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在场地开挖了一条空沟,以落锤式弯沉仪(falling weight deflectometer,简写为FWD)的荷载模拟冲击荷载,通过FWD自带的传感器测得空沟后一定范围内的竖向位移。通过室内试验,获取试验场地的岩土参数,采用非线性动力有限元软件ABAQUS建立二维模型(将远处单元定义为无限单元来模拟吸收边界,从而避免振动波的来回反射)。以空沟中心线的现场测试数据为依据,校核有限元模型。通过分析不同工况模拟的竖向位移,研究得出空沟-荷载间距、沟深、沟宽等对隔振效果的影响。结果表明,(1)空沟-荷载间距越小,隔振效果越好,但实际隔振工程中,为避免振动对空沟侧壁的稳定性的影响,空沟与振源不宜太近,因此可以不计空沟-荷载间距对隔振效果的影响;(2)就提高隔振效果而言,增大沟深比增大沟宽更有效,而相同的隔振效果,窄-深沟的挖方量远小于宽-浅沟;(3)在对冲击荷载进行隔振设计时,对于一般的民用和工业建筑,综合隔振效果、开挖和支护费用等因素,采用宽度为0.5~1.0 m,深度为2.0~2.5 m的空沟较为合理,与某工程实例进行比对,验证结论的合理性。
An empty trench was excavated at the site to simulate the impact load with a falling weight deflectometer (FWD) and the vertical displacement within a certain range after the emptying was measured by the FWD’s own sensor. Through indoor experiments, the geotechnical parameters of the test site are obtained. A two-dimensional model is built by using the nonlinear dynamic finite element software ABAQUS (the remote unit is defined as an infinite unit to simulate the absorption boundary, so as to avoid the back and forth reflection of the vibration wave). Based on the field test data of the open channel centerline, the finite element model was checked. By analyzing the vertical displacement under different working conditions, the effect of the gully-load spacing, groove depth and groove width on the vibration isolation effect was studied. The results show that: (1) The smaller the emptying-load spacing is, the better the vibration isolation effect is. However, in order to avoid the influence of vibration on the stability of the side wall, Therefore, it is not necessary to consider the effect of emptying-load spacing on the vibration isolation effect. (2) To improve the vibration isolation effect, it is more effective to increase the groove depth than to increase the groove width. The same vibration isolation effect, narrow- (3) In the design of vibration isolation impact load, for general civil and industrial buildings, the comprehensive vibration isolation effect, excavation and support costs and other factors, the width of 0.5 to 1.0 m, the depth of 2.0 ~ 2.5 m of the empty trench is more reasonable, compared with a project example to verify the conclusions of the rationality.