摘要:

From consideration of the stress paths and boundary conditions generally applicable to earth slope stability problems it is concluded that long term slope stability analyses should not be based solely on strength data obtained from strain controlled drained triaxial tests (C.I.D. or C.A.D. tests). In particular it is shown that the brittle, time dependent, and anisotropic strength data obtained from such tests on Champlain Sea clay may not be relevant to slope stability problems. Appropriate sampling and testing procedures, design factors of safety, and the possibility of progressive failure are discussed with reference to documented field observations.

ISSN:0008-3674    

DOI:10.1139/t75-052

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

The interaction of an ice cover and a fixed narrow structure was modelled by edge loading large rectangular (0.4 m × 0.5 m) plates of columnar-grained ice. The plates were set on one of the long edges and the load was applied to the opposite edge by means of indentors of widths varying between 12 and 150 mm. Ice plates 25 to 100 mm thick were used. Observations were made of the dependence of the indentation load on indentor width and ice thickness. All loading was within the range of ductile behavior of the ice. The study indicated that the indentation pressure was a function of the width of the indentor, but not of the thickness of the ice plate. The mode of deformation was observed to be primarily two dimensional. The results of this study are in contrast to observations under field conditions, from which it is concluded that the indentation pressure depends on the ratio of the width of the indentor to the thickness of the ice cover. This suggests the presence of an effect which must be given attention in the development of modelling techniques for the ice pressure problem.

ISSN:0008-3674    

DOI:10.1139/t75-053

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

A groundwater supply of 600 imperial gallons per minute (27301/min) was required at Landis, Saskatchewan, for development of an underground gas storage cavern with 1.19 × 106barrel capacity. The cavern was to be developed by dissolving and removing the salts of the Middle Devonian Prairie Evaporite Formation the top of which is 3940 ft (1201 m) below ground surface. It was found that the most productive aquifers were in the glacial drift. Three intertill aquifers were identified. The presence of four till stratigraphic units was used as a basis for the interpretation of the groundwater hydrology. Three pumpwells were completed. Tests and analyses include aquifer coefficients such as transmissivity, storage coefficients, vertical permeability, and estimates of safe yields. A monitoring system was also established to measure the effect of high production on local domestic wells. This project demonstrated the value of establishing a formal stratigraphic system for interpretation of aquifer properties in glacial deposits.

ISSN:0008-3674    

DOI:10.1139/t75-054

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

From a consideration of the Mindlin solution relating to the stresses produced by a subsurface point load in a semi-infinite, homogeneous, isotropic, linearly elastic medium, equations are developed for the intensity of vertical stress on the axis of loading caused by a number of axially symmetrical distributions of subsurface load. The results are also presented in the form of tables of stress coefficients which permit the rapid evaluation of stresses. In the case of a uniform distribution of pressure, the errors associated with the neglect of the depth, below the surface of the medium, at which loading is applied are evaluated. Sufficient data is given to permit the production of influence charts of the Newmark type to cover other distributions of subsurface loadings.

ISSN:0008-3674    

DOI:10.1139/t75-055

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

The marine and lacustrine clay deposits of the James Bay area in Northwestern Quebec are described as a function of their origin, modes of deposition, and identifying characteristics. The stratigraphic and geotechnical parameters of the Fort Rupert marine clays are given in view of elaborating on case histories of regional slides. Based on these parameters and on the results of a laboratory experiment on four samples, the effect of pore pressure buildup on the triggering of a slide and on the progressive development of failure is described.

ISSN:0008-3674    

DOI:10.1139/t75-056

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

In 1971 lateral pile tests were performed at Inuvik, N.W.T. to determine design values in creep for timber and steel pipe piles. Formulation of a theoretical method for prediction of pile load capacity from basic permafrost creep parameters was a part of this program.In 1972 pressuremeter creep tests were performed at the same site so that test pile performance could be predicted independently and compared with measured results. The pressuremeter tests made and the creep parameter values obtained, the predicted pile performance curves and the comparisons with actual test data are presented in this paper.A Menard pressuremeter was used to determine permafrost creep parameters at an average ground temperature of 29.2 °F (−1.6 °C). Values for the representative creep modulus and exponents for this soil were derived from the test data. These were used for calculating pressure–deflection curves and subgrade reaction moduli for the laterally loaded piles.To demonstrate the applicability of the theory, the subgrade reaction moduli derived from the pressuremeter tests were compared with those deduced directly from the pile load tests. A reasonable agreement was found with the subgrade reaction moduli values obtained for the timber piles. However, the steel pipe piles responded as though the modulus was much higher.The confirmation field tests were made at a site having ice-rich permafrost whose behavior approaches that of pure ice. To apply the basic theory generally, additional field confirmation tests would be needed, for example, in ice-poor permafrost and covering much longer periods of time.

ISSN:0008-3674    

DOI:10.1139/t75-057

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

Constant velocity penetration tests were conducted on the different types of soils ranging from gravelly sand through clay of various strengths and moisture contents. The tests were performed for various penetration velocities up to a maximum of 2.66 f.p.s. (81.14 cm/s). From the measured cone pressure and local side friction (sleeve friction), the friction ratio is calculated at various penetration velocities. The experimental results indicate that for granular soils the influence of penetration velocity on friction ratio is insignificant. In cohesive soils the increase in penetration velocity causes an increase in friction ratio which amounted to 80% at the maximum velocity used.

ISSN:0008-3674    

DOI:10.1139/t75-058

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

The dry density of a silty sand compacted at temperatures below 0 °C can be improved by using calcium chloride as an additive. Compaction tests at −7 °C were used to determine the effect of low amounts of calcium chloride on the moisture–density relationship of the test soil. Tests at 20 °C were conducted to provide a frame of reference for comparing the results obtained at the below freezing temperature. The results from the experimental work are analyzed by modeling the pore fluid as a simple eutectic system using the concepts of phase equilibria. The amount of ice in the pore fluid is shown to have a significant effect on the dry density of a soil compacted at temperatures below 0 °C.

ISSN:0008-3674    

DOI:10.1139/t75-059

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

The settlement record of a point on the National Museum building in Ottawa for the period 1951 to 1974 is given. It shows that the average rate of settlement for this period was about 0.003 ft (0.9 mm) per year. Total settlement of the point since the structure was completed in 1910 is estimated to be 0.27 ft (82 mm).

ISSN:0008-3674    

DOI:10.1139/t75-060

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

The diffusion of air through saturated high air entry discs presents a serious problem in the testing of unsaturated soils. When determining either the strength (drained) or volume change characteristics of unsaturated soils, a technique must be available to measure the amount of diffused air in order for the appropriate corrections to be applied to the volume–weight relationships.The described diffused air volume indicator is a simple but effective means of measuring the quantity of diffused air. This technical note explains its construction and procedure of operation. Also outlined is the computational procedure for the correction factor that must be applied to the water volume change measurements. Numerous tests on the indicator show a reliability in the order of ±0.2 cc over a period of 2.5 weeks.

ISSN:0008-3674    

DOI:10.1139/t75-061

出版商:NRC Research Press    

年代:1975

数据来源: NRC