No abstract

This study summarizes the evaluation of the pile static load test as a tool for the prediction of pile behavior in clayey soils. The pile and soil cases were modeled by three different constitutive models; Mohr-Columb (M-C), Hardening Soil (HS), and Soft Soil Creep (SSC). The static loading test scenarios were also numerically modeled to study the pile behavior. The models were analyzed by using numerical finite elements software (PLAXIS 3D Foundation). A construction site located in Mansoura, Dakahleya Governorate, EGYPT, was selected to perform the field tests. In order to simulate the soil in the numerical models, two borings with depth of 25 m were carried out to investigate the soil properties in the same site where field static pile load tests are performed later. The pile capacity and settlement were calculated theoretically for each case by using both Egyptian Code formula and numerical constitutive models. The load test was simulated twice for each pile. The first simulates the standard static load test while the second simulates the real-life loading. The results showed that the pile behavior obtained by standard static load test was extremely exaggerated. A modified quick static load test method was proposed and verified. Also it has been proved that, the Modified Quick Load Test (MQLT) method can be used as an alternative method to the classical static load test method.

Recently, the use of continuous flight auger piles has significantly increased. Higher productivity and greater capacity to transfer larger loads to the subsoil. The Continuous Flight Auger (CFA) pile, installed using a continuous helix auger, was first used in the United States during the fifties and in the seventies in Europe. In Egypt, the use of this type of piling has become more prevalent, especially in the Delta region. One of the factors that led to the spread of this type of piles is its suitability for the soil in the delta region, where the topsoil is mostly medium to stiff clay, followed by sandy soil. Since the use of this pile is increasing, it becomes imperative to understand its behavior. Historical reviewSince the beginning of the invention of CFA piles so far there has been a significant development in technology, and presently they can be installed up to 32m deep, 1200mm in diameter, and torque of up to 390 kN.m. CFA piles became very widespread due to their technical advantages combined with relatively low cost [1].However, these authors warn from the adverse effects during the production process, which may need special attention, especially with pile continuity, soil disturbance due to auger extraction, and failure in weak soils due to high applied pressures causing a sig nificant waste of concrete. Operator skills play an essential role in controlling the construction of CFA piles is the most severe limitation of these piles [2]. The pilling contractor must take all necessary precautions during the installation process, including excavation, auger extraction, and positioning the reinforcements. AdvantagesContinuous flight auger piles are usually installed in most soil conditions. In addition to their efficiency to resist all types of loads including compressive, uplift, and lateral loads, they are also cost-efficient foundation solution. They can be installed up to depths of 32m and diameters of 300 mm to 1000mm, low noise level and no vibration and low noise level so ideal in built-up areas with weak soil conditions and high levels of groundwater, compared to bored piles, construction is rapid as temporary casings or support systems are not needed, and eliminates the soil relaxation.Marchetti dilatometer was used before and after installing a pile to investigate this effect. It was noted that the CFA piling construction method did not cause this relaxation. Bottiau [2] emphasizes that another critical advantage of the CFA pile is the possibility of continuous monitoring, which furnishes documentation on the piles installation.This work is licensed under Creative Commons Attribution 4.0 License CTCSE.MS.ID.000587.