Subjects: Mechanics >> Solid Mechanics submitted time 2024-08-13 Cooperative journals: 《应用力学学报》
Abstract： With the rapid development,subway construction is inevitable to pass through existing urban overpasses,which will significantly impact its settlement and stress state.This research relies on the underpinning engineering of pile foundations of Jianhe bridge passed by Shijiazhuang Metro Line 2.Using finite element software,a three-dimensional finite element model is established,and the whole process of pile foundation underpinning is simulated.The settlement change rule is obtained through numerical calculation and compared with the field data.The results show that the settlement is large in the underpinning position of South Jianhe Bridge,in which the monitoring should be strengthened.Finally,the stress history of the special-shaped slab on the bridge deck and the pile foundation is analyzed,and the laws are as follows.The stress changes of the special-shaped slab on the bridge deck are mainly concentrated in the construction stage of the pile breaking.In the whole process of underpinning construction,for the original pile,the forces show a change law of first decreasing and then increasing,while the effective stress of the newly-built pile foundation showed a continuous increase.The pile-breaking construction effectively transfers the force of the original pile foundation to the newly-built pile foundation,and shield construction has little effect on the stress state of each structure.The results can provide references for the design and construction of similar underpinning projects of pile foundation.
Subjects: Mechanics >> Solid Mechanics submitted time 2024-08-13 Cooperative journals: 《应用力学学报》
Abstract：
Uses ABAQUS finite element software to analyze the nonlinear force performance of exposed rigid-connected box column joints for RC frame-steel structure adding story hybrid structure.On the basis of verifying the correctness of the finite element model,the influence of relevant parameters on the seismic performance of exposed rigid-connected box column joints is conducted in depth,and design suggestions are put forward.The results show that the exposed rigid-connected box column mixed joint is damaged by the plastic hinge failure of the beam,which has strong energy dissipation capacity and plastic deformation capacity,but the stiffness degradation is more serious.Reasonable design suggestions are put forward according to the relevant parameters researches:the upper steel column should be box-shaped or cross-section columns with in-plane and out-of-plane stability as much as possible.In the view of the specimens studied in the paper,it is reasonable to control the axial compression ratio between 0.16 and 0.40.
Subjects: Mechanics >> Solid Mechanics submitted time 2024-08-13 Cooperative journals: 《应用力学学报》
Abstract：
To research the torsional mechanical properties of precast utility tunnel bell and spigot joint,the three-dimensional model of soil and utility tunnel was established by ABAQUS software,the stress distribution of utility tunnel segment torsional deformation bell and spigot joint was analyzed,and the transverse ultimate differential settlement of bell and spigot joint and ultimate differential settlement were obtained.The results show that when the utility tunnel forward and reverse torsional settlement is the same,the bell and spigot joint of stress,maximum principal stress and shear stress distribution law is basically the same.The stress on the bell end wall is large but is small in the middle of the joint top and bottom plate and the axillary corner.The maximum principal stress is concentrated on the bell end side wall and the spigot top and bottom plate.The maximum principal stress at 1 m from top plate the side wall of the bell end to the outside is the largest.The joint shear stress is the smallest in the middle of the top and bottom plate and side wall,gradually increases to sides,and reaches the maximum shear stress at axillary corner.The bell and spigot joint transverse limit differential settlement is 1.2 mm,and there is little difference between the ultimate torque and the results calculated by using box section at the spigot joint; in engineering practice,the box section can be used for the spigot joint torsional design.The research results provide a scientific basis for the precast utility tunnel safe operation.
Subjects: Mechanics >> Solid Mechanics submitted time 2024-08-13 Cooperative journals: 《应用力学学报》
Abstract：
The pumped storage power station(PSPS)is an important measure to achieve the strategic goal of “dual carbon”.As one of the preferred dam types for the upper reservoir dam of PSPS,the concrete faced rockfill dam(CFRD)often has steep along-river slope of dam foundation and is prone to produce slip deformation along slope resulting in poor anti sliding stability of dam slope.It is dangerous for the operation safety of PSPS.Therefore,the numerical model of CFRD on large dip angle dam foundation is established.The law of slip deformation of CFRD on large dip angle dam foundation is studied.The mechanism of slip deformation of CFRD on large dip angle dam foundation is revealed.The physical mechanic and geometric structure design measures are proposed to reduce the slip deformation of CFRD on large dip angle dam foundation.The research results show that the larger sliding force and smaller anti-sliding force are the fundamental reasons why the CFRD on large dip angle dam foundation is prone to produce slip deformation.The larger the dip angle of dam foundation,the greater the force of gravity along slope surface,the greater the slip deformation of dam body,and the smaller the safety factor of dam slope(when the dip angle of dam foundation is greater than 15°,the safety factor of dam slope is less than the minimum value(1.5)required by specifications).Adding pressure slope can effectively reduce the slip deformation of dam body and significantly improve the anti-sliding stability of dam slope.The higher the height and the wider the width of pressure slope platform,the greater the cohesion and internal friction angle of pressure slope,the smaller the slip deformation of dam body,and the greater the safety factor of dam slope.It is recommended to take the height and width of pressure slope platform as 1/2 times the maximum dam height of main dam,and the density(cohesion and internal friction angle)of pressure slope is equivalent to that of main dam's rockfill.The research results can provide technical supports for the design and construction of CFRD for the upper reservoir of PSPS.
Subjects: Mechanics >> Solid Mechanics submitted time 2024-08-13 Cooperative journals: 《应用力学学报》
Abstract：
In order to compare the effect of component of root-soil composite and normal stress on the shear strength of the root-soil composite.The root-soil composite for Pinus yunnanensis and the non-rooted soil,located on the slope(gravel sand areas of Anning River)of Mianshan Town in Xide County of Sichuan Province,were selected as the objects of study.Direct shear test and drying test were conducted.Pearson correlation analysis was conducted to seek the relationship of mass between dry soil,water and dry root in the root-soil composite.The regression analysis model between mass of components of the root-soil composite and the shear strength was established to calculate the standardized regression coefficients.The results showed that:in the root-soil composite for Pinus yunnanensis,mass of dry soil was significantly and negatively correlated with mass of dry root(P=0.002<0.01,r=-0.792),and mass of water was no significantly correlated with mass of dry root or dry soil(P>0.05).The standardized regression coefficients of dry soil mass,dry root mass and water mass with shear strength of the root-soil composite were 0.06,0.03 and 0.03,respectively.It indicated that the effect of dry soil mass on the shear strength was greater than that of water mass and dry root mass.The internal friction angle and the cohesion of the root-soil composite for Pinus yunnanensis increased by 1.31%-1.97% and 16.71%- 34.74% compared with the non-rooted soil,respectively.
Subjects: Mechanics >> Solid Mechanics submitted time 2024-08-13 Cooperative journals: 《应用力学学报》
Abstract：
In order to realize the requirements of safety protection design of power battery under mechanical abuse,the mechanical response characteristics of square lithium-ion battery under different extrusion loadings were studied in this paper.First,the plane compression and local indentation tests of square lithium-ion battery are carried out,and the extrusion mechanical response and internal structure failure mechanism of the battery are given.Then,the finite element model of square lithium-ion battery is established,the force displacement curves of the battery under different extrusion loads are studied,and the effects of different extrusion forms on the mechanical response of lithium-ion battery are discussed.The results show that the finite element analysis results are basically consistent with the experimental results.Plane compression will lead to in-plane fracture mode caused by tension inside the battery,while local indentation will lead to interlaminar fracture mode caused by shear.The mechanical response of lithium-ion battery under different extrusion loads is affected by the size of compression head.With the decrease of the indenter size,the load and failure displacement of the battery will decrease differently.
Subjects: Mechanics >> Solid Mechanics submitted time 2024-08-13 Cooperative journals: 《应用力学学报》
Abstract： When subjected to shallow-buried explosions,a theoretical model was established to characterize the dynamic response of a mass-spring-damping system attached to a monolithic beam.For validation,numerical simulations with the method of finite elements were performed,with good agreement between theoretical and numerical results achieved.The model was then employed to quantify the effects of explosive mass,yield stress of beam material,spring stiffness,damping coefficient,and boundary condition on peak displacement,velocity and acceleration of the beam and the supported mass.With increasing explosion mass or decreasing yield stress,the peak displacement,velocity and acceleration of both the beam and mass increased.When the spring stiffness was constant,with the increase of damping coefficient,the peak displacement of the midpoint decreased,and the peak acceleration of mass increased.When the damping coefficient remained constant,the spring stiffness had little effect on the peak displacement of the beam and the peak acceleration of the mass.As the spring stiffness was varied,selecting a proper damping coefficient could reduce the peak velocity of the mass.With occupant safety considered,the proposed model provides useful design guidance for designing high-performance protective structures for armored vehicles.
Subjects: Mechanics >> Solid Mechanics submitted time 2024-06-17 Cooperative journals: 《应用力学学报》
Abstract： To determine the softening intrinsic model of rubber concrete,wedge splitting test studies and theoretical analyses were performed on concrete specimens with two seam height ratios and five rubber admixtures.Based on the test results,the fracture toughness and fracture energy of concrete specimens were calculated using the canonical formula and the law of energy conservation,and the relevant parameters of the three softening curves of PETERSSON,Euroconcrete Code,XU and REINHARDT were solved.The theoretical values of cohesive toughness were obtained based on the three softening instantonal relationships and compared with the calculated values of cohesive toughness tests.The results show that the softening instability and fracture energy of concrete can be improved by incorporating appropriate amounts of rubber aggregate; the three typical concrete softening models cannot describe the cohesive toughness of rubber concrete well; the softening intrinsic structure model of rubber concrete is obtained by modifying the softening relations of XU and REINHARDT,which can be used to study the cracking resistance of rubber concrete materials.
Subjects: Mechanics >> Solid Mechanics submitted time 2024-06-17 Cooperative journals: 《应用力学学报》
Abstract： The goals of this paper are to study the frost resistance of steel slag fine concrete(SSFC),research the damage mechanisms in cold regions.First,the mass loss rate,strength loss rate,relative dynamic elastic modulus of concrete with different steel slag fine aggregate replacement rates after freezing-thawing cycles were tested,and the freezing-thawing damage law was analyzed.Scanning electron microscopy method was used to observe the hydration products of steel slag concrete and the steel slag-mortar interface transition zone for the analysis of freezing-thawing damage microscopic mechanisms.The results revealed that the steel slag fine aggregate is significantly damaged by freezing-thawing action.Interfacial transition zone of steel slag fine concrete is superior to that of ordinary concrete.The minimum mass and strength loss of concrete at 60% replacement rate of steel slag fine concrete,only 4.06% and 44.2% reduction,respectively.The highest mass and strength loss rates of concrete are 6.05% and 58%,respectively,with 100% replacement of steel slag fine concrete.When the number of freeze-thaw cycles is greater than 50,the relative dynamic elastic modulus of concrete with 60% of steel slag fine concrete is higher than the rest of the dosing group.In order to improve the performance of concrete under freezing-thawing cycles,60% replacement rate of steel slag fine concrete is recommended.Finally,the freezing-thawing damage evolution model of steel slag concrete was established by analyzing the damage evolution s of steel slag concrete specimens.
Subjects: Mechanics >> Solid Mechanics submitted time 2024-06-17 Cooperative journals: 《应用力学学报》
Abstract：
Reliability sensitivity can reflect the influence of the distribution parameter of basic variable on reliability and guide reliability analysis and reliability-based optimization,a non-probabilistic reliability sensitivity analysis method is proposed based on a multidimensional parallelepiped model.The explanation is first given that the non-probabilistic reliability index and the non-probabilistic failure degree are respectively used as the reliability measure of structures when the basic variable domain is entirely within and overlaps with the safe domain.The analytical expressions of reliability sensitivity of a linear system is then derived,and their application in nonlinear system is further discussed.Three numerical examples are finally provided to demonstrate the feasibility and effectiveness of the proposed method.
Subjects: Mechanics >> Solid Mechanics submitted time 2024-06-17 Cooperative journals: 《应用力学学报》
Abstract：
To compared the microwave and conventional heating effects on the mechanical properties of granite,microwave and conventional heating methods were performed to heat granite specimens at different temperature(300,500,600,800 ℃).After heating,the density,P-wave velocity,and uniaxial compression tests were performed.The effects of heating temperature on the density,P-wave velocity,stress-strain curve,uniaxial compression strength and elastic modulus were analyzed under the two heating methods.The microwave and conventional heating effects on the granite properties were discussed.The results show that under the two kinds of heating methods,the density,P-wave velocity,uniaxial compression strength,and elastic modulus all decrease as heating temperature increases,and the reduction rate is the highest from 500 to 600 ℃.Under the same heating temperature condition,the decreasing extent in density,P-wave velocity,uniaxial compression strength,and elastic modulus of granite after microwave heating is higher than that after conventional heating.The difference induced by the two heating methods increases as heating temperature increases.Compared with conventional heating,the microwave heating time is shorter,generally only 1/7 of the conventional heating time.Therefore,microwave heating is more efficient in degrading granite performance.
Subjects: Mechanics >> Solid Mechanics submitted time 2024-06-17 Cooperative journals: 《应用力学学报》
Abstract： An optimization method simultaneously designing the geometric parameters of the cell and non-uniform arrangement along the axial is developed using the static condensation to enhance the strength and stiffness of the honeycomb structure effectively.The equivalent elastic modulus and Poisson’s ratio of the cell are derived by the Castigliano theorem.The honeycomb core is uniformly divided into several substructure columns along the axial,and the stiffness matrixes of the substructures are obtained by finite element method.The super-element stiffness matrixes are established using the static condensation and are assembled according to the node number to obtain the global stiffness matrix of the honeycomb core.The structural deformation of the honeycomb core is calculated under the shear load and compared with that from ANSYS software.The multi-objective structural optimization model,in which the number of the substructures,the angle of the cell and the ratio of splitter width to inclined wall length are taken as design variables,is solved using the improved particle swarm algorithm to maximize the equivalent elastic modulus and minimize the structural deformation,and the static and dynamic characteristics of original and optimized honeycomb cores are analyzed.The results show that after the optimization,the maximum displacement,stress and strain obviously decrease,and the harmonic displacement is the maximum when the excitation frequency is equal to the second-order natural frequency.The research can provide significant guidance for optimizing the variable cell arrangement of the honeycomb structure.
Subjects: Mechanics >> Solid Mechanics submitted time 2024-06-17 Cooperative journals: 《应用力学学报》
Abstract： To study the effects of the replacement rate of recycled coarse aggregate(RCA)and eccentricity on the mechanical properties of recycled aggregate concrete with ferronickel slag filled circular steel tube columns,13 specimens were designed for axial and eccentric compression tests,and load-mid-span deflection curve,lateral deflection curve,stiffness degradation and energy dissipation were analyzed.Based on the research results of ordinary concrete filled steel tube(CFST)column,the prediction formula for the compression-bending capacity of recycled CFST is regressed.Results show that the deflection shape of the biased specimen conforms to the sinusoidal half wave curve.The position of the neutral axis of the cross section deviates to the compression zone during loading.When the replacement rate exceeds 30%,with the increase of RCA replacement rate,the ultimate bearing capacity of the specimen decreases,the stiffness degrades more,and the energy dissipation coefficient of the specimen decreases.With the increase of eccentricity,the ultimate bearing capacity of the specimen decreases,the envelops area of the lateral deflection curve increases gradually,and the stiffness degenerates more.The values calculated by the fitting formulas are in good agreement with the experimental results.
Subjects: Mechanics >> Solid Mechanics submitted time 2024-06-17 Cooperative journals: 《应用力学学报》
Abstract： To study the eccentric compression performance of ultra-high performance concrete filled with steel tubular short columns,12 circular specimens were designed and tested under eccentric compression by taking the load eccentricity and diameter-thickness ratio as variation parameters.The failure mode,load-deflection curves,strain of steel tubes,and deformation coefficient of these members were analyzed.The effects of main factors on the eccentric compression performance of short columns were explored.The results show that the failure of specimens is characterized by the yielding of the steel tube,followed by the crushing of the core concrete.The load-deflection curves have clear peak points,and the greater the eccentricity and the smaller the diameter-to-thickness ratio,the smoother the drop section of the load-deflection curves.At 60% of the peak load,the steel tube begins to produce obvious confinement; at 90% of the peak load,the section deformation no longer meets the plane section assumption.As the eccentricity increases,the load-bearing capacity and stiffness of the specimens decrease,and the decrease in the diameter-to-thickness ratio can reduce this adverse effect.Based on the experiment,the N-M curve of the short column is analyzed by numerical simulation and an expression for the relationship between the critical eccentricity and the confining coefficient is established.The practical calculation method of short column bearing capacity is proposed,and the theoretical and experimental results are in good agreement.
Subjects: Mechanics >> Solid Mechanics submitted time 2024-06-17 Cooperative journals: 《应用力学学报》
Abstract：
Field equation of single and closed flaw tip under compression-shear stress is constructed in this paper.The initiation angle of wing crack,the influence of side pressure coefficient k on stress field and initiation and propagation of wing crack and the influence of flaw angle α on initiation stress of wing crack under uniaxial compression are analyzed by using the maximum tangential stress criterion.The correctness of the theoretical solution is verified by uniaxial compression test and triaxial compression literature data comparison.The research showsthat the effect of T-stress on the initiation angle of wing crack can be ignored when the critical relative size of cracking λ approaches 0 or the flaw angle α approaches 45°.Hoop tensile stress decreases with the increase of side pressure coefficient k,and axial stress required for the initiation of wing crack increases.The confining pressure has an inhibitory effect on the propagation of wing cracks and the inhibitory effect is stronger when effective shear stress of the flaw surface is greater than 0.Wing cracks and a small number of anti-wing cracks and coplanar shear cracks are observed at the tip of the pre-existing flaw.The initiation angle of wing cracks are fluctuated around the predicted value.The initiation stress of wing crack increases with the increase of flaw angle under uniaxial compression,and it also increases with the increase of side pressure coefficient under triaxial compression,and they are consistent with the changing relationship predicted by the model in this paper.
Subjects: Mechanics >> Solid Mechanics submitted time 2024-06-17 Cooperative journals: 《应用力学学报》
Abstract： Drilling pipe leakage is the most common failure form of drilling pipe in service,and the expansion of surface crack of drilling pipe is the direct cause of drilling pipe leakage.In order to evaluate the safety performance of drill pipe with multiple cracks on the surface,a finite element model of double cracks on the surface of drill pipe was established by taking the wellhead section of G105 drill pipe of an ultra-deep vertical well as the research object.The effects of crack spacing,crack size and strike on the J-integral at the leading edge of the circular main crack under tensile and torsional loading were analyzed.The results show that the circumferential secondary cracks arranged in the axial direction are relatively the safest,which can greatly reduce the J-integral of the leading edge of the main crack.The circumferential secondary cracks arranged in the circumferential direction are the most dangerous,which can greatly increase the J-integral of the leading edge of the main crack.The axial secondary cracks can increase the J-integral of the leading edge or part of the leading edge of the main crack in the drill pipe,but the increase is much weaker than that of the circumferential secondary cracks.The influence intensity of secondary cracks on the leading edge J-integral of the main crack decreases with the increase of the distance between two cracks and the decrease of the size of secondary cracks.Therefore,the influence of secondary cracks should be considered when the size of secondary cracks is large and the distance between them is relatively close.When the size of the secondary crack is small or the distance is long,the secondary crack can be ignored,and the model is simplified to a single-crack drill pipe model for analysis.
Subjects: Mechanics >> Solid Mechanics submitted time 2024-04-19 Cooperative journals: 《应用力学学报》
Abstract： Considering that research of circumferential horizontal shear wave(SH wave)has been published on the solid cylinders and cylindrical shell structures,aiming to discuss the existence of SH surface waves on the cylindrical cavity.Since it is impossible to directly obtain the analytical solution of SH surface wave propagating in cylindrical cavity,we compare the tendency of wave structures,strain energy density varying along thickness of SH waves on the surface of cylinders and various cylindrical shells.The governing equation of SH wave of homogeneous elastic material and functionally graded material in cylindrical coordinate system is established.The Bessel functions solution and the power series asymptotic solution of the governing equations of homogeneous elastic materials and functionally graded materials are obtained,respectively.Furthermore,the dispersion curves,the wave structures and the strain energy density are calculated.The results show that the power series method can be employed for solving wave governing equations with variable coefficients with high accuracy,the energy of circumferential SH waves in cylindrical structures is concentrated on the outer surface or subsurface,and the phenomenon of energy concentration is more obvious along thickness.It can be deduced from the distribution of strain energy density that the circumferential SH surface wave cannot propagate in the cylindrical cavity.Finally,for homogeneous material structure and functionally graded material structure,the inverse method is used to prove that any analytical solution cannot satisfy the attenuation condition of SH surface wave in the cavity.
Subjects: Mechanics >> Solid Mechanics submitted time 2024-04-19 Cooperative journals: 《应用力学学报》
Abstract：
The autoclaved aerated concrete block developed by desert sand is a new type of masonry material.A pseudo-static test considering the different vertical compressive stresses and constraints of structural columns is carried out on four pieces of desert sand wall made of autoclaved aerated concrete block in order to study the application of this new block in village buildings.The failure characteristics i.e.,force-displacement curve,skeleton curve,stiffness degradation curve and ductility of the four walls under low cyclic loading arecompared and analyzed. The test results show:1)The wall is mainly shear failure.The main crack of the wall without structural columns runs through the entire wall is about 45°,and the main crack of the wall with structural columns is in the shape of “inverted eight”.And when the vertical compressive stress increases,the seismic capacity of the wall increases,the lateral stiffness improves,but the ductility decreases. 2)Under the same vertical compressive stress,comparative analysis shows that the ultimate bearing capacity of the wall with structural columns is increased by about 2.22 times that of plain wall,ductility increased by about 60%,and the stiffness is also improved. 3)Based on the principal tensile stress theory and Coulomb failure theory,the calculation formulas for the seismic bearing capacity of the new block wall are established, and the calculation formula of seismic bearing capacity established by Coulomb failure theory is more reasonable in application. 4)The skeleton curve of the established restoring force model can reflect the experimental characteristics of the desert sand autoclaved aerated concrete block wall well.
Subjects: Mechanics >> Solid Mechanics submitted time 2024-04-19 Cooperative journals: 《应用力学学报》
Abstract：
In order to study the propagation characteristics of type Ⅰ fractures of concrete with different aggregate sizes,concrete three-point bending beam fracture tests with the maximum aggregate size of 10,20,30,40 mm were carried out,and the data of full-field strain and displacement changes in the calculated area on the specimen surface were measured by using digital image correlation techniques to investigate the changes and development of fracture energy,fracture toughness and fracture process zone of concrete with different aggregate sizes.The relationship between the FPZ extension process and the post-peak loading was investigated.The results show that with the increase of the aggregate size,the compressive strength,peak load and fracture parameters of the specimens show a trend ofincreasing first and then decreasing,and the change of FPZ length of M20 specimens has a strong correlation with post-peak load,and the aggregate has the best restraint effect on microcracks,In addition,by analyzing the development law of FPZ of concrete specimens with different aggregate sizes,it can be learned that specimens with the aggregate size of 20 mm have an improved local deformation capacity after peaking,enhanced fracture energy and fracture toughness,higher bearing capacity and smaller FPZ in the fracture process than other aggregate sizes concrete; therefore,the suitable aggregate size is 20 mm.
Subjects: Mechanics >> Solid Mechanics submitted time 2024-04-19 Cooperative journals: 《应用力学学报》
Abstract：
Basalt fiber reinforced composite(BFRP)has the advantages of strong corrosion resistance,high specific strength and environmental protection.The correct evaluation of the reliability and bearing capacity of BFRP pipeline is the basis for its application in the field of high value-added oil and gas transportation.For composite pipes wound by the basalt fiber(BF),the strength of impregnated fiber bundles is obtained on a meso scale firstly.Then,both axial and circumferential specimens were cut from a pipe and the tensile strength of the two kinds of specimens were measured.Based on both experimental measurement and finite element simulation,damage evolution of structure layers of the pipe wall was studied under conditions of tension,compression and shearing,and the constitutive model of the structure layer is obtained.Finally,a finite element model of the BF-wound composite pipe was established,and influences of fiber performances on the pipe’s carrying capacity were studied.It is shown that the effective fiber content exerts a great influence on the bearing capacity of the pipe.It is important to reduce the dispersion of fiber reinforcement from aspects such as fiber production and pipe forming process for predicting load-bearing reliability accurately and promoting BF composites application in oil and gas pipeline field.
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