| Summary: | 碩士 === 國立臺灣大學 === 土木工程學研究所 === 105 === This study investigated the structure behavior and soil-structure interaction of single-column pier and the group piles model through lateral cyclic loading test. A large biaxial laminar sand box was used to set the model specimen and sand. The upper part of the structure is a single-column pier consisting of a 120 mm×120 mm×20 mm joint face connected with actuator, a solid steel pier with a diameter of 40 mm, 200 mm high and a 150 mm×150 mm×15 mm base plate made by steel. The lower structure is a group pile foundation specimen, consisting of 200 mm×200 mm×15 mm aluminum bottom adapter plate, 150 mm×150 mm×15 mm aluminum base plate with d25 mm×8.25 mm ×800 mm 2 × 2 group pile composition. The experiment divide into pure structure model and model of scouring. The pure structural model is fixed to the shear box and experiment with no sand. The scouring model also fixed the specimen in the shear box and the model with specified exposed length of pile foundation, as a ratio of pile diameter D, from 0D, 3D to 6D to explore the foundation of different depth of exposure. The sand property of dry fine silica sand is controlled by relative density of 50%. In the course of experiment, the lateral displacement of the different sizes is ±1 mm、±5 mm、±10 mm、±15 mm、±20 mm、±30 mm、±40 mm and ±50 mm. In the ±1 mm ~ ±20 mm for three cycles and ±30 mm ~ ±50 mm for two cycles. Among the experiment, the displacement, angel and strain response are recorded. Furthermore, the strain gauge can calculate the value of bending moment and axial force.
The results of the experiment. Displacement: With the depth of the soil exposed, the displacement of the base plate is more obvious. Angle: the angle variation of the actuator elevation is different from that of the base plate, indicating that the pier is not a rigid body. Under the same displacement, as the depth of scouring increases, the rotation angle decreases. Strain: It can be observed that the position of the strain is large at the top and bottom of the pile. In the large strain area, the strain gauge is easy to slip, loose and even damage in the experiment process, so that the strain value of the large position is more prone to abnormal. Axial force: As the souring increase, the axial force of the pile will decrease. Moment: Pure structure, the maximum bending moment is generated at the base of the foundation. The maximum moment of the scouring model appears at the top of the foundation. Hysteresis loop: As the exposed depth increase, the force will decrease.
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