摘要:

By using Schneebeli's rod material for simulating an ideal granular mass in plane strain, a series of model trap-door tests has been performed with the main objective of checking the validity of the classic bin theory when applied to this class of problems. In the tests, the pressure on the trap-door was measured, and the rod displacement trajectories were photographically recorded. A comparison of measured and calculated pressures acting on the trap-door both during its downward and upward movement, shows that the pressures can reasonably well be predicted by assuming the existence of two limiting vertical failure planes as in the classical bin theory, provided proper considerations are made concerning the ratio and the value of normal stresses acting along these planes.

ISSN:0008-3674    

DOI:10.1139/t69-001

出版商:NRC Research Press    

年代:1969

数据来源: NRC

ISSN:0008-3674    

DOI:10.1139/t69-002

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

Measurements of surface settlement, changes in piezometric levels and earth pressures were undertaken on a 10-ft diameter tunnel that passed through extremely sensitive and moderately over-consolidated Leda clay in Ottawa. The instrumentation is described, and the results are given for a period of 5 years, from 1 year before construction until 4 years after completion. Results of the measurements are compared with those obtained from a tunnel of similar size in Detroit clay. Because of the method of construction there was opportunity to conduct measurements on both the rather flexible temporary steel lining and the more rigid permanent reinforced concrete lining.Very little surface settlement was measured owing to overconsolidation of the clay and the method of construction. The tunnel had considerable influence on the piezometric regime in the clay, acting as a drainage sink. Earth pressures were in accordance with previous measurements on tunnels, with vertical pressures approaching the full overburden pressure.

ISSN:0008-3674    

DOI:10.1139/t69-003

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

Settlement observations have been conducted over a 5-year period on a 20-ft-high earth embankment and 2 highway overpass structures founded on spread footings over a thick deposit of Leda clay. The applied stresses were considerably less than the overconsolidation pressure of the clay. In the five years since construction, settlements of approximately 12 cm have occurred, of which about 4 cm occurred immediately. The observed settlements are compared with settlement predictions on the basis of various types of laboratory tests. The observations indicate that significant settlements occur on a long-term basis and can be attributed to a slow yielding of the clay structure. Piezometers failed to detect any excess pore water pressure due to slow process of consolidation.

ISSN:0008-3674    

DOI:10.1139/t69-004

出版商:NRC Research Press    

年代:1969

数据来源: NRC

ISSN:0008-3674    

DOI:10.1139/t69-005

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

The evolution of recommendations for the design of sulfate-resistant concrete is described. The need for such concrete in sulfate-bearing soils such as occur in the Winnipeg area is brought out by descriptions of the nature of the attack and of case histories.

ISSN:0008-3674    

DOI:10.1139/t69-006

出版商:NRC Research Press    

年代:1969

数据来源: NRC

ISSN:0008-3674    

DOI:10.1139/t69-007

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

In addition to its structural role, the foundation usually separates the man-made indoor climate from the actual environment of the ground. The implications of this secondary role are sometimes not fully appreciated by the designer, with serious consequences. The structural success of shallow foundations on volume-changing clays may be governed by their net effects on the subsoil environment. The significance of changes from natural ground conditions by construction must be appreciated at least qualitatively by the foundation designer. Natural and artificial changes in the thermal, the moisture, and the stress environments of subsoils are discussed in this paper, with particular emphasis on the clay soils and the climatic conditions of Western Canada.

ISSN:0008-3674    

DOI:10.1139/t69-008

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

A method for the design and construction of relatively thick highway embankments across muskeg deposits is described. Using theoretical soil-mechanics concepts it is predicted that the long-term stability of the muskeg necessitates the use of berms despite the fact that an undrained strength analysis based on in situ vane tests may predict a reasonable factor of safety. Consideration of both theoretical soil-mechanics concepts and practical considerations suggested that the interaction between the soil and the berm dictates that berm construction should be from the outer limits towards the center and should be placed prior to the central fill.Several case records are presented to support the conclusions drawn and furthermore suggest that the width of the berms should beto 2 times the thickness of the muskeg (peat plus lake marl).

ISSN:0008-3674    

DOI:10.1139/t69-009

出版商:NRC Research Press    

年代:1969

数据来源: NRC