硬岩层对基桩低应变信号影响的分析

Influence of Hard Rock Layer on Low Strain Signal of Piles

基于工程实测数据,探讨了不同深度和厚度的硬岩层对低应变测试信号的影响。揭示了较厚的硬岩层产生的负向反射较强,而且由于入射能量的主体被硬岩层反射回桩顶面和沿着岩层扩散,使得沿桩身下行的能量较弱或无法反射回桩顶,从而导致该岩层之下的岩土特性和桩身施工质量无法得到体现,而较薄的硬岩层产生的负向反射较弱,相对的,沿着桩身向下传播的能量就较大,故可反映部分该岩层之下的岩土特性和桩身施工质量。

Based on the engineering measured data,the impact on the low strain test signal resulted by hard rock layer of different depths and thicknesses are discussed. It reveals that the thicker hard rock layers produce stronger negative reflection signals. Moreover,since most of the energy of the incident wave is reflected by the hard rock layer back to the top of the pile and spread along the rock layer. As a result,the geotechnical characteristics and pile construction quality under the rock formation cannot be reflected. However,thinner hard rock layers produce weaker negative reflections. Correspondingly,the energy that travels down the pile is relatively large,so it can reflect some of the characteristics of the rock and soil below the rock and the construction quality of the pile.