The aim of the project was to test the mechanical performance of the piles. For this purpose, it was decided to perform pushdown, pullout and flexion full-scale on-site tests.
The new semi-conductor production facility in Tainan Scientific Park, Taiwan, was to be built on soil with low mechanical properties. Since proper functioning of such a facility is possible only if a high stability of foundation is assured it was estimated that approximately 3000 piles were necessary. All the piles had the same dimensions, a 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 the mechanical performance of the piles. For this purpose, it was decided to perform pushdown, pullout and flexion full-scale on-site tests. SOFO sensors were used to monitor the behavior of the piles during the tests. Two sets of piles, the first on the east side and the second on the west side of the facility’s foundations, were tested. Each set consisted of three piles and each set was tested to a single influence: compression, traction or horizontal force. The sensors were installed on rebar cages before the pouring of the concrete. The position of the sensors for each test is presented in Figure 1 and their installation on the rebar cages in Figure 2.
NSTALLATION PERIOD
TYPE OF SENSOR
NUMBER OF SENSORS
2000
SOFO
72
Main results:
The load was applied step-by-step by using hydraulic jacks while respecting the prepared schedule. The intensity of the load was monitored on the scale of the loading set-up. Each step of load was maintained during the period (length is dependent on load level). After the maximal load is applied, the piles were unloaded, step-by-step again. Important information is obtained from the test and the results are resumed in Figure 3. For example, the distribution of normal forces in pile and frictional stresses in the soil are presented in Figure 4 for bearing capacity load (480 t) and for maximum applied load (840 t) for the pushdown test. A zone of soil with a poor quality is distinguished in Figure 4.
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
A method for piles monitoring using long-gauge 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