在城市密集建筑区进行超深基坑施工时,基坑施工全过程环境变形的精细分析和控制至关重要。以杭州某超深基坑施工全过程为例,对支护结构施工阶段、基坑开挖阶段和支撑拆除阶段地表沉降、地连墙侧移、邻近建筑物沉降、管道沉降进行了精细化实测统计分析。结果表明:墙体最大侧移位置在基坑底板浇筑完成后基本维持不变,位于0.8倍开挖深度处,而最大侧移量在支撑拆除阶段还存在持续小幅增加,增加量可达累计侧移量的10%;地表沉降、邻近建筑物沉降和管道沉降在基坑施工完成后仍呈现持续发展趋势;对于墙体侧移、地表沉降、邻近建筑物沉降和管道沉降,各施工阶段所占比例大小顺序一般为基坑开挖阶段>支撑拆除阶段>围护施工阶段,墙体侧移和地表沉降主要在基坑开挖阶段产生,基坑开挖阶段所占比例均达到60%以上,最高达到91.95%;邻近建筑物变形和管道沉降主要在基坑开挖和围护施工阶段产生,基坑开挖阶段所占比例多在60%左右,且支撑拆除阶段的比例也可达到30%以上。
It is very important to analyze and control the environmental deformation in the whole process of super deep foundation pit construction in dense urban areas. Taking the whole construction process of a super-deep foundation pit in Hangzhou as an example, the surface settlement, lateral displacement of diaphragm wall, settlement of adjacent buildings and settlement of pipelines in the construction stage of supporting structure, excavation stage of foundation pit and demolition stage of supporting structure are measured and statistically analyzed. It is found that the maximum lateral displacement of the wall remains basically unchanged after the pouring of the foundation pit floor, which is located at 0.8 times the excavation depth, while the maximum lateral displacement continues to increase slightly during the support demolition stage, and the increase can reach 10% of the cumulative lateral displacement. Ground settlement, adjacent building settlement and pipeline settlement still show a continuous development trend after the completion of foundation pit construction. For the wall lateral displacement, surface settlement, settlement of adjacent buildings and pipeline settlement, the proportion of each construction stage is generally in the order of foundation pit excavation stage > support demolition stage > enclosure construction stage. Wall lateral displacement and surface settlement are mainly generated in the foundation pit excavation stage. The proportion of foundation pit excavation stage reaches more than 60%, up to 91.95% ; the deformation of adjacent buildings and the settlement of pipelines are mainly generated in the stage of foundation pit excavation and enclosure construction. The proportion of foundation pit excavation stage is mostly about 60%, and the proportion of support demolition stage can also reach more than 30%.
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