海绵城市透水沥青道路多层构造测厚方法试验研究

针对现有海绵城市透水沥青路面测厚中开挖式方法效率低、可靠性差,传统地质雷达方法多局限单层测厚、多层测厚精度低等问题,开展了基于高频地质雷达的海绵城市透水沥青路面多层构造高精度测厚方法试验研究。分析了路面各层位的介电常数准确性是影响地质雷达对各层构造测厚精度的主要因素之一,开展了沥青路面的各层位介电常数测定试验,研究了各层位介电常数受含水率变化的影响机理,构建了"含水率-介电常数"变换模型。基于变换模型开展了不同含水率情况下的三段具代表性透水沥青路面实测试验。结合由实测数据处理得到的路面各层位分界面信息和从变换模型获得的各层位介电常数计算出不同层位厚度,与实际钻挖测厚结果相比误差在6.6%以内。结果表明:结合"含水率-介电常数"变换模型,高频地质雷达可对海绵城市透水沥青路面实现多层构造的高精度测厚,进而实施路面质量评价。

Experimental study on method of thickness measurement for multilayered structure of permeable asphalt pavement in sponge city

Aiming at the problems from the existing excavation-type method for the thickness measurement of permeable asphalt pavement in sponge city，i． e． low efficiency，poor reliability，the conventional method of GPR ( Ground Penetrating Radar) being limited to measure the thickness of single-layer with low accuracy of the measurement on multi-layer thickness，etc．，the experimental study on a high-frequency GPR-based high accurate thickness measurement method for the multi-layered structure of the permeable asphalt pavement in sponge city is carried out． At first，it is obtained from the relevant analysis that the accuracy of the dielectric coefficient of each layer is one of the main factors to influence the accuracy of GPR thickness measurement on the structure of each layer，and then an experiment on the measurement of dielectric coefficient of each layer of the asphalt pavement is carried out; from which the mechanism of the influence from the change of water content on the dielectric coefficient of each layer is studied，while a water content-dielectric coefficient converting model is built up as well． Based on the converting model， the actual measuring experiments on three sections of representative permeable asphalt pavements are made under the conditions of different water contents． Combined with the information of the interfaces of all the layers of the pavement obtained from process- ing the measured data and the dielectric coefficients of all the layers obtained from the converting model，the thicknesses of all the layers are calculated，of which the relative error is within 6. 6% if compared with that from the thickness measurement made by actually drilling． The study result shows that in combination with the water contentdielectric coefficient converting model，the high accurate thick measurement of multilayered structure of the permeable asphalt pavement in sponge city can be realized by high-frequency GPR，thus the assessment on the pavement quality is to be realized as well．