基于球形全流动触探仪的软土地基不排水强度确定

Evaluation of Undrained Shear Strength from Piezoball Tests in Softsoil Foundation

球形全流动触探仪在软弱土体中具有测试数据稳定且无须修正的特点,因而在近海工程中有着较好的适用性。对球形探头贯入阻力及确定土体不排水剪切强度的方法进行介绍,并讨论了贯入阻力系数取值范围。在此基础上,通过开展离心模型试验,分析比较球形全流动触探和传统锥形静力触探的贯入阻力,以及确定的软土不排水剪切强度。研究结果表明,利用孔压修正后的锥形探头较球形全流动触探探头的贯入阻力大;而基于球形触探结果确定的软土不排水剪切强度值较传统静探方法确定的更为稳定,且与K_0固结条件下强度值较为接近。本研究将为球形全流动触探仪在近海工程中的应用提供依据。

The piezoball test is suitable for the thick deposits of soft clay in offshore engineering, since the data measured from which is steady and no need to correct. The penetration resistance of the piezoball and the corresponding methods for undrained shear strength determination are firstly introduced, and then the value ranges of the resistance coefficient are discussed. Furthermore,the centrifuge tests are conducted to analyze the penetration resistances measured by piezoball and piezocone tests,respectively. Meanwhile,the undrained shear strengths determined by two types of penetrometors are also compared. The results show that the cone penetration resistance corrected with pore water pressure is larger than that measured by the piezoball. In addition,the undrained strength profiles against the depths determined by piezoball are steadier than that from piezocone, which is closed to the strength under K0 consolidation condition. The studies of this paper will provide reference for the application of full flow penetrometers in the offshore engineering.