考虑深基坑不同施工阶段对临近建筑物沉降作用的影响分析

Analysis of Settlement Effects on Adjacent Structures during Various Construction Stages of Deep Excavation Projects

摘要: 深基坑工程的施工会引起基坑周边土体应力场发生显著变化，进而引起临近建筑物发生显著沉降作用。以济南市某深基坑工程为例，建立环临近建筑物闭合水准监测网并对施工全过程进行持续监测，探究了自放坡开挖至主体结构施工完成全周期内的临近建筑物沉降演化规律，分析了基坑不同施工阶段对临近建筑物沉降量与差异沉降作用的影响程度。监测数据表明：临近建筑物沉降将经历缓慢增长期–急剧增长期–稳定平台期–二次增长期–趋于收敛期的演化曲线，分别对应降水、放坡开挖、围护结构施工、基坑开挖、主体结构施工五个典型施工阶段，产生的沉降量与最大差异沉降量分别为4.05~7.20 mm、7.18~14.90 mm、1.08~1.61 mm、7.51~10.67 mm、1.14~1.83 mm和3.29 mm、7.72 mm、0.72 mm、4.71 mm与1.09 mm，差异沉降量与沉降速率均满足相关规范要求；基于沉降演化规律与数据分析可知，应重点关注放坡开挖阶段临近建筑物各区域与基坑土方开挖阶段临近建筑物远离基坑区域的沉降监测，并做好预警与加固处置方案。本文研究成果可为城市深基坑工程施工组织与其他类似市政工程施工提供一定的借鉴与参考。

Abstract: The construction of deep foundation pit projects can cause significant changes in the stress field of the surrounding soil, which in turn leads to notable settlement of adjacent buildings. Taking a deep foundation pit project in Jinan as an example, a closed leveling monitoring network around adjacent buildings was established, and continuous monitoring was carried out throughout the construction process. The settlement evolution law of adjacent buildings during entire construction from slope excavation to the completion of the main structure was explored, and the influence degrees of different construction stages of the foundation pit on the settlement and differential settlement of adjacent buildings were analyzed. The monitoring data show that the settlement of adjacent buildings will follow an evolution curve of slow growth period, rapid growth period, stable platform period, secondary growth period, convergence tending period, corresponding to five typical construction stages: dewatering, slope excavation, retaining structure construction, foundation pit excavation, and main structure construction respectively. The settlement amounts and maximum differential settlement amounts generated in these five stages are 4.05~7.20 mm, 7.18~14.90 mm, 1.08~1.61 mm, 7.51~10.67 mm, 1.14~1.83 mm and 3.29 mm, 7.72 mm, 0.72 mm, 4.71 mm, 1.09 mm respectively. Both the differential settlement amount and the settlement rate meet the requirements of relevant specifications. Based on the settlement evolution law and data analysis, it is necessary to focus on the settlement monitoring of different areas of adjacent buildings during the slope excavation stage and the area of adjacent buildings far from the foundation pit during the foundation pit earth excavation stage, and prepare early warning and reinforcement disposal plans. The research results of this paper can provide certain references for the construction organization of urban deep foundation pit projects and other similar municipal engineering constructions.