基坑开挖及降水对坑外地表沉降的影响.docVIP

基坑开挖及降水对坑外地表沉降的影响 　　摘 要：考虑降水、支护结构变形以及基坑隆起3个因素引起的基坑周围土体的沉降，根据降水引起土体沉降的机理，运用修正的分层总和法单独计算出由降水引起的周围土体沉降。通过研究基坑开挖引起坑外土体沉降的规律，推导出由基坑开挖引起的坑外土体沉降理论公式。把降水引起的沉降及基坑开挖引起的沉降进行叠加，加入修正系数，最终以简化的理论公式合理地计算出基坑周围土体沉降。具体工程验证表明，推导的理论解析解与实测数据十分接近，能有效预估基坑周围土体沉降，为施工方案编制提供可靠的理论依据，最大限度减少基坑施工对周围环境的影响。 　　关键词：土体沉降；降水；支护结构变形；基坑底部隆起；解析解 　　中图分类号：TU46 　　文献标志码：A文章编号：1674-4764（2016）05-0043-06 　　Abstract：Settlement of soil around the foundation pit caused by dewatering， deformation of retaining structure and foundation pit uplift are considered to be the three factors causing ground surface settlement. Using layer-wise summation method to calculate the settlement of surrounding soils caused by dewatering according to the soil settlement mechanism of dewatering. By studying the law of the settlement of the soil caused by the foundation pit excavation， the theoretical formula for the settlement of the soil caused by the foundation pit excavation is deduced. Add up the subsidence caused by the foundation pit precipitation and the settlement caused by the excavation of foundation pit， and revise the results with Modified coefficient， eventually the settlement of soil around the foundation pit is reasonably calculated by the simplified theoretical formula. Through specific engineering verification shows that the derived theory analytical solution is very close to the measured data， the derived theory analytical solution can effectively predict the soil settlement around the foundation pit， thereby this will provides the reliable theory basis for the main body of the construction scheme， to reduce as much as possible the effect on the surrounding environment. 　　Keywords：soil settlement；dewatering；deformation of retaining structure；foundation pit uplift； analytic solution 　　中国资源正逐步集中于密集的城市地区，在繁华地带土体资源出现了紧缺的局面，使得基坑工程周围的施工工况更加复杂，因此，对基坑开挖引起的周围环境的影响的研究更加紧迫。土体开挖对周围环境的影响主要体现在基坑外土体的移动以及土体的不均匀沉降。Migliazza等[1]利用分析和经验公式，并通过建立三维有限元模型，分析隧道在不同开挖阶段及支护阶段由开挖引起的地表沉降。Gordon等[2]提出了一种预测支护墙体最大挠度及最大地表沉降的半经验模型，研究表明，该模型可以