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The authors consider finite element models of a large-span building with a cylinder-and-slab roof as a large spatial mechanical system with different boundary conditions. The first model represents the superstructure of the building with a fixed-end at the soil base level. In the second model, the superstructure is based on the substructure, which includes a pile foundation and a soil base with different physical and mechanical properties. The purpose of the study is a comparative numerical analysis of the stress-strain state of a large-span building with different boundary conditions. The numerical study revealed the influence of the structural features of the substructure of the building, as well as the physical and mechanical properties of the soil base on the stress-strain state of the long-span roof and the building as a whole. Numerical static analysis of spatial finite element models of a large-span building was carried out in the СAE class Femap NX Nastran software package. The results of the static analysis demonstrated a significant structural influence of the substructure of a large-span building on the characteristics of its stress-strain state. In the next article, it is proposed to conduct a modal analysis for these building models.

The evaluation of the bearing capacity of shallow or deep foundations is a major and traditional problem This article deals with the estimation and analysis of this bearing capacity but with a probabilistic method (statistics) therefore the main objective of this work is to do a probabilistic analysis. To answer and achieve this goal, the work has two lines of research: a theoretical one which brings together a bibliographical synthesis on the estimation of the bearing capacity of a pile by the in situ method (in place) such as the pressuremeter test and the second axis is experimental reinforced by a statistical analysis. The results of the pressuremeter test used in the evaluation (determination) of the bearing capacity of a pile considered as a deep foundation which actually represents the abutment of a rail bridge. An experimental study is underway for pressuremeter test on several sites. The geotechnical data comes according to a study of the project for the construction of a deep foundation for a bridge in the region of Tissemsilt in Algeria, after having defined the pressuremeter profile and estimated the bearing capacity by the pressuremeter method, the reliability of the results was tested. by a probabilistic (statistical) analysis using the normal distribution.

The construction of toll roads in South Sumatra faces two problems. First, most of the road sections are built on soft soil deposits, so the soil must be improved to speed up consolidation process and to improve bearing capacity. Second, the embankment required to reach the design elevation of the toll road is quite high so that reinforcement is needed to improve slope stability. This paper contains the results of a study on the effect of soil improvement using PVD and vacuum pressure, installation of geotextile layers and pile at the toe of embankment slopes, on the stability of the embankment. The analysis were carried out using data obtained from the construction of the Kayu Agung – Palembang toll road Section 1A, including geometry data, soil stratification, and configuration of PVD installation and soil reinforcement. Slope stability analysis was carried out using the Morgenstern & Price method which is integrated in SLOPE/W program. The results of the analysis show that the safe embankment height for the original soil condition is 3.5 m while the required height of embankment was 6 m. Analysis made for the 6 m high embankment using soil properties after ground improvement with PVD and vacuum pressure shows the FoS is still below 1.5. The presence of geotextile layers and pile improved the performance of the embankment and increased the FoS to 2.410. The slope is still in a safe condition with FoS of 1.762 after the construction of toll road and traffic load which induces a combined load of 35 kPa.

This paper investigates the torsional dynamic response of a single pile with a circular cross-section embedded in multi-layered soils. The energy principles and variational approach are employed to establish the governing equations of the pile-soil system subjected to dynamic torque applied at the pile head in the frequency domain. The proposed solution is based on the finite element method for a bar on an elastic foundation to provide the torsional dynamic subgrade reaction, angle of twist, torque along the pile and the torsional impedance at the pile head. The accuracy of the proposed method is verified by comparing the analysis results with those of existing analytical solutions. Parametric studies are also performed to investigate the influence of the soil properties and the excitation frequencies on the stiffness and radiation damping of the pile-soil system. [ABSTRACT FROM AUTHOR]

The growing interest in the long-term performance of pile foundations and their ability to resist the negative effects of water exposure and aggressive environmental conditions has led to considering non-corrosive materials such as fibre-reinforced polymer (FRP). The most common applications are light-bearing structures in waterfront environments, while applications for larger structures have not been widely accepted in industry due to the lack of long-term records and design guidelines available. In this study, a numerical model using the finite element method was developed to simulate small-scale load tests of hollow carbon-fibre reinforced polymer (CFRP) and glass-fibre reinforced polymer (GFRP) piles in soft clay. The findings of this research indicate that the number of FRP layers impacts loading behaviour significantly, while inner tube soil height has a reasonable influence on axial load response and fibre orientation has a minor effect under lateral load conditions. [ABSTRACT FROM AUTHOR]

This study explored reinforced concrete piles located in a flexible half-space and loaded with external loads, considering various contact elements and the connection between the pile and the ground massif. Piles are mainly solved as axially loaded elements stressed by a vertical force. However, there are also several cases in the construction industry where a pile is stressed by a horizontal force or by a bending moment, producing a bending loaded pile. A static model of a pile and the surrounding subsoil was constructed using software based on FEM. The pile was modelled from 3D finite elements that were rotationally symmetric around the vertical axis of the pile. Additionally, the flexible half-space was modelled from 3D elements that were rotationally symmetrical around the piles. The boundary conditions were applied on the surfaces around the perimeter and at the bottom of the ground massif. The flexible half-space was modelled up to the area where there was zero deformation. The presented analysis focused on the description of different types of contact elements between the surface of the reinforced concrete pile and the surrounding ground mass. This interaction was modelled as a fixed connection or as point-to-point contact, and a contact surface. In the next part, different boundary conditions on the pile bottom were considered. Floating piles, supported by joints or firmly woven into the ground massif, were considered. All these outputs based on FEM were compared with the analytical solution of the bent pile that was published in the 1980s. The deformations and internal forces during different modelling of the contact between the edge of the concrete pile and the surrounding ground mass were compared. The higher values of the studied quantities were for rigid connections, which is logical. For contact elements, the property of the contact was considered. This property introduces less stiffness, and thus, the resulting values were lower compared to those for a fixed connection. The presented analysis of the FEM analytical and numerical solution is also very valuable for engineers working in construction. [ABSTRACT FROM AUTHOR]

This study aims to evaluate and analyze the improvement of Factor of Safety (FS) using double-row pile addition on the critical sand slope modeling with slope angles 50°. Experimental and numerical modeling was conducted in this study. The small-scaled slope model of sand soil compacted on the steel container (1.5x1.0x1.0 m) was used in the experimental test. Reinforcement piles using aluminum tubes are installed on compacted sandy soil with Rc 88%. The diameter of the first row of piles is 3.2 cm with a pile spacing (D1) of 10 cm, yet the diameter of the second row is 2.0 cm with varied pile spacing from 2d to 5d. The LVDT was installed on the pile, and the model would gradually be loaded using a hydraulic jack until the slope collapsed. The unreinforced slope bearing capacity (qu) on the loading test was used as the external load to numerically analyze the FS of the 2D and 3D FEM using PLAXIS. The results showed that the FS increased against the unreinforced reinforcement of two rows of piles with external load by 7.18% in the 2D FEM and 29.05% in the 3D FEM. The results obtained for the loaded slopes model with one row of pile reinforcement are 4.38% in 2D FEM and 1.49% in 3D FEM. The slope model with the highest FS was the slope model with pile spacing, D1=2d. The type of slope failure was rotational. [ABSTRACT FROM AUTHOR]

The collapsible loess is widely distributed in western China. The special structure and water sensitivity of loess lead to the complex negative skin friction mechanism in pile foundations. Previous studies mainly focused on the negative skin friction of pile foundations and treatment measures, such as casing and coating methods. However, few studies have focused on the influence of the negative skin friction on the settlement and bearing capacity of piles in collapsible loess, especially environmentally friendly methods that can reduce the negative skin friction. In this study, a series of non-immersion and immersion experiments was conducted to investigate the settlement, axial force, and side friction resistance of piles in loess soil under controlled conditions. The results showed that under the non-immersion condition, the settlement of model piles increased with the increasing pile top load. The axial force gradually decreased along the pile length for piles without casing. The axial force attenuation of the casing section of casing piles was almost negligible due to the isolating frictional resistance effect of casing. The settlement of each soil layer increased with the increase in immersion time, and the process was divided into an initial gradual stage, rapid drop stage, and later gradual stage. Both negative and positive skin friction increased with the increasing immersion time and pile top load, and there was a neutral point. The maximum axial force of piles without casing exceeded the peak load at the pile top. The presence of steel casing reduced the failure of pile foundation in collapsible loess. The research results of this paper provide theoretical support for the application of piles in loess areas. [ABSTRACT FROM AUTHOR]

The p–y method as a simplified analysis tool has been widely used to analyze the behavior of laterally loaded piles. This paper develops a novel cyclic p–y elastoplastic model within the framework of the single-surface bounding surface theory. The model can capture the soil stiffness degradation during cyclic loading by incorporating the cumulative plastic displacement to an interpolation function of the elastoplastic resistance coefficient. The model is relatively simple with only four parameters that can be determined from standard soil properties and stress–strain responses measured in direct simple shear tests. The performance of developed model is validated by predicting the cyclic lateral response of piles installed in soft clay during field and centrifuge tests published in the literature. The model can reliably simulate monotonic and cyclic responses of piles under different lateral loading patterns, and capture main characteristics of the pile-head load–displacement curve, such as nonlinearity, hysteresis, displacement accumulation, and stiffness degradation. It can also predict the evolution of the lateral deflection and sectional bending moment along the pile during cyclic loading. [ABSTRACT FROM AUTHOR]

The work reported in this article numerically investigates the structural forces in a tunnel lining after applying an adjacent loaded pile for varying pile tip positions considering the tunnel and soil stratum. Analysis reveals that the structural responses are strongly associated with the distorted elliptical shape of the deformed tunnel, which depends on the relative position of the pile tip with respect to the tunnel crown. The change in bending moment in the tunnel lining is of greater concern than the change in the axial force of the tunnel lining. Although the maximum change in structural forces can be up to 115% of the initial value, assessment in terms of maximum change in the structural forces is unsuitable. This is because the maximum change does not occur at the location that has large initial forces. The total combined bending moment and axial force in the lining at the tunnel spring line and in the tunnel invert zone are recommended for cases where the pile tip level is at the tunnel spring line and cases with the deepest possible pile tip elevation, respectively, for the assessment. [ABSTRACT FROM AUTHOR]

A number of shaking table tests have been carried out to study the effects of earthquake-induced liquefaction and lateral spreading on a group of piles. The ground surface was level in these tests, whereas the base layer was inclined. Therefore, the studied subject in this paper is an intermediate problem, a case between level ground liquefaction and sloping ground lateral spreading, which has not been studied before. The tests results indicated that the soil in the free field liquefied before the soil adjacent to the piles. It was found that shadow effect reduced the bending moments of the pile placed in shadow; and neighboring effect may decrease the bending moment of the piles of the group in comparison to that of a single pile. The results also illustrated that the surface ground slope is a key parameter in imposing kinematic pressure on the piles due to lateral spreading and the base slope of the ground still induces lateral pressure on piles but does not play a major role on kinematic lateral pressure associated with limited lateral spreading. The maximum bending moments in the single pile in the level grounds were between 135 and 233% less than that in the sloping ground. [ABSTRACT FROM AUTHOR]

This article contains the analytical model of the drift of a separate ice field under the action of wind and current, in which velocities and directions can vary over time. The model takes into account the mass of ice, added mass of seawater, and the effects of the wind and current on the ice field in forming the friction on its upper and underwater surfaces and the frontal resistance on its end (forward and backward) surfaces. Simulation of the wind drift of the ice field showed the drift velocity exceeds the considerable known velocity of a compact ice cover drift. A drifting ice field has a certain kinetic energy that should be released when a collision occurs with an unmovable obstacle, and spent on brittle breakdown of a quantity of the ice field. The volume of formed small ice pieces (fragments of ice field) was estimated by comparison of the specific energy of the sea ice brittle destruction and the kinetic energy of the drifting ice field. The article presents the results of the estimation of the possible volume of the ice pieces and the scales of formed piles as a result of a collision with an obstacle, depending on the initial dimensions of the ice field and wind speed. Developed models and the results of computer modeling can be used to estimate the ice pile sizes near the stationary platforms and terminals on the Arctic seas. [ABSTRACT FROM AUTHOR]

In the course of highway construction and use in loess area, subgrade settlement disease is common and has great destructiveness. The cone penetration test (CPT), especially the pore pressure cone penetration test, can provide three continuous readings along the exploration depth cone tip resistance, lateral friction resistance and excess pore water pressure. In this paper, CPT tests are carried out in the losses areas in Shanxi, China. Some data and curves are obtained by using CPT, which are quite different from those obtained by conventional drilling, reflecting the soil layer characteristics of the subgrade section, in order to provide a reference for similar projects. The results showed that CPT has a strong advantage in the analysis of the effect of compacted pile in the treatment of pile length and the improvement and reduction of indicators of different layers along the depth direction. However, the correlation between the static penetration and the compaction coefficient commonly used in the current norms still needs to be further studied to enhance the correlation analysis with detection parameters. [ABSTRACT FROM AUTHOR]

In nature, soil layers possess large variability during their geological process. This variability may also lead to differences in the location and thickness of nonliquefiable and liquefiable soil layers. In practice, the impact of liquefaction on the pile can be ignored at depths greater than 20 m due to high confining stress levels and a lack of liquefaction triggering data. On the other hand, this approach may underestimate design loads in many cases, especially in deep-seated and embedded engineering structures. This paper presents the bending response of piles installed through liquefiable layers located at depths beyond 20 m, and parametric analysis was conducted for a wide range of liquefiable layer thicknesses and depths by using OpenSeesPL (version 3.0.2) software. The numerical results were evaluated considering the inelastic concrete pile behavior under different earthquake records and different peak ground accelerations. The findings show that liquefaction can lead to a failure of piles even at depths greater than 20 m, and thus, a design consideration of piles may require a more comprehensive view considering the liquefiable layer depth and thickness effect. [ABSTRACT FROM AUTHOR]

A nearby construction with a pile foundation in an urban area can cause possible damage or an operational safety concern to the existing tunnels. The response of the tunnel will depend on the relative location of pile tip as compared to the existing tunnel depth. This paper describes an experimental investigation carried out in the laboratory to examine the effect of pile loading on the existing tunnel in Delhi silt. A small-scale testing facility was designed and built to investigate the influence of pile loading in the close vicinity of the existing tunnel. Dimensions of the model tunnel and pile were arrived at based on the physical scaling laws. The model tunnel (outer diameter of 150 mm with thickness of 0.5 mm) and piles (outer diameter of 25.4 mm with thickness of 1.0 mm) are made up of aluminum. Tests were carried out in a fabricated model steel tank (1,100 mm wide, 1,600 mm long, and 1,200 m deep). Experiments were performed at various stages of pile loading at a separation distance of 1.0, 1.5, and 2.0 times the tunnel diameter from its axis. Results indicate that the strain in tunnel lining is significantly affected by various stages of pile loading when the row of pile is placed within the distance of 12 times the pile diameter from the axis of the tunnel. Three-dimensional numerical simulations of model experiments were also carried out, which fairly predicted the phenomena measured in the experiments. [ABSTRACT FROM AUTHOR]

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The bearing capacity of screw cast in situ displacement piles is mostly unexplored. There is also insufficient research on piles in silty soils. Therefore, five cone penetration tests (CPT) and one piezocone penetration test (CPTu) using direct methods were utilised to determine the load-bearing capacity of four displacement piles in Estonia. In addition to the CPT sounding data, staticdynamic test (SDT) results were used to analyse the load-beating capacity of the piles. Both deterministic and probabilistic methods were used in the analysis. Characteristic values as a 95% reliable mean and 5% fractile values for sounding parameters, according to the Eurocode 7, were included. Additionally, Monte Carlo simulation was included in the reliability-based design (RBD). The bearing capacities of screw cast in situ displacement piles in silty soils, here based on the CPT and SDT sounding data, were similar. The adaptation of SDT results for the CPT direct methods for pile load-bearing capacity analysis certainly deserves attention and further investigation. For both sounding types, the Eurocode 7 method provided the best results for all piles. The results of pile-bearing capacities in the absolute difference varied within ±11% between the average, RBD and characteristic values. [ABSTRACT FROM AUTHOR]

Monopiles are the most common foundation form of offshore wind turbines, which bear the vertical load, lateral load and bending moment. It remains uncertain whether the applied vertical load increases the lateral deflection of the pile. This paper investigated the influence of vertical load on the behaviour of monopiles installed in the sand under combined load using three-dimensional numerical methods. The commercial software PLAXIS was used for simulations in this paper. Monopiles were modelled as a structure incorporating linear elastic material behaviour and soil was modelled using the Hardening-Soil (HS) constitutive model. The monopiles under vertical load, lateral load and combined vertical and lateral loads were respectively studied taking into account the sequence of load application and pile slenderness ratio (L/D; L and D are the length and diameter of the pile). Results suggest that the sequence of load application plays a major role in how vertical load affects the deflection behaviour of the pile. Specifically, when L/D ratios obtained by lengthening the pile while keeping its diameter constant are 3, 5 and 8, the relationships between lateral load and the deflection behaviour of the pile under the effect of vertical load demonstrate a similar trend. Furthermore, the cause of increased lateral capacity of the pile under the action of applied vertical load in the common practical application case and in the VPL case was analyzed by studying the variation law of soil stress along the pile embedment. Results confirm that the confining effect of vertical load increases means effective stress of the soil around the pile, thus increasing soil stiffness and pile capacity. [ABSTRACT FROM AUTHOR]

A vertical electro-osmosis method was proposed to improve the bearing capacity of piles in marine soft clay foundations. A top-down electro-osmosis test was conducted by setting an anode and cathode at the top and bottom of the pile, respectively, while the settings of bottom-up electro-osmosis were set in the opposite way. At the same time, a pile without electro-osmosis was also set up for comparison. The variation law of water content, water discharge volume, soil pressure, and surface settlement of soil around the pile during electro-osmosis was tested and analyzed. A direct shear test and static load test were carried out to study the effects of vertical electro-osmosis on the shear strength of soil and the bearing capacity of the pile. The experimental results show that vertical electro-osmosis can significantly improve the bearing capacity of the pile and the shear strength of soil around the pile. The bearing capacity of the piles in the top-down electro-osmosis test was 16.7% higher than that in the bottom-up electro-osmosis test, and the amount of water discharged was 41.69% higher. Compared with the horizontal electro-osmosis around the pile, the vertical electro-osmosis had a faster drainage speed, better soil consolidation, and a slightly smaller increase in the bearing capacity of the pile. Because vertical electro-osmosis is easy to implement on concrete piles, the new method proposed in this study has a broad application prospect. [ABSTRACT FROM AUTHOR]

A p-y curve method of pile near cohesionless soil slope under reversed lateral load is proposed. This method takes into account the failure mode of soil around the pile under reversed lateral load and the interaction mode between pile and soil, and derives the ultimate soil resistance of the pile. Considering the change of the original stress state of soil due to the lateral deflection of the pile foundation, the influence of the relative density, the initial mean effective stress and the lateral deflection of pile foundation on the internal friction angle of the sand is evaluated to further accurately calculate the soil resistance value at each depth. The prediction results of this method are well verified by comparing with the FE results and centrifuge test results. Finally, the influence of the process of lateral deflection of pile on the strength state of soil around the pile and the bearing capacity of pile is studied. [ABSTRACT FROM AUTHOR]

The authors have been developing a new composite foundation composed of piles and soilbags. The foundation is characterized by the laying of soilbags between the pile heads and the footing on which a superstructure stands. The expected effect of the foundation is to cut off the fixed connection between the piles and the footing in order to reduce the bending moment of the piles and the response acceleration of the structure. In this study, in-situ horizontal cyclic loading tests were conducted on the proposed composite foundation with two piles to investigate the seismic response characteristics of the foundation at real scale. It was found from the tests that the horizontal force reached its peak due to the uplift of the footing during horizontal loading, and that larger hysteresis damping was obtained than that of spread foundations due to the hysteresis effect in the shear deformation of the soilbags. As for the sectional force of the piles and the vertical stress inside the soilbags, it was found that the axial force and bending moment of the piles concentrated on the pile on the front side in the loading direction, and that the vertical stresses inside the soilbags concentrated just above the pile head on the front side in the loading direction. Although residual horizontal displacement and settlement occurred due to the cyclic load, little damage to the soilbags was observed.

The paper presents the solution of the problem of interaction of a single reinforced concrete compressible pile with an elastoplastic single-layer soil mass. The settlement is calculated on the basis of the analytical equation in the elastic formulation. A graph-analytical method is proposed to account for the nonlinear behavior of soils, which limits the bearing capacity of the pile on the lateral surface to the strength of the adjacent soil and under the pile toe to the ultimate load determined by the Brinch Hansen formula. The novelty of this method consists in taking into account the mechanism of load redistribution on the pile, the nonlinear behavior of the soil on the lateral surface and under the pile toe, and also the possibility of detachment and slippage of the pile after reaching the ultimate strength. A comparative analysis of the graph-analytical solution with the numerical solution in the geotechnical software Plaxis 2D and with static pile tests was performed. According to the results of the performed calculations, graphs of the dependence of settlement on loads were plotted, and conclusions about the possibility of using the graph-analytical method were drawn and the prospects for further development of the graph-analytical method are proposed.

Piles are often installed before tunnel excavation to support the tunnel structure. However, excavation inevitably causes disturbance to the soil below the excavation surface, significantly changing the soil mechanical behavior. Hence, it is necessary to evaluate the excavation effects on pile load-settlement behavior. This study proposes a semi-analytical approach for estimating the load-settlement behavior of a pile beneath the excavation surface, that considers the excavation effects. Piezocone tests are performed in the Taihu tunnel region to evaluate the excavation effects on the soil mechanical properties. The results show that after excavation, the undrained shear strength of the soil decreases, while the soil effective friction angle remains unchanged. Thus, this study proposes using the soil effective friction angle before excavation to predict the pile load-settlement behavior after excavation. Then, the load-transfer method is employed to simulate the pile settlement behavior. Hyperbolic functions are used to describe the nonlinear loading and unloading pile-soil interface behavior. The proposed semi-analytical approach also considers the shear-induced elastic deformation of the surrounding soil. The predictions of the load-settlement behavior are compared to the results of pile load tests in the Taihu tunnel region, centrifuge model tests, and numerical investigations to validate this approach. The excellent agreement indicates that the proposed approach can reasonably predict the pile load-settlement behavior after excavation. As a case study, it is predicted that the ultimate capacity of a pile in the Taihu tunnel region is 4388 kN, reflecting a 10% loss of pile capacity due to excavation. [ABSTRACT FROM AUTHOR]

This study proposes a new non‐destructive testing method (NDT), namely the apparent wave velocity of piles (AWVP) inverse analysis method, to solve the detection problem of the gradually varying cross‐sectional defects (cracks or necking) and the material property defects (concrete disintegration or steel corrosion) of piles. The analytical solution of the AWVP has been derived based on the additional mass model. The rationality and accuracy of the theoretical model have been validated through the comparisons with the experiment results. The variation mechanism of the AWVP due to the presence of soil has been clarified. A parametric study is conducted to investigate the major factors to determine the variation tendency of the AWVP. The optimum working conditions and parameter combinations of the AWVP based NDT method have been recommend. The main conclusions can be drawn as: (1) the variation of the AWVP with respect to frequency can be generally divided into a sensitive zone and a stable zone. (2) The AWVP initially decreases rapidly with the frequency within the sensitive zone, however when the frequency decreases to the stable zone, this decline tendency becomes much smaller. (3) Although the AWVP varies extensively within the frequency sensitive zone, this frequency range can substantially relax the requirements for the parametric accuracy of the pile–soil system. [ABSTRACT FROM AUTHOR]

Tunnel construction in cities faces many geotechnical challenges, and the effect on pile foundation is possibly one of the most complex ones. Most tall buildings in big cities mostly have pile foundations, and any tunneling nearby might significantly influence those existing foundations. In the present study, a 3-dimensional Finite Element (FE) analysis has been carried out to investigate tunneling effects on pile foundations. The investigation is done for a single pile with multiple stages of tunnel excavation where the pile foundations are assumed to reach below the base of the excavation of tunneling. A tentative rate of excavation was also included in this investigation and found that a faster rate of excavation results in better performance of foundations affected by tunneling. The study also extended to see the effect of tunneling on pile groups. Attempts were made to compare the results with some of the previously published literature. [ABSTRACT FROM AUTHOR]

Load-displacement behavior of a pile is one of the key parameters in the foundation design of a high-rise building. This research studied the relationship between the load and displacement of a pile in sand using a physical model test and the finite element method (FEM). Five types of sandy soil, including Bangkok sandy soil, were tested using the physical model test with a pile 1 cm in diameter and 30 cm in penetrated length. The results showed that the relationship between the load and actual pile displacements in all soil types was nonlinear with an elastoplastic-strain hardening pattern. This relationship was expressed using a polynomial function for a displacement in the range 0-20 percent of the pile diameter. For easy use, the relationship can be considered a linear function only in the first stage of displacement (0-10 percent of pile diameter), confirming that linear pile spring stiffness can be reasonably used for the design of the foundation. In addition, the finite element method was used to investigate the effect of various factors on pile spring stiffness. The results showed that pile spring stiffness depended on diameter, length, and modulus of the pile and on the soil modulus. In natural soil, the modulus of soil was related to the soil strength and the pile spring stiffness also depended on the soil strength. [ABSTRACT FROM AUTHOR]

Population growth in Indonesia affects the rate of urbanization as the increased construction development decreases the available land. The issue of limited land encourages people to make settlements or buildings near the slope edge. Various mitigation methods can be applied to prevent and avoid landslides and to overcome other problems that arise on the slopes, one of which is by strengthening the slopes. In this study, slope reinforcement was carried out by adding two rows of piles to increase slope safety. Firstly, we observed scaled slope models with or without pile reinforcing. Slope modeling was done with a test container of sand soil with a slope angle of 50° and using an aluminum pipe as a model for reinforcement piles. Pile diameter of the test model was varied on the second row (1.5 cm, 2.0 cm, 2.5 cm, and 3.2 cm). The bearing capacity of the scaled-model test results was used to estimate the increase in factor of safety (FoS) assisted by the finite element method (FEM) application in two-dimensional (2D) and three-dimensional (3D) FEM. According to the FEM test results, the FoS value of a reinforced slope with two rows of piles increased by 9.130% in 2D FEM and 34.296% in 3D FEM compared to an unreinforced slope modeling. The most significant FoS value was found in the second row of piles with the largest diameter of 3.2 cm. Additionally, the test results showed that the reinforced slope is susceptible to rotational slope failure. [ABSTRACT FROM AUTHOR]

Stabilization or increasing slope stability is commonly accomplished with piles. In this paper, a response surface method considering soil spatial variability and the seismic condition is successively carried out to propose a reliability-based design for the slope stabilized by one row of piles. Eight configurations of cylindrical and rectangular cross-section pre-stressed concrete piles were designed. Additionally, a parametric study was carried out to examine the effect of various parameters on the pile response and slope stability. According to the research, stabilizing piles should be placed in the upper-middle part of the slope, intersecting the critical slip surface to reach the highest reliability index. This study showed the optimal position of the pile varies with the value of the seismic coefficient. It was found that increasing the pile length becomes unnecessary after a specific size. This research showed the relationship between safety factor, reliability index, and pile reaction force for slopes using probabilistic slope stability design charts. It is demonstrated that the proposed equation can accurately estimate the system reliability index, failure probability, factor of safety, and pile reaction force. Finally, the findings of the research were compared to results from another researcher, and the results of this study showed a reasonable level of agreement. [ABSTRACT FROM AUTHOR]

Determining the load-bearing capacity of piles using the results of in situ tests is one of the most widely used methods. The objective of this study is to examine suitable cone penetration test (CPT)-based methods for predicting the load-bearing capacity of piles in silty soils. In addition, it is analysed whether standard penetration test (SPT)-based methods can be used with dynamic probing super heavy (DPSH-A) test data to evaluate pile capacity. Five CPTs and one piezocone penetration test (CPTu) based on direct methods were applied to determine the load-bearing capacity of piles. In addition, six SPT direct methods were used based on DPSH-A test data to estimate the load-bearing capacity of the investigated piles. The capacity of the pile obtained by various direct methods was compared with the outcome of the pile load test. Of the direct CPT methods, the LCPC (also known as French method) method and the German method demonstrated decent results when CPT probing reached deeper than the pile. The use of SPT-based direct methods with DPSH-A test data for displacement piles in silty soils seems to be promising. Specifically, the Briaud and Tuckers' method provided excellent results for most of the piles studied. [ABSTRACT FROM AUTHOR]

Bar reinforced concrete structures, which include piles, in real working conditions perceive a whole range of internal force factors. Axial tension-compression forces, bending moments and shear forces are the most commonly perceived internal force factors. Of particular interest is the effect on the cross section of the shear force. If a complex curly shape is replaced by elementary form, then the calculation is not difficult. However, when calculating the composite cross section, there is no unambiguous solution. In accordance with the adopted regulatory documentation, it is necessary to accept only a main part, while discarding the surrounding areas. It is important to study the configuration of the shape of a complex section for the perception of a shear force. The purpose of the work was to refine the account of the entire complex section using numerical simulation by the finite element method, analytical calculations and small-scale experiments. Determination of further practical application of the obtained results on real structures was also the goal of the study. The parameters of the distribution of shear force between the main rib and flanges were obtained by numerical analysis and small-scale experiments. Numerical models of rectangular and tee cross sections beams have been developed. Analytical dependences were studied and full-scale tests of reinforced concrete beams of various sections were carried out. It has been established that when taking into account the work of the entire cross-section, the bearing capacity of concrete for the action of a shear force is 20% greater than when calculating only the main section without taking into account the shelves. [ABSTRACT FROM AUTHOR]

A landslide located in northern Sichuan Province, China was investigated. A series of numerical models of the landslide stabilized with piles and anchor cable frame beams were developed using a three-dimensional finite-element method. The Strength Reduction Method was employed to investigate the stability of slopes, the internal forces of piles, and the axial forces of anchor cables. A parametric study consisting of pile position, pile length, and pile spacing was carried out. The results show that compared to anchor cable frame beams, the combination of piles and anchor cable frame beams is a more effective retaining structure to improve slope stability. During slope destabilization, the proportion of thrust shared by piles gradually increases, while the proportion of thrust shared by anchor cables gradually decreases. Piles installed on the leading edge of a trail-mode landslide can make the slope mostly stable. As the piles move from the leading, middle, and trailing edges of the slope, the proportion of thrust shared by the anchor cables gradually increases, while local instability may occur in front of the pile. Increasing the pile length can improve the stability of the slope. However, excessive embedded length of piles has little effect on further improving the slope stability. The critical embedment length of piles found in this study is 1/3 of the total length of the pile. The critical pile spacing found in this study is 2.5 times the width of the pile section. Beyond this spacing, the effective soil arch between the piles is difficult to develop and the anchor cables may share more proportion of the landslide thrust. This study provides a reference for reinforcement system design of engineering projects considering piles and anchor cable frame beams. [ABSTRACT FROM AUTHOR]

This paper presents a new coupled approach to incorporate the effect of vertical load on lateral response of pile in clay, by considering both the lateral and vertical strain of the soil-pile system. Experimental and numerical studies on pile subjected to combined loading carried out by different researchers showed that coupling behaviour cannot be modelled using Beams on Winkler foundation or subgrade reaction approach and use of continuum modelling is essential. However, in this present study an is made to develop a method using FEM by utilizing both the lateral and vertical strain of soil-pile system. The proposed coupled method is capable of simulating the influence of vertical load on lateral response of pile in clayey deposit much more realistically compared to uncoupled method. However, this coupling effect is more prominent for pile subjected to a vertical load equal to ultimate pile capacity (Vu), compared to pile under a load equal to allowable pile capacity (Vall). [ABSTRACT FROM AUTHOR]

In order to study the influence of the creep of soft soil and the corrosion damage of reinforced concrete on the horizontal bearing behavior of piles, the novel p-y curve model was established considering the time-varying characteristics of soil parameters. The attenuation law of the bending stiffness of reinforced concrete piles under chloride erosion was analyzed by introducing the bending stiffness reduction factor. The limit state function of pile reliability analysis was then established considering the time-varying characteristics. The reliability index of a pile under horizontal displacement failure mode was obtained using the quadratic response surface method. Finally, the sensitivity analysis of random variables (cohesion, internal friction angle, concrete cover, and chloride concentration) on the time-varying reliability of a pile under horizontal displacement failure mode was carried out. The influence of the distribution types of soil parameters on the time-varying reliability was considered. The results show that the load-bearing characteristics of the horizontally loaded pile are impacted significantly by the time-varying characteristics of the soil. The maximum horizontal displacement of the pile increases nonlinearly with the increase in service time. When the horizontal displacement failure mode occurs, the variability in the internal friction angle has a significant impact on the reliability of the pile. The reliability index decreases nonlinearly with an increase in service time. When the soil parameters obey the extreme value type I distribution, the corresponding reliability index is greater than that of log-normal distribution and normal distribution. [ABSTRACT FROM AUTHOR]

In the article, the feature of settlement, subsidence, and other deformations in the ground foundations of various structures built in complex engineering-geological conditions with the joint participation of some soils with a stable structure (subsidence loess, silt, low-strength technogenic, soluble) are performed on the example of the Gazakh cement plant, the development of a conceptual solution for the methods of installation in foundations on such soils has been reflected. Analyzing the results of the complex engineer-geological research conducted at the research facility, priority was given to the principle of improving the working conditions of the soils that form the basis of the facilities in order to prevent the predicted large-scale deformation, the application of a foundation system consisting of piles with a large length, with the bottom placed in a layer of argillite-like very stiff clay, was accepted as the most correct technical solution, the dimensions of the pile are determined and installed in the study area and it was determined that the chosen solution was justified by monitoring the deformations. [ABSTRACT FROM AUTHOR]

The design of the piles is always associated with uncertainties which can be partly reduced by calibration of the resistance factor of the LRFD method using reliability analysis. However, another part of this uncertainty, which is the base and shaft resistance, has not been considered in the LRFD method. In order to calculate the resistance factor, both parts of the uncertainty should be considered separately using detailed studies and in situ tests. In this paper, using a database from Iran, the base and shaft resistance factor is proposed for different design methods using the Monte Carlo simulation method. Comparing the method of multiple resistance factors with the LRFD method shows that the factored resistance can be increased or decreased depending on the design method. Furthermore, the effect of the ratio of dead to live loads and the ratio of base to shaft resistance in the resistance factor has been investigated. [ABSTRACT FROM AUTHOR]

The spinning and weaving industry is one of the oldest industries known to man, and it began as a handicraft to which man was guided by his instinct, making for himself what he used to cover his body and protect it from the cold of winter, then it developed after a period of time using mechanical processes in this industry (5)The production of pile textiles represents a wide sector of the textile production sectors because of its importance in covering many functional and aesthetic dimensions of the consumer, It is unique from the common and commonly used types of textiles with its structural theories, design rules, and technical methods for its production, represented by the stages of production and equipment for the production of pile. (1)Webbing textiles are distinguished among all other textiles by their effectiveness towards highlighting and confirming the technical, aesthetic and functional trends of the third dimension of the fabric represented in thickness, which arises mainly from achieving the pile appearance of that type of fabrics, whether cut pile or uncut, each of which plays a major role in determining dimensions and performance rules Functional and aesthetic of pile weaving product (3).The research aims to take advantage of the applied methods of hand tufted carpets as a source for the design and production of textile pendants with Egyptian character and identity, and to achieve the objectives of the study, a group of (10) designs were made, through the foundations of design and technology of hand tufted carpets, using some Islamic of geometric, vegetarian, and Islamic Mafroka, to emphasize and enrich the aesthetic values of the fabric hanging design.A number of designs were selected and implemented using hand tufted carpet techniques (Tuft), and to determine the quality level of designs, their relevance implementation technology, and the achievement of the Egyptian identity, a tool (evaluation form) was designed and applied by referees specialized in the field, after the application of the questionnaire, its data were statistically processed and the best (5) designs were reached, in the end, the study reached a set of conclusions and recommendations, if applied, it can achieve an advanced level in the quality of hand tufting carpet industry in general, and the design and production of pile textile in particular.

Electrokinetic (EK) treatment is an effective method in accelerating the consolidation and improving the geotechnical properties of fine-grained soils. This method stabilizes the soil and increases the bearing capacity of piles by improving the soil shear strength. Changing the soil pH, due to the occurrence of chemical reactions of electrolysis in the soil, can increase its shear strength. However, the electrodes used in this method corrode due to the change in the soil pH, which in turn reduces the electrical potential. Electrode corrosion and loss of electrical potential can significantly reduce the efficiency of the EK method. In addition, when using the EK method to increase the bearing capacity of piles, changing the pH can cause corrosion and damage to the piles. One of the most important factors influencing the change in the pH of soil is the voltage applied during the EK process. It was reported that increasing the voltage affects the intensity of chemical reactions and electroosmotic flow and thus increases the efficiency of EK. However, very limited research has been conducted on the effect of voltage on the performance of EK method. In the present study, the effects of three voltages on soil pH and corrosion resistance of four types of electrodes including iron (Ir), stainless steel (St), copper (Co), and aluminium (Al) were studied. In addition, the effects of pH variations on the corrosion rate of three types of piles including steel pile (SP), reinforced cement concrete pile (RCCP), and reinforced lime-cement concrete pile (RLCCP) were investigated. It was observed that increasing the voltage from a specific limit had no effect on the intensity of electrolysis reactions and the soil pH adjacent to the electrodes did not change more than a specific limit. Moreover, increasing the voltage to higher than 35 V (i.e. 45 V) did not increase the volume of drained water from the soil, but caused more electric current than the allowable current for Ir, St, and Al electrodes, and the corrosion intensity of these electrodes increased significantly. RCCP reduced the soil pH to 2.4 within 7 d of curing due to severe corrosion (13% corrosion rate). The soil pH values adjacent to RCCP and RLCCP within 28 d of curing reduced to 3.7 and 3.8, respectively, but the two piles were not damaged. In general, the results of this research showed that selecting an optimized voltage had a significant effect on the efficiency of EK, and increasing the voltage did not always lead to increase in the efficiency of EK process.