基于波传播特性的钢板桩振动环境效应评价和预测

Evaluation and prediction on vibration environment effect of steel sheet pile based on wave propagation characteristics

通过三轴测振仪,对3个典型地区不同厚度软土的项目钢板桩振动沉桩进行监测,提取了距离沉桩点不同距离处地表的径向、切向和竖向的振动加速度,并利用Mathematica和SeismoSignal软件,分析了振动峰值加速度和振动峰值速度随距离沉桩点不同距离的变化趋势。结果表明,软土地区的振动峰值加速度和振动峰值速度均在距离沉桩点一定距离处发生突变,造成该突变的原因和压缩波传到地面有关,突变点与沉桩点之间的最短距离即为临界距离。采用GDS⁃RCA共振柱三轴测振仪,对3个场地振动沉桩前后距离沉桩点不同距离处的土体剪切模量进行测试,得到影响临界距离的因素,并通过测试数据得到临界距离处振动峰值速度差值与软土层厚度、土阻抗之比和临界距离之间的关系和改进的振动峰值速度预测方程;改进后的方程不仅真实地反映了不同软土层厚度、土层参数以及临界距离对振动峰值速度的影响,而且更真实地反映了软土地区振动衰减规律。

Through use of a triaxial vibration meter,monitoring was conducted on the vibratory driven steel sheet pile installation in soft soil of varying thickness in three typical regions.Radial,tangential,and vertical vibration accelerations at different distances from pile sinking point were extracted from the ground surface.Analysis of trends of peak vibration acceleration and peak vibration velocity with varying distances from pile sinking point was carried out with Mathematica and SeismoSignal software.Results indicate that both peak vibration acceleration and peak vibration velocity in soft soil regions undergo abrupt changes at a certain distance from pile sinking point which result from compressed waves propagating to the ground,defining this distance as the critical distance.Using the GDS⁃RCA resonance column triaxial vibration meter,the shear modulus of soil at different distances from pile sinking point before and after vibratory pile driving was tested at the three sites.Factors influencing the critical distance were determined,and a relationship between the difference in peak vibration velocity at the critical distance and the thickness of the soft soil layer,the ratio of soil impedance,and the critical distance was established.An improved equation for predicting peak vibration velocity was derived from the test data.This improved equation not only accurately reflects the effects of different thicknesses of soft soil layers,soil parameters,and critical distance on peak vibration velocity,but also provides a more realistic representation of the vibration attenuation pattern in soft soil areas.