Search

New approaches are proposed for robustly determining the compressibility and permeability functions for large-strain consolidation (LSC), using limited measurements from one-dimensional tests, such as column or centrifuge experiments. These new methods are developed from several new findings reported in this paper, including (i) new analytical solutions that relate parameters of compressibility functions to the final density profile, (ii) analytical proof of the independence of the shape of the settlement curve from the parameter M, where the permeability or hydraulic conductivity k is given by MeP, e is void ratio, and M and P are material-related constants; and (iii) that when the same k function is employed, for the case of one-dimensional settlement, the optimal values of M and P are located on a unique straight line in the P-lnM space. The third finding was determined from optimization analysis of thousands of LSC simulations. Using different combinations of these new findings, three new methods are developed to estimate the permeability function. The efficiency, robustness, and accuracy of the three methods are investigated by their application to four column tests from the literature. The simplest of the three methods requires only two LSC analyses plus several hand-calculations, demonstrating strong potential for practical use. Key words: large-strain consolidation, deep learning, hydraulic conductivity. De nouvelles approches sont proposees pour determiner de facon robuste les fonctions de compressibility et de permeabilite pour la consolidation de grandes deformations (LSC), en utilisant des mesures limitees a partir d'essais unidimensionnels, tels que des experiences sur colonne ou centrifugeuse. Ces nouvelles methodes sont developpees a partir de plusieurs nouvelles decouvertes rapportees dans cet article, y compris (i) de nouvelles solutions analytiques qui relient les parametres des fonctions de compressibilite au profil de densite final, (ii) la preuve analytique de l'independance de la forme de la courbe de tassement du parametre M, ou la permeabilite ou conductivite hydraulique k est donnee par MeP ou e est l'indice des vides et M et P sont des constantes liees au materiau; et (iii) que lorsque la meme fonction k est utilisee, dans le cas du tassement unidimensionel, les valeurs optimales de M et P sont situees sur une droite unique dans l'espace P-lnM. Le troisieme resultat a ete determine a partir de l'analyse d'optimisation de milliers de simulations LSC. En utilisant differentes combinaisons de ces nouvelles decouvertes, trois nouvelles methodes sont mises au point pour estimer la fonction de permeabilite. L'efficacite, la robustesse et l'exactitude des trois methodes sont etudiees en les appliquant a des tests a quatre colonnes tires de la litterature. La plus simple des trois methodes ne necessite que deux analyses LSC et plusieurs calculs manuels, ce qui demontre un fort potentiel d'utilisation pratique. [Traduit par la Redaction] Mots-cles: consolidation de grandes deformations, apprentissage en profondeur, conductivite hydraulique., Introduction Fine-grained materials are deposited in various geotechnical industrial activities, such as deposition of dredged sludges in or near water bodies (Palermo et al. 2008); in estuaries and offshore for [...]

Soil trenching is extensively used in geotechnical, mining, tunneling and geo-environmental infrastructures. Safe height and stand-up time are two key factors that are required for the rational design of soil trenches. Rainfall infiltration has a significant influence on the safe height and stand-up time of unsaturated soil trenches since it can significantly alter the shear strength of soils by influencing the matric suction. In other words, predicting the variation of matric suction of soils associated with rainfall infiltration is vital to the design of unsaturated soil trenches. In this paper, finite element analysis is carried out to reproduce the variation of matric suction profile in unsaturated soil trenches associated with rainfall infiltration using the published results of a full scale instrumented test trench at the site of BBRI at Limelette, Belgium. The analysis results showed that the variation of matric suction in unsaturated soil trenches can be reliably estimated using the information of environmental factors such as the rainfall measurements.

With regard to the high anti-scouring and abrasion-resistant performance requirements and great temperature control difficulties of lining concrete for large-sized spillway tunnels, in this study, a performance test was conducted on anti-scouring and abrasion-resistant concrete. The finite element method was used to analyze the temperature change rules of sidewall C9050 (design strength of concrete is 50 MPa at 90 days) lining concrete for the spillway tunnel. Further, a new cooling measure was proposed for adopting "early-throughput, high-flow and short-duration". As indicated by the results of this study, fly ash could reduce water consumption and micro-cracks via its "morphological effect". Silica fume could improve the early strength of cement concrete and make up for the strength loss caused by fly ash. Polyvinyl alcohol (PVA) fiber could enhance concrete durability. The doping of these three additives reinforced the strength and abrasion resistance of concrete. The results showed that the temperature of the lining concrete presented a change trend of "rapid increase first, followed by a slow decrease". The peak temperature was reached roughly 2 days after casting. In addition, properly increasing throughput flow or decreasing throughput temperature in the early stage of casting could significantly reduce the highest temperature and maximum temperature difference of concrete. Based on the results from the numerical simulation of temperature control effect, it was proposed to adopt "early-throughput, high-flow, and short-duration" for temperature control and cracking prevention. Specifically, within 2 days after casting, cooling water at roughly 12 °C was guided in at a flow of approximately 3.5 m3/h. Within 3–7 days after casting, river water at around 17 °C was guided in at a flow rate of approximately 1.8 m3/h. After 7 days, the cooling effect can be well achieved by only using the surface flowing water for curing. According to the field monitoring data, the changes in measured temperature were basically consistent with those from numerical simulations, and detection on the temperature of the sidewall lining concrete showed that a qualification rate of >91% was satisfactorily obtained by using the proposed approach. [ABSTRACT FROM AUTHOR]

A complete picture of the deformation characteristics (distribution and evolution) of the geotechnical infrastructures serves as superior information for understanding their potential instability mechanism. How to monitor more completely and accurately the deformation of these infrastructures (either artificial or natural) in the field expediently and roundly remains a scientific topic. The conventional deformation monitoring methods are mostly carried out at a limited number of discrete points and cannot acquire the deformation data of the whole structure. In this paper, a new monitoring methodology of dam deformation and associated results interpretation is presented by taking the advantages of the terrestrial laser scanning (TLS), which, in contrast with most of the conventional methods, is capable of capturing the geometric information at a huge amount of points over an object in a relatively fast manner. By employing the non-uniform rational B-splines (NURBS) technology, the high spatial resolution models of the monitored geotechnical objects can be created with sufficient accuracy based on these point cloud data obtained from application of the TLS. Finally, the characteristics of deformation, to which the geotechnical infrastructures have been subjected, are interpreted more completely according to the models created based on a series of consecutive monitoring exercises at different times. The present methodology is applied to the Changheba earth-rock dam, which allows the visualization of deformation over the entire dam during different periods. Results from analysis of the surface deformation distribution show that the surface deformations in the middle are generally larger than those on both sides near the bank, and the deformations increase with the increase of the elevations. The results from the present application highlight that the adhibition of the TLS and NURBS technology permits a better understanding of deformation behavior of geotechnical objects of large size in the field. [ABSTRACT FROM AUTHOR]