EXPERIMENTAL STUDY ON SEISMIC RESPONSE OF SUBWAY STATION BUILT IN LOESS

Abstract

THE PRESENT INVESTIGATION IS CONCERNED WITH THE DYNAMIC SEISMIC RESPONSE OF SUBWAY STATION BUILT IN LOESS SITE BY ANALYZING THE RESULTS OF A SERIES OF SHAKING TABLE TESTS. ACCORDING TO THE BOCKINGHAM Π THEOREM, THE SCALE RATIO IS DETERMINED FIRST AND THE MODEL SYSTEM IS DESIGNED ACCORDINGLY. THEN, THE POSITIONS OF SENSORS IN THE TESTS ARE OPTIMIZED BY FINITE ELEMENT NUMERICAL ANALYSIS. BASED ON THE GEOLOGICAL ENVIRONMENT AND SEISMOLOGICAL BACKGROUND OF XI’AN, THE INPUT GROUND MOTIONS AND LOADING SCHEME ARE DETERMINED. THE ACCELERATION RESPONSES OF MODEL SYSTEM, STRAIN RESPONSE CHARACTERISTICS OF THE STRUCTURE, DISTRIBUTION OF DYNAMIC SOIL PRESSURE BETWEEN LOESS AND STRUCTURE, AND THE SETTLEMENT OF MODEL GROUND ARE ANALYZED SYSTEMATICALLY ON THE BASIS OF THE TEST DATA. MEANWHILE, THE SEISMIC DAMAGE OF MODEL SYSTEM IS SUMMARIZED BY OBSERVING AFTER THE TEST. THE RESULTS SHOW THAT THE PEAK ACCELERATIONS IN MODEL SOIL INCREASE GRADUALLY FORM THE BOTTOM TO THE TOP OF THE SOIL, AND THE PEAK ACCELERATIONS OF MODEL STRUCTURE IN DIFFERENT HEIGHT CHANGE SLIGHTLY DURING INPUT MOTIONS WITH LOWER PEAK GROUND ACCELERATIONS (PGA). THE PEAK TENSILE STRAINS MEASURED AT THE TOP AND BOTTOM OF THE CENTER PILLARS ARE LARGER THAN THAT OBTAINED AT THE SIDE WALLS, WHILE THE PEAK TENSILE STRAINS IN THE SLAB ARE THE SMALLEST. MOREOVER, THE DYNAMIC SOIL-PRESSURE INCREMENTS BETWEEN LOESS AND STRUCTURE ARE INCREASING WITH THE PGA OF INPUT MOTIONS RISE AND THE INCREMENTS INCREASED FROM THE BOTTOM TO THE TOP OF MODEL STRUCTURE AT THE SAME TEST CASE.