摘要:

The undrained shearing strength of the foundation soil at the site of a failure of a low embankment was investigated by several methods. It was found that both field vane and laboratory compression tests tended to underestimate the strength required for stability. Further consideration of the test specimens from sample tubes showed the undrained shearing strength varied considerably with the position of the sample in the tube. Specimens from tubes from another site yield the same type of results. The two silty clay soils involved were studied in more detail using CIU and CAU triaxial tests and comparingcu/p′ ratios. It was found that in general they yielded the values usually obtained for lacustrine clays.

ISSN:0008-3674    

DOI:10.1139/t69-010

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

The results of field observations of a culvert elongation under a completed stable fill are presented. The measurement of culvert elongation on this and several other stable fills, of similar dimensions, on the same foundation material, showed very large movements. This elongation appeared to take place as an 'elastic' bulging of the fill during the construction. Continuous measurements of culvert elongation are now being used to control further fills built on similar foundations. It is considered that any failure could be anticipated by an increased rate of culvert elongation.

ISSN:0008-3674    

DOI:10.1139/t69-011

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

This paper presents information on the selection and performance of anchors for guyed EHV transmission towers. The information used was obtained during the design and construction of two transmission lines each over 540 miles (>869 km) long in British Columbia.Five anchors have been designed and tested: (1) buried plate with compacted backfill; (2) buried steel mat or grillage with loose backfill; (3) cast-in-place concrete with loose backfill; (4) power installed helical; and (5) grouted rod anchors.The highly variable soil and access conditions along the line necessitated an anchor that could economically be installed in nearly all soil types and by ordinary construction equipment that could easily move between tower sites in rugged terrain.The simply installed, conservatively designed, cast-in-place concrete anchor was found to satisfy these requirements at reasonable cost. Power-installed helical anchors and grouted rod anchors may provide an economical anchor in more uniform soil conditions and where easier access conditions exist. However, these anchors require more detailed soil exploration and contract inspection than the cast-in-place concrete anchors.

ISSN:0008-3674    

DOI:10.1139/t69-012

出版商:NRC Research Press    

年代:1969

数据来源: NRC

ISSN:0008-3674    

DOI:10.1139/t69-900

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

Performance studies of two major, but relatively small (2000-ft (~610m) long, maximum height 20 ft (6.1 m)), sand dykes constructed on perennially frozen ground were initiated in 1958 at the Kelsey Generating Station of Manitoba Hydro on the Nelson River. Permafrost occurred under these dykes in scattered islands or patches of variable thickness and size.Preliminary analyses, though only approximate, indicated that within a 50-year period significant thawing would occur beneath the dyke–water interface and that the permafrost under the reservoir would thaw completely. Ground settlements of as much as 6 ft (1.8 m) were to be expected as thawing took place. To check the estimated performance, field instrumentation was installed and an observational program begun in 1959.A distinct pattern of thawing and settlement each year has been observed. Major thawing and settlement occur during the summer months at rates that are greater than those experienced during the winter. The change in rate of thaw (and thus also the rate of settlement, which is partly a function of thawing) is directly connected with the change in water temperature or rate of heat flow into the ground.

ISSN:0008-3674    

DOI:10.1139/t69-013

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

Earth dams and appurtenant structures in the Prairie Provinces are often constructed on a clay-shale foundation. Concrete structures such as spillways may be damaged due to swelling of the foundation or to differential movements. Various protective devices have been installed to reduce and control the amount of swelling and differential heave beneath structures. Hold down piles have been used, which were mainly reinforced concrete with the bottom flared out. This type, which could take little strain, often became ineffective either through breakage or slippage. To overcome this problem, anchor piles were designed to stretch a certain extent without failure due to load applied through swelling of the shale. It was not intended that this type of pile would eliminate swelling, but that it would reduce the rate and amount of swelling or differential movement. The design includes recommendations regarding depth of anchoring, pile spacing, and size of anchor rod for various bell sizes.

ISSN:0008-3674    

DOI:10.1139/t69-014

出版商:NRC Research Press    

年代:1969

数据来源: NRC

ISSN:0008-3674    

DOI:10.1139/t69-901

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

In this paper, the influence of the soil properties on the dynamic response of a building subjected to different earthquakes is quantitatively analyzed. The proposed mathematical model for foundation and surrounding soil consists of (1) anequivalentsoil-foundation massM0, (2) a translational spring of stiffnessK0, (3) a rotational spring of stiffnessKθ, and (4) dashpots for damping in translational and rocking modes. By using existing theory, values forK0andKθhave been selected for a rigid foundation supported by semi-infinite soil mass. A numerical incremental-iterative type of scheme is devised and a linear acceleration method is utilized to obtain the elastic and inelastic structural response. Digitized earthquake records from El Centro 1934 and 1940 have been utilized to study the influence of foundation conditions on the structural response of a multi-storey building. A range of soil properties and soil damping characteristics are chosen and various response curves are presented; this leaves complete freedom to a soil and foundation engineer to choose any desired value of the soil properties.Numerical analyses of a three-storey building show that for the foundation, the largest relative displacement occurs in the translational mode and the largest foundation rotation can be obtained by combining translational and rotational modes. It is shown that the natural frequency for a building in which the foundation effects are considered is always lower than that obtained for a building in which foundation effects are neglected. It is found that the soil damping characteristics have a major influence on the structural response, but Poisson's ratio of the soil has a minor influence. Various other recommendations regarding earthquake foundation designs are also suggested.

ISSN:0008-3674    

DOI:10.1139/t69-015

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

Case histories are given to illustrate bearing capacity, settlement, and volume changing characteristics of Winnipeg clays. These clays are of glacial lake origin, highly plastic, and generally irregularly varved. I have endeavored to show by calculation the relationship between soil properties determined by tests, and the behavior of the supported structure.

ISSN:0008-3674    

DOI:10.1139/t69-016

出版商:NRC Research Press    

年代:1969

数据来源: NRC

ISSN:0008-3674    

DOI:10.1139/t69-017

出版商:NRC Research Press    

年代:1969

数据来源: NRC