复杂地层大型污水处理构筑物沉井实施方案优化研究

Study on Optimization of Open Caisson Construction Scheme for Large Sewage Treatment Structure in Complex Strata

以某沿海大型污水处理构筑物沉井为例,通过对比分析沉井初沉前不同预制高度(第一节)条件下的基底压力、地基承载力及不同刃脚下沉深度的阻力,对沉井施工过程中可能发生的问题进行预测;提出了基于基底压力、修正地基承载力分别与砂垫层厚度的曲线及交点进行沉井预制前临时基础铺设砂垫层厚度优化,基于地层界面处刃脚下取土和刃脚下留土两种取土方法的下沉系数与合理区间[1.05,1.25]的关系进行沉井实施方案优化的方法。以计算结果和变化规律为基础预测可能发生的问题,与现场实际基本一致;对实施方案进行合理优化,确保了沉井的顺利实施。

Taking the open caisson for a large coastal sewage treatment structure as an example,the base pressure and the foundation bearing capacity in the condition of different prefabrication height(the first section)before initial sinking,and the subsidence resistance at different sinking depth of cutting edge,were compared and analyzed,and on this basis the problem that may occur during the construction of open caisson was predicted.As a result,here proposed the optimization method for the thickness of sand cushion laid in the temporary foundation before caisson prefabrication according to the respective intersections of base pressure,corrected foundation bearing capacity and sand cushion thickness curves,as well as the method for the optimization of caisson construction scheme according to the relation between the subsidence coefficient with reasonable range[1.05,1.25]of two soil sampling methods,i.e.collecting soil under cutting edge and keeping soil under cutting edge at stratigraphic interface.The trouble that may occur predicted depending on the calculation result and the change laws is basically consistent with the actual situation on site.The reasonable optimization of the construction scheme guarantees the successful implementation of open caisson.