GeoStructures: Tainan Semiconductor Fab

Case study: SOFO System

Pile monitoring
Pushdown test
Pullout test
Flexion Test
Foundation monitoring

Project Description

Summary: Piles monitoring during axial compression, pullout and flexure tests

Clients: N/A

Place: Tainan (Taiwan)

Period: 2000 - N/A

Installation: RouteAero

Structure's short description: New semi-conductor production facility in Tainan Scientific Park, Taiwan, is to be founded on a soil with low mechanical properties. An adequate functioning of such a facility is possible only if a high stability of foundation is assured. It was estimated that approximately 3000 piles are necessary. All the piles had the same dimensions, diameter of 1.20m and length of 35 m, and were constructed to have the same mechanical properties.

Aim of monitoring: The aim of the project was to test mechanical performances of piles. For this purpose, it was decided to perform a pushdown, pullout and flexion full-scale on-site tests. SOFO sensors were used to monitoring behavior of piles under the tests. Two sets of piles, the first on east side and the second on west side of the future facility foundations were tested. Each set has consisted of three piles, and each pile in set was tested to a single influence, i.e. compression, traction or horizontal force. The sensors were installed on rebar cages before pouring of concrete. Position of sensors for each test is presented in Figure 1 and their installation on rebars cages in Figure 2.

Number of sensor: 72

Main Results: The load was applied step-by-step using hydraulic jacks and according to previously prepared schedule. The intensity of load was monitored on the scale of the loading set-up. Each step of load was maintained during the period whose length is determined depending on load level. After the maximal load is applied, the piles were unloaded, step-by-step again, and respecting the schedule. Important information is obtained from test and is resumed in Figure 3. As example, the distribution of normal forces in pile and frictional stresses in soil are presented in Figure 4 for bearing capacity load (480t) and for maximal applied load (840t) in case of pushdown test. In the same figure, a zone of soil with a poor quality is distinguished.

Photos taken during installation of sensors on the rebar cage

Foundation performances determined using SOFO sensors

Distributions of normal force in the pile, friction stress and different zones of soil

Bibliography:

Piles monitoring during the axial compression, pullout and flexure test using fiber optic sensors , Branko Glisic, Daniele Inaudi, Claire Nan, 81st Annual Meeting of the Transportation Research Board (TRB), on CD, 02-2701, 2002

Structural Monitoring of Concrete Structures , B. Glisic, D. Inaudi, S. Vurpillot, Third World Conference on Structural Control, 7-12.4.2002, Como, Italy, Vol 2, p 729-238, 2002

Crack monitoring in concrete elements using long-gauge fiber optic sensors , B. Glisic, D. Inaudi, Structural Health Monitoring Workshop, ISIS Canada, 19-20 September 2002, Winnipeg, Canada, 2002

Long-gauge fiber optic sensors for global structural monitoring , B. Glisic, D. Inaudi, Structural Health Monitoring Workshop, ISIS Canada, 19-20 September 2002, Winnipeg, Canada, 2002

Long-gauge sensor topologies for strucutral monitoirng, D. Inaudi, B. Glisic, Fisrt fib world congress, 14-18 October 2002, Osaka Japan, 2002

Strain, deformation and crack monitoring in bended structural members using long-gauge fiber optic sensors, B. Glisic, D. Inaudi, Test 2003, 13-15 May 2003, Nurenberg, Germany, paper A3.4 on conference CD, 2003

Components of structural monitoring process and selection of monitoring system, Branko Glisic, Daniele Inaudi, Daniele Inaudi, 6th International Symposium on Field Measurements in GeoMechanics (FMGM 2003), September 15-18, 2003, Oslo, Norway, pages 755-761, 2003

A method for piles monitoring using long-gage fibre optic sensors, Branko Glisic, Daniele Inaudi, Samuel Vurpillot, Claire Nan, 6th International Symposium on Field Measurements in GeoMechanics (FMGM 2003), September 15-18, 2003, Oslo, Norway, pages 499-506, 2003

Piles monitoring using topologies of long-gage fiber optic sensors , B. Glisic, D. Inaudi, S. Vurpillot, E. Bu, C.-J. Chen, First International Conference on Structural Health Monitoring and Intelligent Infrastructure, Tokyo, November 13-15, 2003

Field Applications of Fiber Optic Strain and Temperature Monitoring Systems , D. Inaudi, B. Glisic, Opto-electronic Sensor-based Monitoring in Geo-engineering,Nanjing, P.R.China, November 23-24, 2005

Finite Element Structural Monitoring Concept , Glisic B., Inaudi D., The 2nd fib International Congress June 5-8, 2006, Naples, Italy, on conference CD, ID 17-18, 2006

Overview of Fiber Optic Sensing Technologies for Geotechnical Instrumentation and Monitoring , Daniele Inaudi, Branko Glisic, Geotechnical News, Volume 25, Number 3, Pages 4-8, 2007

Fibre Optic Methods for Structural Health Monitoring , Branko Glisic and Daniele Inaudi, Johh Wiley & Sons, Ltd, 2007