- Email: [email protected]
Foundation impedance functions: theory versus experiment
307A relevant parameters are outlined, and the applicability of laboratory derived parameters to field situations is considered. Simple contaminant movement models are illustrated, and design of landfill sites to minimise contamination is discussed. 905424 Procedures most frequently used in Mexico for construction of piles in the presence of the phreatic level Serrano, J A P Proc 1st International Geotecimical Seminar on Deep Foundations on Bored and Auger Piles, Ghent, 7-10 June 1988 P343-348. Publ Rotterdam: A A Balkema, 1988 Construction of cast in situ piles below the water table is complicated by groundwater inflow and wall instability. Three case studies are presented where these problems were overcome. In sandy soils, a bentonite mud was used. For bridge foundations, a mid-river artificial island was constructed behind sheet piles and piles formed under bentonite. For a saturated layer between clay layers, a tubular casing was first sunk. After drilling and concreting inside the casing, it was withdrawn.
and HaskeU matrix formulation. Displacement continuity between the two regions is ensured by least squares error minimization. Surface and shallow embedded structures excited by steady,-plane waves propagating with oblique incidence are studied. 905428 Seismic response of piles to obliquely incident SH, SV, and P waves
Mamoon, S M; Ahmad, S J Geoteci~ Engng Dbo ASCE 1/116, N2, Feb 1990, P186-204 A hybrid BEM analysis is presented. Piles are idealised as compressible beam columns and the soil as a hysteretic viscoelastic half space. The governing differential equations of motion for the pile are solved exactly for distributed periodic loading intensities, and the solutions coupled with BEM numerical solutions for the soil domain, satisfying equilibrium and displacement compatibility conditions. The dependence of response on a wide range of geometrical and material parameters is illustrated using nondimensional charts. Results compare well with available published data.
Influence of dynamic loads 905425 Mechanics and performance of a tied-back wall under seismic loads Neelakantan, G; Budhu, M; Richards, R Eartlul Engng Struct Dynam V19, N3, April 1990, P315-331 Stability of a tied back wall against failure by rotation about the top of the wall under seismic loading is analysed and results compared to data from a seismic simulator. Pseudostatic analysis using the Mononobe-Okabe earth pressure coefficients, where dynamic effects are converted to equivalent static loads, is used. Wall friction on the passive side increases the stability of the flexible wall against seismic loads, and walls retaining dry cohesionless soils can be very efficient. Stability increases with embedment depth up to a limit, for moderate earthquakes. Design charts are presented. 905426 Influence of phase on calculation of pseudo-static earth pressure on a retaining wall Steedman, R S; Zeng, X Geotechnique 1/40, N1, March 1990, P103-112 A phase change in lateral acceleration in backfill behind a retaining wall as shear waves propagate from the base of the model to the ground surface, associated with variation with depth of fill properties, is seen in centrifuge tests. Design calculations for dynamic earth pressure generally assume uniform acceleration throughout the fill. An analysis taking account of this phase change is presented. Magnitude of total earth pressure is little affected, however the dynamic increment of earth pressure acts at a point above one third wall height. Selection of the most appropriate design value for lateral acceleration coefficient is discussed. 9O5427 Soil-structure interaction in a layered medium Romanel, C; Kundu, T lnt J Engng Sci 1/28, N3, 1990, P191-213 A hybrid method based on the Green's function formulation is presented. The structure and surrounding soil are modelled by finite elements, and the far field problem is solved using a continuum approach based on an adaptation of the Thomson
905429 WAK test to find spread footing stiffness Briaud, J L; Lepert, P J Geotech Engng Div ASCE VII6, N3, March 1990, P415431 A cheap, nondestructive method to obtain the stiffness of soil beneath a spread footing is presented. This dynamic test involves hitting the footing with an instrumented hammer and recording soil-footing response with two geophones on the footing. Analysis of the force and velocity signals using the Fast Fourier Transform gives estimates of stiffness of the footing-soil assembly in good agreement with those from loading tests. 9O543O Foundation impedance functions: theory versus experiment Crouse, C B; Hushmand, B; Luco, J E; Wong, H L J Geotech Engng Div ASCE VII6, N3, March 1990, P432449 Forced-harmonic-vibration tests using an eccentric-mass shaker were carried out on a square slab foundation with corner piers embedded in moderately stiff alluvial deposits, and a rectangular slab resting directly on softer deposits. Experimental foundation impedance functions computed from vibration response data are close to theoretical values in the latter case, but significantly different in the former. This discrepancy is probably due to overestimation of S wave velocities in the top layers of the soil directly under the foundation, and to a lesser extent using a single disc model for the complex foundation. 905431 Vibro pile-driving of metallic sheet piles under reconstruction and urban development conditions Tseitlin, M G; Izofov, V 0 Soil Mech Found Engng V26, N2, March-April 1989, P37-40 Sheet piles are often installed using vibratory techniques, but this may have damaging dynamic consequences for nearby structures. The influence of vibratory frequency and of run up and run down of the vibratory pile driver on amplitude of movement of floors of an adjacent building has been studied in order to help optimise the vibratory driving technique.
© 1990 Pergamon Press plc. Reproduction not permitted R MMS 2~ .~-L
and HaskeU matrix formulation. Displacement continuity between the two regions is ensured by least squares error minimization. Surface and shallow embedded structures excited by steady,-plane waves propagating with oblique incidence are studied. 905428 Seismic response of piles to obliquely incident SH, SV, and P waves
Mamoon, S M; Ahmad, S J Geoteci~ Engng Dbo ASCE 1/116, N2, Feb 1990, P186-204 A hybrid BEM analysis is presented. Piles are idealised as compressible beam columns and the soil as a hysteretic viscoelastic half space. The governing differential equations of motion for the pile are solved exactly for distributed periodic loading intensities, and the solutions coupled with BEM numerical solutions for the soil domain, satisfying equilibrium and displacement compatibility conditions. The dependence of response on a wide range of geometrical and material parameters is illustrated using nondimensional charts. Results compare well with available published data.
Influence of dynamic loads 905425 Mechanics and performance of a tied-back wall under seismic loads Neelakantan, G; Budhu, M; Richards, R Eartlul Engng Struct Dynam V19, N3, April 1990, P315-331 Stability of a tied back wall against failure by rotation about the top of the wall under seismic loading is analysed and results compared to data from a seismic simulator. Pseudostatic analysis using the Mononobe-Okabe earth pressure coefficients, where dynamic effects are converted to equivalent static loads, is used. Wall friction on the passive side increases the stability of the flexible wall against seismic loads, and walls retaining dry cohesionless soils can be very efficient. Stability increases with embedment depth up to a limit, for moderate earthquakes. Design charts are presented. 905426 Influence of phase on calculation of pseudo-static earth pressure on a retaining wall Steedman, R S; Zeng, X Geotechnique 1/40, N1, March 1990, P103-112 A phase change in lateral acceleration in backfill behind a retaining wall as shear waves propagate from the base of the model to the ground surface, associated with variation with depth of fill properties, is seen in centrifuge tests. Design calculations for dynamic earth pressure generally assume uniform acceleration throughout the fill. An analysis taking account of this phase change is presented. Magnitude of total earth pressure is little affected, however the dynamic increment of earth pressure acts at a point above one third wall height. Selection of the most appropriate design value for lateral acceleration coefficient is discussed. 9O5427 Soil-structure interaction in a layered medium Romanel, C; Kundu, T lnt J Engng Sci 1/28, N3, 1990, P191-213 A hybrid method based on the Green's function formulation is presented. The structure and surrounding soil are modelled by finite elements, and the far field problem is solved using a continuum approach based on an adaptation of the Thomson
905429 WAK test to find spread footing stiffness Briaud, J L; Lepert, P J Geotech Engng Div ASCE VII6, N3, March 1990, P415431 A cheap, nondestructive method to obtain the stiffness of soil beneath a spread footing is presented. This dynamic test involves hitting the footing with an instrumented hammer and recording soil-footing response with two geophones on the footing. Analysis of the force and velocity signals using the Fast Fourier Transform gives estimates of stiffness of the footing-soil assembly in good agreement with those from loading tests. 9O543O Foundation impedance functions: theory versus experiment Crouse, C B; Hushmand, B; Luco, J E; Wong, H L J Geotech Engng Div ASCE VII6, N3, March 1990, P432449 Forced-harmonic-vibration tests using an eccentric-mass shaker were carried out on a square slab foundation with corner piers embedded in moderately stiff alluvial deposits, and a rectangular slab resting directly on softer deposits. Experimental foundation impedance functions computed from vibration response data are close to theoretical values in the latter case, but significantly different in the former. This discrepancy is probably due to overestimation of S wave velocities in the top layers of the soil directly under the foundation, and to a lesser extent using a single disc model for the complex foundation. 905431 Vibro pile-driving of metallic sheet piles under reconstruction and urban development conditions Tseitlin, M G; Izofov, V 0 Soil Mech Found Engng V26, N2, March-April 1989, P37-40 Sheet piles are often installed using vibratory techniques, but this may have damaging dynamic consequences for nearby structures. The influence of vibratory frequency and of run up and run down of the vibratory pile driver on amplitude of movement of floors of an adjacent building has been studied in order to help optimise the vibratory driving technique.
© 1990 Pergamon Press plc. Reproduction not permitted R MMS 2~ .~-L