摘要:

Sequential hydrodynamic response—or slug tests in a well during well development—provide an easy method for objective measurement of well development and comparison of the various development techniques that may be employed. Slug-test equipment developed in Saskatchewan permits precise continuous recording of changing water levels for all times except the first few seconds after the introduction of the slug into the well. Three examples of slug-test analysis indicate jetting and air development to be the most successful techniques for well development in a sand aquifer in southeastern Saskatchewan; mechanical surging, on the other hand, actually reversed the development process in the aquifer. The substitution of a bentonite mud for clear water in drilling out the completion zone in one well proved to be highly undesirable because considerably more effort and time were required to develop this well.

ISSN:0008-3674    

DOI:10.1139/t75-001

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

Two methods of calculating the damping ratio for structures on compliant foundations are presented. One method employs the calculation of the system damping ratio from the dynamic amplification factor, the other the modal damping ratio from energy considerations. The numerical results for both methods are compared and interpreted. Three sources of damping are considered: inter-storey damping, radiation damping, and foundation material damping. The numerical results demonstrate that with the introduction of compliant foundations the damping ratio of the system can be larger or smaller than that of the corresponding fixed-base structure. Material damping in the foundation soil has been shown to contribute significantly to the over-all damping ratio.

ISSN:0008-3674    

DOI:10.1139/t75-002

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

Fractures in glacial till and glaciolacustrine clay were observed in excavations up to 20 ft (6.1 m) in depth and in drill cores at the Whiteshell Nuclear Research Establishment (WNRE) in southeastern Manitoba. The fractures are characteristically coated with carbonate and oxide precipitates, which indicate groundwater movement through the fractures. The fractures impart an effective bulk hydraulic conductivity to the clay–loam till and lacustrine clay, as evidenced by tritium tracer experiments and piezometer responses in the till and clay to pumping of an underlying sandy aquifer.The intergranular hydraulic conductivity of clay–loam till and glaciolacustrine clay in the Interior Plains, as determined from laboratory consolidation test data, is in the range of 2 × 10−10to 9 × 10−11 ft s−1(6 × 10−9to 2.7 × 10−9 cm s−1). The bulk hydraulic conductivity of the fractured clay–loam till at WNRE, as determined from finite-element mathematical modeling, is about 6 × 10−9 ft s−1(1.8 × 10−7 cm s−1). The model value represents the effective hydraulic conductivity imparted to the till by the fractures.Seven pumping tests, ranging in duration from 8.75 to 120 h were conducted on the sandy aquifer and drawdown data in the aquifer were analyzed to obtain the hydraulic conductivity and storativity of the aquifers.A 32 day pumping test on the aquifer showed that many of the piezometers in the till and clay respond quickly and strongly to the aquifer drawdown, while others show no noticeable response. The responding piezometers intersect open fractures whereas the others do not. Analysis of the piezometer drawdowns during the long-term pumping test using the Neuman and Witherspoon ‘ratio’ method indicates that the rapid piezometer drawdowns in the confining layers can be accounted for by assigning specific storativity values in the range of 1 × 10−5to 5 × 10−6 ft−1(3 × 10−5to 1.5 × 10−5 m−1) to the clay–loam till and lacustrine clay. These values are typical of fractured rock. If intergranular specific storage values are used, the calculated piezometer drawdowns are very small or negligible.

ISSN:0008-3674    

DOI:10.1139/t75-003

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

The results are reported of a field and laboratory investigation of the geotechnical properties of the surficial bottom, or near-surface, sediments of the Strait of Canso, Nova Scotia. The investigation procedures includedin situshear vane tests performed using a diver-operated apparatus lowered to the bottom from the survey ship, and undisturbed sampling using the Lehigh University Gravity Corer, which provides a 10 cm diameter sample.Soils encountered within the sampling depth (0–1.5 m maximum) consisted of layered and bioturbated coarse-grained and fine-grained sediments. Most of the investigative work was concerned with the fine-grained sediments, clayey silts, and clays, which were found to be soft and compressible, but possessed a reserve resistance in both shear and one-dimensional consolidation which give them the characteristics of overconsolidated clays. This reserve resistance has been attributed to chemical alteration, including the effects of organic compounds.

ISSN:0008-3674    

DOI:10.1139/t75-004

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

During the summer of 1972, a barge load of heavy construction equipment under tow to the James Bay Project on the eastern shore of James Bay became grounded on a shoal at the mouth of the Fort George River, only a few miles from its intended destination. Federal Commerce and Navigation Limited retained Foundation of Canada Engineering Corporation Limited (FENCO) to study the feasibility of removing the heavy equipment from the barge by an overice crossing. FENCO personnel visited the site in November and December, 1972, compiled the necessary environmental data and designed a crossing consisting of ice built up by flooding. Following the completion of the 100 ft wide (30.48 m) and 74 in. thick (1.88 m) bridge by Sainte-Marie Construction, the ice bridge was instrumented and tested prior to and during the unloading process. Parameters measured were thickness, width, temperature, ice soundness, and deflections. Tide readings were also taken.Loads of 70 t and heavy trucks were removed with no problem. Deflections were very small and cracking was confined to the tidal zone.

ISSN:0008-3674    

DOI:10.1139/t75-005

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

Shear tests on undisturbed samples of clay at low normal effective stresses have proved to be useful in order to understand the actual nature of cohesion. Drammen plastic clay was considered to be a suitable material for this study as it is nonfissured and noncemented. Triaxial compression and extension tests without membranes were performed on this clay in the low stress range. The samples in compression failed along inclined planes, while those in extension failed nearly along a horizontal plane. It was found that the shear resistance in the case of extension tests was independent of the average effective normal stress in the low stress range. The magnitude of the cohesion was nearly the same as the cohesion observed in compression tests. The reasons for these differences are discussed in terms of a proposed model. The shear resistance in extension tests is probably a structural cohesion and no friction seems to be mobilized under these conditions. When the samples were reconsolidated toin situstresses, the shear parameters in extension tests were the same as in compression tests. It is, therefore, suggested that mobilization of friction depends on the nature of the contacts which undergo modification when disturbance of structure on account of reconsolidation takes place.

ISSN:0008-3674    

DOI:10.1139/t75-006

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

The recent urban and rural developments in west central Scotland have involved the execution of much more widespread, and often deeper, excavations than previously undertaken in the boulder clays of the area. A number of failures in deep trenches and slope excavations have occurred, whose character appeared to be influenced by the presence of macrofabric features. A detailed field study has confirmed the presence of fissures and showed that they exhibit definite preferred orientation patterns. The influence of these fissure patterns on undrained shear strength and consolidation properties have been assessed using test specimens ranging from 76 to 254 mm diameter and correlations between observed laboratory anisotropic behavior and behavior in excavations have been suggested.

ISSN:0008-3674    

DOI:10.1139/t75-007

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

This study presents the solution to a simple model for deformations due to secondary creep in permafrost slopes. By introducing a constitutive relationship, or flow law, for ice into the model it is shown that significant creep deformations can occur in frozen slopes. Evidence is reviewed that suggests that secondary creep in ice-rich soils may be faster than that of ice alone.

ISSN:0008-3674    

DOI:10.1139/t75-008

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

The development of the areas surrounding urban centers in Saskatchewan has become of increasing concern because of slope instability problems. Proglacial meltwater channels and spillways provide seemingly attractive sites for rural estates. An investigation revealed that most of the slopes along these channels are unstable where Regina lacustrine clay or Bearpaw shale are exposed. A large building constructed near Lumsden is experiencing severe damage because it was constructed on landslide debris. South of Saskatoon, a similar problem exists along the east bank of the Saskatchewan River where a high water table is present in a deltaic sand overlying a soft lacustrine clay. An old barn at the Riverside Golf Course is spectacular evidence of the history of the movement of a large slide block in this terrain.Certain problems exist in convincing the public that a stability problem exists in these areas. Some form of landuse zoning based on risk of failure is needed. However, local municipal governments do not have the resources to conduct the necessary research to establish effective controls.

ISSN:0008-3674    

DOI:10.1139/t75-009

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

The importance of the micro stress field in the failure of discontinuous rocks is emphasized. The factors controlling failure are identified as, the micro stress set up at the ends and at irregularities of joint segments, the macro stress which controls the growth of the microfracture to macroscopic dimensions, and the external constraint which may arrest the propagating failure surface. By causing microfracture, the micro stress is largely responsible for the destruction of the rock bridges and the asperities occurring along the plane of weakness. In the initial stages of failure, the various types of tensile and shear microfractures form a zig-zag pattern which on continued deformation becomes incorporated in a wide shear zone running along the original plane of weakness.

ISSN:0008-3674    

DOI:10.1139/t75-010

出版商:NRC Research Press    

年代:1975

数据来源: NRC