Settlement Of Pile Groups Research Articles

Numerical Analysis of Bridge Foundation in Dry and Saturated Soils with Effect of Halabjah Earthquake (Case Study)

The importance of this study comes from the expected risks as the bridge foundations is exposed and their effects on the lives of users. So, the aim of this study is to investigate the influence of earthquakes loading on the bridge foundation subjected to combined loading as a case study for Al-Shareef Bridge/ Diyala province in Iraq. The numerical analysis highlights the foundation settlement firstly, in flat ground and secondly, in slope ground with applied different value of axial loads starts from the zero-working load (no loading) to maximum working load. All cases were investigated in dry and saturated soil under effect of Halabjah earthquake. Plaxis 3D is one of the finite element programs that had been used to simulate the soil foundation interaction by Mohr-Coulomb failure criteria for the soil model and linear elastic for concrete materials. The conclusions of this study showed that the settlement of pile group is increased in saturated soil about 5% more than the dry soil under the effect of static loads for both groups, but, the settlement in group (2) is increased about 10% more than the group (1) in dry and saturated condition. The settlement in saturated soil is increased to 12% more than the dry soil when Halabjah earthquake loads is applied.

Estimation of Settlement of Pile Group in Clay Using Soft Computing Techniques

Estimation of Settlement of Pile Group in Clay Using Soft Computing Techniques

Effects of excavation and construction sequence on behavior of existing pile groups

In congested urban areas, new structures are regularly constructed next to high-rise buildings. At different stages of excavation for the new structures, settlement and tilting of the adjacent piled buildings may be occurred. Thus, attention here will be focused on the interaction behavior between deep excavation and adjacent piled foundations. Accurate prediction of soil movement and pile response plays an important role in preventing damages to adjacent buildings. Finite-element models are employed to compute the pile group responses. The parametric study has been performed by varying pile group configurations, center-to-center pile spacing, and new building load. Two, four, and six capped head pile groups next to excavation sites have been examined. In this paper, discussion centers on settlement and tilting of the pile groups nearby an excavation in fully saturated sand. The influence of pile group configuration and new building loads are systematically investigated. New building can be constructed in the excavated area after completion of the excavation. The effect of new building construction sequences is also investigated. Results provide confirmatory evidence that, excavation depth has the most significant effect on pile settlement and pile cap tilting. High pile cap tilting and small pile group settlement are apparent in case of two piles near the excavation. For the four pile group, the induced tilting of pile cap decreases as spacing between the piles increases. Due to construction of the new building, the settlement is exacerbated but the tilting is moderated.

Analisis Daya Dukung Fondasi Bored Pile Pada Rumah Sakit Sultan Imanuddin Pangkalan Bun

This study intended to analyze the bearing capacity of single bored pile, the bearing capacity of the bored pile group, the load carried, the safety factor, and the settlement that occurs. The first calculation method is Schmertmann and Nottingham method, and the second calculation method is Meyerhof method. Based on the calculation of the bearing capacity of a single bored pile using the Schmertmann and Nottingham method obtained a value Qu = 49005,88 kN, while the Meyerhof method obtained a value Qu = 1633.71 kN. The calculation results for bearing capacity of the pile group using the Schmertmann and Nottingham method obtained a value Qg = 164169,70 kN and the Meyerhof method obtained a value Qg = 5472.93 kN. The results of the load carried by the bored pile group using Schmertmann and Nottingham method is Qi = 353.98 kN ≤ Qg = 164169.70 kN which means it’s still within safe limits. Using the Meyerhof method is Qi = 353.98 kN ≤ Qg = 5472.93 kN which means it is still within safe limits. The safety factor using the Schmertmann and Nottingham method obtained SF = 463.78 and using the Meyerhof method obtained SF = 15.46 which means it is very safe. Total settlement of a single bored pile is S = 0.0142 m ≤ 0.04 m which means it is safe. And the settlement of the bored pile group is Sg = 0.03 m ≤ 0.08 m which also means it is safe

Three-dimensional numerical analysis of the generalized group effect in monitored continuous flight auger pile groups

The interaction mechanisms related to the group effect between piles and between pile groups significantly influence the soil-structure interaction process. This interaction causes the superposition of stresses and, in general, makes the pile group settlement different from the settlement of an isolated pile. The objective of the present paper is to evaluate the soilstructure interaction mechanisms of buildings with foundations of monitored continuous flight auger piles (CFA) in a stratified soil mass, with the presence of an intermediate soft soil layer. Hence, it is particularly analyzed the group effect between piles of a group and the group effect between all pile groups from a foundation of a study case instrumented by means of numerical modeling, considering the effect of the soft soil layer. The results show the significant group effect on displacements, showing the increase in settlement due to the overlapping of the tension bulbs of the piles and neighboring pile groups.

Analysis of Settlement of Group Pile Foundation in Linear Viscoelastic Soil

The settlement of a group pile foundation is the result of elastic-plastic settlement of the pile and rheological settlement of the soil. Unfortunately, most research only considers elasto-plasticity settlement of piles or rheological settlement of soils. Classical theories like the Poynting-Thompson model only provide some prediction for the elasto-plasticity behavior of pile groups, which cannot satisfactorily reflect the total settlement characteristics of pile group foundation. In the current paper, we presented a method to study settlement behaviors of pile group foundation in linear viscoelastic soil based on the pile-pile interaction factors, the calculated equation of settlement of single piles and pile groups under vertical loads that are derived, the influence law of pile end resistance, pile spacing, slenderness ratio, elastic modulus ratio, and Poisson ratio on pile end load ratio, and the interaction factors that have been presented. Finally, some typical predictive examples have been presented for a 2 × 2, 3 × 3 group pile showing settlement from a field test. It is found that the pile-pile interaction factors increase with the increase of the pile-soil elastic modulus ratio and length-to-diameter ratio but decrease with the increase of the ratio of distance to diameter, and the ratio of distance to diameter has little effect on the interaction factor when pile spacing is more than 10 d (d is the diameter of the pile). The error between the field test results and computed data is 14.9%, the settlement calculated by the present method shows good agreement with the reported results, and the correlativity coefficients R2 are greater than 0.9223, which signifies that the present method is suitable for the theoretical calculation and prediction of the composite foundation settlement of linear viscoelastic soil when piles are used to strengthen the foundation. The method would provide a unique view to quantitative prediction of the settlement characteristic of group pile foundation.

Parametric Study of Twin Tunneling Effects on Piled Foundations in Stiff Clay: 3D Finite-Element Approach

Due to urbanization, development of society, and growth of population, there are new demands for tunneling technique to facilitate the public transport as well as high-rise buildings to accommodate an increasing population. Piled foundations are commonly preferred for the construction of high-rise buildings. It is, therefore, unavoidable that tunnels must be constructed near extant buildings resting on piled foundations. Inevitable movement of the ground due to stress changes induced by a tunnel can induce additional settlement and reduce the load-carrying capacity of nearby pile foundation systems. This numerical parametric study investigates the responses of two-by-two piled raft to twin side-by-side tunnels either near the mid-depth of the pile shaft or adjacent to or below the pile toe in stiff clay. In addition, it investigates the effects of different group configurations of the piled raft and elevated pile group. The ground in all the finite-element analyses was modeled using the hypoplasticity (clay) model because of its ability to capture degradation of soil stiffness at a small-strain level. Twin tunneling below the pile and near the middepth of the pile shaft caused the largest and smallest settlement of the piled raft, respectively. Unlike induced piled raft settlement, the most significant transverse tilting of the raft is induced after the advancement of the first tunnel. After the twin tunneling near the pile shaft was completed, the raft was separated from the ground, and a portion of the working load carried by the raft was transferred to the piles. The computed results have revealed that the induced settlement of the elevated pile group was significantly larger than that of the piled raft. A significant effect number of piles in the group was found on the piled raft responses to tunneling.

Model Test Study on Bearing Capacity of Nonuniformly Arranged Pile Groups

The uniform arrangement of pile groups widely used in practice often causes obvious differential settlement of pile foundations. To decrease differential settlement of pile groups, individual piles nonuniformly arranged can be adopted. This paper presents a model test study on the bearing capacity of pile foundations under different pile arrangements. A versatile full-automatic loading system and data acquisition and analysis systems of the model test were developed. Using the model test setup, the response of a single pile subjected to axial load was clarified, and the reinforcing effect between an axially loaded pile and a load-free pile was then analyzed. Furthermore, model tests were carried out to assess the behavior of the pile groups composed of individual piles with variable length and diameter. For practical purposes, some suggestions on the nonuniformly arranged individual piles within pile groups were given to decrease differential settlement among each individual pile and make maximum use of the bearing capacity of each individual pile.

Response of Piles Group embedded in Sandy Soil with Cavities to Seismic Loading

This research is looking at the impact of cavities on the group pile foundation settlement subjected to seismic loads in the dry sandy soil of dry unit weight 16 kN/m3. The finite element software (Plaxis 3D 2020) was used to represent the way of behaving of gypseous soil under the group of piles with cavity formation. The study included the presence of a single cavity, the group of cavities, and different diameters of the cavity in different locations. The horizontal distance from the centerline of the cavity to the centerline of the pile or group of piles is defined as (X), and the vertical distance from the bottom of the pile to the cavity centerline is defined as (Y). The variations in cavity locations, numbers, and diameters were all studied. The results showed that the impact of the earthquake (El Centro) of the settlement of pile group with cavity increased the settlement when the cavity was located near the edge of piles and that when the diameter of the cavity increased, the settlement has been increased for the same vertical distance of the cavity below the group piles and under the influence of the earthquake. The effect of cavity diminishes at a horizontal distance a cavity at horizontal depth (X = 4D).

Settlement of Pile Groups in Sand.(Dept.C)

This article describe the methods for predicting the settlement of the pile groups in sand, and a development was done based on (Vesic 1967) and (Berezantzev 1961) taking into account the stats of soil, relative density, of sand and method of installation. The method was used to predicts the settlement of pile groups for actual pile groups of B high rise tower in Cairo, good agreement between the observed and the predicted settlement recommend the use of this method.

On the Influence of Pile Foundation Settlement of Existing High-Rise Buildings on the Surrounding Buildings

Pile foundation settlement is a kind of foundation form. In recent years, because of the increasing population and economic development in China, high-rise buildings have emerged in people’s vision. Due to the development of engineering construction, the type and technology of pile foundation, as well as the control and detection of the single pile and pile group have been greatly improved. In view of the influence of pile foundation settlement on the surrounding environment of high-rise buildings, this paper mainly studies from the angle of single pile settlement and pile group settlement. According to the construction method of pile foundation, the static pressure sinking pipe cast-in-place pile can produce soil squeezing effect in pile foundation construction. The experimental analysis was carried out. According to the engineering example, finite element numerical simulation is used to analyze the influence degree of pile foundation settlement on adjacent buildings with and without raft, and the feasibility and correctness of numerical simulation are analyzed by comparing the simulation results with the measured values. This paper mainly studies the influence of pile foundation settlement of high-rise buildings on surrounding buildings from the aspects of problems and solutions.

Finite element modelling to predict the settlement of pile groups founded above compressible layers

It is widely accepted that the presence of compressible layers beneath pile groups can substantially increase the settlement of a pile group. Furthermore, as the size of the pile group increases this effect is magnified and further complicated by the load distribution across the pile group. A number of simplified methods, such as the equivalent raft or equivalent pier method, are often employed to estimate the settlement of pile groups founded over a compressible layer, however, such methods can lead to both overly conservative and un-conservative results and large variations in results between methods. More recent methods have explored the use of power law functions or energy principles to analyse piles and pile groups in non-homogeneous soil conditions, however, these methods can be difficult to apply in practice. With the availability of modern computers and the advancement of commercially available numerical analyses packages, it is now possible to use the finite element method to analyse pile groups overlying compressible soil layers in order to better understand this problem. This technical note presents some initial results and associated design charts based on the finite element method to provide preliminary estimates of settlement of pile groups overlying compressible layers. Some dimensionless design charts are provided for a range of commonly encountered geotechnical conditions and pile group geometries.

Reliability analysis of settlement of pile group

Considering the highly variable nature of soil, reliability analysis of pile foundation is being explored in the modern scientific era. The paper investigates the application of relevance vector machines (RVM), generalized regression neural network (GRNN), genetic programming (GP) and adaptive-network-based fuzzy inference (ANFIS) in reliability analysis of settlement of pile group. The simulation is checked using Monte Carlo simulation (M-C). The performance of models is ascertained using various performance parameters and Taylor diagrams. The normality and homogeneity in performance of the models is tested by carrying out Anderson–Darling (AD) test and Mann–Whitney U (M–W) test, respectively. The paper concludes that the performance of RVM, GP and ANFIS were excellent while that of GRNN was poor.

PILE SETTLEMENT INDUCED FROM SOIL MOVEMENT DUE TO BREAKDOWN OF RETAINING WALL

Very few studies measured the settlement of retaining wall supported piles foundation under a soil movement. This study explores the pile settlement induced from the sudden breakdown of a closely located retaining wall using a small-scale experimental model. Various factors affect the pile settlement, but the influence of the embedment ratio of the pile and collapsed height of the retaining wall is relatively more visible. The induced settlement decreases with pile embedment depth and increases with the collapsed height of the retaining wall. The pile settlement initially increases at a higher rate with an increase in the collapsed height to a certain extent, beyond which, becomes relatively less observable. Pile group settlement reduces with the increase in spacing and the number of piles in longer piles. However, opposite trends have been observed in piles with a smaller embedment ratio. The settlement reduces logarithmically with the increase in the distance between piles and the retaining wall. Pile groups with small embedment ratio are severely more affected by the breakdown of the retaining wall than the piles of a large embedment ratio. Pile groups placed parallel to the retaining wall are more affected than those placed orthogonally.

Reliability Analysis of Settlement of Pile Group in Clay Using LSSVM, GMDH, GPR

Robust and reliable design at certain levels of safety has earned lot of attention in recent. To build over the limitations of FOSM based reliability analysis, the paper proposes least square support vector machine (LSSVM), The Group Method of Data Handling (GMDH) and Gaussian process regression (GPR) based reliability analysis of pile group resting on cohesive soil. LSSVM is an improvement over support-vector machines (SVM) which uses linear systems instead of complex quadratic equations. GMDH is a self-organized neural network capable of solving complex non-linear problems. GPR is an effective Bayesian tool of machine learning the performance of the developed models is ascertained using various statistical parameters and Taylor curves. The reliability indices of the simulated values are compared to that of the actual values obtained from FOSM. The results show that all the models are applicable for reliability analysis of settlement of pile group.

Finite element prediction on the response of non-uniformly arranged pile groups considering progressive failure of pile-soil system

A uniform arrangement of individual piles is commonly adopted in the conventional pile group foundation, and basin-shaped settlement is often observed in practice. Large differential settlement of pile groups will decrease the use-safety requirements of building, even cause the whole-building tilt or collapse. To reduce differential settlement among individual piles, non-uniformly arranged pile groups can be adopted. This paper presents a finite element analysis on the response of pile groups with different layouts of individual piles in pile groups. Using the user-defined subroutine FRIC as the secondary development platform, a softening model of skin friction and a hyperbolic model of end resistance are introduced into the contact pair calculation of ABAQUS software. As to the response analysis of a single pile, the reliability of the proposed secondary development method of ABAQUS software is verified using an iterative computer program. The reinforcing effects of individual piles is then analyzed using the present finite element analysis. Furthermore, the response of non-uniformly arranged pile groups, e.g., individual piles with variable length and individual piles with variable diameter, is analyzed using the proposed numerical analysis method. Some suggestions on the layout of individual piles are proposed to reduce differential settlement and make full use of the bearing capacity of individual piles in pile groups for practical purposes.

Centrifuge and numerical modelling of stress transfer mechanisms and settlement of pile group due to twin stacked tunnelling with different construction sequences

Abstract This study reports a series of centrifuge model tests, aiming at investigating the effects of construction sequence of twin stacked tunnels advancement on an existing pile group under working load in dry sand. Twin stacked tunnelling was simulated after the other with the first tunnel excavated near the mid-depth of the pile shaft and the second either next to the toe of the pile (test ST) or below the pile (test SB). In addition, two tests were performed with change of construction sequence of twin stacked tunnels (i.e. tests TS and BS). The first tunnel was excavated either near the pile toe (test TS) or below the pile (test BS) and second tunnel near the mid-depth of the pile shaft. The centrifuge tests were back-analysed by three-dimensional finite element analyses using a hypoplastic model, which takes strain-dependent and path-dependent soil stiffness into account. The measured and computed results have revealed that change of twin stacked tunnels construction sequence had substantial effects on pile group settlement, pile cap tilting and lateral movement in the pile group. In contrast, no significant effect was found on induced bending moment and load transfer mechanism in the piles.

New Method for Calculating the Settlement of Single Pile and Pile Group in Soft Soil Area

This paper fits the τ‐z curve of a single pile by mathematical methods. Based on the one‐dimensional similarity of the τ‐z curves, the τ‐z curves of single pile under different loads are derived. It studies the distribution of the axial force of a single pile by taking the self‐weight of the pile and the pile‐end resistance ratio into account and establishes the calculated equation of settlement for single pile. The mutual reinforcing effect between the piles is fully considered, and the settlement of each foundation pile in the pile group is deduced in use of shear displacement method. The example analysis shows that the axial force distribution of single pile considering the self‐weight and the pile‐end resistance ratio is in good agreement with the experimental data. The settlement error of a single pile calculated by the traditional method is 18.52% compared with measured value. When the self‐weight and end resistance ratio are not considered, the error reaches 2.26%. However, the error could reduce to 1.64% when they are taken into consideration. It has a good applicability to calculate the settlement of pile group through the τ‐z curves of single pile. Also, it can better forecast the settlement behavior of the pile group under similar conditions.

Numerical Parametric Study of Settlement and Load Transfer Mechanism of Pile Group Due to Twin Stacked Tunnelling with Different Construction Sequences

Construction of tunnels in urban cities may induce excessive settlement and tilting of nearby existing pile foundations. In this study, numerical parametric study was conducted to investigate the influences of twin stacked tunnelling with different construction sequences on an existing (2 × 2) pile group. Twin stacked tunnelling was simulated one after the other with the first tunnel excavated near the mid-depth of the pile shaft and the second either next to the toe of the pile (case ST) or below the pile (case SB). In addition, two more analyses were performed with change of construction sequence of twin stacked tunnels (i.e. cases TS and BS). The first tunnel was excavated either near the pile toe (case TS) or below the pile (case BS) and second tunnel near the mid-depth of the pile shaft. The different construction sequence of twin stacked tunnels at different depth had a limited effect on induced pile group settlement, tilting, lateral deflection and load transfer mechanism. The computed cumulative pile group settlement was about 22% larger for tunnelling sequence TS than for tunnelling sequence TS.

Three-dimensional centrifuge modelling of the effects of tunnelling on vertical behaviour of pile group

In densely built urban cities, tunnels are likely to be constructed adjacent to existing deep foundations. Tunnelling activity inevitably induces soil stress changes and soil movements in the ground, which may affect nearby existing pile foundation. Although a number of studies have been carried out by various researchers to investigate tunnelling effects on piles, the three-dimensional effects of tunnelling on pile group have not been well-investigated and understood. In this paper, a three-dimensional centrifuge test was carried out to investigate the effects of tunnel construction on a pile group in dry sand. The diameter of each pile was designed as 0.8m (in prototype) and the diameter (D) of the simulated tunnel is 6.08m. Tunnel advancement was modelled in-flight by controlling a volume loss of 1.3%. The tunnelling process was divided into four stages to model the three-dimensional tunnelling effects. The closest distance between the tunnel and the pile group was 1.5m at the pile toe. Measured settlement of pile group, as well as axial force distribution of piles in the pile group are reported and discussed.