摘要:

This paper describes the behaviour of two test piles (one bored and postgrouted and one simply bored, both 31.7 m long and 0.75 m in diameter) subjected to horizontal loads. These full-scale pile tests were carried out for the actual design of the pile foundation of a pier of the Evripos cable-stayed bridge. This bridge will link the Euboea Island to mainland Greece. The two piles have already been subjected to bearing capacity tests under axial loadings. The inclinometer measurements, taken during the present tests, yielded, in particular, the deformed shape of the piles as well as the bending moments. Conclusions could be drawn for the final design of the pile foundation with respect to horizontal loadings. Furthermore, various calculation methods usingp–yreaction curves for cohesionless soils have been checked: the Ménard pressuremeter method, the method of the American Petroleum Institute recommendations, and the Standard penetration test method of Christoulas. These pile tests show that simple measurements, taken on construction sites, can yield interesting results on the actual behaviour of horizontally loaded piles.Key words: pile, horizontal loading, full-scale test, horizontal loads, bending moment, subgrade reaction modulus,p–ycurve, cohesionless soil, Standard penetration test, pressuremeter test.

ISSN:0008-3674    

DOI:10.1139/t93-001

出版商:NRC Research Press    

年代:1993

数据来源: NRC

摘要:

The North Portal for the Edmonton South Light Rail Transit (SLRT) extension is located on the north slope of the North Saskatchewan River Valley west of the High Level Bridge. There was no evidence that the north slope at this location had experienced major, deep-seated slope movements prior to SLRT construction. Since commencement of the North Portal construction, translational slope movements along near-horizontal bentonite layers within the bedrock have developed. Initiation and acceleration of slope movement are believed to be due to the earthwork activities, coupled with precipitation and associated rise in groundwater table. As an interim measure, four deep wells were installed close to the toe of the upper slope in May 1989. The piezometric levels observed after installation of the wells suggest that the drilling of the wells hydraulically connected the various coal–bentonite layers and effectively lowered the higher perched water in the upper coal?bentonite layer. Subsequent slope inclinometer measurements indicate negligible slope movements since the well installations. This paper describes the detailed geotechnical investigations, slope stability assessments, instrumentation, and monitoring records over a 5-year period during and after construction. The paper also describes the implementation of the stabilizing measures and their effects on slope stability.Key words: South Light Rail Transit, North Saskatchewan River Valley, coal–bentonite layers, slope stability, vertical wells.

ISSN:0008-3674    

DOI:10.1139/t93-002

出版商:NRC Research Press    

年代:1993

数据来源: NRC

摘要:

The geomechanical aspects of oil sand behaviour are important for the understanding of the thermal processes for bitumen recovery from oil sands. The paper describes the study of the geomechanical response of oil sand to fluid injection, which causes formation parting in oil sands. The behaviour of constitutive models in the low effective stress range is examined, and it is shown by modelling that the frictional properties at low effective stress control the development of the failure zone around injection wells and fractures. Based on the matching of laboratory data for the PetroCanada–CanOXY–Esso–JACOS (PCEJ) project, a generalized hyperbolic model is proposed. Modelling of a field design involving horizontal fracture shows that the stress paths and the amount of dilation experienced by the formation can be very different from those measured in standard laboratory tests. Laboratory measurements should be done at the very small stresses and along the stress paths expected in the field. These can be predicted by modelling.Key words: oil sands, constitutive models, fluid injection, hyperbolic model, sand dilation, horizontal fracture, oil sands modelling, bitumen recovery, sand failure.

ISSN:0008-3674    

DOI:10.1139/t93-003

出版商:NRC Research Press    

年代:1993

数据来源: NRC

摘要:

A pile load test program carried out in Iqaluit, Northwest Territories, to provide design information for the Short Range Radar sites is described. The program consisted of testing 10 steel pipe piles with various surface modifications backfilled with clean sand and 4 Dywidag bars backfilled with Ciment Fondu™ grout. All tests were performed in saline permafrost. This paper describes the site conditions, installation procedures and pile uplift load testing procedures, and results of the pile load tests. The beneficial effect of modifications to the pile surface and backfill material is identified. The analysis and discussions of the results are presented in a companion paper.Key words: permafrost, saline, piles, load tests, field,in situ, capacity.

ISSN:0008-3674    

DOI:10.1139/t93-004

出版商:NRC Research Press    

年代:1993

数据来源: NRC

摘要:

The results obtained from 14 pile load tests carried out in saline permafrost at Iqaluit, Northwest Territories, are analyzed with respect to (i) the development of load along the length of the piles as determined from strain gauges mounted along the embedded portion of the piles; (ii) the time-dependent displacement of the piles under a constant load; and (iii) the performance of grout as a backfill material. The grout used as a backfill material cured adequately and provided sufficient bond strength between the anchor and the grout to cause either the anchor to yield or failure in the surrounding frozen soil. The development of load along the pile resulted in a nearly uniform stress distribution for smooth-surfaced piles but was highly nonuniform when lugs were added. Time-dependent displacement of the piles without lugs can be described using a power-law relationship.Key words: permafrost, saline, pile, load test, field,in situcapacity, load transfer.

ISSN:0008-3674    

DOI:10.1139/t93-005

出版商:NRC Research Press    

年代:1993

数据来源: NRC

摘要:

Weathering of soft mudstone in nature, characterized by the presence of an oxidized zone and an underlying dissolved zone, was simulated in the laboratory in 15 °C water with a pH of 3–7 and dissolved oxygen contents of 4–16 mg/L under stresses up to 0.49 MPa for as long as 70 days. When the water is acid, hydrogen ions diffuse from the rock–water interface through the rock and attack acid-labile calcite in mudstone preferentially and easily at a well-defined dissolution front, leaving a dissolved zone behind the front. Density decreases, porosity increases, ultrasonic P-wave velocity decreases, and shear strength decreases in the dissolved zone. The dissolution front migrates toward unreacted rock, and the migration rate is controlled by the diffusion of hydrogen ions in the reacted dissolved zone, so the rate is influenced by the stress exerted on the rocks; the effective diffusivity becomes smaller when the rock is stressed. Oxygen also diffuses through the rock to a well-defined oxidation front and changes the rock color from greenish grey to pale brown by oxidation. Slight deterioration occurs with the color change and change in density, P-wave velocity, and porosity. Depletion of pyrite by oxidation and the complete color change take a long time in comparison with the slight color change. Chlorite seems to transform into smectite in acid and highly oxidizing conditions.Key words: mudstone, dissolution, oxidation, weathering.

ISSN:0008-3674    

DOI:10.1139/t93-006

出版商:NRC Research Press    

年代:1993

数据来源: NRC

摘要:

Field observations on 449 debris flows in the Queen Charlotte Islands, British Columbia, are summarized. Movement of debris is classified according to seven characteristic types designated for the purposes of the study. Data on the physical characteristics of the events are presented. An analysis of the data is made with reference to event initiation, yield, and deposition using both mechanistic and morphological criteria. For those events which initiate on an open slope, the infinite slope model is used to establish a relationship between field drainage class and slope angle, for assumed frictional and cohesive soil strength parameters. The field drainage classes are directly related to the postulated location of the groundwater surface within the depth of the rupture plane. Deposition of channelized events is found to be influenced by the ratio of channel width to channel gradient, with the onset of deposition expected when the ratio exceeds unity. Five classes of depositional area are proposed. The magnitude of debris material deposited by an event is described by a channel debris yield rate which shows considerable variation with each event type. The conclusions of this study are based on postevent field measurements of deposited and eroded debris material. A limitation of the study arises from the difficulty of accurately describing an event some years after it has taken place.Key words: slope stability, debris flow, infinite slope analysis, debris yield.

ISSN:0008-3674    

DOI:10.1139/t93-007

出版商:NRC Research Press    

年代:1993

数据来源: NRC

摘要:

This paper describes a simple nonlinear pile-soil interface model incorporated into a modified boundary element analysis to simulate the behaviour of piles in calcareous soils subjected to both static and cyclic loading. A shaft resistance degradation model and a cyclic secant soil modulus degradation model are proposed, and implemented in the nonlinear analysis. Parametric solutions are presented which examine the overall characteristics of axial pile response determined from the nonlinear analysis. Comparisons are made between the theoretical predictions and the measured results of laboratory model tests and published field tests of grouted piles in calcareous soils. These comparisons enable some conclusions to be drawn regarding the suitability of alternative nonlinear analyses.Key words: grouted piles, cyclic loading, calcareous soils, nonlinear analysis.

ISSN:0008-3674    

DOI:10.1139/t93-008

出版商:NRC Research Press    

年代:1993

数据来源: NRC

摘要:

A numerical method called the block-spring model for analyzing heavily jointed rocks is presented in this paper. This model permits the assessment of stability of both underground and surface excavation in jointed rock mass and is capable of simulating large displacements. The model simulates the jointed rock mass by an assemblage of rigid blocks interacting through contacts. By relating the contact forces to the relative displacements between the blocks and directly applying the equilibrium equations, the displacements of the blocks and subsequently the contact forces can be determined. An iteration procedure is applied to describe the progressive failure along the joints. The proposed model can identify unstable blocks by considering the rearrangement of the blocks. A computer program has been written inFORTRANbased on the procedures of the proposed model. Some simple examples are presented in the present paper to demonstrate the capability of the proposed model. Advanced features of the model including simulation of rock bolts and groundwater are presented in a companion paper, in which two case histories have been analyzed in detail with the proposed model.Key words: jointed rocks, stress, deformation, analysis, numerical model, excavation, anchors, groundwater.

ISSN:0008-3674    

DOI:10.1139/t93-009

出版商:NRC Research Press    

年代:1993

数据来源: NRC

摘要:

The present paper is an extension of the companion paper in which the formulation of a new numerical model called the block-spring model for jointed rock mass was presented. The work reported herein presents further investigations of the model which include the simulation of rock bolts for ground support and groundwater pressure. The rock bolts are modelled by a series of one-dimensional elements interacting with the rock blocks through nodal points. The model can be used to analyze both the end-anchored and the fully grouted rock bolts, either pretensioned or untensioned. The model also evaluates the water pressures imposed on the surfaces of the rock blocks which are then introduced into the equilibrium equations of the blocks. Several applications of the proposed model are presented including detailed analyses of two case histories. The numerical results have been compared with the field instrumentation data. Good agreement has been observed between the results of the proposed model and the field measurements in both cases. It is demonstrated that the proposed model can be used for the analysis of excavations in jointed rocks in practice.Key words: jointed rocks, stress, deformation, analysis, numerical model, excavation, anchors, groundwater.

ISSN:0008-3674    

DOI:10.1139/t93-010

出版商:NRC Research Press    

年代:1993

数据来源: NRC