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在广州某典型含较厚淤泥质砂层和粗砂层的地铁车站详细地勘资料基础上,以有限元数值模拟为主要手段,对初步选定的钻孔灌注桩加深层搅拌桩围护体系,按照实际施工及内支撑的“先变形,后支撑”情况,计算分析了钻孔灌注桩与邻近地层的内力和变形分布规律。模拟显示,钻孔灌注桩加深层搅拌桩围护体系能满足基坑安全施工要求。作为支护体系配筋构件的钻孔桩最大正负弯矩对称分布,进行对称配筋能节约造价且便于施工。作为被支护体系的邻近地层,应力应变具有明显空间分布和时间分布规律:空间上塑性区主要分布在淤泥层、粗砂层和桩脚部位;时间上在第二次开挖就达到最终变形量的90%,实际施工中应加强对以上情况的监测。
Based on the detailed survey and data of a typical metro station with thick silt layer and grit layer in Guangzhou, taking the finite element numerical simulation as the main method, the preliminary selected bored pile and deepening mixing pile retaining system , According to the actual construction and internal support “first deformation, after the support ” situation, calculated and analyzed the bored piles and adjacent strata of internal force and deformation distribution. The simulation shows that the bored piles deep mixing piles retaining system can meet the requirements of safety construction of foundation pits. The maximum positive and negative bending moment of the bored piles as the reinforcement component of the supporting system is symmetrical, and the symmetrical reinforcement can save the cost and facilitate the construction. As the adjacent formation of the supported system, the stress and strain have obvious spatial and temporal distribution: the spatial plastic zone is mainly distributed in the silt layer, grit layer and pile foot section; the final deformation will be achieved in the second excavation time 90% of the amount, the actual construction should strengthen the monitoring of the above situation.