软粘土层上的油罐差异沉降

根据某一大型油罐软基加固处理工程方案设计和优选需要,按照离心模型相似律,开展了三组模型试验,分别模拟了天然地基、土工合成材料袋装碎石垫层和既在填土层中设置袋装碎石垫层又在淤泥质粘土层设置土工合成材料排水板三种情况,以研究这一加固布置形式对减小高压缩性软土层地基上油罐罐底的差异沉降效果反应。模型油罐地基采用原型土重塑制备,现场土工合成材料袋装碎石采用柔性机织玻璃纤维细管塞装粗砂条模拟,并在不停机运转条件下模拟了多次充放水预压加载。试验结果表明,油罐软弱地基经土工合成材料袋装碎石加固后,罐底总沉降值和差异沉降值均明显小于天然地基情形下对应的沉降值,罐底畸变得到显著减小,就本文所述的土质条件、土层厚度和预压荷载强度,地基经加固处理后,油罐罐底畸变减小了近50 %。最后就土工合成材料在加固油罐地基布置形式的合理性进行了初步探讨。

Differential settlement of oil storage foundation on soft clay

Centrifuge model tests of oil storage tanks on soft, compressible clay deposits are carried out. Natural ground is simulated by one of the centrifuge models, and grounds with geosynthetic sacked stone columns are stimulated by other models. The effect of geosynthetic plane drain on consolidation settlement is also studied by installing sand columns in soft, compressible clay deposit. The sacked stone columns and plane drain are modeled by sand columns wrapped by flexible glass fiber tube. The water loading and unloading process is implemented at the specified centrifuge acceleration by means of a pneumatic water filling apparatus, which is specially developed for this study. The centrifuge model test results shows that significant reduction of differential settlement beneath a tank bottom can be achieved if the tank foundation is properly reinforced by embedding geosynthetic sacked stone columns. In the case of the soft, compressible clay and the intensity of the water load in this study, nearly 50 % of distortion of oil tank bottom could be reduced. It is also found that the consolidation settlement of soft, compressible clay deposit with plane drain becomes stable earlier than that without drain.