确定软岩地基桩基承载力参数的新方法与应用

南水北调中线一期工程输水总干渠第三系软岩地基占线路总长的68%,桩基数量为国内外土建工程之最.由于软岩具有易扰动性的显著特征,软岩地基和桩基力学参数获取的手段单一并存在欠陷,导致参数取值的不确定性,在此情况下,带来设计指标估计有较大富余,对工程投资影响巨大.因此现阶段研究软岩地基桩基承载力特性工作显得尤为迫切.文章介绍了采用模拟桩极限侧阻力试验、自平衡试桩法等获取参数的新方法以及其成功应用工程的实例;并简要介绍了离心机模拟试验、计算机数值仿真技术、桩基动力检测方法以及提高桩基承载力的新方法.建议不失时机地将这些新方法应用于设计和施工方案的优化,控制基础的不均匀变形,缩短工程周期,减少设计变更.

New Methods for Determination Bearing Capacity Parameter of Pile Foundation in Soft Rocks and Its Application

Soft rock foundation length of the water distribution main channel in Mid-Route of the South-to-North Water Diversion is 68% of the to tal. Number of pile foundation is the largest in domestic and overseas civil engineering field. Mechanical parameters can not be gained exactly because the means gaining them is defective. It makes project investment increase greatly. New methods of ultimate pile side resistance simulation test and self regulation test pile are demonstrated in the paper. And application of the new methods is introduced. Centrifuge simulation experiment, the computer simulation technology, the pile foundation power examination method and new construction methods improving bearing capacity are demonstrated. It is suggested that all the above new methods are applied in design and in optimizing construction scheme to control unequal foundation settlement, shorten project time and cut down design alteration.