Quaternary sediments in central Edmonton, Alberta, Canada: stratigraphy, distribution and geotechnical implications

UNDERGROUND EXCAVATIONS:GEOLOGICAL FACTORS the time domain through properly defined constitutive models. The bounded soil zone taken should be large enough in both methods to reduce the adverse effects of the far-field linearization. -from Author 945254 Finite element analysis of interaction between u n d e r g r o u n d steel distributor and s u r r o u n d i n g rock (in Chinese) Zhong Bingzhang & Lu Qiang, Shuili Xuebao/Journal of Hydraulic Engineering, 2, 1994, pp 18-23. In the paper, the finite element method (FEM) is used to analyze the stress of the underground steel distributor with gaps existing between distributor, concrete and surrounding rock. Concrete is assumed only to transmit load to rock, and rock is considered to apply elastic reactions to the distributor. After several times of iteration, the results could be approached. Application of this method in some engineering projects show that the surrounding rock has great influence on distributor stresses. -English summary 945255 An important parameter in geotechnical engineering for earthquake disaster mitigation - shear wave velocity (in Chinese) Wang Wenshao, Shuili Xuebao/Journal of Hydraulic Engineering, 3, 1994, pp 80-84,89. The phenomena of soil liquefaction deformation, cracking and loss of stability of soil masses, are all governed by the mechanical property of the soil mass, especially by the rigidity or shear modulus of the soil mass. As the shear wave velocity is proportional to the square root of the shear modulus of the soil, it becomes an useful physical quantity in the geotechnical earthquake engineering. There are several uses of shear wave velocity as a parameter in the field of geotechnical earthquake engineering, e.g., 1) for classification of construction sites with different subsoil conditions; 2) for assessment of liquefaction potential of saturated soils; 3) for determination of shear moduli of soils used in seismic response analyses; 4) used as a control criterion in making reconstituted saturated sand sampies in laboratory to recall the dynamic property of the undisturbed saturated sand in situ. -Enghsh summary 945256 Material damping for lumped-parameter models of foundations J. W. Meek & J. P. Wolf, Earthquake Engineering & Structural Dynamics, 23(4), 1994, pp 349-362. In foundation dynamics two mechanisms of energy dissipation exist, wave radiation and material damping. Elastic continuum models of the soil capture only the radiation effect. To incorporate material damping, use is made of the fact that the dynamic-stiffness relationships of all elastic foundations may be simulated by discrete assemblages of springs dashpots and masses. The analysis, which is effected solely in the time domain, is illustrated by an example from earthquake engineering. -from Authors 945257 An analytical solution for the probabilistic response of SDOF non-linear r a n d o m systems subjected to variable amplitude cyclic loading G. M. E. Manzocchi, M. Chryssanthopoulos & A. S. Elnashai, Earthquake Engineering & Structural Dynamics, 23(5), 1994, pp 489-506. Design for a specific ductile failure mode is assuming a role of increasing importance for earthquake-resistant structures. This necessitates an accurate assessment of the distribution of overstrength in the structure, in order that the predefined failure mode can be realized. Consequently, the variability of the response for a given variability in the salient material properties, such as yield strength for steel structures, should be assessed and accounted for. In this paper an analytical method is proposed for the evaluation of the probability density functton of the response of a single-degree-of-freedom hysteretic system with random parameters subject to a variable amplitude cyclic load history. A simple algorithm is derived which may be used to obtain the system response as a function of the system parameters. -from Authors

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945258 Influence of soft clays on the response spectra for structures in eastern Canada

R. Tinawi, M. Sarrazin & A. Filiatrault, Soil Dynamics & Earthquake Engineering, 12(8), 1993, pp 469-477. The 1990 edition of the National Building Code of Canada makes a clear distinction between eastern and western Canada in terms of seismic acceleration and velocity zones. This paper develops ground amplification curves for clays having depths between 10 and 70 m excited by typical eastern Canadian ground motions scaled to two different values of peak horizontal accelerations. Simplified free-field spectral design curves, which could be used by structural designers, are proposed. The curves show that maximum spectral accelerations occur for structural periods between 0.2 and 0.5 s. In addition, soil depth does not appear to be an important parameter controlling the response of typical clay deposits m eastern Canada. -from Authors 945259 Influence of membrane forces on transverseshear reinforcement design P. Adebar & Weishi He, Journal of Structural Engineering- ASCE, 120(4), 1994, pp 1347-1366. A procedure is presented for the design of transverse reinforcement in concrete slabs and wails subjected to combined transverse shear, membrane forces, and b-~nding moments, such as what commonly occurs in ice walls of concrete offshore structures. The slab or wall is treated as an equivalent beam in the principal transverse-shear direction, and a unifield shear-design procedure based on the modified compression field theory is used to design the reinforcement. The method includes a rational concrete contribution, making it suitable for members with little or no transverse reinforcement. The biaxial membrane strains at the level of the flexural tension reinforcement are estimated using a generalized tress (sandwich) model, assuming cracked-linear response of concrete. The normal-strain component in the principal transverse-shear direction is assumed analogous to the longitudinal strain in a beam. Comparisons of the proposed design method with a complex three-dimensional analysis model and some recent experimental results show very good agreement. -Authors

UNDERGROUND EXCAVATIONS

Geological factors of importance in underground excavations 945260 Q u a t e r n a r y sediments in central Edmonton, Alberta, Canada: stratigraphy, distribution and

geotechnical implications

K. Feltham, Quaternary International, 20, 1993, pp 13-26. The Quaternary sediments overlying Upper Cretaceous sedimentary bedrock, mapped by borehole logs, consist of preglacial fluvial sand and some gravel, glaciofluvial sand and gravel, a glacial diamicton complex composed of meltout and flow diamictuns, glaciofluvial sand and silt, glaciolacustrine silt and clay, and minor deposits of postglacial fluvial sand. The diamicton complex has an intermediate stratigraphic position in the Quaternary sequence, is generally thick and laterally continuous, and serves as a satisfactory substrate for many deep foundations and tunels, including part of the Light Rail Transit system. eepage and block failures during tunnelling in the diamicton complex are mainly due to abundant saturated sand lenses in the upper part of the complex. Tunnelling is difficult and costly within the sand, due to seepage and collapse. Mapping of the meltwater channel and associated outwash deposits allowed adjustment of the tunnel alignment to avoid intersection with the channel. -Author

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