关键词: 高速铁路, 有砟轨道, 路基, 振动台试验

Abstract: Taking the Beijing-Shanghai high-speed railway CRH380BL EMU as the prototype, a 1:10 ratio railway ballast track subgrade shaking table model test was carried out based on the law of similarity to analyze the acceleration, earth pressure and displacement response of the subgrade. The model is 9.6 m×3.5 m×1.0 m (length×width×height), including the train, ballasted track and subgrade part. Some findings are as follow. As the altitude increases, the amplification factor of peak horizontal acceleration increases gradually, and the value is basically stable between 1.0 and 2.5; while the amplification factor of peak vertical acceleration firstly increases and then decreases, and the value is basically stable within 1.5. As the input ground motion intensity increases, the amplification factor of the peak horizontal acceleration is directly proportional to the elevation, and the non-linear relationship is gradually strengthened. The maximum amplification factor of vertical peak acceleration is shifted from the bottom H/3 to 2H/3 and the peak magnification of horizontal and vertical accelerations reach the maximum when the input seismic wave PGA is 0.3g. As the input ground motion intensity increases, the peak earth pressure intensity in the filler increases gradually. When the input seismic wave PGA reaches 0.4g, the earth pressure intensity reaches the maximum. The earth pressure intensity at the center section of the subgrade tends to increase firstly and then decrease with the increase of elevation, and the maximum earth pressure gradually shifts from H/3 to 2H/3 at the bottom of the subgrade. When the input seismic wave PGA is 0.05g, the earth pressure intensity on the subgrade surface and the subgrade bottom is linearly distributed along the horizontal direction of the subgrade. The farther the former is from the subgrade, the greater the earth pressure, and the latter is basically unchanged. When the input seismic wave PGA is 0.15g, 0.30g and 0.40g, the earth pressure intensity is the smallest at the edge of the ballast, followed by the earth pressure intensity at the center of the subgrade, and the earth pressure presents a triangular distribution along the horizontal direction of the subgrade; the horizontal displacement of the middle and top of the subgrade slope gradually increases, and the former is smaller than the latter, showing an approximately linear distribution and the gradual reduction in the difference between them. At the top of the subgrade, the difference between the displacement on the slope and that on the top of the center line of the subgrade increases gradually with the intensity of the input ground motion intensity, and the difference between both gradually increases, and the stable finally; When the seismic wave is at the bottom of the embankment, the main frequency is concentrated in 5?15 Hz. As the elevation increases, the subgrade has a strong amplification effect on the 30?40 Hz frequency band, but the influence on the remaining frequency bands is not significant.

Key words: high-speed railway, ballast track, subgrade, shaking table test