Experimental Studies on Three Types of Vibration Isolators for Buildings Near Subways

This paper presents three types of vibration isolators to enhance the comfort for residents inside buildings near subways. Stacked sandbags formed the first type of isolator. An elastic and closed capsule filled with sand and rubber particles is the second type of isolator. The third type of isolator is laminated thick rubber bearing with a sliding bottom. The materials and components of the three isolators are described first. Then, the vertical stiffness values, the damping ratios, and the ultimate bearing capacities of the above isolators are tested in a laboratory, and the suppression effectiveness for subway-induced vertical vibrations are investigated by two full-scale buildings near subway transportation. The results indicated that the bearing capacity of the first isolator is the lowest, but the damping ratio is the highest. For the second isolator, the vertical stiffness and damping ratio can be adjusted by changing the mixture ratio of sand particles, and the bearing capacity is improved significantly. For the third isolator, the damping ratio is the smallest, but the sliding bottom is capable of isolating earthquake ground motions. After installation of the three isolators, the human comfort inside the buildings satisfied the limit values, proving that they are effective as base isolation methods for buildings near subways.