Numerical and Experimental Studies of Wave Propagation Induced by Pile Driving

. This paper presents results of numerical and experimental studies to predict the peak particle velocity (ppv) induced by a pile driving. By utilizing a professional finite element software, Plaxis 2D Dynamic, this study analyzed ppv due to pile driving in clays for various soil stiffness and various embedded pile lengths. For verification, a full scale field test of pile driving was performed in East Kalimantan with installed instrumentations of accelerations. Results of both instrumentation and numerical analysis show that ppv depends on distance and soil rigidity. The closer the object to pile tip, the larger the ppv that will be produced. The more rigid the soils at the pile tip, the larger the ppv, too. The results also show that both field test and numerical analysis results are comparable. Finally, this paper proposes a chart to predict the ppv of soils due to pile driving in clays. The output of the proposed method is the predicted ppv for various distances from pile driving location

Modelling the response of single passive piles subjected to lateral soil movement using PLAXIS

Response of single pile subjected to lateral displacements of soil mass using 3D finite element software (PLAXIS) is studied. Embedded pile feature in which the pile composed of beam elements with special interface elements to represent pile-soil interaction is used. The Mohr–Coulomb elastic–plastic constitutive model was employed for the soil stress-strain behaviour. A good agreement between laboratory and predicted results is observed in the validation analysis. A parametric study was conducted to investigate the influence of soil Young's modulus and soil movement profile on the response of single "passive pile". The software results revealed that the distribution of bending moment along the pile length vary considerably and was in a very good agreement with the real pile behaviour when adopting a variation of soil elastic modulus with depth instead of choosing a constant value

Seismic Performance and Design of Bridge Foundations in Liquefiable Ground with a Frozen Crust

INE/AUTC 12.3

Interaction of piled foundation with a rupturing normal fault

Post-seismic observations in the 1999 Kocaeli earthquake in Turkey have indicated that piled foundations may be less suitable than stiff mat foundations in defending a structure against a major normal fault rupturing underneath. This paper explores the interplay of such a rupture, as it propagates in a moderately dense sand stratum, with an embedded two by four pile foundation (typical of common highway overpass bridges). An experimentally validated numerical scheme and constitutive law for sand are utilised in the analysis, with due attention to realistically modelling the non-linear pile–soil interface and the structural inelasticity of the piles. Parametric results identify and elucidatethe development of different rupture mechanisms as a function of the exact location of the group relative to the fault and of the magnitude of the tectonic displacement (the fault offset). It is shown that even for a moderate fault offset (less than 0.5 m), lightly reinforced piles will fail structurally, while also forcing the pile cap and the bridge pier on top to undergo substantial rotation anddisplacement. Even heavy reinforcement might not prevent potentially disastrous displacements. Pile inelasticity is unavoidable and should be acceptable as part of a ductility-based design. However, despite the possible survival of the piles themselves, letting them reach the limit of their ductility capacity may lead to large cap rotation and displacements, which are likely to impose severe demands on the superstructure. Piled foundations may indeed be inferior to rigid raft foundations in protecting a structure straddling an active seismic fault, but with few notable exceptions

Nonlinear analysis of single model piles subjected to lateral load in sloping ground

Uncertainty associated due to soil-pile interface and unreliable assessment of the pile bearing capacity constructed in sloping ground have been cited as barriers to the wide utilizations of the deep foundations in sloping ground. Extensive studies were conducted concerning the failure mechanism of laterally loaded piles penetrated in horizontal ground. However, the number of studies regarding the pile in sloping ground is scarce in literatures. In this research, a detailed of numerical modelling using Winkler theory is discussed on the basis of finite element and experimental tests for models input parameters to examine the behaviour of the model piles penetrated in sandy soil subjected to lateral load. An Aluminium of open-ended model piles were utilized embedded in dense dry sloping sand of 1.5 horizontal to 1 vertical (1.5H: 1V). Three piles aspect’s ratio of (18, 24 and 30) were selected to examine the behaviour of both flexible and rigid pile. The results revealed that lateral soil stiffness, effective passive wedge, flexural rigidity, EI, pile slenderness’ ratio (lc/d) and sand morphology as confirmed by scanning electronic microscopy, SEM observation play a key-role on the factors effecting the pile capacity and its lateral response

Numerical evaluation of the pipe-pile buckling during vibratory driving in sand

The buckling of steel pipe piles during vibratory driving is numerically studied using the Multi-Material Arbitrary Lagrangian-Eulerian (MMALE) method. This method handles the large soil deformations that occur during pile driving and other geotechnical installation processes. The Mohr-Coulomb and an elastic-perfectly plastic material model are used to model the soil and the pile mechanical behavior, respectively. The result of a small-scale pile driving experiment is used to validate the numerical model. The penetration trend agrees well with the experimental measurements. Thereafter, four case scenarios and their possible effects on pile buckling, namely the presence of heterogeneity in the soil (a rigid boulder inside the soil) and the existence of geometrical imperfection modes in the pile (ovality, out-of-straightness, flatness) are investigated. This study shows that a combination of local and global buckling initiates at the pile tip and the pile shaft, respectively. During the initiation of buckling, a decrease in the penetration rate of the pile is observed compared to the case where no or minimal buckling occurs. It is shown that a less portion of the driving energy is spent on the pile penetration and the rest is spent on other phenomena such as buckling, resulting in less pile penetration. The cross section of the pile tip after buckling takes a form of a “peanut”, yet with a different geometry for each case. In cases where the model was initially symmetric, an asymmetric shape in cross section of the pile tip was obtained at the final stage which can be attributed to complex soil-structure interaction. The results of the numerical approach provide promising results to be used as an evaluation tool to reach reliable predictions in pile installation practice

Seasonally Frozen Soil Effects on the Seismic Performance of Highway Bridges

INE/AUTC 12.0

Performance of axially loaded single pile embedded in cohesive soil with cavities

The stability of a single model pile located adjacent to a continuous cavity was studied. This paper is an attempt to understand the behaviour of axially loaded single pile embedded in clayey soil with the presences of cavities. The performance of piles located in such soils was studied analytically. A verification analysis was carried out on available studies to assess the ability of analytical model to correctly interpret the system behaviour. The study was adopted by finite element program (PLAXIS). The study included many cases; in each case, there is a critical value in which the presence of cavities has shown minimum effect on the pile performance. Figures including the load carrying capacity of pile with the affecting factors are presented. These figures provide beneficial information for pile design constructed close to underground cavities. It was concluded that the load carrying capacity of the pile is reduced by the presence of the cavity within the soil mass. This reduction varies according to the size and location of cavity

High-Mast Light Poles Anchor Nut Loosening In Alaska - An Investigation Using Field Monitoring and Finite-Element Analysis

INE/AUTC 14.0

Prediction of vertical bearing capacity of waveform micropile

This study proposes a predictive equation for bearing capacity considering the behaviour characteristics of a waveform micropile that can enhance the bearing capacity of a conventional micropile. The bearing capacity of the waveform micropile was analysed by a three-dimensional numerical model with soil and pile conditions obtained from the field and centrifuge tests. The load-transfer mechanism of the waveform micropile was revealed by the numerical analyses, and a new predictive equation for the bearing capacity was proposed. The bearing capacities of the waveform micropile calculated by the new equation were comparable with those measured from the field and centrifuge tests. This validated a prediction potential of the new equation for bearing capacity of waveform micropiles