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Xiu Li Feng - One of the best experts on this subject based on the ideXlab platform.

  • inversion and prediction of Consolidation Settlement characteristics of the fluvial sediments based on void ratio variation in the northern modern yellow river subaqueous delta china
    Journal of Ocean University of China, 2018
    Co-Authors: Xiu Li Feng
    Abstract:

    The modern Yellow River delta is formed near the estuary of the Yellow River with the characteristics of short formation time, efficient sedimentation rate and loose structure which make sediments prone to be compacted and consolidate under the geostatic stress and overburden stress. It is one of the key areas with land subsidence disasters in China, bringing a series of safety hazards to production and living. Based on the data of massive surface cores and ten drill holes ranging from 12 to 40 m obtained from the northern modern Yellow River subaqueous delta, the inversion method suitable for the calculation of Consolidation Settlement characteristics of the modern Yellow River subaqueous delta is discussed, and the Consolidation Settlement characteristics of the delta sediments are inversed and predicted in this paper. The actual void ratio of the delta sediments at the depth from 3 to 15 m shows a significant power function relationship with the depth, while the void ratio of the sediments below 15 m changes little with depth. The pre-Consolidation Settlement (from deposition to sampling) of the delta sediments is between 0.91 and 1.96 m, while the Consolidation Settlement of unit depth is between 9.6 and 14.0 cm m−1. The post-Consolidation Settlement (from sampling to stable) of the subaqueous delta sediments is between 0.65 and 1.56 m in the later stage, and the Consolidation Settlement of unit depth is between 7.6 and 13.1 cm m−1 under the overburden stress. The delta sediments with a buried depth of 3 to 7 m contribute the most to the possible Consolidation Settlement in the later stage.

  • sediment Consolidation Settlement of chengbei sea area in the northern huanghe river subaqueous delta china
    Chinese Journal of Oceanology and Limnology, 2017
    Co-Authors: Xiu Li Feng
    Abstract:

    One of the most important factors controlling the morphology of the modern Huanghe (Yellow) River delta is Consolidation Settlement, which is impacted by fast deposition, high water content, and low density of seafloor sediment. Consolidation Settlement of the Huanghe River subaqueous delta was studied based on field data, laboratory experiments on 12 drill holes, and the one-dimensional Consolidation theory. Results show that vertical sediment characteristics varied greatly in the rapidly forming sedimentary bodies of the modern Huanghe River subaqueous delta. Sediments in the upper parts of drill holes were coarser than those in the deeper parts, and other physical and mechanical properties changed accordingly. On the basis of the one-dimensional Consolidation theory and drilling depth, the final Consolidation Settlement of drill holes was between 0.6 m and 2.8 m, and the mean Settlement of unit depth was at 1.5–3.5 cm/m. It takes about 15–20 years for the Consolidation degree to reach 90% and the average sedimentation rate within the overlying 50 m strata was at 5 cm/a to 12 cm/a. This study helps to forecast the final Consolidation Settlement and Settlement rate of the modern Huanghe River subaqueous delta, which provides key geotechnical information for marine engineers.

  • Consolidation Settlement of the modern yellow river subaqueous delta
    Applied Mechanics and Materials, 2013
    Co-Authors: Xiu Li Feng
    Abstract:

    In this paper, the Consolidation Settlement and Settlement rate were studied based on the drilling data of the Yellow River subaqueous delta. The results show that surface sediments of ZK-2 are significantly coarsen than ZK-1, and correspondingly with varying physical and mechanical properties in different cores. Based on the one-dimensional Consolidation theory, 50m thickness of layer could produce a total of 1.70m Settlement in ZK-1, and 60m could produce 2.34m Settlement in ZK-2. The Consolidation Settlement of unit depth is at 0.1~9cm/m. The Consolidation degree needs about 15~20 years to reach 90% and the average sedimentation rate is at 7-9cm/a.

Wei-qiang Feng - One of the best experts on this subject based on the ideXlab platform.

  • a new simplified method and its verification for calculation of Consolidation Settlement of a clayey soil with creep
    Canadian Geotechnical Journal, 2017
    Co-Authors: Wei-qiang Feng
    Abstract:

    The calculation of the Consolidation Settlement of clayey soils with creep behaviour has been a challenging issue with a long history. After a brief review the assumptions made in the two methods based on Hypothesis A and Hypothesis B, the authors present a new simplified hypothesis B method for calculation of Consolidation Settlement of a clayey soil with creep. Equations of this method are derived based on the “equivalent time” concept for different stress–strain states. This simplified Hypothesis B method is then used to calculate the Consolidation Settlement of a number of typical Consolidation problems. The approximation and verification of this simplified method are examined by comparing the calculated Settlements with Settlements computed using two fully coupled finite element (FE) Consolidation analysis programs using elastic viscoplastic (EVP) constitutive models (Hypothesis B) and the Hypothesis A method. It is found that the curves calculated using the new Hypothesis B simplified method with a ...

  • A new simplified method and its verification for calculation of Consolidation Settlement of a clayey soil with creep
    Canadian Geotechnical Journal, 2017
    Co-Authors: Jian-hua Yin, Wei-qiang Feng
    Abstract:

    The calculation of the Consolidation Settlement of clayey soils with creep behaviour has been a challenging issue with a long history. After a brief review the assumptions made in the two methods based on Hypothesis A and Hypothesis B, the authors present a new simplified hypothesis B method for calculation of Consolidation Settlement of a clayey soil with creep. Equations of this method are derived based on the " equivalent time " concept for different stress–strain states. This simplified Hypothesis B method is then used to calculate the Consolidation Settlement of a number of typical Consolidation problems. The approximation and verification of this simplified method are examined by comparing the calculated Settlements with settle-ments computed using two fully coupled finite element (FE) Consolidation analysis programs using elastic viscoplastic (EVP) constitutive models (Hypothesis B) and the Hypothesis A method. It is found that the curves calculated using the new Hypoth-esis B simplified method with a factor ␣ = 0.8 are close to curves from two FE model simulations with relative errors in the range 0.37%ϳ8.42% only for three layers of Hong Kong marine clay (HKMC). In overall, the Settlements calculated using Hypothesis A method are smaller than those from the two FE simulations with relative error in the range 6.52%ϳ46.17% for the three layers of HKMC. In addition, this new simplified Hypothesis B method is used to calculate the average strain of Consolidation tests done by Berre and Iversen in 1972. The calculated results are compared with the test data, and values from a fully coupled finite difference (FD) Consolidation analysis using Yin and Graham's EVP constitutive model (Hypothesis B), and Hypothesis A method. It is found that, again, the results from the new simplified Hypothesis B method are very close to the measured data. In conclusion, the new simplified Hypothesis B method is a suitable simple method, by spread-sheet calculation of the consolida-tion Settlement of a single layer of a clayey soil with creep. Résumé : Le calcul du tassement de Consolidation des sols argileux avec un comportement de fluage a été un enjeu difficile avec une longue histoire. Après un bref examen des hypothèses formulées dans les deux méthodes basées sur l'Hypothèse A et l'Hypothèse B, les auteurs présentent une nouvelle méthode d'Hypothèse B simplifiée pour le calcul du tassement de la Consolidation d'un sol argileux avec fluage. Les équations de cette méthode sont dérivées basées sur le concept de « temps equivalent » pour différents états de contrainte–déformation. Cette méthode d'Hypothèse B simplifiée est ensuite utilisée pour calculer le tassement de la Consolidation d'un certain nombre de problèmes typiques de Consolidation. Le rapprochement et la vérification de cette méthode simplifiée sont examinés en comparant les tassements calculées avec les tassements calculées en utilisant deux programmes d'analyse de Consolidation par éléments finis (EF) entièrement couplés en utilisant des modèles élastiques viscoplastiques constitutifs des méthodes (Hypothèse B) et l'Hypothèse A. On constate que les courbes calculées en utilisant la nouvelle méthode simplifiée d'Hypothèse B avec un facteur ␣ = 0.8 sont proches de courbes à partir de deux simulations de modèles à EF avec des erreurs relatives dans la gamme de 0,37ϳ8,42 % seulement pour trois couches d'argile marine de Hong Kong (« Hong Kong marine clay (HKMC) »). Dans l'ensemble, les tassements calculées en utilisant une méthode d'Hypothèse A sont plus petits que ceux des deux simulations d'EF avec erreur relative dans la gamme de 6,52ϳ46,17 % pour les trois couches de HKMC. En outre, cette nouvelle méthode d'Hypothèse B simplifiée est utilisée pour calculer la déformation moyenne des essais de Consolidation réalisés par Berre et Iversen en 1972. Les résultats calculés sont comparés avec les données d'essai, et les valeurs d'une analyse de Consolidation de la différence finie entièrement couplée en utilisant le modèle constitutif viscoplastique élastique de Yin et Graham (Hypothèse B), et l'Hypothèse A. On constate que, encore une fois, les résultats de la nouvelle méthode d'Hypothèse B simplifiée sont très proches des données mesurées. En conclusion, la nouvelle méthode d'Hypothèse B simplifiée est une méthode simple appropriée, par le calcul du tassement de Consolidation d'une couche unique d'une terre argileuse avec fluage. [Traduit par la Rédaction] Mots-clés : argile, tassement, Consolidation, en fonction du temps, fluage, viscoplastique.

Michael Brown - One of the best experts on this subject based on the ideXlab platform.

  • an estimation method for predicting final Consolidation Settlement of ground improved by floating soil cement columns
    Soils and Foundations, 2016
    Co-Authors: Ryohei Ishikura, Noriyuki Yasufuku, Michael Brown
    Abstract:

    Abstract Ground improvement using floating soil cement columns with shallow stabilization is an effective technique for the treatment of deep soft soil layers under infrastructure embankments. In order to investigate the Settlement performance of this improvement technique, model load testing of model column analogues for visualization of ground behavior under plane strain conditions was performed and field observations at full scale test embankments were investigated. The results of model testing and field investigation show that the ground below an embankment founded on a floating column system can be considered as two separate layers with a confined portion and a consolidating layer which can be related to the degree of improvement used at a particular site such as the improvement ratio and the depth of improvement. A simplified estimation method for final Consolidation Settlement is proposed using a stress distribution ratio which considers the contribution from skin friction at the surface of floating columns. The advantage of this method is that is possible to determine the consolidating layer thickness as a function of simple parameters such as the degree of improvement, loading conditions and undrained soil strength. The predicted Settlements of the improved ground correspond well to that measured in full scale case studies.

Wei Gang - One of the best experts on this subject based on the ideXlab platform.

  • RESEARCH ON THEORETICAL CALCULATION OF LONG-TERM GROUND Settlement CAUSED BY SHIELD TUNNELING
    Chinese journal of rock mechanics and engineering, 2020
    Co-Authors: Wei Gang
    Abstract:

    Post-construction Consolidation Settlement of soil above tunnel axis caused by shield tunneling is studied. Initial excess pore water pressure,due to stress release by unloading of soil excavation,is triangle-shaped distributed. Assuming that linings are undrained,soil is under single-drainage condition,and thickness of compressed soil equals that of soil above tunnel;theoretical calculation formula of post-construction Consolidation Settlement is obtained based on Terzaghi's one-dimensional Consolidation theory. Long-term Settlements of ground are divided into Settlement during construction and post-construction Consolidation Settlement. Furthermore,theoretical calculation formula of long-term ground Settlement is deduced. As shown in analytical calculation,the calculated results are in good agreement with the field data. It is analyzed that long-term ground Settlements caused by shield tunneling construction in soft soil of Shanghai are very noticeable. Final Settlements of ground can reach above 80 mm,and 80%～90% of Settlements are Consolidation Settlement. Assuming that the earth thickness above the tunnel lining is 5 m,Consolidation Settlement will be stable after at least 2 years.

  • Research of Consolidation Settlement caused by shield tunnel construction
    2011 International Conference on Electric Technology and Civil Engineering (ICETCE), 2011
    Co-Authors: Wei Gang, Wei Xin-jiang
    Abstract:

    The ground Settlement caused by shield tunnel construction increased gradually over time. The long-term Settlement caused by shield tunnel construction was divided into three stages. The stage 2 between the end of shield tunnel construction and the beginning of subway operation was emphatically analyzed. The research methods in stage 2 were summarized as follows: the predict method based on measured data, analytical solutions and finite element method, and the research progress and relative merits for each method were discussed, and the further research was also proposed. Finally, the distribution and calculation method of the soil excess pore water pressure were discussed, and the method to determine the scope of soil excess pore water pressure was put forward.

Liu Ji - One of the best experts on this subject based on the ideXlab platform.

  • engineering properties and Consolidation Settlement of the modern yellow river subaqueous delta
    Periodical of Ocean University of China, 2014
    Co-Authors: Liu Ji
    Abstract:

    In this paper,the Consolidation Settlement of the Yellow River subaqueous delta was studied based on the drilling data of the Yellow River subaqueous delta and forecasted the final Settlement.In result,surface sediments of ZK-1was significantly coarsen than ZK-2,and correspondingly with varying physical and mechanical properties in different cores.Based on the one-dimensional Consolidation theory,60mthickness of layer could produce a total of 2.08mSettlement in ZK-1,and 50mcould produce 1.70mSettlement in ZK-2.The Consolidation Settlement of unit depth was at 0.2~9.6cm/m.The Consolidation degree needed about 15~20years to reach 90%and the average sedimentation rate was at 6.5~8.5cm/a within 50mlayer thickness.