Arching Effect Research Articles

Numerical solution for nonlimit-state earth pressure considering interlayer shear stress and the soil arching effect

The earth pressure of multilayer cohesive soils is affected by interlayer interaction and the soil arching effect. However, only the soil arching effect is considered in the existing methods for calculating earth pressure, and the interlayer shear stress caused by principal stress deflection is ignored. For a vertical rigid retaining wall with a horizontal backfill surface, the trajectory of the minor principal stresses in the soil behind the wall takes the form of an arc of a circle. On this basis, the horizontal and vertical stress equilibrium equations of the differential soil elements behind the wall are derived. The interlayer shear stress, wall displacement and soil arching effect are incorporated into the horizontal slice model, and the numerical scheme of the nonlimit-state earth pressure, the resultant force and the location of the action point are determined with the numerical solution method. Furthermore, the rationality of the proposed solution is demonstrated through comparison with experimental data and other solutions.

Predicting volatility of bitcoin returns with ARCH, GARCH and EGARCH models

The ınvestment decisions of institutional and individual investors in financial markets are largely influenced by market uncertainty and volatility of the investment instruments. Thus, the prediction of the uncertainty and volatilities of the prices and returns of the investment instruments becomes imperative for successful investment. In this study we seek to identify the best fit model that can predict the volatility of return of Bitcoin, which is in high demand as an investment tool in recent times. Using the opening data of weekly Bitcoin prices for the period of 11.24.2013–03.22.2020, their logarithmic returns were calculated. The stationarity properties of the Bitcoin return series was tested by applying the ADF unit root test and the series were found to be stationary. After reaching the average equation model as ARMA (2.2), it was tested whether there was an ARCH effect in the ARMA (2,2) model. As a result of the applied ARCH-LM test, it is reached that the residuals of the average equation model selected have ARCH effect. Volatility of Bitcoin return series after detection of ARCH effect has been tried to predict with conditional variance models such as ARCH (1), ARCH (2), ARCH (3), GARCH (1,1), GARCH (1,2), GARCH (1,3), GARCH (2,1), GARCH (2,2), EGARCH (1,1) and EGARCH (1,2). While the obtained findings indicate that the best model is in the direction of GARCH (1,1) according to Akaike info criterion, it was found that GARCH (1,1) model does not have ARCH effect as a result of the applied ARCH-LM test. Thus, our empirical findings highlight an ample guide on appropriate modeling of price information in the Bitcoin market.

Volatility analysis of chili price at Bengkulu Province using ARIMA approach

Chili is an inflation-forming commodity (volatile food). Prediction of chili price time series data using the ARIMA model approach has good performance for predicting chili prices in the future. The second highest average per capita consumption of chili for a month is Bengkulu Province, below West Sumatra Province. This shows that the level of consumption and demand for chili is relatively high in Bengkulu Province. High demand has an impact on the price volatility of chili. The volatility analysis illustrates the standard deviation or diversity of chili prices that fluctuate over a certain period. Based on the description above, it is necessary to conduct research on the analysis of chili price volatility in Bengkulu Province. This research uses data sourced from the National Strategic Food Price Information Center. chili price volatility analysis using the ARIMA model with the help of R studio software. ARIMA models are suitable for time series data. The stages in this study were stationarity test, building the ARIMA model, selecting the best model, evaluating the model, identifying the ARCH effect and building the ARCH GARCH model, and calculating the volatility value. If there is no ARCH effect, there is no need to create an ARCH GARCH Model. the output of this research was the form of an international conference. The results of the data forecast using the ARIMA model (1,1,2) show prices that are relatively stable but have an upward trend. This shows that the level of volatility can be controlled and this is reinforced by the results that the model has no ARCH effect. The absence of an ARCH effect means that the data is still considered to have relatively the same diversity of variance and is in line with a relatively small volatility.

Analysis of Arch Forming Factors of Shallow Buried Hard Rock Tunnel under Overlying Load

To investigate the arching effect of shallow buried hard rock tunnels under overlying load, the engineering scenario of a subway station on Qingdao Metro Line 6 is utilized. A large-scale tunnel loading model test is conducted, in conjunction with finite element numerical simulations, to analyze the impact of various overburden ratios on strata arching. The results show that: when the tunnel excavation span is certain, with an increase in the overlying rock mass, the stress diffusion process of the surrounding rock can be better accomplished to form the arch effect. This means that the thickness of the overburden of the tunnel determines whether or not the surrounding rock appears to have a stratified arch effect. When the tunnel overlying rock thickness is certain, the span of the tunnel determines the shape of the formation into an arch, that is, the curvature of the arch. The joint surface is an important factor in tunnel stability. When the overlying load increases to a certain value, the rock mass at the joint plane slips relatively, leading to the displacement phenomenon of the surrounding rock, which then affects the formation and shape of the formation arch.

Effects of headgear timing on dental arch changes from 7 to 18 years of age: a follow-up study.

Dental arch effects after cervical headgear (CHG) treatment have been researched from several different perspectives. However, the long-term effects of CHG timing are still unknown. To analyse the long-term effects of CHG timing on dental arches. A total of 67 children with Angle Class II malocclusion comprised the study group in this trial. The participants were randomized into two equal-sized groups. In the early group (EG, n = 33), treatment was started after the eruption of the first upper molars. In the later-timed group (LG, n = 34), treatment was started 18 months later compared with the early group. Long-term effects were measured from dental casts taken at five time points between 7 and 18 years of age. The total maxillary dental arch length was achieved earlier, the gained length persisted better in the long term, and significantly more space was achieved in EG compared with LG (P = .048). The intermolar width in the maxillary dental arch was more stable and was reached earlier in EG compared with LG (P = .002). The results showed that in terms of total mandibular arch length increases, EG males benefited the most and LG females the least from CHG treatment (P = .031). Both genders benefited from earlier CHG treatment. The maxillary dental arches remained longer, and the final width was gained earlier in EG compared with LG.

Study on Shielding Effect of the Pile Group in a Soft-Soil Foundation

Pile groups are frequently employed to reinforce soft soil foundations, while the piling process frequently disturbs the adjacent foundation. The shielding effect, which prevents the transmission of disturbances from pile installation, is indispensable for minimizing engineering disturbances and optimizing pile group construction techniques. However, current research focuses predominantly on characterizing the phenomenon of shielding, with a limited exploration of the mechanism. To eliminate the limitation, a numerical investigation of the shielding mechanism of pile groups in a pile–soil system is performed this study. Using the finite difference program FLAC3D and the cavity expansion theory, a three-dimensional numerical model of a pile–soil foundation was created. During the sequential penetration of piles, the response characteristics of the soil surrounding the piles were investigated. Displacement field was first investigated to determine the presence of shielding effects in the pile group and then highlighted the effective role of the existing piles in controlling deformation. Furthermore, through a combined analysis of the stress and strain fields during piling, the mechanism of the shielding effect induced by pile construction is proposed, which is attributed to the direct obstruction effect of piles and the “soil arching effect” created by the soil between piles. The former is reflected by the direct barrier of the existing pile to the soil displacement induced via the installation of the new piles. The latter is reflected by the obstruction of soil between two existing piles to the displacement of soil passing through the two existing piles. This research provides a comprehensive understanding of the mechanical behavior of the pile–soil system and has practical implications for controlling disturbances and optimizing construction techniques in piling engineering projects.

Centrifuge modelling of blast effects in dry sand: Coriolis effect and soil arching

Centrifuge model tests are conducted to investigate the dynamic response of dry sand under blast loading. The characteristics and propagation mode of blast waves in dry sand are studied. The Coriolis effect on blast-induced cratering is carefully scrutinised, and both the theoretical and experimental results are provided and agree with each other. In the explosion-induced cratering process, the sand ejecta is subjected to horizontal and vertical Coriolis forces simultaneously; the former directly determines the horizontal motion offset, while the latter affects the particle motion by altering the flight time, and the Coriolis effect on cratering can only be observed apparently for soil ejecta with a relatively small launch angle. Redistribution of the static earth pressure (blast-induced arching effect) in deep-buried, fully confined explosion events under hypergravity is observed. The friction between sand particles is significantly enhanced by the hypergravity to serve as the supporting arch springing. Conceptual analysis is conducted to further reveal the mechanism of the blast-induced arching effect based on the trapdoor test, from the three aspects of displacement mode, stress development and post-detonation stress distribution.

DEM study on evolution of soil arching in a deep trapdoor in seismic shaking conditions

In this study, the soil arching formed in a deep trapdoor model was investigated using the discrete element method, considering the magnitude, frequency, and direction in seismic shaking conditions. The parameters were validated using prior trapdoor test results. The results showed that the ultimate soil- arching ratio increased after shaking, indicating that the soil arching effect had degraded. The fluctuation range of the soil arching ratio increased with increasing shaking frequency. The ultimate average coordination number of the region above the trapdoor steadily increased as the shaking magnitude increased. Soil arching was more significantly influenced by shaking in the vertical (z-axis) direction than in the horizontal direction. The force chain in the arched region above the trapdoor progressively increased as the shaking magnitude increased, and clearly degenerated above the stationary region. As the shaking amplitude increased, the ultimate soil arching ratio increased; however, the ultimate coordination number decreased.

Novel Spatial Soil Arching Effect on a Steep-Slope High Embankment in a Double-V Narrowing Gully

A novel spatial soil arching (SSA) effect and the arching mechanisms and characteristics of a steep-slope high embankment in a double-V narrowing gully (DVNG) were investigated. First, the consistency between the results obtained via a lab-scale experiment and the three-dimensional finite-element model (FEM3D) confirmed the existence of SSA in the DVNG (DVNG-SSA) and validated the numerical model feasibility. The enlarged FEM3D revealed that the DVNG-SSA was generated by stress redistribution caused by uneven soil displacement. Moreover, the DVNG-SSA could generally be divided into horizontal (H-) and vertical (V-) DVNG-SSAs, which could interact with each other to form large-scale spatial soil arches at the front and bottom of the embankment. Parameter sensitivity analysis revealed that increasing the Poisson’s ratio of the soil negatively affected both arches. The H-DVNG-SSA only had side banks acting as arch feet, while the V-DVNG-SSA had an additional ditch bottom. Compared with H-DVNG-SSA, V-DVNG-SSA had a broader range, flatter shape, longer length, deeper thickness, lower height, and smaller maximum rise–span ratio. Finally, the strength of the DVNG-SSA was lower than that of the conventional pile–soil SSA despite its extensive coverage, which could considerably impact the overall embankment stability.

Analytical model of vertical load acting on jacked pipe considering soil arching effect in cohesionless soil

For the project of pipe jacking in cohesionless soil, it is key to determine the vertical load on jacked pipe so as to predict the jacking force accurately. In this paper, a new parabolic soil arching model was proposed to calculate the vertical load on jacked pipe. This proposed analytical model was composed of parabolic soil arching zone, parabola-typed collapse zone and friction arch zone. Combined with existing literature, the key parameters (i.e., height of parabolic soil arching, horizontal pressure coefficient and width and height of friction arch) were determined. In addition, considering that the trajectory of major stress is parabola, the formula of horizontal pressure coefficient was deduced in the friction arch. The parabolic soil arching zone is assumed as a three-hinged arch with reasonable arch axis, and the formula of load transfer was derived considering the transition effect of parabolic soil arching. The results of experiment, theoretical models and numerical model were adopted to verify the proposed analytical model. Finally, the influence of the key parameters on the vertical load on jacked pipe were also discussed in detail. This work provides a meaningful reference for evaluating the vertical load on jacked pipe for design of pipe jacking.

A simplified analysis of a configuration of geosynthetic reinforcement in GRPS embankments

Geosynthetic-reinforced and pile-supported (GRPS) embankments are increasingly used in recent years to reduce the differential settlement and increase the bearing capacity of the embankments. A new theoretical model is proposed to calculate the tensile force distribution and cross-sectional configuration of the geosynthetic reinforcement used in the Geosynthetic-reinforced and flexible pile-supported GRRPS and Geosynthetic-reinforced and rigid pile-supported GRFPS embankments. The accuracy of the proposed methods is verified by the results from laboratory model tests, centrifuge model tests and theoretical models in the literature. It is found that the tensile forces along the geosynthetic are distributed unevenly both in GRRPS and GRFPS embankments with the maximum and minimum magnitudes located at the edge and centre of the pile cap, respectively. The soil arching effect contributes more to the bearing capacity of the GRPS embankment than the membrane effect. It is found through the analyses of the centrifuge and model tests data that the soil arching effect contributes 65–75% of the total load transfer efficiency.

Exploring Asymmetric Linkages and Volatility Transmission between Stock Market and Foreign Exchange (FOREX)

This study examines the direction and nature of volatility transmission between the stock market and the foreign exchange market (FOREX) of Pakistan. For this purpose, daily data is gathered to conduct the analysis for both markets. Stock market returns are measured by using the KSE-100 index and the daily Pakistan Rupee-PKR to the United States Dollar-USD exchange rate is used for the foreign exchange market. Noticeably, both the variables are stationary at their first difference. Normality is examined through Skewness and Kurtosis, Autocorrelation through Correlogram Q-statistics, and the ARCH effect through the ARCH-LM test. Volatility transmission between the two markets is examined by using bivariate diagonal BEKK-GARCH and bivariate E-GARCH models. The results of the study indicate that bi-directional volatility transmission exists between the stock market and the foreign exchange market (FOREX) of Pakistan. Results from the E-GARCH model further indicate that the nature of volatility transmission between these two markets is asymmetric, which means bad news of one market has a greater impact on the volatility of another market than the good news. Hence, the results of this study also indicate that past variances of the stock market and foreign exchange market has a significant effect on their own current volatility.

A study on soil arching effect of anti-slide pile considering different pile arrangements

A study on soil arching effect of anti-slide pile considering different pile arrangements

Structural design and engineering of Striatus, an unreinforced 3D-concrete-printed masonry arch bridge

This paper describes the structural design and engineering of “Striatus”, a 3D-concrete-printed unreinforced masonry pedestrian bridge built in Venice in 2021 as part of the Time Space Existence exhibition organised by the European Cultural Centre. The project combines the latest developments in 3D concrete printing with the structural principles of historic unreinforced masonry. Typically, the structural applications of 3D concrete printing are limited to elements such as columns and walls loaded vertically, perpendicularly to the horizontal printing layers, to formwork elements or secondary structural elements. Indeed, fabrication constraints, delamination issues and the low tensile strength of the concrete have been seen as limiting factors to 3D concrete printing for structural applications demanding resistance to bending or predominant loading directions not perpendicular to the printing layers. By using unreinforced-masonry structural principles, this paper shows that structural elements spanning space horizontally, such as a pedestrian bridge, can be built by using the 3D concrete printing components as the main structure, working only in compression, loaded perpendicularly to the printed layers. Furthermore, as a compression-only structure following masonry principles, Striatus enabled the use of unreinforced concrete without any mechanical or chemical connections between the elements and the separation of concrete and steel, only used for the supports and to equilibrate the horizontal thrust of the arch effect through the tension ties. This work shows how the application of unreinforced masonry principles to 3D concrete printing offers new opportunities in terms of structural design and represents a strategy to increase sustainability by reducing material consumption and allowing reusability and recyclability of the structure. Finally, this paper discusses the critical aspects related to the design of Striatus from an engineering and construction point of view.

Analysis of Influence Factors of Anti-Slide Pile with Prestressed Anchor Cable Based on Bearing and Deformation Characteristics of Pile Body

In order to deeply study the mechanism of prestressed anchor anti-slide pile, an indoor model experimental device was developed, and a finite difference and particle flow numerical analysis model of slope anchor cable anti-slide pile was established based on the reinforcement project of prestressed anchor cable anti-slide pile in a mountain road slope. Based on the analysis of the force and displacement characteristics of the anti-slide pile, the influence of the prestress of the anchor cable, the inclination angle of the anchor cable, the width and column spacing of the anti-slide pile and the inclination angle of the landslide, the height and nature of the filling soil on the force and deformation characteristics of the pile are discussed, and some design parameters are optimized. Results show that the larger the prestress of the anchor cable, the smaller the displacement of the pile body, but the excessive stress is not conducive to the safety of the pile body. The optimal tension should be 50–70% of the designed tension of the anchor cable. With the increase in the inclination angle of the anchor cable, the displacement of the pile decreases first and then increases, and there is an optimal inclination angle of the anchor cable. In the double row piles, with the increase in pile spacing, the front row piles gradually change from supporting the soil between the double row piles to supporting the sliding body with the back row piles, and the double row piles are plum-shaped. When the pile spacing is 2.5 times the pile diameter, the force of the front and rear piles is the most reasonable. In the process of soil arching evolution, the influence of cohesion on the soil arching effect is greater than that of the internal friction angle.

Evolution of the Soil Arching Effect in a Pile-Supported Embankment Considering the Influence of Particle Breakage

Evolution of the Soil Arching Effect in a Pile-Supported Embankment Considering the Influence of Particle Breakage

Study of Stress Paths in Arching Effect Using Frictional Strain Hardening and Softening in Fine Sand

Arching is one of the most common phenomena that occur in most geotechnical structures. To determine the properties and quality of this phenomenon, a physical model has been designed and constructed. The apparatus comprises rectangular trapdoors with different widths that can yield downward while stresses and deformations are recorded simultaneously. As the trapdoor starts to fail, the whole soil mass deforms elastically. However, after an immediately specified displacement, depending on the width of the trapdoor, the soil mass behaves plastically. This behavior of sand occurs due to the flow phenomenon and continues until the stress on the trapdoor is minimized. Then the failure process develops in the sand, and the measured stress on the trapdoor shows an ascending trend. This indicates a gradual separation of the yielding mass from the whole soil body. Finally, the flow process leads to the establishment of a stable vault of sand called the arching mechanism or progressive collapse of the soil body. To simulate this phenomenon with continuum mechanics, the experimental procedure is modeled in ABAQUS software using stress- dependent hardening in an elastic state and plastic strain-dependent frictional hardening-softening with Mohr Coulomb failure criterion applying user sub-routine. The results show that the experimental data have an acceptable corresponding to the numerical analysis data. So the selected soil behavior could indicate the main aspects of the arching effect, such as the flow that occurs in specific periods of strains. In the following, the stress path in p, q, and p, ν space was extracted from numerical analysis, and the results have been discussed.

Study on distribution of sidewall earth pressure on open caissons considering soil arching effect

Based on the soil arching effect theory, the magnitude and distribution of sidewall earth pressure on open caissons when the embedded depth is large was analyzed by using theory of non-limit state earth pressure theory and horizontal differential element method. The theoretical formula was deduced. The theoretical calculation results are compared with the field test results and centrifugal model test results respectively. The results show that when the embedded depth of the open caisson is large, the distribution of earth pressure on the side wall of the open caisson first increases with the increase of embedded depth, reaches a peak value, and then sharply decreases. The peak point is located at 2/3 ~ 4/5 of the embedded depth. In engineering practice, when the embedded depth of the open caisson is 40 m, the relative error between the field test value and the theoretical calculation value is − 55.8% ~ 1.2%, with an average error of 13.8%. When the equivalent embedded depth of the open caisson in the centrifugal model test is 36 m, the relative error between the centrifugal model test value and the theoretical calculation value is − 20.1% ~ 68.0%, with an average error of 10.6%, The results are consistent well. The results of this article provides reference for the design and construction of open caisson.

Напряженно-деформированное состояние плотины Юмагузинского гидроузла

Introduction. The stone-and-earth dam of the Yumaguzinskiy hydroelectric complex on the Belaya river is constructed in complicated geological conditions on heterogeneous foundation. The results of computational research of stress-strain state (SSS) of the dam, carried out for the variant of an earth dam with the central core are presented. When calculating the deflected mode of dams, the real structure of ground characterized by its relation of elastic and plastic bonds should be taken into account. The change of this structure takes place along with the change in stresses and is reflected in the values of coefficient of relative strength and coefficients of reliability. The values of the safety coefficients can be used to judge the strength state of the dam. Materials and methods. The stress-strain state of the dam was determined on the basis of the energy model of the developed by L.N. Rasskazov. The area of the selected fragment of the dam has been divided into single-type elements; a triangular grid of the finite element method has been adopted, by means of which the structure of the soil dam and the foundation have been described. Results. Numerical calculations have shown that when water level in the reservoir rises to the level of the forced retaining level the character of stress distribution σxx changes. At the base of uppermost buttress prism at the boundary with the core there appears an area with small positive values, the largest of which is obtained in the transition zone. The entire hydrostatic load is transferred to the pressure face of the core and, consequently, the entire work of external forces is transferred to the internal deformation energy of this element, causing a stress concentration in it. The transition zone material is forced to follow the deformations of the core, resulting in the development of tensile stresses in the core. Therefore, increasing the stiffness of the core results in less deformation of the core and correspondingly less tensile stress in the transition zone. The nature of stress distribution σyy is symmetrical. Conclusions. Increasing the rigidity of the core entails elimination of the arch effect, which is particularly noticeable at lower reservoir levels. For this reason the use of skeleton material in the core of the dam is desirable.

Review of the Double-Row Pile Supporting Structure and Its Force and Deformation Characteristics

The conventional support forms of foundation pit retaining piles include single-row piles, double-row piles, anchor-row piles, and so on. The double-row pile supporting structure is widely used in the deep foundation pit supporting the engineering of wharves, bridges, subways, tunnels, and high-rise and super-high-rise buildings. This study on double-row pile supporting structures mainly focuses on four aspects: (1) The influence of dimension parameters, such as pile diameter and pile length, and engineering parameters, such as pile spacing and row spacing, on the deformation control of a double-row pile structure and the stability control of foundation pits; (2) Influence of the soil arch effect on the stress and deformation of the double-row pile supporting structure; (3) Study on the deformation characteristics and rules of the components and the whole structure of the double-row pile supporting structure; (4) Study on the calculation model of pile-soil interactions. Based on the above four aspects, this paper summarizes the latest research status of the existing double-row pile supporting structure and its stress and deformation characteristics. The deformation characteristics and calculation model of the pile-soil interaction of double-row piles are reviewed and evaluated. Finally, the problems and deficiencies in the research on double-row pile support are summarized. These results provide a reference for future research on the double-row pile supporting structure of the foundation pit and the numerical analysis and calculation model and lay a solid foundation for further development of the theory.