软岩桩基承载性能试验研究

 地王商会中心和佳得鑫广场是南宁市两座相邻的高层建筑，其基础均采用人工挖孔扩底桩，桩端嵌入第三系泥岩。广西南宁盆地广泛分布的第三系泥岩是典型的软岩，通常被选择作为建筑物桩基的持力层。为掌握软岩桩基的工程性质，采用自平衡试桩法进行上述2个工程共8根嵌岩桩的承载性能试验。考虑到各试桩的嵌岩深度和尺寸不同，为获得较好的试验结果，桩身荷载箱的设置采用不同型式。通过试验解决大吨位软岩扩底桩承载力测试难题，为工程设计提供所需的重要参数。对试验数据进行对比分析结果表明，浸水对软岩桩基的承载性能有较大的削弱。根据试验研究结论，施工中采取有效措施防止泥岩浸水，为今后类似工程的建设积累了宝贵的经验。

RESEARCH ON BEARING PERFORMANCE OF SOCKETED PILE IN SOFT ROCK

Diwang Commercial Center and Jiadexin Crystal Mansion are both high-rise buildings in Nanning，and they are close to each other. Foundations of them are both made of manual digging socketed belled piles in tertiary mudstone. Tertiary mudstone is a typical soft rock distributing widely in Nanning Basin，Guangxi Autonomous Region. It is usually chosen as the bearing stratum of pile foundation. In order to master the engineering characteristics of socketed pile in soft rock，the self-balanced loading test is conducted to test eight piles of two high-rise buildings. The cell assembled in the pile body is the key equipment of the test. To get better test effect，assembly of cell has been taken different modes in terms of depth that pile socketed in rock and dimension of enlarged toe. By the self-balanced loading test，the problem that the ultimate bearing capacity of the large tonnage socketed belled pile in soft rock is hard to be acquired is solved. Several key parameters required in design are obtained. In terms of test results，the bearing performances of the piles are studied. By comparing the test curves of pile tip，pile side and the equivalent converted curves of the whole pile，it reveals apparently that the bearing capacity of the socketed pile in mudstone will decrease after mudstone has been immerged. Since effective measures have been taken；mudstone is prohibited from being immerged during construction. And valuable experience has been accumulated for similar projects construction henceforth.