摘要:

Thomas Roy was a civil engineer and geologist who lived in Toronto from 1834 to 1842; he was probably Canada's first geotechnical engineer. In 1835 he carried out the survey for what would have been Canada's first railway if it had then been constructed. He acted as City Engineer for the fledgling city. Nothing is yet known of his life before 1834 but the search continues. In 1837 he presented to the Geological Society of London a paper on the former, raised water levels of the Great Lakes, based on his field observations while surveying. In 1841 he wrote and had published a remarkable little book on road making, in some ways far ahead of its time; significant extracts are herein presented.Key words: road building, archival, geology.

ISSN:0008-3674    

DOI:10.1139/t88-001

出版商:NRC Research Press    

年代:1988

数据来源: NRC

摘要:

Two methods are presented to estimate the load-carrying capacity of driven piles. These methods use a new wave equation model that incorporates the loss of energy to the soil mass through radiation damping of the soil. Conventional soil parameters are used in this new model. Both methods use the load-test result of a test pile to estimate the soil parameters at the site by set matching. These soil parameters are then used to predict the load-carrying capacity of similar piles at the site in subsequent analyses from set measurements. The two methods are demonstrated by the prediction of the load-carrying capacity of 21 piles at four sites.Key words: load-carrying capacity, pile foundations, pile driving, soil setup, wave equation model.

ISSN:0008-3674    

DOI:10.1139/t88-002

出版商:NRC Research Press    

年代:1988

数据来源: NRC

摘要:

Significant salt content in the pore phase of permafrost causes dramatic reduction in strength or bearing capacity. Previous experience with laboratory tests and limited field testing discussed in the Soviet literature indicate that creep rates can be accelerated many times and foundation bearing capacities reduced by factors of 2–3 if pore water salinities exceed 10–20 ppt. At Clyde River on the northwest coast of Baffin Island, pile load tests were carried out in 1982. A combination of high salinities and significant excess ice contents at some locations suggested that a limited program of pile load testing should be carried out to confirm or modify the initial pile loadings based on previously published material. No fully documented case history was available to support initial pile design loads.Three piles were subjected to loads of five different magnitudes for different durations. Creep settlement was initiated and persisted in all cases. Continuous curve fitting was carried out by computer, and the resulting smoothed strain rate plotted with time. The minimum settlement rates were compared with earlier predictions. They were generally somewhat faster than results from previous laboratory saline creep testing combined with theoretical pile design based on creep settlement.The tests highlight the dramatic reductions in foundation bearing capacity and acceleration in pile creep rates that can be expected in permafrost exhibiting significant pore water salinity. A simplified testing procedure suitable for laboratory or field testing is described.Key words: permafrost, saline, piles, load tests, laboratory, field,in situ, capacity, creep, creep rate, salinity test.

ISSN:0008-3674    

DOI:10.1139/t88-003

出版商:NRC Research Press    

年代:1988

数据来源: NRC

摘要:

A method for characterization of normally consolidated and overconsolidated clay subjected to undrained constant shear strain amplitude cyclic loading is presented and verified. The method is based on laboratory evidence that shows that clays exhibiting static normalized behavior with respect to the vertical consolidation stress, i.e., along the lines of the SHANSEP method, also exhibit a similar cyclic normalized behavior. The method is illustrated by cyclic results obtained on an offshore clay for the range of overconsolidation ratio (OCR) from 1 to 4, and is verified by predicting the initial backbone curve, cyclic stiffness degradation, and pore pressure variation for the same clay for OCR = 1.4. The predicted behavior for OCR = 1.4 successfully describes the corresponding laboratory results. Also, very consistent relationships between cyclic shear strain and other cyclic parameters obtained by means of cyclic strain-controlled testing in this and other similar studies confirm that the cyclic shear strain is probably the most fundamental parameter governing the undrained cyclic behavior of clay.Key words: clay, laboratory test, model, ocean soil, overconsolidation, soil dynamics, repeated loading, simple shear test.

ISSN:0008-3674    

DOI:10.1139/t88-004

出版商:NRC Research Press    

年代:1988

数据来源: NRC

摘要:

A series of Casagrande resistance envelopes are presented for use in the preliminary design and evaluation of uniform rock and rockfill slopes. The influence of tension cracks on the safety factors for such slopes is examined. A comparison is also made between the safety factors obtained using the resistance envelope method and those obtained using published stability charts for rockfill slopes having nonlinear shear strength envelopes.Key words: rock, rockfill, slope, stability, Casagrande resistance envelope, safety factor.

ISSN:0008-3674    

DOI:10.1139/t88-005

出版商:NRC Research Press    

年代:1988

数据来源: NRC

摘要:

The postulate that the constant-volume friction angleof a granular material is unique and a function of mineral composition is verified experimentally. Granular materials comprised of particles ranging from minerals to metals are tested in a ring shear apparatus. Test samples are subjected to large shear displacements until a constant lower bound friction angleis mobilized. Possible effects of confining pressure, initial packing density, gradation, and particle shape on the value ofare investigated. Friction angles mobilized in drained shear at the instant of maximum contraction and in undrained shear at phase transformation and steady state are compared withvalues. The experimental results confirm a broader fundamental significance ofas a material parameter in that it is a consistent minimum drained friction angle equal to friction angles mobilized at phase transformation and steady state in undrained shear.Key words: granular materials, sand, friction angles, constant volume, steady state, phase transformation state, ring shear test.

ISSN:0008-3674    

DOI:10.1139/t88-006

出版商:NRC Research Press    

年代:1988

数据来源: NRC

摘要:

The technique of installing prefabricated wick drains is well established in Europe and Japan, but is relatively new to North America. This paper describes the use of piezometer cone data to predict the performance of wick drains in a soft clayey silt in Burnaby, British Columbia. A description of the testing procedures and the theory to calculate the rate of consolidation are briefly presented. The predicted rate of consolidation using the piezometer cone data and the measured performance is compared and discussed; good agreement between the two was found.Key words: wick drains, piezocone, prediction, preload, settlement.

ISSN:0008-3674    

DOI:10.1139/t88-007

出版商:NRC Research Press    

年代:1988

数据来源: NRC

摘要:

Traditionally, the bearing capacity and the settlement of footings on clay are determined independently by theoretical analyses: the bearing capacity for short-term conditions and the settlement for long-term conditions. Bearing capacity methods usually assume that the clay has a rigid-plastic behaviour and they neglect prefailure deformations. Conventional settlement methods ignore failure conditions. However, field load tests give load–settlement curves in which it is impossible to dissociate settlement and bearing capacity.This paper examines whether the calculated theoreticalqultis realistic. A long-term load–settlement curve can be easily calculated using an oedometric equation. The curve ofsoed/Bversus load is a good approximation of the true long-term settlement curve and can be used to determine whether the (short-term) bearing capacityquis realistic: ifsoed/Bhas a high value for a load smaller than the computedqu, it means that thisquis not a valid evaluation of the bearing capacity, the true value of which remains unknown. To establish when conventional analyses give erroneous bearing capacities four cases are analyzed, encompassing the influence of the compressibility of the clay material and the influence of downward groundwater gradients on the compressibility. The results show that groundwater conditions have a major influence upon the bearing capacity of highly compressible, slightly overconsolidated clays but practically no influence upon the bearing capacity of clays of low compressibility.Key words: shallow foundations, clay, deformability, bearing capacity, settlement.

ISSN:0008-3674    

DOI:10.1139/t88-008

出版商:NRC Research Press    

年代:1988

数据来源: NRC

摘要:

This paper describes an experimental investigation on the effect of sample size on consolidation characteristics of fissured London Clay. Pore pressure dissipation tests on 38, 100, and 300 mm diameter samples were undertaken in the laboratory. Constant-headin situpermeability tests were conducted in four boreholes at different depths in the clay. Conventional oedometer tests on 76 mm diameter samples recovered from the same depths at whichin situpermeability tests were carried out were also undertaken. The results show that both the coefficient of compressibilitymvand the coefficient of consolidation determined in the laboratory are not significantly affected by sample size. It is concluded that estimate ofin situcoefficient of consolidation can best be made frommvdetermined in the laboratory, and fromin situpermeability measurements.Key words: consolidation, compressibility, fissured clay, permeability, size effect, testing.

ISSN:0008-3674    

DOI:10.1139/t88-009

出版商:NRC Research Press    

年代:1988

数据来源: NRC

摘要:

A global analysis of the consolidation of natural clays is realized considering the consolidation process to be a combination of the effects of compressibility and of permeability. The compressibility or stress–strain curve followed is strongly influenced, both in the laboratory andin situ, by the strain rate. The self-boring permeameter appears to be an excellent tool for permeability measurement; however, in homogeneous clays direct measurement in the laboratory also gives representive results. The coefficients of consolidation determined graphically strongly underestimate thein situcoefficient. The consolidation must thus be analysed by considering compressibility and permeability parameters measured separately.Key words: consolidation, clay, compressibility, permeability.

ISSN:0008-3674    

DOI:10.1139/t88-010

出版商:NRC Research Press    

年代:1988

数据来源: NRC