基于模糊隶属度的孔压静力触探技术分析复杂土层界面

Analysis of Complex Soil Layer Interface Using Piezocone Penetration Test Data Based on Fuzzy Memberships

基于孔压静力触探(CPTu)的土层识别方法多以经验图表为主,对大容量CPTu实测数据识别时耗费大量资源,并且土层的形成过程受应力历史、地质条件等复杂因素影响,常伴生界面不分明,多出现过渡层、混合层等现象;为了解决以上问题,应用模糊隶属度知识,基于归一化的锥尖阻力和孔压比,对土层界面进行识别和合理归并,并结合输出的棒状图、隶属度结果和参数空间分布图进行分析;选择2个典型的CPTu试验场地与临近孔钻探资料进行对比验证。结果表明,模糊隶属度不仅对土层界面的识别较准确,而且可以判断出土体中过渡层和混合层的具体位置及发育规模。

In methods of soil layer identification based on piezocone penetration test （CPTu） , the soil layer was usual identified by empirical charts, which consumed a lot of resources identifyinga high capacity CPTu data. The formation process of the soil layer was affected by complicated factors such as stress history, geological conditions and so on. It was often associated with the unclear interface, transition layer, mixed layer, and other phenomena. To solve the above pro-blems ,fuzzy membership theory was applied to identifying and reasonably merging the soil layer inteifacebased on normali-zation static point resistance and pore water pressure ratio. The soil layers combined with the output of bar graphs, mem- bership results, and space distribution graphs of parameters were analyzed. CPTu tests from two typical sites were com-pared with the adjacent hole drilling data. The results show that the fuzzy membership theory is not only suitable for iden-tification of the soil layer interface accurately, but also can determine the positions and scales of the transition layer and mixed layer in soil.