轨道交通单排非连续隔振屏障隔振效果模型试验研究

Model tests for effects of rail transit's single row discontinuous vibration isolation barriers

为了研究轨道交通隔振屏障中的非连续隔振屏障的隔振效果,通过进行隔振井(空井、PVC空井)及混凝土桩(实心桩、空心桩)的室内模型试验,以地表振动加速度级为评价指标,对上述非连续隔振屏障的隔振效果给出了评价,进一步对空心混凝土桩的隔振效果进行了分析。结果表明:高频振动波衰减迅速,中低频振动波是引起土体振动的主要原因;混凝土桩隔振性能优于隔振井,具体隔振效果比较为:混凝土桩>空心混凝土桩>空井≈PVC空井;对于空心混凝土桩,桩体的空心率越大,隔振性能相对越差;桩体外截面为圆形的空心混凝土桩的隔振效果大于方形;截面内部形状对隔振效果影响较小;空心混凝土桩内填充松散橡胶颗粒、泡沫等阻尼材料无法进一步提高空心桩隔振性能;若填充原场土,填土密度对其隔振性能没有影响。

In order to study vibration isolation effects of rail transit ’s discontinuous barriers,taking vibration acceleration of ground surface as the evaluation index,a series of indoor model tests were conducted for vibration isolation wells including empty wells and PVC ones,and concrete piles including solid piles and hollow ones,then the vibration isolation effect of the above mentioned discontinuous barriers were evaluated. Further,the vibration isolation effect of hollow concrete piles was evaluated. Results showed that vibration waves with higher frequencies decay rapidly,medium frequency and lower frequency waves are the main reason to cause soil body vibration; the vibration isolation performance of concrete piles is better than that of vibration isolation wells be; the vibration isolation effect of solid piles that of hollow piles that of empty wells or PVC ones; for hollow piles,the larger the hollow ratio,the worse the vibration isolation performance; the vibration isolation performance of cylindrical hollow piles is bigger than that of square hollow ones,the internal shape of hollow cross-section has little influence on the vibration isolation effect; hollow concrete piles filled with loose rubber particles,foam and other damping materials can’t improve their vibration isolation performance; if they are filled with raw soil,the fill density has no influence on their vibration isolation performance.