Open-ended pipe piles (OEPPs) are widely used in offshore foundations, yet accurately predicting their driving responses remains challenging due to soil plug complexities. Existing pile driving analysis models inadequately characterize the effects of soil plug, potentially leading to driving problems such as hammer refusal, pile running, and structural damage. This paper proposes an effective soil plug (ESP) model for OEPP driving analysis. The ESP model considers the effective range of soil plug, which exerts internal resistance that increases exponentially with depth while the beyond of effective range contributes only mass inertia. It also accounts for the relative slippage at the pile-soil plug interface. A differential iterative method is developed to solve the ESP model. Subsequently, investigations including the model validation and parameter analysis are conducted. Model validations against existing models and field measurements confirms the reliability of the ESP model. Parameters sensitivity analysis reveals the importance of soil plug length and distribution type of internal resistance on the pile dynamic responses. In addition, if soil plug slippage occurs, the displacement peak of soil plug increases with depth rather than one-dimensional wave attenuation. Furthermore, contrary to previous assumptions of continuous slippage, the soil plug experiences a discontinuous jump-sliding mode under long-duration impact loading. These findings provide theoretical basis for OEPP driving simulation and interpretations of high-strain dynamic test.

This paper presents a field pile load test program conducted on four 0.36 m closed-end steel pipe piles with lengths ranging between 11 and 13 m installed in fine-grained soils. Subsurface investigations with standard penetration tests and cone penetration tests with pore pressure measurements were performed at the site. Three pushed-in piezometers at incremental offsets from the piles were also installed to monitor pore water pressure changes during and after the installation of piles. Several dynamic load tests were performed at different times to observe the change in pile resistance. A static load test was also performed on one of the piles. Some load test results showed an unexpected decrease in the resistances of some piles with time. The study showed that construction activities, e.g., installation of other piles, disturbs the soil and groundwater conditions which can significantly affect the pile resistance measured during load tests. This investigation revealed that pile driving and restrikes should be scheduled such that the effect of construction activities on load tests results will be avoided or minimized.

This paper presents an analysis of long, large-diameter bored piles' behavior under static and dynamic load tests for a megaproject located in El Alamein, on the northern shoreline of Egypt. Site investigations depict an abundance of limestone fragments and weak argillaceous limestone interlaid with gravelly, silty sands and silty, gravelly clay layers. These layers are classified as intermediate geomaterials, IGMs, and soil layers. The project consists of high-rise buildings founded on long bored piles of 1200 mm and 800 mm in diameter. Forty-four (44) static and dynamic compression load tests were performed in this study. During the pile testing, it was recognized that the pile load-settlement behavior is very conservative. Settlement did not exceed 1.6% of the pile diameter at twice the design load. This indicates that the available design manual does not provide reasonable parameters for IGM layers. The study was performed to investigate the efficiency of different approaches for determining the design load of bored piles in IGMs. These approaches are statistical, predictions from static pile load tests, numerical, and dynamic wave analysis via a case pile wave analysis program, CAPWAP, a method that calculates friction stresses along the pile shaft. The predicted ultimate capacities range from 5.5 to 10.0 times the pile design capacity. Settlement analysis indicates that the large-diameter pile behaves as a friction pile. The dynamic pile load test results were calibrated relative to the static pile load test. The dynamic load test could be used to validate the pile capacity. Settlement from the dynamic load test has been shown to be about 25% higher than that from the static load test. This can be attributed to the possible development of high pore water pressure in cohesive IGMs. The case study analysis and the parametric study indicate that AASHTO LRFD is conservative in estimating skin friction, tip, and load test resistance factors in IGMs. A new load-settlement response equation for 600 mm to 2000 mm diameter piles and new recommendations for resistance factors phi qp, phi qs, and phi load were proposed to be 0.65, 0.70, and 0.80, respectively.

Large-diameter bored piles can safely transmit loads from structures by skin friction to the surrounding soil strata and end bearing at the bedrock layer, thereby providing a high compressive capacity. High-Strain Dynamic Testing (HSDT) provides a unique alternative technique to traditional Static Load Testing (SLT) for determining the static compressive resistance of the bored piles, considering its quicker performance and significant cost reductions. This article's main objective is to numerically explore the performance of large-diameter bored piles during the HSDT and to understand their dynamic behavior under an axial compressive impact force. This research is based on testing pile foundations for reinforced concrete mixed-use towers in the coastal zone of New Alamein City, Egypt. The tested pile is a 1.20 m diameter bored pile. Numerical modeling is performed to simulate both the HSDT and the SLT for two piles at the same site. Non-linear axisymmetric finite element modeling is employed to validate both test records and develop some sort of matching between the two tests. As lumped models, the developed numerical models use the signal-matching process, which is conducted by varying and adopting the strength parameters and deformation characteristics of the ground or soil deposit and the soil-pile interface. The predicted load-displacement curves, developed from analyzing dynamic records employing the Modified Unloading Point (MUP) method, are consistent with the field records. The verified non-linear models are utilized to accomplish a comparative parametric analysis to better understand the drop-mass system aspects. The analysis results emphasize the significance of employing adequate impact energy (i.e., dropping height and mass) to move the pile top to a sufficient extent to mobilize its full resistance. However, a longer impact duration, i.e., larger mass, is more effective for achieving a deeper high-strain wave. The impact load should be developed by a larger drop mass with a lower drop height, not a smaller drop mass with a higher drop height. The results also indicate that, for relatively longer piles, the skin friction of the upper layers surrounding the pile shaft is fully mobilized, whereas the skin resistance of the lower layers is not fully mobilized, regarding the stress wave phenomenon effect. Finally, this study's findings can be employed to develop guidelines and design procedures for the HSDT to be effectively performed on bored piles.

The integral abutment bridge concept allows removal of expansion joints, bearings, piles for horizontal earth loads, and other uneconomical details. These details not only add to construction costs but also increase the maintenance work and expenses. When expansion joints are eliminated from a bridge, thermal stresses must be accounted for in the design. This paper describes the design challenges for a 45.6 m one-span integral abutment bridge, nearby Gatineau, Quebec, Canada. According to the geotechnical report, the soil under the foundation of the bridge consists of a 1.0-5.4 m granular embankment mixed with organic material and layers of wood chips, 15 m layered deposits of granular and cohesive soils, and a 35.7 to 40.8 m thick clay that is laid on a till layer. Because a 5.3 m granular backfill of abutments would lead to remarkable consolidation settlement and maintenance issues, it was decided to substitute 3.7 m of the granular backfill with a lightweight material to minimize the long-term settlement problem. A 3D bridge model in CSiBridge was used to simulate the construction stages and nonlinear behavior of soil around the piles to predict the induced efforts in the bridge due to different loads, including thermal and deck shrinkage loads. Structural design of piles was accomplished by taking into account the plastic hinge at the top of the piles and estimating the buckling free length of piles based on analysis of pile under lateral load in L-PILE software. While some Canadian provinces have developed standard details for approach slab joints, Quebec's ministry of transportation (MTQ) does not propose any standard expansion joint detail for integral bridges. Therefore, the typical strip seal expansion joints detail of MTQ was adapted for this project to reduce water infiltration inside the joint even though it is away from the deck and is located at the end of approach slab. During the construction, the result of test piles revealed that excess pore water pressure due to pile driving operation needs some time to disappear. Thus, minimum waiting times for the main stages of construction were defined. [GRAPHICS] .