孟加拉国PADMA公铁两用大桥地质条件为深厚沉积粉细砂层,设计桩长超过100m,深部砂土层极密实,常规静力触探因不易穿透密实层、探杆侧向约束不足、测试深度有限等,远远不能满足设计、施工要求。本文采用自主研发的多重套管技术,采集分析多个超过120m静力触探孔数据,并结合地质钻孔及标准贯入试验成果进行分析,结果表明:多重套管可增加探杆侧向约束、提高探杆抗弯和定位导向能力,进而提高贯入深度;测试数据与常规静力触探数据(未采用多重套管)、地质钻孔剖面、标准贯入试验吻合,验证了多重套管技术对测试数据影响较小,对孔压静力触探技术的拓展和相关设备的研发具有一定的参考意义;多重套管技术可以应用于水域、陆域,极大地扩展了静力触探的勘察范围。

The geological conditions of PADMA multipurpose bridge in Dhaka of Bangladesh are located the layer of fine sand which is very dense in deep layer. The design length of the main bridge piles are over100 meters. Due to the probe difficult to penetrate the dense layer,the small lateral constraint and the test depth limitation,the traditional static cone penetration test can not satisfy the requirements of the design and construction. By using self-developed multi-casing technique,the data from the super-deep piezocone penetration with more than 120 meters are collected and analyzed after comparing the stratum sections and standard penetration tests. The testing results show that the multi-casing technique can increase the lateral rigidity and bending ability of rods string with the positioning and guiding,and increase the penetration depth. Secondly,the data conform to the traditional static cone penetration test results( not using the multi-casing technique),the geological drilling sections and the standard penetration tests. Therefore,it is known that the influence on test data from the multi-casing technique is very small,and the results could give the reference and guidance for the expansion application of piezocone penetration tests and the related equipment development. The multi-casing technique can be applied to the land or marine engineering,which greatly expands the reconnaissance range of piezocone penetration tests.