Load-settlement modelling of axially loaded drilled shafts using CPT-based recurrent neural networks

The design of pile foundations requires good estimation of the pile load-carrying capacity and settlement. Design for bearing capacity and design for settlement have been traditionally carried out separately. However, soil resistance and settlement are influenced by each other, and the design of pile foundations should thus consider the bearing capacity and settlement inseparably. This requires the full load–settlement response of piles to be well predicted. However, it is well known that the actual load–settlement response of pile foundations can be obtained only by load tests carried out in situ, which are expensive and time-consuming. In this paper, recurrent neural networks (RNNs) were used to develop a prediction model that can resemble the full load–settlement response of drilled shafts (bored piles) subjected to axial loading. The developed RNN model was calibrated and validated using several in situ full-scale pile load tests, as well as cone penetration test (CPT) data. The results indicate that the developed RNN model has the ability to reliably predict the load–settlement response of axially loaded drilled shafts and can thus be used by geotechnical engineers for routine design practice

Antiviral therapies against Ebola and other emerging viral diseases using existing medicines that block virus entry

Emerging viral diseases pose a threat to the global population as intervention strategies are mainly limited to basic containment due to the lack of efficacious and approved vaccines and antiviral drugs. The former was the only available intervention when the current unprecedented Ebolavirus (EBOV) outbreak in West Africa began. Prior to this, the development of EBOV vaccines and anti-viral therapies required time and resources that were not available. Therefore, focus has turned to re-purposing of existing, licenced medicines that may limit the morbidity and mortality rates of EBOV and could be used immediately. Here we test three such medicines and measure their ability to inhibit pseudotype viruses (PVs) of two EBOV species, Marburg virus (MARV) and avian influenza H5 (FLU-H5). We confirm the ability of chloroquine (CQ) to inhibit viral entry in a pH specific manner. The commonly used proton pump inhibitors, Omeprazole and Esomeprazole were also able to inhibit entry of all PVs tested but at higher drug concentrations than may be achieved in vivo. We propose CQ as a priority candidate to consider for treatment of EBOV

Artificial neural network (ANN) approach for modelling of pile settlement of open-ended steel piles subjected to compression load

This study was devoted to examine pile bearing capacity and to provide a reliable model to simulate pile load-settlement behaviour using a new artificial neural network (ANN) method. To achieve the planned aim, experimental pile load test were carried out on model open-ended steel piles, with pile aspect ratios of 12, 17, and 25. An optimised second-order Levenberg-Marquardt (LM) training algorithm has been used in this process. The piles were driven in three sand densities; dense, medium, and loose. A statistical analysis test was conducted to explore the relative importance and the statistical contribution (Beta and Sig) values of the independent variables on the model output. Pile effective length, pile flexural rigidity, applied load, sand-pile friction angle and pile aspect ratio have been identified to be the most effective parameters on model output. To demonstrate the effectiveness of the proposed algorithm, a graphical comparison was performed between the implemented algorithm and the most conventional pile capacity design approaches. The proficiency metric indicators demonstrated an outstanding agreement between the measured and predicted pile-load settlement, thus yielding a correlation coefficient (R) and root mean square error (RMSE) of 0.99, 0.043 respectively, with a relatively insignificant mean square error level (MSE) of 0.0019. © 2018, © 2018 Informa UK Limited, trading as Taylor & Francis Group

Load transfer curves from a large-diameter pipe pile in silty soil

This paper presents load transfer curves interpreted from a static load test performed on a large-diameter pipe pile in silty soils. In large-diameter driven piles and drilled shafts, appreciable movement is needed to mobilize toe resistance and thus settlement may control the design. Advanced load transfer methods require the prediction of the load transfer behavior along the shaft (i.e. t-z curve) and beneath the toe (i.e. q-z curve) of the pile. A number of generic load transfer curves for sand and clay are reported in the literature but limited information is available for large diameter piles and intermediate soils such as silt. This study develops t-z and q-z curves for silty soils from the analysis of a static loading test performed on an 1.8-meter diameter pipe pile in Rhode Island. The t-z curves from the test pile showed a softer load-movement response in comparison to those from slender piles in the literature. The results suggest that use of existing empirical t-z curves developed from slender piles in sands could lead to inaccurate load transfer analyses in large-diameter piles in silty soils. © 2012 American Society of Civil Engineers

The bellow-hose settlement gauge

Bellow-hose settlement gauges were used to measure vertical soil heave during the installation of concrete piles in sensitive marine clay. The equipment is described and the sources of error are discussed.Des tassom\ue8tres \ue0 tube compressible ont \ue9t\ue9 utilis\ue9s pour mesurer les soul\ue8vements verticaux du sol lors de l'installation de pieux de b\ue9ton dans une argile marine sensible. On d\ue9crit l'\ue9quipment et on discute les causes d'erreurs.Peer reviewed: YesNRC publication: Ye

Soil disturbance from pile driving in sensitive clay

Soil disturbance due to the driving of two groups of 116 concrete piles each in sensitive marine clay was studied on a construction project in eastern Canada. Pore-water pressures, heave, and lateral movement of soil and piles, and tests of strength, compressibility, and consistency limits of the soil were observed prior to and up to 3 months after pile driving whereas observations of pore-water pressures were continued for an additional 5 months. Driving of the piles had little effect on the compressibility and consistency limits of the marine clay, but the in situ shear strength and cone penetration resistance were reduced by about 15 and 30%, respectively. Soil heave within the group of piles decreased linearly with depth from a maximum of 450 mm (18 in.) at the ground surface to about zero at the pile tips, and in volume amounted to approximately 55% of the soil displaced by the piles. The vertical heave outside the pile group was confined to a horizontal distance of 12 m (39 pile diameters). During pile driving, the lateral movement of previously driven piles was as much as 175 mm (7 in.). Horizontal soil movements measured by inclinometers varied up to 125 mm (5 in.). Pore-water pressures generated during piling exceeded the total overburden pressure by 35-40%. The excess pore pressures dissipated in about 8 months after the piling was completed.Le remaniement caus\ue9 par le foncage dans l'argile marine sensible de deux groupes de 116 pieux de b\ue9ton a \ue9t\ue9 \ue9tudi\ue9 sur un chantier de construction de l'Est du Canada. Les pressions interstitielles, de soul\ue8vement et le mouvement lat\ue9ral du sol et des pieux, de m\ueame que les valeurs de la r\ue9sistance, de la compressibilit\ue9 et des limites de consistance du sol ont \ue9t\ue9 observ\ue9s avant et jusqu'\ue0 3 mois apr\ue8s le foncage des pieux; de plus, les observations des pressions interstitielles se sont poursuivies durant 5 mois additionnels. Le foncage des pieux n'a eu que peu d'effet sur la compressibilit\ue9 et les limites de consistance de l'argile marine, mais la r\ue9sistance au cisaillement en place et la r\ue9sistance au c\uf4ne ont \ue9t\ue9 r\ue9duites d'environ 15 et 30% respectivement. Le soul\ue8vement du sol \ue0 l'int\ue9rieur du groupe de pieux diminuait lin\ue9airement en fonction de la profondeur, soit d'un maximum de 450 mm (15 po.) \ue0 la surface du sol jusqu'\ue0 environ z\ue9ro \ue0 la pointe des pieux; en volume, ce soul\ue8vement correspondait \ue0 approximativement 55% du sol d\ue9plac\ue9 par les pieux. Le soul\ue8vement vertical en dehors du groupe de pieux se limitait \ue0 une distance horizontale de 12 m, soit 39 diam\ue8tres de pieux. Durant le foncage, le mouvement lat\ue9ral des pieux fonc\ue9s pr\ue9alablement atteignait 175 mm (7 po.). Les mouvements horizontaux du sol mesur\ue9s par des inclinom\ue8tres ont vari\ue9 jusqu'\ue0 125 mm ( 5 po.). Les pressions interstitielles g\ue9n\ue9r\ue9es durant le foncage ont d\ue9pass\ue9 de 35 \ue0 40% les valeurs des pressions isostatiques. La dissipation de l'exc\ue9dent des pressions interstitielles s'est termin\ue9e environ 8 mois apr\ue8s la fin du foncage.Peer reviewed: YesNRC publication: Ye