Field Monitoring Challenges. Episode 1. Unforseen piling details and damage to Inclinometer Casing

Geotechnical News - March 2013
By Marcelo Chuaqui and Wing Lam

We have agreed with the editor of GIN to contribute a series of articles, titled Field Monitoring Challenges. In these articles we will describe situations where the recommended monitoring practices could not be performed, followed by the solutions to and consequences of these challenges.

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Instrumental Approach

Civil Engineering Magazine – November 2007
By Marcelo Chuaqui, Samantha Ford, Ivan Barua, and Matthew Janes, P.Eng.

Construction at a water treatment plant in Toronto that has rendered many years of service required assurances that facilities there would experience little or no movement. An extensive monitoring regime incorporated into the project's design and construction helped to ensure that this challenge was met.

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Precision Surveying Monitoring of Shoring and Structure

By Colin J. Hope, Marcelo Chuaqui

ABSTRACT: This paper provides a synopsis of the state of practice of manual total station movement monitoring. Different variables such as instrument used, accuracy under varying and challenging conditions, sources of error, establishment of accurate baseline readings, set-up and control of survey networks, and reporting, distribution and archiving of data are examined. A specific project located in downtown Toronto provides an example of practical and technical aspects of precision survey monitoring. The excavation for the project was seven-stories deep and occupied an old, open parking lot next to several sensitive and/or significant buildings. Sixty-five targets placed on surrounding structures were monitored with a total station theodilite. Inclinometers, crack-gauges and preconstruction condition surveys of abutting structures were also part of the monitoring for the excavation portion of the project.

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Shoring Monitoring – A Case History of Shoring Design and Performance Monitoring at a Toronto Waterfront Site

By Marcelo Chuaqui, Brian Isherwood and M. Janes

ABSTRACT: The paper is presented in two parts: the first section provides a description of the typical shoring monitoring methods used in the Greater Toronto Area, while the second section presents a case history of the Pinnacle project and monitoring data. The case history highlights the vital link between design and performance monitoring of shoring systems. Emphasis is placed on the purpose and value of monitoring data in general and to the Pinnacle project specifically.

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Mix Design and Quality Control Procedures for High Mobility Cement Based Grouts

By Marcelo Chuaqui and Donald A. Bruce

ABSTRACT: Measures of success for any grouting program should include superior technical performance and cost effectiveness. These can be achieved by designing grouts with properties that are specifically tailored to the application. This requires a fundamental understanding of the fluid and set performance characteristics needed for a specific application. For high mobility cement based grouts (HMG), these properties include bleed, segregation, resistance to pressure filtration, control of particle agglomeration, anti-washout characteristics, rheology, evolution of cohesion with time, set time, matrix porosity, ultimate strength, resistance to chemical attack, and durability. A description of how each property is quantified, evaluated and optimized is provided, and related to appropriate standards. A three-step process for the design and quality control of an HMG project is outlined. The first step is a laboratory—scale testing program to determine basic formulations, optimized for performance characteristics and cost. The second step is full-scale trial batching performed on site with the materials and equipment that will be used on the project. The third step is quality control testing during production grouting to ensure that the grouts being used are being hatched correctly and will perform appropriately in situ. A digest of mix HMG designs used on recent projects is provided for illustration and reference.

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Real Time Observational Compenation Grouting, Rio Piedro Project, Puerto Rico

By J-P. Hamelin, J-G Fonta, M Chuaqui

ABSTRACT: Ground movements induced by underground excavations are always of critical concerns, particularly in urban areas. Compensation grouting now appers as a safe means to control these movements. The paper presents the new concept of a feed-back loop including advanced 3D model for settlement prediction and new softwares to bring at all stages of the project an efficient control of operations. A case history is presented, taken from the construction site of Tren Urbano, Rio Piedras Section, constructed beneath a historic commercial section of San Juan de Puerto Rico.

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By CJ Hope, SW Dawe

This paper provides a summary of the state of practice of reflectorless precision survey monitoring using a manual total station to track and record movements. Topics covered include instrument selection, achievable accuracy under varying and challenging conditions, sources of error, reflectorless controls and establishing accurate baseline readings. The authors provide their oppinion , with respect to when this technology is a valuable alternative to standard surveying and when it is not appliable.

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