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Since the Gs/GD/96-lineage highly pathogenic avian influenza virus (HPAIV) (H5N1) was identified in 1996, H5 HPAIVs have evolved into divergent clades and caused continuous outbreaks in birds (1-11). Moreover, long-distance [...]

The loading frequencies in cyclic tests and the rate of strain or stress in monotonic tests have a significant effect on the soil behaviour, particularly of clayey soil. This study aimed to determine the common characteristics of the behaviour of clay under cyclic loading at different frequencies and the relationship between cyclic and monotonic behaviours. Monotonic triaxial tests and cyclic triaxial tests at frequencies of 0.1 and 0.001 Hz were conducted on undrained saturated reconstituted soft clay. The results showed that the frequency of 0.001 Hz is sufficiently low to make the soil response comparable to that in monotonic tests. Second, there exists a unique 'feature line' for cyclic tests in the plot of allowable stress versus strain, independent of the frequency. Third, the feature lines for the cyclic and monotonic tests are close and parallel to each other. Therefore, although the cyclic and monotonic loadings are quite different from each other, there are connections between these different loadings in terms of the relationship between the allowable stress and strain. Key words: soft clay, cyclic tests, monotonic tests, relationship, low frequency Les frequences de chargement dans les essais cycliques et le taux de deformation ou de contrainte dans les essais monotones ont un effet significatif sur le comportement du sol, en particulier des sols argileux. Cette etude vise a determiner les caracteristiques communes du comportement de l'argile sous chargement cyclique a differentes frequences et la relation entre les comportements cyclique et monotone. Des essais triaxiaux monotones et des essais triaxiaux cycliques a des frequences de 0,1 et 0,001 Hz ont ete realises sur de l'argile molle reconstituee saturee non drainee. Les resultats montrent que la frequence de 0,001 Hz est suffisamment basse pour rendre la reponse du sol comparable a celle des essais monotones. Deuxiemement, il existe une 'ligne caracteristique' unique pour les essais cycliques dans le trace de la contrainte admissible en fonction de la deformation, independamment de la frequence. Troisiemement, les lignes caracteristiques des tests cycliques et monotones sont proches et paralleles les unes aux autres. Par consequent, meme si les charges cycliques et monotones sont tres differentes les unes des autres, il existe des liens entre ces differentes charges en termes de relation entre les contraintes et les deformations admissibles. [Traduit par la Redaction] Mots-cles : argile molle, essais cycliques, essais monotones, relation, basse frequence, 1. Introduction The cyclic deformation of soils in the field caused by, for example, traffic loading and wave loading is a major concern in practical engineering and has attracted significant [...]

Control of the disturbed displacement of adjacent tunnel during excavation is a significant issue for design and construction. Based on the multi-objective optimization method, the multi-type monitoring data in the excavation of the excavation are integrated, the key soil parameters are inverted and identified, and the time effect of the tunnel displacement is quantified and corrected. A dynamic multi-objective optimization method with adaptive infill criterion (DMO-AIC) is proposed to improve the updating efficiency of dynamic surrogate models. The proposed method takes into account the computational redundancy of dynamic surrogate models in engineering optimization, and designs an adaptive point-adding discrimination strategy, which can autonomously identify invalid updates of surrogate models on the optimization path. The results show that the proposed DMO-AIC significantly reduces the invocations of the black-box model during optimization while ensuring the good search performance and the convergence speed of the algorithm. The improved computational efficiency of DMO-AIC is helpful for the application of dynamic surrogate models in engineering optimization. The results of the virtual numerical example show that DMO-AIC can predict and update multiple model responses during excavation, such as wall deflections and tunnel displacements. The engineering practice of Shanghai Bund 596 excavation indicates that the time effect is properly updated, and the staged vertical displacements of the adjacent tunnel are accurately predicted.

In the vacuum treatment of dredged slurries via prefabricated vertical drains (PVDs), both filtration and consolidation may happen to dredged slurries when subjected to the vacuum gradient. Similar to the consolidation, the filtration may provide equally useful information on interpreting the constitutive behavior of the slurry. In this paper, a new approach utilizing the filtration process is devised to evaluate the constitutive behaviors of dredged slurries. The approach is composed of a vacuum filtration device and an iterative curve fitting algorithm. Two types of tests, namely step-vacuum filtration and constant-vacuum filtration followed by compression test, must be conducted on the slurry specimens, and only the time variations of the filtrate discharge should be recorded. On the basis of the recorded data, the curve fitting algorithm is adopted for determining the parameters of the constitutive equations. The effectiveness of the proposed approach is verified through comparing the obtained compressibility and permeability of the slurries with the data provided by the oedometer test and with the empirical relationships from different sources. The comparisons demonstrate that the constitutive relationships determined by the present approach can predict the compressibility and permeability characteristics of dredged slurries with an acceptable degree of accuracy. Key words: dredged slurries, vacuum filtration, compressibility, permeability. La filtration et la consolidation peuvent se produire lors du traitement sous vide des boues de dragage via des drains verticaux prefabriques (PVD) lorsqu'elles sont soumises au gradient de vide. Le filtrage, de meme que la consolidation, peut fournir des informations tout aussi utiles concernant l'interpretation du comportement constitutif de la boue. Nous avons concu dans ce document une methode nouvelle utilisant le processus de filtration pour evaluer le comportement constitutif des boues de dragage. Elle est composee d'un dispositif de filtration sous vide et d'un algorithme d'ajustement de courbe iteratif. Il est necessaire de realiser sur les echantillons de boues deux types d'essais, notamment la filtration sous vide par etapes et la filtration sous vide constant suivie d'un essai de compression, et d'enregistrer uniquement les variations temporelles de la decharge du filtrat. A partir des informations enregistrees, l'algorithme d'ajustement des courbes permet de determiner les parametres des equations constitutives. Nous avons verifie l'efficacite de l'approche suggeree par la comparaison de la compressibilite et de la permeabilite des boues obtenues avec les donnees fournies par l'essai oedometrique et avec les relations empiriques de differentes sources. Il ressort de ces comparaisons que les relations constitutives determinees par cette approche sont en mesure de predire les caracteristiques de compressibilite et de permeabilite des boues de dragage avec une precision acceptable. [Traduit par la Redaction] Mots-cles : boues de dragage, filtration sous vide, compressibilite, permeabilite., 1. Introduction With the rapid economic development and population growth of coastal cities in China, the tideland deposition of artificially dredged slurry is an effective method to solve the problem [...]

In view of the extensive geology of overlying soil and underlying rock in mountainous areas, a pile-anchor composite foundation has been used in transmission line tower engineering. To reveal the uplift bearing mechanism and supplement the calculation method of the uplift capacity and the bearing exertion coefficient k, the verification model of field test case was established by using the PLAXIS 3D finite element software to study this problem. Parameter studies were conducted on this foundation. The influence of elastic modulus and cohesion of rock and soil and foundation condition on coefficient k was studied. The results show that there is asynchronism of ultimate uplift limit state of upper and lower parts of the pile-anchor foundation. The bearing ratio and coefficient k of the upper and lower parts of the foundation are related to geology and foundation structure. In combination with the parameter study and the relevant analytical solution of the relationship between the uplift load and the displacement, a theoretical calculation method of the coefficient k considering the foundation weight was proposed. Three test cases were used to perform confirmatory calculations for this method. By comparing with field tests and numerical calculation results, the correctness of this method has been verified. This method provides a theoretical reference for the design and application of this type of new foundation.