西安地区PHC管桩上浮问题初探及预防

Preliminary Study on Upfloat of PHC Pipe Pile in Xi’an Area and the Prevention

摘要:

在西安地区，随着预应力高强混凝土管桩（PHC）在工程中的广泛应用，施工中出现的质量问题也逐渐增多。个别工程项目甚至出现了在南方饱和软土地区常见的因桩身上浮导致单桩承载力大幅降低的工程病害。结合西安地区东郊某静压管桩（PHC）工程的特点，分析并阐述了挤土效应和桩身卸压回弹造成饱和黄土场地静压PHC管桩出现场地隆起、桩身上浮形成“吊脚桩”的原因和机理，并据此提出了针对饱和黄土场地管桩施工所应注意的关键环节和预防措施。

Abstract:

Prestressed high strength concrete drilled caisson (PHC) is used extensively in projects for Xi'an area, the quality problem appearing in construction gradually increases. Project disease of individual project, such as pile capacity largely reducing, and this is often seen in saturated soft soil for south area because of shaft uplift .The paper with Xi'an eastern suburb analyzes the cause and mechanism for heave, shaft uplift, and “hanging foot pile” of static pressure PHC drilled caisson in saturated loess because of squeeze effect and shaft decompression modulus, and key links and precautionary measure has been suggested for drilled caisson construction of saturated loess site.〗Pre-stressed high strength concrete pipe pile (PHC) is extensively used for projects in Xi’an area with the construction quality problems gradually increasing. Engineering disease of individual project, such as pile capacity largely reducing, is often seen in saturated soft soil in south area because of shaft upfloat .The paper analyzes the causes and mechanism of heave by squeezing effect and shaft decompression rebound; “suspending pile” by shaft upfloat with a PHC pipe pile project in eastern suburb of Xi’an. Based on the above, the key links and preventive measures have been suggested for PHC pipe pile project construction in saturated loess site.