Vertical Displacement Distribution Research Articles

Numerical simulation of the deformation behavior of a composite foundation consisting of rubber particle loess-CFG under dynamic loading

The CFG pile technology is primarily employed for foundation reinforcement, offering cost-saving benefits and demonstrating significant reinforcement effects. Consequently, it has gained widespread utilization. However, due to its unique composition and exceptional strength characteristics, investigating the dynamic properties of rubber particle loess-CFG poses significant challenges. In this study, a numerical simulation approach is employed to investigate the dynamic characteristics of rubber particle loess-CFG and its deformation response under dynamic loading is analyzed. The results indicate that the deformation of rubber particle loess-CFG remains minimal under static loading, while it significantly increases under dynamic loading. However, the vertical and horizontal displacements at the top of the mattress layer are comparatively smaller than those observed in loess-CFG, highlighting their seismic stability. The mattress layer of the rubber particle loess-CFG undergoes vertical compression and deformation, while being horizontally squeezed towards the central region. The horizontal displacement and its variation range are significantly greater than that of the entire pile and the soil between piles. Therefore, it is crucial to analyze the material properties, thickness, and extent of the mattress layer during design in order to mitigate its influence. When subjected to dynamic loading at the base of the model, the rubber particle loess-CFG exhibits a strip distribution of vertical displacement which gradually decreases from bottom to top. Moreover, as focal depth increases, the impact of dynamic loading on foundation deformation diminishes. Consequently, rubber particle loess-CFG provides a dual functionality of enhancing foundation strength while effectively resisting dynamic deformations. These research findings provide a theoretical basis for designing reinforced foundations using rubber particle loess-CFG and offer an innovative approach for recycling waste tire rubber particles.

Establishment and effect analysis of traffic load for long-span bridge via fusion of parameter correlation

Traffic flow is the main driver behind the dynamic response in operation of long-span bridges. To further improve the effectiveness of safety analysis for long span bridges, the bridge dynamic response should be analyzed under traffic flow. This paper investigated the simulation method of traffic flow and the bridge dynamic response under it. Firstly, the potential parameter correlation in the traffic flow was analyzed based on WIM data. Secondly, a refined simulation method of stochastic traffic flow that considers the correlation in vehicle arriving sequence and axle weight (AW) was proposed and validated. The Markov Chain Monte Carlo (MCMC) method and the correlation random sampling Monte Carlo simulation (CMCS) method were used to simulate the correlation of vehicle arriving sequence and axle weight, respectively. Finally, the constructed stochastic traffic flow is used to evaluate the influence of parameter correlation of traffic flow on dynamic response for long span suspension bridges. Results highlight the correlation of traffic flow. For the vehicle arriving sequence, those vehicles with a small quality rarely follow those with a large quality. The vehicles of different types follow certain transfer relationship. The correlation of vehicle arriving sequence can be effectively simulated that the vehicle type distribution and transition probability of the samples are both close to the WIM data. Meanwhile, the correlation of vehicle AW is mainly observed among multi-axle vehicles, and that in two- and three-axle vehicles is not significant. In the bridge application, the proposed method outperforms the MC method in the simulation of multi-axle vehicles. The parameter correlation of traffic flow has obvious influence on the response of the girder of long-span suspension bridge. The distribution of vertical displacement and bending moment of SC is closer to WIM data, and due to the small ratio of live load to dead load, some indexes such as the suspender force are less affected. The consideration of parameter correlation brings the load effect closer to the WIM data, the parameter correlation should be considered in the evaluation of the fatigue life of components, which can positively contribute to the long-term evaluation of bridge response under traffic flow.

Overburden and surface subsidence with slicing paste filling mining in thick coal seams

To overcome the difficulties of overburden failure and surface subsidence induced by the slicing mining of extra-thick coal seams, slicing filler paste is typically utilized. In this paper, a continuous curved beam mechanical model of paste filling mining was established by theoretical analysis against the background of the 3305 working face of Yangcheng Coal Mine, the main controlling factors of surface subsidence were analyzed using an orthogonal experiment method (OEM) and an analytic network process (ANP) coupled comprehensive assignment, and the vertical displacement distribution of the overlying rock under different filling intensity was simulated using numerical simulation software. The following main findings were obtained. First, the elastic modulus of the backfill is the primary regulating factor, as demonstrated by the results. Second, the greater the filling body’s elastic modulus, the more efficiently it carries the overburden load and minimizes the maximum surface subsidence. Third, the distance from the open-cut mine likewise reflects the degree of surface subsidence, with the amount of subsidence increasing as the distance from the mine increases.

Numerical Analysis of Factors Influencing the Ground Surface Settlement above a Cavity

In this study, ground stability was evaluated through vertical displacement distribution and surface settlement results. In particular, a finite element analysis was conducted considering various factors (namely, cavity type and area, traffic load, pavement thickness, and elastic modulus) that affect a road above a cavity. The aim of this study was to evaluate the effect of pavement layer and traffic load condition on surface settlement according to the cavity shape. Field measurement results were analyzed and compared with the results of previous studies to verify the reliability of the numerical analysis method applied herein. After performing the numerical analysis using the verified method, ground stability was evaluated by analyzing the underground mechanical behavior of a road above a cavity. To this end, the correlations among the vertical displacement distribution, surface settlement, and influencing factors obtained from the analysis results were analyzed. In the numerical analysis, the ground was simulated with a hardening soil model based on the elastoplastic theory. This mechanical soil model can accurately reproduce the behavior of actual ground and can closely represent the mechanical behavior of the soil surrounding a cavity according to the cavity generation. In addition, the elapsed time was not considered when applying a load on the pavement layer, and a uniformly distributed load was applied. Consequently, it was found that, with increasing cavity area and traffic load and decreasing pavement thickness and elastic modulus, the vertical displacement and maximum surface settlement above the cavity increased, and the reduction in ground stability was greater. Furthermore, the reduction in ground stability was greater when the cavity was rectangular than when it was circular.

Long-term uplift pattern recorded by rivers across contrasting lithology: Insights into earthquake recurrence in the epicentral area of the 2016 Kumamoto earthquake, Japan

Topography results from the interplay between rock uplift and erosion, and studying river responses to active tectonics may enable the rates and spatial distribution of rock uplift to be inferred. Normalized channel steepness index (ksn) is widely used to infer rock uplift rates, and rock erodibility plays a significant role in determining the variation of channel steepness in response to external forces. Various measures may be applied to evaluate rock erodibility; however, since they are essentially qualitative, it is difficult to quantify relationships between rock mass strength and channel forms. In this study, we inferred long-term rock uplift rates along the Futagawa fault, an active normal-dextral fault, and the Idenokuchi fault, an active normal fault, in southwestern Japan, based on morphological characteristics of rivers across substrates with contrasting erodibility. The widely used detachment-limited model predicts that, when the rock uplift rate is spatially uniform, the ratio of erodibility of different rock types can be written by an inverse ratio of their ksn values. We employed this theoretical prediction to quantitatively calibrate the effects of rock mass strength on channel steepness. Within the study area, channel steepness was larger in the eastern part where volcanic rocks were exposed than in the western part where less resistant sedimentary rocks predominated. We calculated ratios of substrate erodibility using drainage basins close to the Futagawa fault that experienced similar rock uplift. Calibrated ksn exhibited a clear difference between the eastern and the western part of the fault, suggesting that contrasting erodibility alone cannot explain the observed channel steepness. We also confirmed that the observed channel steepness could not be explained without differential rock uplift, even when considering the combined effects of channel width, precipitation, and erosion process. The distribution of long-term rock uplift rates inferred from calibrated ksn and vertical slip rates of the fault compiled from published papers agree with the distribution of vertical displacement of the earthquake that occurred on the fault in 2016, suggesting that earthquakes similar to the 2016 event have occurred repeatedly in the study area.

Dynamic mechanical behavior of rocks containing double elliptical inclusions at various inclination angles

Inclusions embedded in rock materials highly affect their mechanical response and fracture behavior under external loadings. In this study, dynamic uniaxial compressive tests were performed on sandstone specimens containing double elliptical inclusions with various inclination angles to investigate the effects of inclusion conditions on the dynamic mechanical properties and failure mechanism of rock specimens using a split Hopkinson pressure bar (SHPB) system and the digital image correlation (DIC) technique. The results reveal that the inclusions effectively enhance the dynamic strength of flawed specimens, but its variation trend versus the flaw inclination angle is similar to that of unfilled specimens. Remarkable transformations were observed in the initiation position and propagation path of cracks after filling the flaw, which can be represented by the vertical displacement distribution along the inclusion periphery. The interaction mechanism between the double inclusions was dominated by a shear slip crack at the flaw inclination angle of 45° and tensile cracks at the flaw inclination angles of 0° and 90°. The effect of inclusions on the final failure pattern becomes slight with the increasing flaw inclination angle.

Constraining Paleoseismicity of the Wulashan Piedmont Fault on the Northern Margin of the Ordos Block From Fault Scarp Morphology

Fault scarps preserve important information about past earthquakes on a fault, and thus can be applied to investigate the fault slip histories and rupture patterns. In this study, the morphology of fault scarps was used to constrain the paleoseismicity of the Wulashan Piedmont Fault located on the northern margin of the Ordos Block based on high-resolution LiDAR topography. We constructed the vertical displacement distribution of the fault through measuring the heights of a large number of scarp profiles extracted on different geomorphic surfaces along the fault. Through statistical analysis of the dense collection of vertical displacement dataset, a total of seven paleoseismic events were identified which followed a characteristic slip pattern with an average slip of ∼1.0 m. We further detected slope breaks in the fault scarp morphology to quantify the number of paleoearthquakes that occurred on the scarps, and discriminated at least five individual surface-breaking events. Both the number and slip of paleoearthquakes recognized from the morphology of fault scarps were in good agreement with previous paleoseismic trenching records. Based on the empirical scaling relationship between moment magnitude and rupture parameters, a moment magnitude ofMw6.7–7.5 was determined for the paleoearthquakes occurred on the fault. With the fault slip rate derived by previous studies, we estimated an average recurrence interval of 1.3–1.8 kyr for the paleoseismic events, which is very close to the elapsed time since the most recent earthquake, indicating a high potential seismic hazard on the Wulashan Piedmont Fault.

ON ONE METHOD FOR CALCULATING THE STRESS-DEFORMED STATE OF ESCALATOR TUNNELS

In the article, based on the finite element method, the main stages of the study of free oscillations are given, since the separation of normal coordinates in the system of differential equations of vibrations of structures is possible only with constant global stiffness and damping matrices of the system. The method of calculating the stress-strain state of the subway escalator tunnel structure under the influence of both constant and seismic loads, as well as with a special combination of loads, is given in order to scientifically substantiate the design and construction of its lining made of monolithic reinforced concrete in Almaty, which allows, in general, to obtain significant economic efficiency compared with the traditional method of lining made of cast-iron tubing. A comparative analysis of the stress-strain state of the lining is performed from the main combination of loads, seismic impact and a special combination of operational loads. The authors proposed a finite element design scheme of the lining and the surrounding soil massif. The analysis of the distribution of vertical displacements in the tunnel lining is carried out on the basis of the application of the dynamic theory of seismic resistance for building structures of special responsibility.

Flexural behavior of carbon fiber-reinforced concrete beams under impact loading

The flexural behavior of carbon fiber-reinforced concrete (CFRC) beams under impact loading was studied herein. A modified molding process was proposed for manufacturing CFRC beams to achieve the uniform dispersion of 20-mm long carbon fibers in the concrete matrix. Different fiber volume fractions and impact velocities were considered. Their effects on the tensile and compressive strain, distribution of vertical displacement and acceleration, energy absorption, and dynamic increase factor (DIF) were analyzed to investigate the mechanical properties. The results indicated that the CFRC beams with 0.35% fiber content absorbed the highest energy (about 2.3 times that of beams without fibers). Based on the approximate linear distribution of inertial force along CFRC beams, an equation was deduced to calculate the generalized inertial force. The results indicated that the DIF increased with strain rate, and an empirical equation was proposed to describe the strain rate effect.

Impact of “wet conservation” of mining enterprises on constructing buildings of lightweight materials

The analysis of the influence of flooding of the developed areas of closed mining enterprises on the mechanical characteristics of clay rocks is given. The deformation characteristics of clay shale under prolonged moistening conditions have been experimentally established and proved. Simulation of stress-strain state of soil massifs and building structures by method of finite elements is considered and the influence of power of developed spaces on settlement of building foundations of buildings of light materials is established. The distribution of vertical displacements in the rock massif is presented, the graphs of the dependence of the foundation settlement on the excavation power are plotted, the excess of the standard values of settlement is noted when buildings are located directly above the preparing workings.

Simulation analysis of mechanical properties of shear connectors of steel-concrete composite beams

In order to further study the mechanical properties and development distribution of shear connectors of steel-composite beam under the influence of concrete shrinkage and creep. In this paper, on the basis of the existing experimental research, ABAQUS software is used to establish the steel-composite beam model. The structural forms of the model include simply supported beam and continuous beam, and the shear connectors of steel-composite beam include three types: stud connectors, PBL connectors and composite connectors. The time development and spatial distribution of vertical displacement, connector shear force and slip at interface of each composite beam with concrete creep are calculated by finite element software, and some calculated results are in good agreement with the existing test results. By comprehensively comparing the calculation results of the key sections of each composite beam at some time points, the mechanical properties and their respective applications of the shear connectors of the steel-composite beam are analyzed and summarized, and the research results can guide the design and engineering application of the shear connectors of the steel-composite beam.

Safety of Aircraft Structures in the Context of Composite Element Connection

Recently, there has been a growing trend towards an ever greater use of composite materials in aircraft structures. This necessitates a search for effective ways of joining these materials. The desirable characteristics of such joints are predominantly high strength and low mass, both of which are features offered by rivet nuts. The study was conducted on one type of glass fabric material, from which two types of composite specimens were prepared. Each specimen used the same type of fibre of the same number of 3 layers, yet of different lay-up. Specimens were joined with aluminium alloy and steel rivet nuts to produce single and multi-row parallel models of riveted joints for further testing and analysis. The specimens were clamped in the grips of tensile machine and subjected to a tensile strength test. In the work, the course of the forces in the rivet nuts joint and the failure modes and effects of joint failure were analysed. The distribution of vertical displacement was examined according to the joint material and two fibre orientation variants. To determine the distribution of displacements, the FE (Finite Element) method was used. Upon completion of the experimental stage, the obtained results were subjected to comparative analysis.

Numerical analysis of tunnel deformation affected by spatial position of landslide-tunnel system

In order to reveal the deformation law of tunnel structure under different spatial positions of landslide tunnel system, the rock deformation around tunnel under 12 working conditions was compared and analyzed by numerical simulation method. The results show that the vertical displacement distribution of rock around the tunnel at different locations is determined by the upper and lower regions of the sliding zone, and the settlement around the tunnel is greater than that of the tunnel under the sliding zone. The settlement decreases with the increase of the distance from the slip zone. The analysis results can provide reference for the design and construction of tunnel site selection.

Analytical and numerical solution of the stress-strain state of sleeper foundations

The article presents the results of numerical modelling of strip sleeper foundations. The analysis of the influence of the distance between the sleepers in the conditions of a two-dimensional problem. As a comparison, the results of the calculation of the analytical corner points method is presented. The results of the study of sleeper foundations with different distances between sleepers up to 3b are shown. The analytical solution shows the distribution of stress over depth when changing the size of sleepers, distances between sleepers. An analytical solution for the distribution of vertical displacements over depth is obtained. The results of the numerical solution show the components of stress and strain at different distances between sleepers, the dependence of precipitation on the applied pressure and the distance between sleepers. These studies are confirmed by the results of experiments of various authors. Designs of sleeper foundations are implemented in the construction of buildings and structures, which reduce the cost of the zero cycle, reduce the material consumption in comparison with standard solutions. The article is of interest to specialists in the field of soil mechanics, geotechnics, and foundation engineering.

О КОЛЕБАНИЯХ НА ПОВЕРХНОСТИ ПРЕДНАПРЯЖЕННОГО ТЕРМОУПРУГОГО СЛОИСТОГО ПОЛУПРОСТРАНСТВА

The contact problems of the excitation of harmonic oscillations by an oscillating rigid stamp on the thermoelastic layered pre-stressed body surface are considered. The body is represented by a layer lying on half-space. At the interface, two modes of mechanical boundary conditions are assumed: rigid adhesion and the absence of friction along one of the coordinates. In addition thermal contact condition is assumed. The initial deformed state is created due to thermal and mechanical effects. To find a solution of contact problems we introduced a boundary value problems with homogeneous boundary conditions on the surface. The Green function of auxiliary problems is constructed. Using operational calculus, the system of integral equations for the stress distribution function is reduced to a one-dimensional integral equation. Its solution is constructed by using the method of fictitious absorption. As an example, the contact problems on vibrations of a half-space of magnesium oxide coated with cadmium sulfide are considered. The solution to the contact problems, the distribution of vertical displacements over the entire surface of a thermoelastic prestressed body, is calculated and presented graphically. The influence of preheating and conditions at the interface is studied on the distribution of vertical stresses and displacements over the surface of a layered half-space. It is shown that under conditions of preheating and stretching of the layer in the direction of the horizontal coordinate under the action of a hard stamp on the surface the larger vertical stresses arise in the case of hard pinching of the coating with the base than with non-ideal adhesion. On the contrary, preheating and extension of the layer affect vertical displacements outside the contact area more when imperfect coupling.

Numerical study of the effect of console length of the main roof hanging on the geomechanical parameters of the mine face

This article presents the results of scientific research aimed at establishing the effect of console length of the main roof hanging above the gob on geomechanical parameters in the vicinity of the mining face. According to the results of numerical modeling of the stress-strain state of the rock massif, the nature of the distribution of vertical displacements and stresses in the vicinity of the face was established with a consistent increase in the console length of the hanging main roof, the dynamic loads on the roof support sections, the hydraulic props settlement, the inrush area of roof rocks and the coal sloughing from the seam surface in the face. The results of the conducted research allow the preventive measures to be developed, the implementation of which will ensure the stable and safe operation of the working faces during underground coal mining in difficult mining and geological conditions.

Visualisation and quantification of geogrid reinforcing effects under strip footing loads using discrete element method

Geogrids have been commonly used in reinforced soil structures to improve their performance. To investigate the geogrid reinforcement mechanisms, discrete element modelling of unreinforced and geogrid reinforced soil foundations and slopes was conducted under surface strip footing loads in this study. For unreinforced and reinforced soil foundations, the numerically obtained footing pressure-settlement relationships were validated by experimental results from the literature. In the numerical modelling of unreinforced and reinforced soil slopes, identical models and micro input parameters to those used in the numerical modelling of unreinforced and reinforced soil foundations were used. The geogrid reinforcing effects under strip footing loads were visualised by the qualitative contact force distributions in the soil structures, as well as the qualitative and quantitative tensile force distributions along the geogrids. In addition, the qualitative displacement distributions of soil particles in the soil structures and the quantitative vertical displacement distributions along soil layers/geogrids also indicated the geogrid reinforcing effects in such practical reinforced soil structures. The discrete element modelling results visualise and quantify the load transfer and spreading behavior in geogrid reinforced soil structures, and it provides researchers with an improved understanding of geogrid reinforcing effects at microscopic scale under strip footing loads.

High kt2 Exceeding 6.4% Through Metal Frames in Aluminum Nitride 2-D Mode Resonators.

This work describes a new method to enhance the electromechanical coupling coefficient ( kt2 ) of 2-D mode resonators (2DMRs). This approach exploits the multimodal excitation of different Lamb waves to achieve a quasi-uniform vertical displacement distribution in the electrode regions of 2DMRs. To do so, the 2DMRs reported in this work rely on the use of metal frame structures placed at the edges of each metal strip forming the electrode gratings. To demonstrate the effectiveness of this new technique in enhancing kt2 , we report the design and simulated performance through the finite-element methods of a 2.5-GHz 2DMR using metal frames. Our analysis proves that this device can simultaneously exhibit high kt2 in excess of 6.4% and wide lithographic frequency tunability in excess of 10%, thus approaching the reported performance of aluminum nitride (AlN) film bulk acoustic resonators (FBARs) operating within the same frequency range.

Experimental Study of Micropile Lateral Resistance Effectiveness

Abstract The range of soil around the micropile when the pile is mobilized by force and the sensitivity of design parameters variation to the effect of micropile was studied by the prototype test and numerical calculation of the effect of lateral resistance of micropile. During the experiment, the variation of soil pressure around the micropile was monitored under the step loading, and the influence distance of lateral resistance on the pile is analyzed, and the high, middle, and low impact radius is defined according to the degree of influence. The distribution of vertical displacement of soil around pile when the pile diameter, pile length, and soil physical properties change was analyzed using numerical calculation, as well as the effects of normalized parameters on the influence of lateral resistance. Results showed that to better utilize the anti-slide coupling effect between piles where the soil overlying on the slope is formed by silty clay, pile spacing should be within the mid to high impact radius. Compared to other parameter changes, optimizing the pile length had the greatest effect on increasing pile lateral resistance and impact radius. Results provided a basis for designing effective pile spacing in anti-slide micropile groups.

Optimization of Nonstationary Thermal Displacements in a Given Cross Section of a Half Space in the Plane Strain State

We construct the solution of the problem of optimal control over the distribution of nonstationary vertical thermal displacements of a half space in the plane strain state. The power of internal heat sources concentrated in a plane parallel to the boundary is chosen as the control function. Under the assumption of existence of the control function guaranteeing the attainment of the greatest lower bound of the uniform deviation of the controlled distribution of vertical displacements from the given distribution, we reduce the problem of optimization to the inverse problem of thermoelasticity. The solution of the obtained inverse problem is constructed and analyzed.