Soil Consolidation Behavior Assessed by Seismic Velocity Measurements*

Abstract

HAMDI, FALAH A.I. and TAYLOR SMITH, D. 1981, Soil Consolidation Behavior Assessed by Seismic Velocity Measurements, Geophysical Prospecting 29, 7 15-729.Large gravity platforms are often used as alternatives to the more conventional pilesupported structures in hydrocarbon exploitation. A gravity structure, as opposed to the piled structure, is sitting on the sea floor by virtue of its weight and base width; as such it poses considerable problems for the site investigation engineer. One such problem is the calculation of the settlement of the structure and its time history; these depend upon the permeability and compressibility of the soil and its drainage conditions. The required data are usually obtained by sampling for subsequent laboratory testing. The collection of an undisturbed sample is beset by problems so that the consolidation behavior of the foundation material can only be inadequately assessed by laboratory testing. However, a series of laboratory consolidation experiments during which seismic velocities have been measured on the sample as consolidation proceeds shows that it is possible to reconstruct the stress-strain and time-dependent curves from the seismic data, once the initial void ratio and permeability of the soil are known. This leads the way to an in situ technique for predicting settlement using a combination of geophysical techniques (electrical resistivity and seismic velocities) to obtain the required engineering properties.

Geotechnical Parameters from Seismic Measurements: Two Field Examples from Egypt and Saudi Arabia

“…In most instances, such determinations were required for only the first 100-200 m of the subsurface (Dobecki and Romig, 1985). Other applications included dam site investigations (Henriet et al, 1983;Dutta, 1984;Kim et al, 2010), groundwater resource exploration (Frohlich, 1974;van Overmeeren, 1975van Overmeeren, , 1980van Overmeeren, , 1981Vandenberghe, 1976;Worthington, 1976Worthington, , 1977Carmichael and Henry, 1977), industrial plant foundation design (Dinis da Gama and Bernardo, 2002), fracture density and uniformity (e.g., Bless and Ahrens, 1977;Sjogren et al, 1979;Hamdi and Smith, 1981), dynamic processes monitoring, which includes groundwater, petroleum, mining, and geothermal provinces either by repeat, active survey methods or by continuous, passive survey monitoring (Dusseault and Nyland, 1982;Bartel, 1982;Holzhausen et al, 1985;Arai and Tokimatsu, 2004;Goertz et al, 2012), clay mapping (Bazin and Pfaffhuber, 2013;Adamczyk et al, 2013;Shan et al, 2014), void detection (Hanafy, 2010;Nolan et al, 2011), and certification (safety) of existing structures such as dams (Bogoslovsky and Ogilvy, 1973a;Davenport and Hadley, 1984;Kim et al, 2010), mines (Fajk, 1983;Hanafy et al, 2009;Hanafy and Schuster, 2011), and concrete shafts (Hearne et al, 1979).…”

Deep-Sea Sediment Compression Curves: Some Controlling Factors, Spurious Overconsolidation, Predictions, and Geophysical Reproduction

“…sediment sample of Atterbe rg limits quality and a standard velocity ] void ratio s . graph Figure 15 , it is possible to reconstruct an e y log p compression curve s from the geophysical data see Hamdi & Taylor Smith, 1981 2. The effect of carbonate on the physicomechanical propertie s is conside rable: in the case of consolidation, as the void index profiles show, the effect is dramatic; additionally, both sound velocity and vane shear strength increase, the clay ostensibly having been provided with a much stronger structure .…”

Assessing the Validity of Seismo-Acoustic Predictor Equations for Obtaining Seabed and Sub-Surface Sediment Physical Properties

“…In order to simulate the behavior of sediments at greater burial depths, subsamples from the cores were subjected to incrementally increasing loads in consolidation cells (oedometers) that have been modi ed to carry acoustic instrumentation (Hamdi and Taylor Smith, 1981). The principal setup of such a cell is shown in Figure 5.…”