盾构隧道下穿既有车站变形控制研究

文章以某盾构隧道下穿既有车站为研究背景,首先,对区间隧道下穿既有车站变形机理进行数值模拟计算,得到车站结构的竖向位移随各开挖步变化规律。然后分别从车站主体结构变形、地层变形等方面对比分析,提出底板加厚、周边加固、板凳桩加固和桩+袖阀管注浆加固4种控制变形技术措施方案,得到最优的板凳桩+袖阀管注浆加固措施方案;最后对板凳桩围护结构设计分别从不同桩体长度、桩体纵向间距和桩体直径三方面来进行研究,以车站底板沉降和结构竖向位移以及地表沉降等对象来对比分析,最终选定板凳桩长度为桩端底部至拱底以下5~7 m范围内,桩间距在1.6~2.2 m范围内,桩直径为1 m,使盾构开挖施工对既有邻近建筑物影响程度变小。

Research on Deformation Control of Shield Tunneling Under Subway Station

Taking a shield tunnel underpassing an existing station as the research background,firstly,the numerical simulation of the deformation mechanism is carried out,and the change law of vertical displacement of the station structure with each excavation step is obtained.Then,from the comparison of the main structure deformation and stratum deformation of the station,4 technical solutions for controlling deformation,namely,the bottom plate thickening,peripheral reinforcement,bench pile reinforcement and pile+sleeve valve tube grouting reinforcement,are proposed to obtain the optimal bench pile+Sleeve valve tube grouting reinforcement scheme;finally,the design of the bench pile retaining structure is studied from 3 aspects:length of pile,longitudinal spacing of piles and pile diameter.Comparative analysis is taken on the settlement of the station floor,the vertical displacement of the structure and the ground surface settlement.Finally,the length of the bench pile is selected from the bottom of the pile end to the bottom of the arch to the range of 5~7 m The distance between the piles is in the range of 1.6~2.2 m,and the pile diameter is 1 m,which makes the shield excavation has smaller influence on the existing adjacent buildings.