Characterization of properties of an unripe marine clay soil, I. Shrinkage processes of an unripe marine clay soil in relation to physical ripening

93A 932170 Constitutive equation of one-dimensional consolidation derived from inter-connected tests Imai, G; Tang, Y X Soils Found V32, N2, June 1992, P83-96 An interconnected consolodimeter with a series of thin subspecimens has been developed to investigate the general relation between void ratio, effective stress, and time at any element in a consolidating clay specimen. Subspecimens are in individual consolidation cells with successively connected drainage channels. A constitutive model in terms of void ratio, effective stress, and void ratio rate is developed, which can be used to explain the effects of layer thickness on compression strain by consolidation. Permeability characteristics were also examined. Permeability coefficient is seen to vary exponentially with void ratio. 932171 Characterization of properties of an unripe marine clay soil, I. Shrinkage processes of an unripe marine clay soil in relation to physical ripening Kim, D J; Vereecken, H; Feyen, J; Boels, D; Bronswijk, J J B Soil Sci V153, N6, June 1992, P471-481 Initially reclaimed marine soils show poor physical properties but they will develop a stable texture after cycles of shrinkage and swelling (ripening). Shrinkage behaviour of a marine clay from the northern coastal region of Holland has been studied. Three-dimensional volume shrinkage was characterised using the shrinkage characteristic (void ratio-moisture ratio) curve determined on soil clods. One dimensional behaviour geometry of shrinkage was determined on undisturbed cores at different ripening stages and applied loads. Both volumetric shrinkage and geometry of shrinkage are transient features of physical ripening. 932172 Motion equations of the dynamic theory of consolidation from the point of view of the theory of transient pipe flows Kolodziej, J A; Kaczmarek, M Trans Porous Media V8, N3, July 1992, P227-241 An elastic, fluid-saturated porous medium is modelled as an array of parallel, regularly arranged cylindrical tubes, aligned parallel to the direction of fluid movement. Pore space contains a viscous compressible fluid. A cell model and the theory of transient pipe flow are used to derive governing equations for the medium. Macroscopic constants in these equations are defined by individual material constants of the fluid and solid phases. The interaction force includes an additional term not found in Biot theory. 932173 Computing the land subsidence of Shanghai by a finite element method Dassargues, A; Li, X L Proc 4th International Conference on Land Subsidence, Houston, 12-17 May 1991 P613-624. Publ Wallingford: IAHS Press, 1991 Accurate simulation of subsidence in Shanghai has been possible using a transient 3D flow model and a coupled nonlinear ID flow-compaction model implemented within the finite element code LANGAMINE. The study is limited to the central zone of Shanghai and the upper 70m of loose sediments. Spatial discretization is sufficient to allow representation of heterogeneities and facies variation of the layers. Subsidence for the period up to the year 2000 has been computed for both a neutral groundwater pumping/injection case and for heavy groundwater overdraft.

932174 Prediction of future subsidence with quantified uncertainty by an inverse analysis procedure Honjo, Y; Darmawan, P Proc 4th International Conference on Land Subsidence, Houston, 12-17 May 1991 P625-634. Pubi Wallingford: IAHS Press, 1991 An improved method for the prediction of subsidence is proposed. Past observational data on head of aquifers and compression of aquitards are used to estimate the parameters in Terzaghi's one dimensional consolidation equation. Nonlinear regression is used in parameter estimation and the estimation uncertainty involved is quantified. These parameters are used to predict future aquitard compression under time dependent boundary conditions obtained from the initial procedure. The first order second moment method is used to calculate propagation of uncertainty through the consolidation model. The method is illustrated applied to both long term and short term observational data. 932175 Time delay effect of subsidence Xu, D M; Yong, R N; Mohamed, A M O Proc 4th International Conference on Land Subsidence, Houston, 12-17 May 1991 P635-643. Publ Wallingford: IAHS Press, 1991 Subsidence related to groundwater pumping results from drop of hydraulic pressure followed by time dependent consolidation deformation. The time factor between the two processes must be considered when assessing effects of natural or artificial recharge on subsidence. A model is developed which indicates that two factors govern the time delay effect, water table recovery rate and the ratio of volume compressibility coefficient to expansion coefficient of the aquitard soil. 932176 Finite element analysis of land subsidence due to the variation of groundwater level Shimizu, M Proc 4th International Conference on Land Subsidence, Houston, 12-17 May 1991 P645-654. Publ Walling)Cord: IAHS Press, 1991 A relatively simple analysis is presented to describe past subsidence around the city of Tottori, Japan, and predict future behaviour. A one dimensional consolidation finite element code is used to investigate the consolidation of a thick layer of alluvial clay as a result of variation in the groundwater level in the underlying sand layer. Data from site geophysical survey and simple laboratory tests are used in the analysis. Limitations are discussed. 932177 Analysis of ground water level fluctuations and borehole extensometer data from the Baytown Area, Houston, Texas Bravo, R; Rogers, J R; Cleveland, T G Proc 4th International Conference on Land Subsidence, Houston, 12-17 May 1991 P655-666. Publ Walling)Cord: IAHS Press, 1991 Despite groundwater management, piezometric levels in the Baytown area continue to fluctuate as a result of consolidation of compressible beds in the subsoil. Water level data from piezometric wells and records of consolidation between land surface and borehole extensometers at depths 13 l m and 450m have been used to generate stress strain diagrams. Head decline and recovery plotted against consolidation gives a series of open loops representing the elastic and inelastic parts of the consolidation curve. Records have been analysed to

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