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以某工程为例介绍超大深基坑技术难点与问题,并针对性地提出了解决方法和措施。如钻孔灌注桩增大成孔过程中泥浆比重和黏度、增加除砂设备和添加外加剂等措施有效控制了成孔过程中塌孔和成渣厚度;地下连续墙调准地下钢筋笼封头筋间隙和增加刷壁次数有效减少了基坑开挖后地下连续墙接缝处渗漏,避免了发生流砂、管涌的安全事故;通过设置定位卡、封盖板和钢筋笼吊筋等措施,确保了接驳器定位和成活率;基坑降水增加降水井数量和群井减压试抽试验有效提高了基坑降水效果,为基坑开挖作业和大底板施工创造了有利条件;基坑开挖设定基坑开挖各阶段报警值和开工前深化施工方案等方法有效控制围护结构变形,保障了基坑安全。
Take a project as an example to introduce the technical difficulties and problems of super deep foundation pit and put forward the solutions and measures pertinently. Such as the bored piles to increase the proportion of mud into the hole during the process of viscosity and density, adding sand removal equipment and additives such as effective measures to control the process of hole collapse and slagging thickness; underground diaphragm wall alignment underground reinforcement cage head Clearance and increasing the number of brushing effectively reduce the seepage of underground continuous wall joints after foundation pit excavation and avoid the safety accident of sand flow and pipe pouring. By setting positioning cards, capping plates and steel bar suspending bars, etc., The location and survival rate of the feeder were increased; the number of precipitation wells increased by the foundation pit dewatering and the pumping test of the well under reduced pressure effectively improved the effect of foundation pit dewatering, which created favorable conditions for the excavation work and the large floor construction of the foundation pit; Digging set the excavation of each phase of the alarm value and the deepening of construction before the start of construction methods and other methods to effectively control the deformation of the envelope to protect the safety of foundation pit.