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Soil models in offshore engineering
55A . 862127 Earth pressure on retaining walls and buried pipes Fukuoka, M; Imamura, Y Proc Internutionuf Confcrencc on Cuse Histories in Geotechnical Engineering, Rob, Missouri, 6-11 May 1984 VI, P355-362. Pub1 St Louis: Geotechnical Engineering, 1984 Results of earth pressure measurements on retaining -walls and buried pipes are described. Conventional earth pressure gauges fixed on the walls were not used, instead, panel type earth pressure gauges which cover the whole wall surface were used. Vertical and tangential components of the resultant earth pressures were measured. Auth.
862128 Improved technique of in-situ measurement of fracture zones surrounding coalmine gateroads Smart, G D; Isaac, A K; Nicholas, P K In: Rock Mechanics in Productivity and Protection (Proceedings of the Twenty-Fifth Symposium on Rock Mechanics, Evanston, Illinois, 2527 June 1984) P680-687. Pub1 New York: AIME, 1984 The magnetic rod extensometer system has been developed to monitor movement in zones around roadways and gateways in underground mines. It is based on the principle of measuring the relative positions of small rectangular magnets inside a borehole. Details of the system, the scanning of the extensometer probes and the processing of the data gathered are given. In laboratory and field testing it has proved robust, accurate, low-cost, simple to operate, and intrinsically safe.
Analysis Techniques and Design Methods See also: 862004, 862012, 862017, 862058, 862068, 862099, 862169.
862129 Quasi-explicit modification of the two time level family of schemes for non-linear transient analysis Kujawski, J; Desai, C S Int J Num Anal Meth Geomech V9, N5, Sept-Ott 1985, P437-45 I Transient problems in geotechnical engineering include consolidation, seepage, heat flow, visco-elastic flow and soil-structure interaction with rheological effects. Two popular two time level algorithms, the generalised trapezoidal method (GTM) and the generalised midpoint method (GMM), for non-linear time integration are transformed into corresponding quasiexplicit algorithms. The new quadratic quasi-explicit systems show high stability, accuracy and non-oscillatory behaviour and are examined for different non-linear situations. The modification of the GTM showed the higher stability and nonoscillatory behaviour. 0 R.M MS.23:2-G
Stress analysis See also: 862046. 862104, 862171, 862194, 862241 862130 Soil models in offshore engineering Janbu, N Geotechnique V35, N3, Sept 1985, P241-281 Report of the twenty-fifth Rankine Lecture. Over the last lo15 years, the modelling of soil behaviour within the resistance concept has been used extensively for typical offshore problems. The Geotechnical Division at the Norwegian Institute of Technology have developed elements of the soil model. The basic elements are defined. Simple stress field theories were developed to express the state of equilibrium stress in the subsoil. Examples of the results of multi-stage triaxial testing are shown to illustrate its potential for future research. As examples of the application of the soil models, simplified analyses were carried out for a large gravity platform in deep water, whose foundations penetrate through the softest top soil layers. 56 refs. 862131 Constitutive model for the stress-strain-time behaviour of ‘wet’ clays Borja, R I; Kavazanjian, E Geotechnique V3.5, N3. Sept 1985, P283-298 A recently developed constitutive model is described to characterize the stress-strain-time behaviour of ‘wet’ clays in general three dimensional stress and strain conditions. It is based on Bjerrum’s concept of total strain decomposition into an immediate (time-independent) part and a delayed (time-dependent) part, generalized to three dimensional situations. The mathematical characterization of the constitutive model is given by the constitutive equation expressed in a form suitable for direct numerical implementation (ie finite element formulation). The equation is shown to predict accurately the stressstrain-time behaviour of an undisturbed ‘wet’ clay in triaxial and plane strain stress conditions. 862132 Calibration of coastitutive models of granular materials using data from biaxia1 experiments Vardoulakis, I; Graf, B Geotechnique V35, N3, Sept 1985, P299-317 The predictive capability of a class of rate-type constitutive equations for describing the behaviour of frictional dilatant materials is tested in plane strain compression experiments. The examination is restricted on shear band bifurcation states, where small deviations of the deformations from rectilinear extensions can be assumed. For predicting correctly both the state of bifurcation and the shear band inclination, the incipient shear modulus parallel to the geometric axis has to be estimated as the modified secant modulus. In addition a second hardening modulus, related to incipient contraction during the process of shear band formation, must be considered. Auth. 862133 Transfer matrix approach for nonlinear pile group response analysis Nogami, T; Paulson, S K Int J Num Anal Meth Geomech V9, N4, July-Aug 1985, P299-316 A transfer matrix method is applied for the analysis of nonlinear pile group responses. The closed form expression of the transfer matrix was obtained by idealizing the non-linear
1986 Pergamon Press Ltd. Reproduction
not permitted
862128 Improved technique of in-situ measurement of fracture zones surrounding coalmine gateroads Smart, G D; Isaac, A K; Nicholas, P K In: Rock Mechanics in Productivity and Protection (Proceedings of the Twenty-Fifth Symposium on Rock Mechanics, Evanston, Illinois, 2527 June 1984) P680-687. Pub1 New York: AIME, 1984 The magnetic rod extensometer system has been developed to monitor movement in zones around roadways and gateways in underground mines. It is based on the principle of measuring the relative positions of small rectangular magnets inside a borehole. Details of the system, the scanning of the extensometer probes and the processing of the data gathered are given. In laboratory and field testing it has proved robust, accurate, low-cost, simple to operate, and intrinsically safe.
Analysis Techniques and Design Methods See also: 862004, 862012, 862017, 862058, 862068, 862099, 862169.
862129 Quasi-explicit modification of the two time level family of schemes for non-linear transient analysis Kujawski, J; Desai, C S Int J Num Anal Meth Geomech V9, N5, Sept-Ott 1985, P437-45 I Transient problems in geotechnical engineering include consolidation, seepage, heat flow, visco-elastic flow and soil-structure interaction with rheological effects. Two popular two time level algorithms, the generalised trapezoidal method (GTM) and the generalised midpoint method (GMM), for non-linear time integration are transformed into corresponding quasiexplicit algorithms. The new quadratic quasi-explicit systems show high stability, accuracy and non-oscillatory behaviour and are examined for different non-linear situations. The modification of the GTM showed the higher stability and nonoscillatory behaviour. 0 R.M MS.23:2-G
Stress analysis See also: 862046. 862104, 862171, 862194, 862241 862130 Soil models in offshore engineering Janbu, N Geotechnique V35, N3, Sept 1985, P241-281 Report of the twenty-fifth Rankine Lecture. Over the last lo15 years, the modelling of soil behaviour within the resistance concept has been used extensively for typical offshore problems. The Geotechnical Division at the Norwegian Institute of Technology have developed elements of the soil model. The basic elements are defined. Simple stress field theories were developed to express the state of equilibrium stress in the subsoil. Examples of the results of multi-stage triaxial testing are shown to illustrate its potential for future research. As examples of the application of the soil models, simplified analyses were carried out for a large gravity platform in deep water, whose foundations penetrate through the softest top soil layers. 56 refs. 862131 Constitutive model for the stress-strain-time behaviour of ‘wet’ clays Borja, R I; Kavazanjian, E Geotechnique V3.5, N3. Sept 1985, P283-298 A recently developed constitutive model is described to characterize the stress-strain-time behaviour of ‘wet’ clays in general three dimensional stress and strain conditions. It is based on Bjerrum’s concept of total strain decomposition into an immediate (time-independent) part and a delayed (time-dependent) part, generalized to three dimensional situations. The mathematical characterization of the constitutive model is given by the constitutive equation expressed in a form suitable for direct numerical implementation (ie finite element formulation). The equation is shown to predict accurately the stressstrain-time behaviour of an undisturbed ‘wet’ clay in triaxial and plane strain stress conditions. 862132 Calibration of coastitutive models of granular materials using data from biaxia1 experiments Vardoulakis, I; Graf, B Geotechnique V35, N3, Sept 1985, P299-317 The predictive capability of a class of rate-type constitutive equations for describing the behaviour of frictional dilatant materials is tested in plane strain compression experiments. The examination is restricted on shear band bifurcation states, where small deviations of the deformations from rectilinear extensions can be assumed. For predicting correctly both the state of bifurcation and the shear band inclination, the incipient shear modulus parallel to the geometric axis has to be estimated as the modified secant modulus. In addition a second hardening modulus, related to incipient contraction during the process of shear band formation, must be considered. Auth. 862133 Transfer matrix approach for nonlinear pile group response analysis Nogami, T; Paulson, S K Int J Num Anal Meth Geomech V9, N4, July-Aug 1985, P299-316 A transfer matrix method is applied for the analysis of nonlinear pile group responses. The closed form expression of the transfer matrix was obtained by idealizing the non-linear
1986 Pergamon Press Ltd. Reproduction
not permitted