Vertical Pile Groups Research Articles

Effect of combined lateral and uplift loads on vertical and batter pile groups in cohesion less soil

Effect of combined lateral and uplift loads on vertical and batter pile groups in cohesion less soil

Performance of vertical and batter pile groups under vertical vibrations: a comparative assessment using model-scale field testing and numerical study

Performance of vertical and batter pile groups under vertical vibrations: a comparative assessment using model-scale field testing and numerical study

Numerical Simulation of a Barge Impact on Bridges with Different Configurations of Pile Group Foundations

Three-dimensional finite element dynamic analyses were conducted to evaluate the effect of barge impact of different speeds on the lateral performance of three pile group (PG) configurations (vertical, battered, mixed) in terms of peak lateral displacement, peak shear force, lateral stiffness of PGs, and contribution of piles and pier columns to the total resisting force. The concrete material was modeled using the Concrete Damaged Plasticity model. The clay behavior was described using the Modified Cam Clay model; while the sand was modeled using the Drucker Prager model. The results showed that the vertical PG had the lowest lateral stiffness; while the battered and mixed PGs had closely larger stiffness, which allowed the development of larger impact force and pile cap displacement in vertical PG as compared to other PGs. The results of shear force showed that the foundation contributed up to 82% of the total lateral force in battered and mixed PGs. The results also showed that in vertical PG, the first row had slightly higher percentage of lateral force compared to other rows; while in battered PG, the load percentage was evenly distributed between rows. A contrast performance was observed for mixed PG. The results of bending moment (BM) showed that the piles in vertical PG had notably higher BM than the piles in other PGs due to larger pile cap displacement. In all PGs, the piles in the edge column had higher BM ratio, with the leading row (L) had the highest BM ratio (69–72%) in all PGs.

Practical macro‐element for vertical and batter pile groups

AbstractThis paper presents a novel macro‐element for vertical and batter pile groups. The numerical scheme is based on de‐coupled, single pile response. Each pile consists of two separate load‐displacement formulations (axial and transverse) that take a displacement increment as input and return a diagonal tangent stiffness value. The effect of rotation is implicitly incorporated in the transverse load‐displacement formulation. The presented macro‐element does not require pre‐defined failure surfaces or other parameters, and is therefore not restricted to a specific foundation configuration, soil profile or soil type. The macro‐element may be calibrated using any type of non‐linear pile‐soil model. The developed macro‐element is validated using rigorous numerical models for a variety of configurations.

Investigation of the vertical responses of 2 × 2 square flexible batter pile groups in sand

The vertical bearing behaviors of the flexible batter pile groups in sand are investigated in this study. A series of model tests are carried out to study the effects of the batter angle (θ) on the vertical bearing capacities (V g) and distributions of internal forces of the pile groups. In addition, finite-element (FE) analysis is performed to explore the vertical bearing behaviors of the pile groups with various configurations, and the vertical bearing mechanism of the batter pile groups is analyzed. Moreover, a design method is proposed for predicting the bearing ratios (β) of the batter pile groups. The results show that the batter pile groups generally can provide higher vertical bearing capacities than the vertical pile groups with the same configuration. The batter angles for providing the greatest vertical stiffness are decreased with the increase of length–diameter ratio (R) and are not affected by the variation of relative density (D r). The predicting results obtained from the design method match well with the model test and FEM results. Some suggestions are proposed for guiding the application of the batter pile groups in practice engineering.

Dynamic p-y curves for vertical and batter pile groups in liquefied sand

Dynamic p-y curves for vertical and batter pile groups in liquefied sand

Kinematic response of vertical and batter pile groups in non‐linear soft soil

AbstractThis paper presents a comprehensive numerical study on kinematic response of vertical and batter pile groups in soft soil, where soil non‐linearity, batter angle, pile spacing and excitation frequency are related to pile‐cap displacements, rotations, maximum pile moments, shear forces and axial forces. The finite element model is constructed in OpenSees MP, and parallel computing is utilized for a better (faster) performance. Results reveal that soil non‐linearity has a profound impact on the kinematic interaction. Increasing batter angle decreases horizontal displacements but increases rotations. Batter pile groups yield lower spectral accelerations compared to vertical pile groups. For high , the spectral accelerations of the pile‐cap may be lower compared to the spectral acceleration of the seismic input motion. Estimation using non‐linear interaction factors conservatively estimates pile‐cap displacements and rotations, while roughly captures the effects with respect to batter angle and frequency content within the specified framework.

Performance of high-rise pile group adjacent slope

For the consideration of required elevation, pile shafts are partially buried in the soil stratum and partially exposed above the ground surface, known as high-rise pile group (HRPG). The HRPG is extensively used in the construction of infrastructures and is usually adjacent the slope. It is frequently subjected to high lateral loads from the superstructure, leading to considerable displacement and bending moment. To alleviate the deformation and internal force of HRPG, a batter pile is employed, forming the high-rise batter pile group (HRBPG). A numerical simulation is conducted to observe the response of HRPG foundation subjected to downwards lateral load adjacent slope. The effects of slope angle, cap elevation, and lateral loading magnitude are determined. Results of HRBPG are compared with traditional high-rise vertical pile group (HRVPG). Conclusions can be drawn as follows. (1) The slope has significant effect on the displacement and bending moment of HRPG, so it should be considered in the design process. The displacement and bending moment of pile shaft increase gradually with the slope angle (0°–30°) and then they have a sharp growth (45°–60°). (2) With the rise of cap elevation, the displacement increases dramatically, whereas the bending moment rises and then falls. The displacement is highly sensitive under lateral loading with a high cap elevation; the higher the elevation is, the greater the displacement will be. Special attention should be paid when a high pile cap is adopted under large lateral loading. The displacement and bending moment of HRBPG are considerably smaller than those of HRVPG at a high pile cap elevation. (3) The displacement and bending moment are relatively small when a diminutive lateral loading is performed; however, they have a sharp growth under large lateral loading. The larger the load is, the greater the bending moment and displacement will be. (4) The displacement of the leading pile is slightly larger than that of the trailing pile, whereas the bending moment of the rear pile is larger than that of the leading pile. The pile shaft displacement above the ground surface is considerably larger than that below. The maximum bending moment occurs at the pile head, and the pile toe has minuscule bending moment. (5) The use of batter pile is beneficial for reducing the displacement and bending moment, whereas the slope and lateral loading are detrimental.

Comparative Assessment of Dynamic Behavior of Vertical and Batter Pile Groups under Horizontal Excitation

Comparative Assessment of Dynamic Behavior of Vertical and Batter Pile Groups under Horizontal Excitation

Study on Vertical Piles Batter Piles and Pile Groups Under Uplift Load Conditions in Non-Cohesive Sub-soil

Model study was carried out in the laboratory to know the effect of uplift loads on vertical piles, batter piles and pile groups. Mild steel piles having 22 mm outer diameter and 1 mm thickness were considered for the study. Different slenderness ratios of 18, 28, and 38 and various angles such as 0°, 15°, 25°, 35°, and 45° were considered for the study. Sand was poured at a fixed relative density in the mild steel tank. The experimental study shows that the pile and pile group attain a maximum value of uplift load capacity when the batter angle reaches to 35°. Further, increase in batter angle causes a reduction in the uplift capacity of the pile. It is also noticed from the experiment that the uplift capacity increases with the slenderness ratio of the pile but its variation is not linear. Pile group of four piles with two vertical piles having L/D ratio 38 and two batter piles of L/D ratio 28 offers same resistance as of the same pile group with all the piles having L/D ratio 38. Numerical modeling was performed using Plaxis-3D to analyse the behavior of vertical piles, batter piles and pile groups under uplift loads. A good correlation between Plaxis-3D results and experimental results was observed.

Experimental study of vertical and batter pile groups in saturated sand using a centrifuge shaking table

Experimental study of vertical and batter pile groups in saturated sand using a centrifuge shaking table

Experimental investigation of inclined RC pile groups under horizontal static and impact loads

In engineering practice, inclined pile groups have been widely used for resisting lateral loads owing to their great lateral stiffness. This paper investigates the structural performance of inclined reinforced concrete (RC) pile groups subjected to horizontal static and impact loads through experimental studies. Using the horizontal impact facilities, a total of twelve 2 × 1 inclined RC pile groups were tested under horizontal static or low-velocity impact loads. The twelve test specimens include three types of pile groups including two types of inclined pile group with inclination angle of 9° and 18° and one type of double vertical pile group with inclination angle of 0°. For each type of pile group, four specimens with identical geometric dimension are prepared and tested under horizontal static load and three different level of horizontal impact loads initiated from different impact velocities, respectively. It can be found that, the variation of inclination angle significantly affects the static and dynamic behaviour of pile groups. Two, three and four plastic hinges are developed at the static or impact loading for the RC pile groups with inclination of 18°, 9° and 0°, respectively. With the increase of inclination angle from 0° to18°, the failure modes of the RC pile groups under impact transits from ductile to brittle type.

Temporal Evolution of Clear-Water Local Scour at Aligned and Skewed Complex Bridge Piers

Scour at bridge piers is time-dependent. In this paper, temporal evolution of clear-water scour at complex bridge piers is studied experimentally. The pier model has a typical form comprising three components, namely a rectangular column, a rectangular pile-cap, and a group of vertical piles underneath. Various relative pile-cap positions and skew angles (α) from 0° to 45° were used to investigate their influence on scour evolution. New functions are proposed to fit temporal data and determine the equilibrium scour depth with better accuracy. The results show that the locations for scour initiation and the maximum scour depth may be different, and their relationship varies with pile-cap position and pier skew angle. Highly skewed piers tend to overcome the influence of width ratio of column to pile-cap (Dc/Dpc) on scour evolution, as the column itself becomes dominant. The sensitivity of scour evolution to pier skew angle decreases with higher pile-cap position, especially when it is entirely above the original bed. Four scour development stages were identified for complex piers, including initiation, stagnation, a developing stage, and equilibrium, with each stage being highly dependent on the degree of exposure of each of the pier components. The description of each development stage for different situations is given. The equilibrium time scale t* and the equilibrium scour depth dse for complex piers have similar dependence on flow shallowness ratio (y0/De) and sediment coarseness ratio (De/d50), as per the equation proposed by an authors’ previous study (Yang et al. 2018). A new equation is proposed to correct the percentage rate of scour development. The correction is especially useful for aligned complex piers, for which the rate of scour time development may be much lower than that for single-column piers. In general, we recommend using the modified Sheppard-Melville method and the corrected time-scale equation in this paper to predict clear-water equilibrium scour depth and scour evolution at complex bridge piers.

Behavior of batter pile group models embedded in sandy soil under monotonic loading

This paper introduces an attempt to examine the effect of vertical monotonic load on the batter pile group models on its ultimate vertical load capacity. A fourteen steel solid pile models are used in this research. Three lengths of piles are selected (300, 400, and 500 mm) for embedment ratios (depth to width) 15 and 25, respectively. Batter piles are embedded in three different relative densities of sand bed (loose, medium and dense). The constant rate penetration test (CRPT) method was selected using a manufactured driving hammer to install the pile models in a steel box with dimensions (1000, 750 and 700) mm. The vertical cyclic load is conducted by a special hydraulic apparatus. The results indicate that the batter-vertical load capacity (BVLC) ratio increased by the increase in the embedded pile length. The batter pile group has a higher capacity at 20 degrees batter angle as compared with the vertical groups. Vertical pile groups exhibited more efficiency, which increases when pile length increases while decreases when the relative density is increased. The batter-vertical load capacity ratio increases when the embedded pile length increases and decreases with the increase in the relative density.

Evaluating the effect of pile spacing and configuration on the lateral resistance of pile groups

In this study, the effects of pile spacing and pile group (PG) configuration on the static lateral resistance of PGs are investigated using finite element (FE) numerical modeling. Three-dimensional FE models for a 4 × 4 vertical, battered, and mixed PG configurations were developed and analyzed at three pile spacings (3D, 5D, 7D) and for three clay soils (soft, medium, stiff). The nonlinear pile and soil behaviors were accounted for using elastoplastic constitutive models and a pile–soil interface model. The effects of pile spacing and configuration on the group efficiency, axial reaction in piles, and p-multipliers are discussed. The results showed that the battered PG had the largest group efficiency followed by mixed PG and then vertical PG at all pile spacings. The axial reaction in piles decreased only in two pile rows when the pile spacing increased in the three PGs. The back-calculated p-multipliers were different between the PGs with the largest values in the battered PG. Modifications to the p-multipliers used in practice are proposed to account for the effect of configuration in the battered and mixed PGs.

Model Researchon Oblique Load Carrying Capacity of Batter Pile Groups

Experimental investigations on model vertical and batter pile group in uniform sands are presented. Mild steel piles in two different medium ofsand are used in this investigation. The tests are conducted on model steel pile installed in medium, and dense sand withL/d ratio is 18.75 and different batter angles of 0°, 10°, 20°, and 30°. These piles are constructed in sand and subjected to uplift loads of 60° inclination. It was found that the uplift capacity of vertical and batter piles under inclined pulls increased with increase in inclination of piles.it is also observed it a negative batter pile has greater uplift load than positive batter pile

Variations in the dynamic response of structures founded on piles induced by obliquely incident SV waves

SummaryAlthough the seismic actions generally consist of a combination of waves, which propagates with an angle of incidence not necessarily vertical, the common practice when analyzing the dynamic behavior of pile groups is based on the assumption of vertically incident wave fields. The aim of this paper is to analyze how the angle of incidence of SV waves affects the dynamic response of pile foundations and piled structures. A three‐dimensional boundary element‐finite element coupling formulation is used to compute impedances and kinematic interaction factors corresponding to several configurations of vertical pile groups embedded in an isotropic homogeneous linear viscoelastic half‐space. These results, which are provided in ready‐to‐use dimensionless graphs, are used to determine the effective dynamic properties of an equivalent single‐degree‐of‐freedom oscillator that reproduces, within the range where the peak response occurs, the response of slender and nonslender superstructures through a procedure based on a substructuring model. Results are expressed in terms of effective flexible‐base period and damping as well as maximum shear force at the base of the structure. The relevance and main trends observed in the influence of the wavefront angle of incidence on the dynamic behavior of the superstructure are inferred from the presented results. It is found that effective damping is significantly affected by the variations of the wave angle of incidence. Furthermore, it comes out that the vertical incidence is not always the worst‐case scenario.

Interactions between multi-directional irregular waves and a pile group in a side-by-side arrangement: Statistical analysis

Pile groups are widely used structures in coastal and ocean engineering, such as in cross-sea bridges and offshore wind turbine foundations. The effect of a pile group must be considered when calculating the wave forces on piles. In addition, real sea waves are multi-directional waves. However, the associated regulations and studies have mainly concentrated on the action of a unidirectional wave on pile groups. Few studies have considered the interactions between multi-directional irregular waves and pile groups. In this study, we experimentally investigated the interactions between multi-directional irregular waves and a small scale, vertical bottom-mounted pile group comprising nine piles in a side-by-side arrangement. We propose a new parameter: KCLD1/3 = KC1/3 × L/D, to comprehensively consider the effects of the relative pile diameter D/L and KC1/3 number on the wave inline force and transverse force on piles. The results show that directional spreading has a significant effect on the interaction between multi-directional irregular waves and piles, especially on the transverse force of piles. The relationships between the inline force, transverse force, and resultant force are studied, and the differences in the wave force among different piles are determined. These results may provide a reference to facilitate the design of engineering structures.

Behavioural analysis of vertical and batter pile groups under vertical and lateral loading in sand

Laboratory model tests were carried out to study the behaviour of vertical piles and batter pile groups under vertical and lateral load. The model pile groups were made up of mild steel rod of 8-mm diameter. Parameters such as degree of batter and different length to diameter ratios of 7.50, 15.00 and 22.50 were considered in this study. The size of the model tank was 1000 mm × 1000mm × 800 mm. Experiments were performed on 3 × 3 model pile groups with a row of batter piles both positive and negative in addition to vertical pile groups with batter angle 0° in sandy soil subject to vertical and lateral loads. It was observed that the behaviour of vertical pile groups and group of piles with batter piles were similar but it showed substantial variation in the capacity of pile groups. Results indicated that the load–settlement relationships were non-linear for all model pile groups both under vertical and lateral loading. Numerical FEM analysis using ABAQUS/CAE 6.11 was also used to compare and validate the load carrying capacity of pile groups obtained from the experimental model tests.

Experimental investigation of vertical and batter pile groups subjected to dynamic loads

In the present work, the dynamic responses of cast in-situ reinforced concrete vertical and batter pile groups constructed in the silty sand have been investigated. An experimental study was carried out on four pile groups: a group of three vertical piles and a group of three batter piles arranged in triangular pattern, and a group of four vertical piles and a group of four batter piles arranged in square pattern. All batter piles were inclined at 20° to the vertical. Each pile group had a rigid pile cap supporting the oscillator-motor assembly for generating the dynamic loads. The pile groups were tested by varying the exciting force level in different loading direction, and their responses were compared in terms of resonant frequency and peak displacement. The peak displacement of the batter pile group shows a significant reduction (about 25% and 50% in vertical and lateral directions, respectively) compared to their respective vertical pile groups.