摘要:

This paper reports the observation and analysis of the rate and magnitude of settlement under the test embankment at Canadian Forces Station Gloucester. The embankment has been in existence for 7 years and, because of extensive instrumentation, a sufficiently complete record has emerged. An advanced finite element method has been used for the computation of the induced stresses in the foundation soil.Both block samples and 5 in. (12.7 cm) diameter Osterberg samples were recovered at various depths from the site. An experimental program, including the use of the 6 in. (15.2 cm) Rowe cell, has been carried out and an analysis of the test results based on the Gibson and Lo theory. The test results have also been used in the estimation of the field performance.From the present study it is found that: the coefficient of consolidation and the primary and secondary compressibility can be adequately determined from samples of size 4.5 in. (11.3 cm) diameter by 2 in. (5.1 cm) high or larger; the secondary compression contributes significantly to the total settlement for the soil considered; and the Gibson and Lo theory predicts fairly accurately both the time rate and magnitude of settlement in the field.

ISSN:0008-3674    

DOI:10.1139/t76-036

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

An analytical method for predicting the settlement of a horizontal stratum of dry sand subjected to earthquake excitation is presented. An equivalent linear viscoelastic dynamic analysis is used to determine the time-history of shear strains at various levels within the stratum. The vertical strains caused by these shear strains are calculated by an empirical relationship shown to be in close agreement with laboratory test data over a wide range of relative densities. This allows the settlement distribution with depth to be calculated as a function of time.The method was applied to a 50 ft (15 m) stratum of sand. A base acceleration corresponding to 0–10 s of the N–S component of El Centro earthquake was used. Settlement distributionvs. depth, as well as surface settlements for various relative densities and earthquake scaling factors are shown. The effect of surcharge loading on settlements is investigated in an approximate manner.The results may be used to estimate differential settlement of a structure due to an earthquake. The results show that while the compaction of the upper layers may be sufficient to reduce the settlements due to static loads to tolerable amounts, deep-seated settlements will still occur during an earthquake.

ISSN:0008-3674    

DOI:10.1139/t76-037

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

Construction of embankments using frozen soils can cause excessive settlement and loss of stability after the soil thaws. This paper contains observations and test results obtained during cold weather construction of a small embankment. Included in the construction phase was ripping of a frozen granular soil, placing and compacting frozen embankment material, and installation of settlement plates and thermistors. Field tests were conducted to determine the size and gradation of the frozen chunks used in the embankment, monitor dry density and moisture content during compaction of the fill, and measure settlement and soil temperatures within the embankment. Results from the field tests were analyzed to assess the effectiveness of field compaction of frozen soil and to quantify settlements that occur as the soil thaws. The results provide the basis for recommendations concerning winter earthwork.

ISSN:0008-3674    

DOI:10.1139/t76-038

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

Dynamic experiments with small pile foundations were conducted in the field. Individual piles and a group of piles were tested. The experimental data were compared with theoretical predictions made on the basis of a theory described previously by Novak. It was found that the theory predicts the general characteristics of the response very well. Resonant amplitudes and natural frequencies can be predicted reasonably well when a shear modulus of the soil derived from a static test of a pile is used and when a correction for the effect of pile group (interaction) is made.

ISSN:0008-3674    

DOI:10.1139/t76-039

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

The density and compressibility of miscible and immiscible air–water mixtures are formulated on the basis of the conservation of mass. Boyle's Law accounts for the compressibility of free air and Henry's Law accounts for the amount of air that goes into solution. The rate of air diffusion into water in the soil is used to choose either the case of complete solution or no solution of air. Formulas are given by which it is possible to predict the density and compressibility of the fluid phase of unsaturated soils.The difference between the air and water pressures in a soil is of interest only in the compressibility formulation. It is not necessary nor advisable to use Kelvin's capillary model equation to account for the difference in air and water pressure since it incorporates an unmeasurable variable, and gives rise to an anomaly. It is recommended that a measurable pore pressure parameter,BaworBwabe used in the solution of engineering problems.

ISSN:0008-3674    

DOI:10.1139/t76-040

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

In Montreal, knowledge of extent of saturated sands and marine clays is essential before the construction period begins as many foundations require the excavation of these materials. Details of clay seams in limestones and decomposed igneous sills and dykes are needed, but the discovery of areas where there is an upper zone of 10 to 20 ft (3 to 6 m) of disturbed bedrock is of greater importance. Thus investigations should be concentrated in local problems.The maintenance of an up-to-date central inventory of all geological and geotechnical data together with information on the constructional difficulties and costs involved is desirable, but it appears only practicable to index work as a general rule.The review of a past investigation showed that in an area of simple geology the standard spacing of drillholes was appropriate and successfully defined bedrock morphology and elevations; however, elsewhere on the Island only chance or a greater density of investigation may reveal bad conditions.Investigations can only be optimum if the ‘users’, the structural designers, quantity estimators, construction supervisors as well as contractors are required to acknowledge formally the impact of the geological and geotechnical appraisals upon their planning and operations including the effects of conditions suspected to be present but not actually confirmed.

ISSN:0008-3674    

DOI:10.1139/t76-041

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

Simple shear devices are used fairly extensively in soil mechanics research, lately especially in connection with cyclic testing. This presentation starts out by extending existing isotropic, elastic analyses of stresses and strains in the simple shear test. The effects of partial differential boundary slippage at the interface between the soil specimen and the top and bottom caps of the apparatus are analyzed. A comparison is made between constant volume and truly undrained simple shear tests.Because there is a coupling of shear and normal strains in soils, both may result from either shear or normal stresses, and vice versa. Therefore, an applied simple shear state of strain will not in general produce a simple shear state of stress in a soil sample, and it is shown analytically and experimentally that significant changes in lateral stresses do occur in simple shear tests. Such patterns of behavior are thereafter incorporated in the interpretation of cyclic loading simple shear tests on sand.

ISSN:0008-3674    

DOI:10.1139/t76-042

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

Vane shear strength and cone resistance for Scandinavian soft to medium stiff clay has been compared for six different sites in Norway and Sweden.At five of the sites, three in Drammen, one in Onsøy, and one in Gøteborg, the clays have been sedimented in an entirely marin environment. At the Skå-Edeby site the conditions have been marine-brackish or brackish-marine.When compared with the standard field vane shear strength, the cone factor,Nk(in the formula:qc = Nk∙f + γ∙z), varies between 13 and 24 for the five marine clays. For the Skå-Edeby clay theNkvalues lie in the range 8 to 12.Corrections of field vane shear strength result, for the five marine clays, inNkvalues between 15 and 19 with an average of 17. ThisNkvalue can be used for Scandinavian marine normally consolidated clays, but may not be valid in other types of clays. An example of this is the Skå-Edeby brackish-marine clay where the correctedNkvalues fall between 11 and

ISSN:0008-3674    

DOI:10.1139/t76-043

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

This paper presents a discussion of the effect of horizontal consolidation on the differential settlements of footings on clay. Plane symmetry is considered. The solution of the two-dimensional consolidation equation is expressed in integral form, and evaluated numerically for different initial stress distributions.It was found that under certain conditions, horizontal consolidation can cause temporary differential settlements that are up to 50% larger than those expected on the basis of vertical consolidation only. The conditions favourable to such a phenomenon are: high stress concentration in the periphery of a structure, high anisotropy of the clay, thick clay layer, and small separation between the footings.

ISSN:0008-3674    

DOI:10.1139/t76-044

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

This paper deals with predictions and measured observations of the behaviour of a warm gas pipeline on permafrost. In the paper, descriptions of the theoretical background for a mathematical model developed by the Canadian Arctic Gas Study Limited will be made. The model incorporates the following aspects: (a) transient heat conduction mechanism during freezing and thawing in the ground, in which the latent heat is considered as a heat source in the energy balance equation; (b) heat exchange mechanism at the ground surface with respect to meteorological data such as ambient air temperature, solar radiation, greenhouse factor, wind velocity, snow depth, and evapotranspiration; and (c) changes in geometry of the thermal domain due to thaw subsidence.Verification of the model was made using field data obtained from a hot-berm module with a gas temperature of 65 °F (18.3 °C), at the Norman Wells Test Facility of Canadian Arctic Gas Study Limited. Good correlation was found for predicted and measured values of: (a) ground temperature profiles in instrumented locations, (b) ground surface settlement, (c) pipe settlement, and (d) heat flux around the pipe.

ISSN:0008-3674    

DOI:10.1139/t76-045

出版商:NRC Research Press    

年代:1976

数据来源: NRC