Search

Anchoring force loss is critically concerned for the in-service performance of prestressed ground anchors. This time- dependent loss of pretension exerted at the anchor head is caused primarily by stress relaxation, which integrally manifests the rheological properties of the anchor and the geomaterial in which the anchor is embedded. A load-transfer modeling framework was established to derive the time-dependent anchoring force response. The modeling parameters were directly calibrated via element-scale pullout stress relaxation test using a specially developed setup. The applicability and effectiveness of this analytical modeling framework were verified via large-scale laboratory model tests and in situ tests of prestressed anchors. The predictions derived using the presented modeling framework were in good agreement with measurements in both laboratory model tests and in situ tests, particularly for evolutions of anchoring force over time. Sensitivity evaluation of the model parameters was performed to study their respective impact on the anchoring force loss response. This work can provide insights into the understanding of the anchoring force loss behavior of prestressed ground anchors and facilitate their design practice for in-service performance. Key words: prestressed ground anchor, anchoring force loss, relaxation, load transfer La perte de la force d'ancrage est un probleme critique pour la performance en service des ancrages de sol precontraints. Cette perte de la precontrainte exercee a la tete de l'ancrage, qui depend du temps, est causee principalement par la relaxation des contraintes, qui se manifeste integralement par les proprietes rheologiques de l'ancrage et du geomateriau dans lequel il est encastre. Un cadre de modelisation du transfert de charge a ete etabli pour deriver la reponse de la force d'ancrage en fonction du temps. Les parametres de modelisation ont ete directement calibres par un essai de relaxation de la contrainte d'arrachement a l'echelle de l'element a l'aide d'une configuration specialement developpee. L'applicabilite et l'efficacite de ce cadre de modelisation analytique ont ete verifiees par des essais a grande echelle en laboratoire et des essais in situ sur des ancrages precontraints. Les predictions obtenues a l'aide du cadre de modelisation presente etaient en bon accord avec les mesures effectuees lors des essais sur modele en laboratoire et des essais in situ, en particulier pour l'evolution de la force d'ancrage dans le temps. L'evaluation de la sensibilite des parametres du modele a ete realisee pour etudier leur impact respectif sur la reponse de la perte de la force d'ancrage. Ces travaux peuvent permettre de mieux comprendre le comportement de la perte de force d'ancrage des ancrages de sol precontraints et faciliter leur conception pour les performances en service. [Traduit par la Redaction] Mots-cles : ancrage de sol precontraint, perte de force d'ancrage, relaxation, transfert de charge, 1. Introduction Ground anchors have been widely adopted in various anchored geotechnical applications, such as dams, slopes, tunnels, and deep foundation pits, owing to their unique virtues of simple constructability, [...]

The bond–slip behavior of concrete pile–cemented soil interface is crucial for load transfer analysis of stiffened deep cement mixing piles, which is greatly influenced by ground temperature and age during long-term curing. However, the thermal–temporal effect on the frictional characteristics of this interface remains unclear. In this paper, an element-scale specimen of concrete pile–cemented soil interface was first designed. Then interfacial shear tests were performed on batches of samples subjected to varied curing temperatures (T) and ages (t) to obtain interfacial bond–slip (τ‒s) curves. The test results showed that the interfacial peak shear strength (τu) increased with the growth of T and t. Based on the experimental observations, a strength development model for τu considering the thermal effect was established. Subsequently, a disturbed state concept (DSC)-based constitutive model incorporating the thermal–temporal effect was proposed for the investigated interface. Both prepeak and postpeak stages of the τ‒s curves can be effectively described by the developed DSC model, exhibiting robust performance in fitting and predicting experimental results. Finally, the DSC model was cross-validated by the interfacial τ‒s data sets collected from reported experimental publications. Across all data sets, the coefficient of determination (R2) exceeded 0.9, and the mean absolute percentage error of τu remained below 10% when comparing predictions with measurements, which strongly highlights the generalization capability of the DSC model. [ABSTRACT FROM AUTHOR]

We investigate the tidal displacement signals of two principle semidiurnal ( M 2 ) and diurnal ( O 1 ) tidal constituents in New Zealand. We calculate the predicted loading displacements using the latest ocean tide models and Earth models. The results show that, for the M 2 constituent, the tide models FES2014b and TPXO9-Atlas have subtle differences, and the vector differences between the Earth models shows that the regularity of the influence of the Earth model is weak. The vector difference of O 1 constituent have significant spatial coherence (about 0.2 mm). The residuals of M 2 constituent in the up component subtract about 0.2 mm across the entire areas after considering the anelastic dispersion. We find that the clear regional-scale spatial coherence of the residuals exists in both constituents in all models even if spatial water density and compressibility have been considered. However, the spatial coherence of residuals disappears when the network-mean value removed, and the reduction of RMS for O 1 constituent is close to the theoretical error of body tide (about 0.5 mm). We also find that for the different ocean tide models, part of the differences in residuals between the observations and predictions would be attributed to the choice of geocentric reference frame. [ABSTRACT FROM AUTHOR]