软弱地基上储油罐群蠕变沉降及控制措施研究

发布时间：2018-05-08 04:21

本文选题：储罐 + 软土地基　；参考：《中国石油大学(华东)》2015年硕士论文

【摘要】：目前,储罐基础及地基设计中,储罐沉降计算一般是指地基主固结沉降的计算,很少定量考虑其蠕变沉降。为了研究软土蠕变对储罐沉降及不均匀沉降的影响,及储罐软土地基蠕变的控制措施,为大型储罐软土地基加固处理提供参考,本文以厚土层储罐软土地基为例,采用FLAC3D软件,研究了储油罐群充水阶段的固结沉降及投入使用之后的蠕变沉降性状,并模拟了多种常用方式对储罐软土地基的处理效果,得出结论如下:1)考虑软土地基的蠕变,储罐在正常使用过程中的沉降及不均匀沉降都比无蠕变时大很多,软土的蠕变对储罐沉降及不均匀沉降影响很大,储罐设计中必须进行考虑。2)充水检漏阶段,若罐群各储罐同步充水,则在充水完成后各储罐沉降及不均匀沉降相同,并往相互靠近方向倾斜。若各储罐先后充水,则先充水的储罐沉降及不均匀沉降都较大,并按充水顺序逐渐降低,但相互差距不大;最终各储罐也基本上都往相互靠近方向倾斜。3)正常使用阶段,因软土地基的蠕变,储罐沉降在早期阶段内增长速率相对较快,随后增速降低并保持不变;在早期短时间内,储罐不均匀沉降呈缓慢降低趋势,随后逐渐增大。各储罐充水顺序及罐群效应对正常使用阶段储罐蠕变沉降影响不大。4)充水预压法处理储罐软土地基,可有效降低储罐正常使用过程中的沉降和不均匀沉降,但降低幅度不是很大。延长预压时间能提高储罐沉降和不均匀沉降的降低幅度,但效果不明显。5)强夯置换法处理储罐软土地基,能降低储罐沉降和不均匀沉降,但其对控制下卧软土层的蠕变沉降效果不大;加大置换厚度及提高加固层弹性模量对储罐沉降及不均匀沉降的降低程度很小。6)与天然软土地基、预压法及强夯置换法处理地基相比,CFG桩复合地基能有效地控制储罐地基的蠕变沉降,大幅度地降低储罐的沉降,对于大厚度储罐软土地基,其处理方式应首选CFG桩复合地基。增大桩长、桩径及减小桩间距都能降低储罐沉降,但降低幅度不大。在实际工程中,应综合考虑经济成本、施工难度及工期等多种综合因素确定合理桩参数。
[Abstract]:At present, in the design of tank foundation and foundation, the calculation of tank settlement usually refers to the calculation of the main consolidation settlement of the foundation, and the creep settlement is seldom considered quantitatively. In order to study the influence of soft soil creep on tank settlement and uneven settlement, and the control measures of tank soft soil foundation creep, this paper takes the thick soil tank soft soil foundation as an example, adopts FLAC3D software, and provides a reference for the reinforcement treatment of large storage tank soft soil foundation. In this paper, the consolidation settlement and creep settlement behavior of oil storage tanks during water filling stage are studied, and the effects of various common methods on the treatment of tank soft soil foundation are simulated. The conclusion is as follows: 1) the creep of soft soil foundation is considered. The settlement and uneven settlement of storage tank in normal use are much larger than those without creep. The creep of soft soil has a great influence on tank settlement and uneven settlement. If the tanks are filled with water at the same time, the settlement and uneven settlement of the tanks are the same and inclined to each other in the direction of approaching each other. If each tank was filled with water successively, the settlement and uneven settlement of the tank filled with water were larger, and gradually decreased in the order of filling, but the difference between each other was small. Finally, the tanks were basically inclined to each other in the direction of close to each other. 3) normal service stage. Because of the creep of soft soil foundation, the tank settlement increases relatively quickly in the early stage, then decreases and remains unchanged, and in the early short time, the uneven settlement of the storage tank decreases slowly, and then increases gradually. The order of tank filling and tank group effect have little effect on the creep settlement of storage tank in normal service stage. 4) the soft soil foundation of storage tank can be treated by water filling preloading method, which can effectively reduce the settlement and uneven settlement during the normal operation of storage tank. But the reduction is not much. Prolonging preloading time can increase the decrease range of tank settlement and uneven settlement, but the effect is not obvious. 5) the dynamic tamping replacement method can treat the soft soil foundation of the storage tank and reduce the tank settlement and uneven settlement. However, it has little effect on controlling creep settlement of lying soft soil, increasing replacement thickness and increasing elastic modulus of strengthened layer can reduce tank settlement and uneven settlement very little. 6) and natural soft soil foundation, Compared with CFG pile composite foundation, preloading method and dynamic tamping replacement method can effectively control the creep settlement of storage tank foundation and reduce the settlement of storage tank by a large margin. For the soft soil foundation of storage tank with large thickness, the CFG pile composite foundation should be chosen as the first treatment method. Increasing pile length, pile diameter and decreasing pile spacing can reduce tank settlement, but the reduction range is not significant. In the actual project, the reasonable pile parameters should be determined by taking into account the economic cost, construction difficulty and time limit.
【学位授予单位】：中国石油大学(华东)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU433

【参考文献】