An Analysis of System Flexibility and its Effect on Time-Lag in Pore-Water Pressure Measurements

Gibson, R. E.

doi:10.1680/geot.1963.13.1.1

Cited by 77 publications

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“…The conventional Asaoka (1978) method is used to calculate the values of c v (e.g. Mesri & Huvaj-Sarihan, 2009;Prakash et al, 2013) for Δt = 500 s. The intersection of 45°line from the origin with the settlement data will give a reading corresponding to EOP consolidation. Figure 5 presents the plot of u j+1 against u j for clay 1 for a pressure increment of 0-20 kPa.…”

Section: Theoretical Considerationmentioning

confidence: 99%

“…Lot of laboratory experimental studies have been carried out, in the past, on the measurement of pore water pressure during consolidation (e.g. Whitman et al, 1961;Gibson, 1963;Northey & Thomas, 1965;Sonpal & Katti, 1973;Robinson, 1999;Robinson & Soundara, 2008). Most of the studies were carried out by mounting a pore water pressure measurement device at the base of the consolidation apparatus.…”

Section: Introductionmentioning

confidence: 99%

“…Asaoka (1978) proposed a graphical approach for estimating the value of c v and EOP compression based on Mikasa's consolidation theory. The mathematical deduction for the method is not very simple (Mesri & Huvaj-Sarihan, 2009); however, the graphical approach is simple and widely used by practising engineers. The procedure consists of plotting settlement/deformation data taken at regular intervals against the elapsed time.…”

Section: Introductionmentioning

confidence: 99%

“…More details on the procedure for evaluating c v based on the settlement data can be found elsewhere (e.g. Asaoka, 1978;Tan & Chew, 1996;Mesri & Huvaj-Sarihan, 2009;Prakash et al, 2013). Recently, Mesri & Huvaj-Sarihan (2009) proposed a simple mathematical deduction for Asaoka's (1978) method for the settlement data obtained from one-dimensional consolidation test.…”

Section: Introductionmentioning

confidence: 99%

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Laboratory determination of coefficient of consolidation from pore water pressure measurement

Vinod¹,

Sridharan²

2015

Géotechnique Letters

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ICE Publishing: all rights reserved. In the recent past, many studies have been carried out on the determination of coefficient of consolidation (cv) from the time (t)-deformation (d) data obtained from conventional consolidation tests. Several researchers have also proposed different curve fitting procedures for determining cv from the t-d data. It is anticipated that the cv values obtained from the t-d data may be influenced by initial and secondary compressions. Nevertheless, the pore water pressure data measured during the consolidation process will be independent of initial and secondary compressions. In this study, the conventional Asaoka (1978) method is extended to evaluate cv and end-of-primary (EOP) consolidation from the pore water pressure data measured from laboratory experiments. Laboratory experiments were carried out on the modified one-dimensional consolidation apparatus on different remoulded clay samples measuring pore water pressure during the consolidation process. The cv and EOP computed from the proposed approach have been compared with the results of the t-d data and found to be in good agreement. It is anticipated that the c v values obtained from the t-d data may be influenced by initial and secondary compressions. Nevertheless, the pore water pressure data measured during the consolidation process will be independent of initial and secondary compressions. In this study, the conventional Asaoka (1978) method is extended to evaluate c v and end-of-primary (EOP) consolidation from the pore water pressure data measured from laboratory experiments. Laboratory experiments were carried out on the modified one-dimensional consolidation apparatus on different remoulded clay samples measuring pore water pressure during the consolidation process. The c v and EOP computed from the proposed approach have been compared with the results of the t-d data and found to be in good agreement.

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Section: Theoretical Considerationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Laboratory determination of coefficient of consolidation from pore water pressure measurement

Vinod¹,

Sridharan²

2015

Géotechnique Letters

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“…A characteristic time tc for the gas in a spherical bubble to reach equilibrium after a pressure change can be estimated from existing solutions for diffusion from a spherical source into a surrounding infinite homogeneous medium as, for example, given by Gibson [1963 time assumes that the free gas is evenly distributed in equal-sized bubbles. Exact solutions for spherical diffusion are not likely to be directly applicable because gas solution from bubbles in a porous medium involves poorly understood processes such as diffusion at the pore scale and surface tension effects.…”

Section: -Ng)•w Q-rigfig Q-(1 -Ng)co(•g -Fio• -•) (5)mentioning

confidence: 99%

Theory for the effects of free gas in subsea formations on tidal pore pressure variations and seafloor displacements

Wang¹,

Davis²,

Kamp³

1998

J. Geophys. Res.

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Abstract. Loading of the seafloor by regional-scale pressure variations, such as those imposed by ocean tides, is supported by both the rock matrix and interstitial fluid. The nature of the partitioning of the support between the two depends primarily on the compressibility of the fluid and the compressibility and fluidtransport properties of the rock matrix. In this paper, we examine theoretically the influence of free gas on pore fluid compressibility, on the nature of time-dependent load partitioning, and on the consequent vertical rock deformation and seafloor displacement. An example is the gas trapped below deep-sea gas hydrate. We have derived an expression for the steady state compressibility of pore fluid considering the influence of gas solubility in water. The effect of gas solubility is seen to be important at low, such as tidal, loading frequencies and thus must be included when observations of tidally induced pore fluid pressure variations or seafloor displacements are used to constrain gas content. For very low gas concentrations na (much less than 0.1%), the steady state fluid compressibility can be enhanced by gas solution/dissolution over the loading cycle by several factors at high ambient pressure and more than an order of magnitude at low ambient pressures (< 5 MPa). At na > 2%, the fluid compressibility increases sensitively with na and greatly affects the tidal response of the pore fluid pressure regardless of the solubility. Thus, with careful experimental design, tidally induced pore pressure variations may be used to detect very small amounts of free gas and constrain the quantity if na > 2%. This method is complementary to using acoustic velocity to constrain the quantity of free gas, which works well in the na = 0.2-2% range. We have also given an expression for the vertical deformation of subsea formations and hence of the seafloor displacement under tidal loading. The presence of free gas enhances tidally induced seafloor displacement, but the maximum effect is limited by the compressibility of the matrix frame. Given relatively low frame compressibility, tidally induced seafloor displacement is small, of the order of 1 mm, which is presently difficult to detect at tidal frequencies.

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Finite Element Modelling of a Deep Sea Clay in Long‐term Laboratory Creep Tests

Brandes

Sadd

Silva

1996

Num Anal Meth Geomechanics

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SUMMARYA new finite element program is introduced and its predictive capabilities are compared to results from two long-term, drained laboratory creep tests on a deep sea clay. The constitutive behaviour is based on Cam clay critical state plasticity theory with creep and time-dependent hardening. Creep is computed using either Singh-Mitchell's three-dimensional equation or Taylor's secondary compression relationship. The experimental creep data include a triaxial specimen subjected to two deviatoric stress increments and a onedimensional consolidation specimen subjected to three vertical stress increments. In addition, the pore pressure behaviour following an increase in stress is examined in the triaxial sample. Predictions compare favourably to test data, which provide confidence for applying the chosen constitutive model and numerical formulation to solve seabed-related problems on the continental slope that are of interest to geologists, the oil industry and the navy, among others.

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An Analysis of System Flexibility and its Effect on Time-Lag in Pore-Water Pressure Measurements

Cited by 77 publications

References 0 publications

Laboratory determination of coefficient of consolidation from pore water pressure measurement

Laboratory determination of coefficient of consolidation from pore water pressure measurement

Theory for the effects of free gas in subsea formations on tidal pore pressure variations and seafloor displacements

Finite Element Modelling of a Deep Sea Clay in Long‐term Laboratory Creep Tests

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