scholarly journals The Performance of Tied-Back Sheet Piling in Clay

1972 ◽  
Vol 9 (2) ◽  
pp. 206-218 ◽  
Author(s):  
G. C. McRostie ◽  
K. N. Burn ◽  
R. J. Mitchell
Keyword(s):  
Field Measurements ◽  
Triaxial Tests ◽  
Deep Excavation ◽  
Sheet Pile ◽  
Vertical Movements ◽  
Field Situation ◽  
Stress Changes ◽  
Temporary Support ◽  
Current Design ◽  
Horizontal Displacements

In Ottawa in 1969 a tied-back sheet pile wall was installed to provide temporary support in one side of a 12 m deep excavation through Champlain Sea deposits to shale bedrock. The wall was designed to permit as little yield as possible in order to safeguard the vital operation of an adjacent transformer building.To assess the performance of this structure, measurements of vertical movements of the surface adjacent to the wall, horizontal displacements of the wall, tendon loads and ground-water pressures were made as the excavation progressed.A series of triaxial tests was carried out in the laboratory to determine the form and magnitude of soil deformations under stress changes approximating those derived from the field measurements. Reasonable correlation is obtained when the results of these tests are used to estimate soil displacements in the field situation. The measured tendon loads are compared with those that would be expected using current design methods.

scholarly journals DISPLACEMENT MONITORING AND SENSITIVITY ANALYSIS IN THE OBSERVATIONAL METHOD

2013 ◽  
Vol 35 (3) ◽  
pp. 25-43 ◽  
Author(s):  
Karolina Górska ◽  
Zbigniew Muszyński ◽  
Jarosław Rybak
Keyword(s):  
Sensitivity Analysis ◽  
Computational Model ◽  
Cohesive Soil ◽  
Calculation Model ◽  
Observational Method ◽  
Deep Excavation ◽  
Sheet Pile ◽  
Displacement Monitoring ◽  
Excavation Support ◽  
Construction Works

Abstract This work discusses the fundamentals of designing deep excavation support by means of observational method. The effective tools for optimum designing with the use of the observational method are both inclinometric and geodetic monitoring, which provide data for the systematically updated calibration of the numerical computational model. The analysis included methods for selecting data for the design (by choosing the basic random variables), as well as methods for an on-going verification of the results of numeric calculations (e.g., MES) by way of measuring the structure displacement using geodetic and inclinometric techniques. The presented example shows the sensitivity analysis of the calculation model for a cantilever wall in non-cohesive soil; that analysis makes it possible to select the data to be later subject to calibration. The paper presents the results of measurements of a sheet pile wall displacement, carried out by means of inclinometric method and, simultaneously, two geodetic methods, successively with the deepening of the excavation. This work includes also critical comments regarding the usefulness of the obtained data, as well as practical aspects of taking measurement in the conditions of on-going construction works.

A Probabilistic High-Pressure Zone Model for Local and Global Loads During Ice-Structure Interactions

2019 ◽  
Vol 141 (5) ◽  
Author(s):  
Rocky S. Taylor ◽  
Martin Richard ◽  
Ridwan Hossain
Keyword(s):  
High Pressure ◽  
Field Measurements ◽  
Zone Model ◽  
Probabilistic Framework ◽  
Local Pressure ◽  
Pressure Zone ◽  
Current Design ◽  
Ice Loads ◽  
High Pressure Zone ◽  
Ice Failure

For temperate ice regions, guidance provided by current design codes regarding ice load estimation for thin ice is unclear, particularly for local pressure estimation. This is in part due to the broader issue of having different recommended approaches for estimating local, global, and dynamic ice loads during level ice interactions with a given structure based on region, scenario type, and a variety of other conditions. It is essential from a design perspective that these three scenarios each be evaluated using appropriate definitions for local design areas, global interaction area, and other structural details. However, the need for use of different modeling approaches for ice loads associated with each of these scenarios is not based on ice mechanics but rather has largely evolved as a result of complexities in developing physics-based models of ice failure in combination with the need to achieve safe designs in the face of limited full-scale data and the need for implementation in a probabilistic framework that can be used for risk-based design assessments. During a given interaction, the ice is the same regardless of the design task at hand. In this paper, a new approach is proposed based on a probabilistic framework for modeling loads from individual high-pressure zones acting on local and global areas. The analysis presented herein considers the case of thin, first-year sea ice interacting with a bottom-founded structure based on an empirical high-pressure zone model derived from field measurements. Initial results indicate that this approach is promising for modeling local and global pressures.

Tunnelling in Brasília porous clay

1996 ◽  
Vol 33 (4) ◽  
pp. 565-573 ◽  
Author(s):  
J AR Ortigao ◽  
R Kochen ◽  
M M Farias ◽  
A P Assis
Keyword(s):  
Field Measurements ◽  
Residual Soils ◽  
Tunnel Face ◽  
Tunnel Design ◽  
Tunnel Diameter ◽  
Underground Transportation ◽  
Surface Settlements ◽  
Horizontal Displacements ◽  
Design Construction

The Brasília underground transportation system comprises 6.5 km of shallow tunnel excavated in a soft red soil known as porous clay that overlies harder residual soils. The tunnel diameter is 9.6 m. Settlement observations indicated that surface settlements were two to three fold the initially predicted value, although no indication of excavation instability was observed. Settlements reached, at one section, 500 mm without failure. Another striking feature was settlement amplification between the top of the excavation and the surface by a factor that averaged 1.2 but reached up to 4. This occured because of the collapsible nature of the porous clay, which presented a considerable reduction of volume as the tunnel face advanced. This paper describes tunnel design, construction, and instrumentation; and summarizes geology and soil properties from in situ and laboratory tests. Field measurements of settlements and horizontal displacements are described and analysed. The main cause of the large settlements was collapse of the porous clay structure. Key words: tunnelling, porous clay, settlements, collapse.

Spread footings on "reinforced" soil

1970 ◽  
Vol 7 (3) ◽  
pp. 318-326
Author(s):  
B. O. Kuzmanović ◽  
À. Balla
Keyword(s):  
Bearing Capacity ◽  
Wall Thickness ◽  
Thick Layer ◽  
Model Tests ◽  
Reinforced Soil ◽  
Stress Conditions ◽  
Sheet Pile ◽  
Medium Quality ◽  
Spread Footings ◽  
Horizontal Displacements

In case of foundations on thick layer of weak or medium quality, short tubes or sheet-pile mantles encompassing the footings and of small wall-thickness driven into the ground can increase considerably the bearing capacity of the soil. The footings are in this way artificially deepened and the horizontal displacements of the subsoil within the tube or mantle are confined. Thus, only vertical compression is possible within the "reinforcement" of the soil. The paper produces theoretical solution for the stress conditions and vertical settlement. Two illustrative examples with model tests are also included.

Analysis of a geotextile-reinforced embankment constructed on peat

1984 ◽  
Vol 21 (3) ◽  
pp. 563-576 ◽  
Author(s):  
R. K. Rowe ◽  
M. D. Maclean ◽  
K. L. Soderman
Keyword(s):  
Finite Element ◽  
Major Effect ◽  
Strength Properties ◽  
Soil Reinforcement ◽  
Triaxial Tests ◽  
High Modulus ◽  
Element Analysis ◽  
Vertical Movements ◽  
Observed Behaviour ◽  
Settlement Analysis

This paper describes a finite element analysis of two instrumented sections of a geotextile-reinforced embankment constructed on peat. The results from the analysis provide very encouraging agreement with the field observations for both instrumented sections at the endof the two major stages of construction. It is shown that the drained strength parameters c′ = 1.8 kPa, [Formula: see text] determined from simple shear apparatus provided the best agreement between predicted and observed behaviour. Analyses were also performed using both the field vane strength and the drained shear parameters (c′ = 0, [Formula: see text]) determined from triaxial tests, and the implications of these analyses are discussed. The geotextile–fill interface strength properties are also presented and it is suggested that, in this embankment, interface slip was not a factor affecting embankment performance.The analysis indicates that the major effect of the high modulus geotextile (Geolon 1250) used in the deepest section of the deposit was to reduce lateral movements, although it may have slightly reduced vertical movements as well. It is concluded that even a very high modulus geotextile will not prevent large consolidation settlements of embankments on peat. Key words: embankment, muskeg, peat, geotextile, settlement, analysis, finite element, shear strength, soil reinforcement.

Horizontal displacements induced by rock excavation: Scotia Plaza, Toronto, Ontario

1989 ◽  
Vol 26 (1) ◽  
pp. 114-121 ◽  
Author(s):  
W. A. Trow ◽  
K. Y. Lo
Keyword(s):  
Field Measurements ◽  
Horizontal Displacement ◽  
Time Dependent ◽  
Rock Excavation ◽  
Initial State ◽  
Deformation Parameters ◽  
Adjacent Structures ◽  
Rock Anchors ◽  
Horizontal Displacements

The design and construction of a 69-storey building, the Scotia Plaza in downtown Toronto, Ontario, necessitated an assessment of the horizontal displacements induced onto adjacent existing structures as a result of rock excavation. Field and laboratory tests were performed to measure the elastic and time-dependent deformation parameters as well as the in situ horizontal stresses in rock. With the deformation parameters and initial state of stresses determined, analyses were performed to predict the magnitude and distribution of elastic and time-dependent deformation. During excavation, horizontal displacements were monitored by (a) a field slot test to verify the rock mass modulus, (b) inclinometers and extensometers, and (c) internal taping of floors of adjacent structures. The results of these field measurements are compared with those predicted in the design analysis, and are found to be within the predicted limits and design requirements. The use of rock anchors to partially suppress time-dependent displacements is also briefly discussed. Key words: rock excavation, horizontal displacement, time-dependent deformation, in situ stresses, rock anchors.

Test fill brought to failure on soft plastic marine clay at Onsøy, Norway

2018 ◽  
Vol 55 (4) ◽  
pp. 563-576
Author(s):  
Toralv Berre
Keyword(s):  
Field Measurements ◽  
Triaxial Tests ◽  
Marine Clay ◽  
Second Stage ◽  
Direct Simple Shear ◽  
Back Calculation ◽  
The Subject ◽  
The Town ◽  
Foundation Failure

A test fill at Onsøy, close to the town of Fredrikstad in Norway, was built on a very soft marine clay with in situ vane strength as low as 11 kPa and a plasticity index varying from 34 to 50. The dimensions at the bottom of the long test fill were 20 m × 60 m with a height of 2.3 m. The fill, as placed in the first stage, had a computed factor of safety against foundation failure of 1.35 based on in situ vane strength. The fill was allowed to sit for about 3 years (from 1972 to 1975) before it was, in a second stage, brought to failure in about 4.3 days by raising the height. This second stage is the subject of this paper. Back-calculation of the failure by undrained stability analysis based on in situ vane tests performed shortly before the start of the second stage, based on undrained triaxial and constant volume direct simple shear tests on specimens from tube samples taken shortly before the start of the second stage and reconsolidated to the in situ effective stresses, gave factors of safety varying from 0.88 to 1.45 depending on type of analysis. Settlement values computed at the centreline of the fill for the second stage based on the results from undrained compression triaxial tests agreed reasonably well with the field measurements.

scholarly journals Performance of soil nails in Dublin glacial till

2008 ◽  
Vol 45 (12) ◽  
pp. 1685-1698 ◽  
Author(s):  
Christopher O. Menkiti ◽  
Michael Long
Keyword(s):  
Large Scale ◽  
Design Methods ◽  
Glacial Till ◽  
Deformation Pattern ◽  
Soil Nailing ◽  
Short Term ◽  
Soil Nail ◽  
Design Procedures ◽  
Temporary Support ◽  
Current Design

Soil nailing is being used in many projects in glacial tills in Ireland, particularly to provide temporary support to steep slopes. Little design guidance is available for such materials, and it is known that the application of design procedures developed for other material is conservative. Detailed nail instrumentation and field monitoring has been undertaken during large-scale soil nailing works for the Dublin Port Tunnel project. It was found that the short-term behaviour of nails was the reverse of that assumed in current design methods. Most of the load was induced as a results of drilling and nailing the lift immediately below the nail being monitored rather than due to excavation-induced stress relief. The highest forces were developed in the upper nails where the largest ground movements occurred. This is the reverse of most current design methods where the highest soil–nail bond is assigned to the deepest nails. It seems that the observed short-term, prefailure behaviour of nailed slopes is governed more by the deformation pattern of the slope than by large-scale development of failed wedges. Current design procedures should be reviewed. Despite this, the trial confirmed that the currently used procedures are highly conservative for Dublin glacial till.

scholarly journals Deep excavation in urban areas – defects of surrounding buildings at various stages of construction

2018 ◽  
Vol 146 ◽  
pp. 02012 ◽  
Author(s):  
Jarosław Rybak ◽  
Alexander Ivannikov ◽  
Elena Kulikova ◽  
Tomasz Żyrek
Keyword(s):  
Urban Areas ◽  
Soil Mass ◽  
Technical Condition ◽  
Deep Excavation ◽  
Sheet Pile ◽  
Ground Anchors ◽  
New Construction ◽  
Diaphragm Walls ◽  
Wall Construction ◽  
City Centres

Deep excavation and tunnelling works in city centres always bring some risks to surrounding structures, especially in the case of old town centres, where the technical condition and structural stiffness of historical buildings is rather doubtful. When the new desired excavation depth goes deeper than the foundation of the surrounding buildings or when tunnelling works are conducted directly under them, the existing objects are subject to stress, vibrations and displacements imposed at almost every stage of building the new construction. The presented paper outlines, on the basis of the authors’ experience, the typical damages appearing during the supporting wall construction (sheet pile driving, piling and formation of diaphragm walls) and tunnelling works. Other damages appear due to soil mass unloading (caused by excavation stages) and horizontal loading during pre-stressing of struts or ground anchors. The selected case studies of steel sheet pile wall installation is given with regard to typical failures caused by an unplanned excavation and its impact on neighbouring structures.

Research of an Slope under Rainfall and Deep Excavation Condition with UDEC

2013 ◽  
Vol 353-356 ◽  
pp. 756-760 ◽  
Author(s):  
Li Xuan Ren ◽  
Ning Kai
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Distinct Element ◽  
Actual Situation ◽  
Deep Excavation ◽  
Field Situation ◽  
Practical Engineering ◽  
Main Factors ◽  
The Stability ◽  
Element Method

The landslides often due to the rainfall and the excavation inside. Although both of them could influenced the stability of the slope, in the different combination of the condition of rainfall and excavation. The results would make a big difference from condition. The analysis results of Finite Element Method have a large difference with the actual situation, especially in the large deformation and landslide. Therefore, we use the Distinct Element Method to simulate and analysis the collapse of Zengziya in Chongqing. We collect different parameters to simulate the changed conditions of the combination of rainfall, half excavation and whole excavation. Then we will get the data of displacement of the rock and the stress redistribution of the slope. By the analysis of the those data, and the comparison from the field situation, we will draw a conclusion that the main factors of the landslides is the rainfall, and the excavation sometimes can simulate the landslides. At last, our research results can make some help of the practical engineering.

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