Sand dykes and sills and vented sand boils on the Fraser River delta and adjacent Serpentine River floodplain in southwestern British Columbia record one or more major liquefaction events. The source of the dykes is a shallow subsurface saturated sand unit that was deposited in foreslope and distributary-channel environments during Holocene progradation of the Fraser delta. The dykes cut steeply through a crust of delta topset muds and locally flatten out as sills in overlying peaty sediments. At two sites, evidence was found for venting of sand onto a subaerial or intertidal surface. Liquefaction and upward movement of sand and water locally deformed the intruded sediments, causing some subsidence and uplift of the delta surface. All observed liquefaction features are younger than ca. 3500 BP, and at least some are younger than 2400 BP. It is not clear, however, whether they formed during one or several separate events. A review of possible causes suggests that the liquefaction features probably are seismically generated; they thus may provide the first direct evidence for moderate to large, prehistoric earthquakes in the Vancouver metropolitan area.

The standard penetration test (SPT) split-spoon sampler is too small for investigations in gravelly soils. For this reason, several researchers have developed scaled-up versions of the SPT, commonly referred to as "large penetration tests" (LPT), and attempted to correlate the measured blow counts to SPT blow counts. Several LPTs have been in use worldwide; each with different drill rods, sampler dimensions, and hammer energies; hence existing published LPT–SPT correlations differ for each system. This paper summarizes the LPT data in the literature and presents a fundamental method for predicting LPT–SPT correlations. The proposed method is based on wave equation analyses of SPT and LPT and considers variations in test equipment, penetration resistance, and energy. It is shown that the method provides a unified approach for assimilating the various published LPT–SPT correlations. Additional SPT and LPT data were collected at a sand research site to check the proposed method and to expand the LPT database. The observed and predicted correlation factors are shown to be in good agreement. The proposed correlation method will be useful as a logical framework for the comparison of LPT data collected throughout the world. Additional research will be required to extend this procedure to gravel sites.Key words: large penetration test, LPT, fundamental correlation method, wave equation analysis, grain size effects.

The Becker penetration test (BPT), through correlations with the standard penetration test (SPT), is widely used for foundation design and liquefaction assessment in gravelly soils. Most of the existing correlations, however, do not adequately account for the variable energy output of the diesel hammer used in the Becker system, and shaft friction on the Becker casing is ignored. An alternative and more rational approach to BPT–SPT correlations is presented, based on experimental and numerical studies conducted at the University of British Columbia. The research involves performing SPT, BPT, and other in situ tests at several sites in British Columbia and includes dynamic measurements of energy transfer in the SPT and BPT. Stress-wave measurements and wave-equation analyses are used to evaluate the effect of friction on the BPT blow count. New BPT–SPT correlations are proposed that consider the energy transfer in both tests and explicitly consider casing friction in the BPT. A recommended procedure for estimating equivalent SPT N60 from BPT blow count is presented. Key words : Becker penetration test, standard penetration test, dynamic measurement, pile driving, stress-wave propagation.

The nonlinear subgrade reaction method is widely used for the design of laterally loaded piles. This method replaces the soil reaction with a series of independent springs. The nonlinear behavior of the soil springs is represented by P-y curves, which relate soil reaction and pile deflection at points along the pile length. Most of the existing methods for obtaining P-y curves are highly empirical. Often little account is taken of the method of pile installation. The pressuremeter offers an almost ideal in-situ modelling tool for determining directly the P-y curves for a pile. As the pressuremeter can either be driven or self-bored into the soil, the results can be used to model either a displacement or a non-displacement pile. The driven pressuremeter used in the study described in this paper was essentially a standard pressuremeter with a solid 60° cone shoe at the tip. The instrument was pushed into the soil. This paper provides a detailed description of the equipment, testing procedures, and the theory that enables the family of P-y curves for laterally loaded displacement piles to be obtained. A case study, using the driven pressuremeter results to predict and compare the performance of two full-scale field lateral pile load tests, is presented.

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