摘要:

A computer simulation model which uses weather data as the time-variable surface boundary condition and employs a finite-difference solution to the heat conduction equation gives predictions of frost penetration beneath highways with a maximum error of 15%. The pattern and timing of freezing and thawing are also well reproduced. Further, the model is shown to be capable of reliable and consistent results using limited input data, already quite widely available. The simulated use of styrofoam insulation is shown to reduce maximum frost penetration by 45%, a value in good agreement with observation.

ISSN:0008-3674    

DOI:10.1139/t77-018

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

A review of the existing quasi-static methods of analysis used for predicting the thaw bulb around a buried pipe in permafrost has been made. The quasi-static solutions are compared with the results obtained by numerical techniques so that the accuracy of the approximate method can be examined. Consequently, a modification to the approximate method is suggested to improve its applicability to preliminary engineering design.

ISSN:0008-3674    

DOI:10.1139/t77-019

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Under natural conditions, the western limit of the Olympic Park site along Sherbrooke Street is formed by a terrace of marine clay deposited in the Champlain Sea. This terrace has an average height of 60 ft (18 m) and overlies shallow fine grained deposits of fluvio–glacial or glacial origin, which are encountered at ground surface in the eastern part of the site. The bedrock, of Ordovician age, is part of a monoclinal structure which dips at 3° to 5° towards the northeast; bedding planes and vertical fractures form the main planes of discontinuity. The surficial part of the bedrock has been strongly disturbed by the action of glaciers during the Wisconsin glaciation: a displaced rock slab now covers the main part of the site and has greatly affected the design of the foundations for the various structures.Geotechnical investigations carried out by the City of Montreal on or near the site for earlier tunneling projects were used to establish a geotechnical map of the Olympic Park site. Based on this map, the foundation elevations for the different buildings, the type of earth supporting structures, and the geometry of cut slopes could be selected. Along Sherbrooke Street, 70 ft (21 m) deep excavations were necessary in an area where lateral movements could not be tolerated. Consequently a program for monitoring the cast-in-place diaphragm retaining wall and the slopes was carried out by the City of Montreal with the participation of the Ecole Polytechnique de Montréal.[Journal translation]

ISSN:0008-3674    

DOI:10.1139/t77-020

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

From a study of 205 slab avalanches it is concluded that failure initiates where the slope is 25° or steeper, that slab failure stress is in the range 102–104 N/m2, and that the slab failure plane is most commonly at a temperature of −5 °C or warmer.Theinsitumeasurement of shear strength is still an unresolved problem. A statistical analysis of a shear-frame device shows that the device is sensitive to the rate of pull and to the frame area. The larger the frame area, the smaller the measured shear strength. Approximately 10 measurements are required to sample a mean shear strength of a slab failure plane to within 15% accuracy at 90% confidence.

ISSN:0008-3674    

DOI:10.1139/t77-021

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

This paper reports the findings of two series of tests which are part of a continuing study into the behaviour of laboratory scale anchored retaining walls supporting cohesionless soil. In each test field construction was simulated and the behaviour of the wall, anchors, and soil was monitored. The behaviour of a wall supported by horizontal anchors has been examined as the overconsolidation ratio of the retained sand increases. The effect of anchor inclination has also been examined when the wall supports overconsolidated sand. The tests showed that the soil stress history had a very significant effect on the wall and retained sand behaviour.

ISSN:0008-3674    

DOI:10.1139/t77-022

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Contamination profiles below two youthful landfills founded on thick silty clay deposits near Sarnia, Ontario were obtained by squeezing pore water from Shelby tube samples and analyzing this water by absorption flame photometry for Ca++, Mg++, Na+, and K+. Pollution fronts were observed below both sites, the contaminant cation concentrations attenuating with distance to normal background values.The older landfill was about 7 years old, was founded at 5.6 m depth below the weathered crust on intact silty clays, and was characterized by a downward flow gradient from the base of the fill. Pollution (cation) migration had proceeded downwards for a distance of 30 cm compared to the calculated maximum possible advance of the seepage front of only 4 cm.The younger landfill was about 2.5 years old, was founded at 2.3 m depth within the crust on weathered and fissured soils, and was characterized by upward flow into the landfill due to heavy loads created by the large mound of waste. Pollution migration had proceeded for a distance of 50–80 cm opposite to the prevailing direction of seepage flow and is presumed to have occurred along well developed fissures in the soil.At both sites the diffuse pollution fronts are attributed to cation (chemical) diffusion which, in the early stages of both landfills, has overwhelmed seepage flow.

ISSN:0008-3674    

DOI:10.1139/t77-023

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

A study to observe the effects of overburden pressure and other parameters on the freezing behavior of a saturated soil was undertaken. A linear relationship between effective overburden pressure and the flow of water into or out of a freezing soil was observed. The effective pressure at which no flow occurred was termed the shutoff pressure. At pressures less than the shutoff pressure water was sucked to the freezing front resulting in segregated ice, ice lensing, and heaving. This heaving could significantly exceed the heave due to the volumetric expansion of theinsituporewater. At pressures greater than the shutoff pressure water was expelled from the freezing front thereby reducing the volume ofinsituwater and resulting in a relatively small amount of heave. Shutoff pressure was observed to depend on soil type, stress history, and freezing temperature. The effects of overburden pressure upon flow of water in a freezing soil and frost heave were recommended as additional criteria for assessing soil frost susceptibility.

ISSN:0008-3674    

DOI:10.1139/t77-024

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

The breakout capacity of eight model underwater suction anchors was investigated in a 30-in. (76-cm) wide, 72-in. (183-cm) long, and 32-in. (81-cm) deep unpressurized cast iron tank. The test soils were a medium fine sand, a silt, and a clay. A pullout rate of approximately 0.1 in./min (0.3 cm/min) was used for all tests.A breakout capacity equation for the suction anchor was developed based upon the Mohr–Coulomb failure theory. Predicted breakout capacities compare favorably with the measured values from the laboratory model study. The breakout capacity equation which is developed is therefore satisfactory for the range of conditions studied.The suction anchor possesses a high degree of mobility and would be particularly useful for short-term anchorage. Potential applications of the suction anchor include the anchorage for research submersibles, coring platforms, and certain salvage and dredging operations.

ISSN:0008-3674    

DOI:10.1139/t77-025

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

The stability of a rock wedge resting on two intersecting discontinuities is examined under excavation unloading forces. The variation of the factor of safety as well as the external force required to restore a certain factor of safety is examined for a range of values of ambient stress coefficient and for a variation in the distance of a crack from the cut face of the wedge.

ISSN:0008-3674    

DOI:10.1139/t77-026

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

This note describes a sampler used to obtain block samples from the bottom of a borehole. Soil disturbance by the sampler was investigated using a pocket penetrometer and a lab vane apparatus. Minor disturbance occurred near the edge of the sampler; the amount was comparable to that associated with Shelby tube sampling.

ISSN:0008-3674    

DOI:10.1139/t77-027

出版商:NRC Research Press    

年代:1977

数据来源: NRC