a modest decrease in shear strength and a marked increase in shear fracture elongation. The shear strength declines a little, and the shear break elongation increaseds significantly, MS sealant 4# has been disbonded from the substrate, yet the shear strength retention rate exceeds 80% after aging. The MS sealant strain fatigue test provides references for the design of MS sealant applied in rail vehicles, aviation and other fields. [ABSTRACT FROM AUTHOR]

Copyright of Arid Zone Research / Ganhanqu Yanjiu is the property of Arid Zone Research Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Foundry Technology (1000-8365) is the property of Foundry Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Hydrogeology & Engineering Geology / Shuiwendizhi Gongchengdizhi is the property of Hydrogeology & Engineering Geology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Engineering Geology / Gongcheng Dizhi Xuebao is the property of Journal of Engineering Geology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Engineering Geology / Gongcheng Dizhi Xuebao is the property of Journal of Engineering Geology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to study the influence of bimodal pore structure on the mechanical properties of unsaturated soil, two typical bimodal pore structure clays in Nanning and Guilin in Guangxi were selected as target materials and the shear strength characteristics under different saturation conditions were analyzed. The effect mechanism of pore water distribution status on the strength of two kinds of soils with bimodal pore structure was explored by filter paper method and nuclear magnetic resonance (NMR) technique. The results show that the T2 distribution curves of the two samples have bimodal structure under saturated condition. Moreover, on the whole, the water retention characteristics of soil samples show bimodal soil-water characteristic curve. The stress-displacement relationship of the two kinds of soil is similar and the shear strength is closely related to saturation. The change trend of soil sample cohesion changes when the saturation is 40%, while the internal friction angle reaches the minimum at a saturation of 80%. [ABSTRACT FROM AUTHOR]

This study aims to compare the impact mechanisms of soil reinforcement by plants in the Jinyun Mountain area of Chongqing and the loess hilly area of Yan'an City, Shanxi Province, China. A systematic analysis was performed on the root morphological and soil mechanical parameters of trees (Rhus typhina and Ulmus pumila) and shrubs (Vitex negundo and Ziziphus jujuba). Four species were then selected to determine the soil shear strength. The RBMw model was employed to calculate the soil reinforcement benefits provided by these plants. The soil reinforcement of different plant species was evaluated to explore the components and contributions of soil reinforcement benefits. The results showed that: 1) The V. negundo shared the largest values for the root length per unit root volume, total root surface area, number of root forks, and root tips, while the R. typhina was the smallest values among the four species. There were no significant differences in the average root diameter of the four species. Moreover, the root length, number of root forks, and number of root tips of the R. typhina and U. pumila planted in Chongqing were significantly higher than those in Yan'an. While the V. negundo and R. typhina showed no significant differences. 2) The root tensile strength was inversely related to the root diameter in a power-law function. The V. negundo shared the highest average tensile strength. There was no significant difference of tensile strength of roots from the same plant species between different regions. By contrast, the V. negundo roots exhibited the higher tensile strength in Chongqing, compared with Yan'an. 3) The root systems of the four plant species were provided soil reinforcement efficiencies ranging from 0.65 to 4.12 kPa, with the significant differences among species. Among individual plants, V. negundo in Chongqing exhibited the highest soil reinforcement effects, while Z. jujuba was the lowest in Yan'an. The highest soil reinforcement efficiency was observed in the R. typhina in Chongqing, whereas, the lowest was found in the U. pumila in Yan'an. The root-soil composite effective cohesion of the two tree species planted in Chongqing was higher than that of bare soil (by 10%), while the shrubs was generally slightly lower. The root-soil composite shear strength in the V. negundo planting area was approximately 50% lower than that of the bare soil. The soil effective cohesion significantly decreased in the first year of V. negundo planting in Chongqing. The root system of V. negundo in Chongqing was contributed 30% to the root-soil composite effective cohesion, followed by the R. typhina in Chongqing (21.30%), and the U. pumila in Yan'an was the lowest (3.63%). The soil reinforcement effects and efficiencies of the four tree species planted in Chongqing were significantly higher than those in Yan'an. There was no variation in the exception of the individual soil reinforcement efficiency of Z. jujuba. The soil under R. typhina exhibited the highest comprehensive soil cohesion, while the high number of roots of V. negundo was resulted in the extremely low soil shear strength, leading to the soil cohesion lowest in the V. negundo planting area. As such, plants can be expected to reinforce the soil via their root systems. The finding can provide the theoretical basis to select the tree species for soil reinforcement and slope protection in different regions. [ABSTRACT FROM AUTHOR]

Copyright of Bulletin of Soil & Water Conservation is the property of Bulletin of Soil & Water Conservation Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Materials Engineering / Cailiao Gongcheng is the property of Journal of Materials Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The study on the mechanical properties of soil-structure interface is the basis to solve the problem of soil-structure interaction, which involves many aspects of practical engineering. By modifying the conventional unsaturated direct shear apparatus and using the modified unsaturated direct shear apparatus, the shear tests of unsaturated sand-structure interface were carried out, and the effects of the matrix suction, the structural interface type and the net normal stress on the shear strength of the interface were studied. The experimental results show that the influence of matrix suction on the interface cohesion of unsaturated sand-structure interface is great, while that on the interface friction angle is small. With the increase of matrix suction, the shear strength of unsaturated sand-concrete interface increases first and then decreases, indicating a peak effect. The shear strength of unsaturated sand-steel interface was less affected by matrix suction. Under the condition of constant matrix suction, the shear strength of sand-steel interface increases nonlinearly with the increase of net normal stress. The influence of net normal stress on the friction angle (δb) corresponding to matrix suction is little. Finally, a shear strength formula of unsaturated sand-concrete interface was established based on peak effect. [ABSTRACT FROM AUTHOR]

Copyright of China Rural Water & Hydropower is the property of China Rural Water & Hydropower Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Engineering Mechanics / Gongcheng Lixue is the property of Engineering Mechanics Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Mountain Research (10082786) is the property of Mountain Research Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Purposes For the Shanxi Coal Measures, the slip soil in coal bearing soft rock landslides generally contains a large number of clay minerals, and is a typical slip soil with certain expansibility and is different from the conventional slip soil in mechanical properties. Methods Four typical cases of clayey slip soil in coal bearing soft rock landslides in the Yellow River Basin in Shanxi Province are taken as research objects to reveal the unique mechanical properties. The research methods include X-ray diffraction test, slow shear test, and free expansion rate test. Findings The results show that: 1) The clay minerals of the clayey slip soil are mainly composed of montmorillonite, kaolinite, illite, and chlorite. The percentage contents of montmorillonite mineral quality are 40.95% (for a landslide in Dongshan), 38.30% (for a landslide in Linxian), 34.52% (for a landslide in Xiangning), and 17.65% (for a landslide in Zezhou), respectively. 2) The cohesion and internal friction angle of clayey slip soil show two modes with water content (negative index/negative correlation). The content range of the montmorillonite that affects the regular pattern is 17.65%~34.52%; 3) The attenuation degree of clayey slip soil shear strength shows two correlation with montmorillonite conten (t positive/negative correlation). The critical value of the montmorillonite content that affects the degree of attenuation is 34.52%. Conclusions From the perspective of mineral composition, the attenuation law of clayey slip soil shear strength is expounded and the unique strength property of this kind of slip soil is revealed. This research has certain theoretical significance for further revealing the landslide-induced disaster-causing mechanism of coal bearing soft rock landslides in the Yellow River Basin region.

The study of mechanical properties of soft crushed coal is of great significance for roadway support and prediction of coal and gas outburst, but there is a lack of effective equipment for sampling, sample preparation and mechanical properties analysis of soft crushed coal. Therefore, a set of sample preparation and shear test system for soft crushed coal was developed, which was mainly composed of sampling device, sample preparation device and mechanical property parameter test system. The main functions and characteristics of each part was as following. ① The single-action three-tube coring device in the sampling device was comprised of 3 parts of head assembly, outer tube assembly and inner tube assembly. A stability ring was arranged between the inner and outer tube to ensure that the inner tube and the outer tube were concentric. A liner was arranged inside the inner tube assembly cavity to store coal cores, and the inner tube does not rotate with the outer tube during coring and drilling. When the drilled coal core was full of liner, then the coring device was withdrawn. The liner was disassembled and taken out, and the coal cores and liner were taken out and packaged together. The sampling device was flexible, portable and easy to disassemble and carry. ② The sample preparation device was comprised of 4 prats of stripping instrument, cutting machine, refrigerator and hot fan. The stripping instrument was used to strip the outer lining pipe of coal core. Cutting machine, refrigerator and hot fan was used to cut, freeze and heat shrink coal core. The production of the standard coal core sample is divided into 3 steps of punching and wetting, freezing and cutting, heat shrinking and stripping. Adopting the technology of partial freezing and cutting at the end, and synchronizing the demolding and heat shrinkage uniformly to achieve the sample preparation with various standard size, with perfect sample making method and high success rate. ③ The mechanical property parameter test system was comprised of 3 parts of main structure servo oil source control device and software system, which can realize restrictive and non-restrictive straight shear test function. It was mainly used to carry out straight shear test under different normal stress and triaxial compression test under different confining pressure of soft crushed coal standard specimen. The overall design structure was simple and convenient to operate. A single action three-tube corer was used to obtain soft crushed coal, and a sample preparation device such as a demolding instrument was used to prepare them into standard specimen in this study. Then the straight shear test and triaxial compression test of soft crushed coal standard specimen by using the mechanical property parameter test system were conducted under normal stress of 0.04, 0.05, 0.06, 0.07, 0.08, 0.09 MPa and confining pressure of 0.2, 0.3, 0.4 MPa, respectively. The shear strength parameters such as cohesion and internal friction angle of soft crushed coal was obtained under the two test conditions. The cohesion and internal friction angle obtained from straight shear test were 0.125 kPa and 37.2°, and those obtained from triaxial compression test were 0.121 kPa and 36.4°, respectively. The results show that the system has great practicability and reliability, and provides a better test platform and method for studying the mechanical characteristics of soft crushed coal.

Objective The red-bed soft rocks is easy to disintegrate and weaken its strength when it encounters water, which is easy to cause poor stability and economic loss or even casualties in slope construction. It is of great significance to reveal the variation characteristics of cohesion and internal friction angle of red-bed soft rocks under the action of dry and wet cycling for the design of slope treatment measures. Methods Investigating the three groups of red-bed soft rock formations within the Lower Cretaceous Chaochuan Formation situated in the Shengzhou-Xinchang region of Zhejiang Province, this study delves into the disintegration and strength attention tendencies inherent in these formations. This exploration unfolds through a comprehensive suite of method ologies, including dry-wet cycle tests, point load strength tests of disintegrated rock blocks and direct shear tests of disintegrated particles. Results The results reveal that the sample undergoes disintegrates, in the form of fragments, particle slag, and mud paste due to successive dry-wet cycles. The main disintegration process can be divided into four distinct stages: Initial disintegration, rapid disintegration, fine reconfiguration, and eventual stabilization. The point load strength of the sample decreases with the increase as the number of dry-wet cycles increases, while the disintegration resistance index Idn shows a positive exponential relationship with the point load strength Is(50). Notably, the point load strength Is(50) of the sample experiences rapid weakening between 80% to 100% and 50% to 80% of the disintegration resistance index Idn, demonstrating gradual attenuation characteristics. The peak shear strength of the sample ranges between 1.219 MPa and 0.567 MPa, which mostly occurs before and after the shear displacement of 3 mm. Under the consistent axial pressure, the peak shear strength of the same group decreases with an increasing number of cycles. Additionally, the internal friction angle of disintegrated particles of the sample ranges from 22.28° to 33.03°, while the cohesion is between 0.46 MPa and 0.74 MPa. Both the friction angle and cohesion of the sample show a negative exponential relationship with the number of dry-wet cycles. Conclusion The test results indicate that siliceous cementation exhibits better disintegration resistance compared to argillaceous cementation, and the rock with high clay minerals more easily disintegrates. Additionally, the water absorption and expansion capacity of "white mineral" albite significantly lag behind that of clay minerals, with a lesser variance in its content compared to clay minerals.

Epoxy resin/carbon fiber composites have the problems of high brittleness and poor impact toughness. In order to improve the properties of epoxy resin/carbon fiber, graphene was used to modify epoxy resin/carbon fiber. Graphene was grafted with silane coupling agent KH-560. Grafted graphene was reacted with waterborne epoxy resin to prepare epoxy resin/carbon fiber/graphene composites. The results show that when graphene content is 5%, the interface properties between carbon fiber and epoxy resin are the best. After KH-560 grafting, the elastic modulus, tensile displacement, and interfacial shear strength of epoxy resin were improved. [ABSTRACT FROM AUTHOR]

Copyright of Electronic Components & Materials is the property of Electronic Components & Materials and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this paper, the optimal estimation method of rock shear strength parameters is studied. Aiming at the heteroscedasticity problem in rock shear strength data, a weighted linear regression method is introduced. In the linear regression analysis of rock shear strength, it is generally assumed that the observation errors of dependent variables obey the same normal distribution, but the heteroscedasticity problem in triaxial strength data is ignored. In this paper, the open-pit sandstone in the southwest of Sichuan Province is used as the research object, and the triaxial strength data of sandstone under different confining pressures are obtained. The weighted linear regression method is used to analyze and solve the problem of heteroscedasticity of the data. This paper first introduces the theoretical basis and related statistical methods of rock shear strength and then elaborates on the concept and application scope of weighted linear regression. The theoretical formula and test method of weighted linear regression are proposed, and the definition and calculation method of weight in weighted regression are explained. Finally, the experimental data of open-pit sandstone in the southwest of Sichuan Province are verified. The research results prove the effectiveness of the weighted least squares method in the estimation of rock shear strength parameters. The research results can provide a relevant theoretical basis for the selection of shear strength parameters. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Engineering Geology / Gongcheng Dizhi Xuebao is the property of Journal of Engineering Geology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Engineering Geology / Gongcheng Dizhi Xuebao is the property of Journal of Engineering Geology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of New Building Materials / Xinxing Jianzhu Cailiao is the property of New Building Materials Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Electronic Components & Materials is the property of Electronic Components & Materials and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Coal Science & Technology (0253-2336) is the property of Coal Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Acta Materiae Compositae Sinica is the property of Acta Materiea Compositae Sinica Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)