盾构始发端头垂直冷冻加固技术

Vertical Freezing Reinforcement Technology at the Starting End of Shield Tunneling

盾构始发和接收是地铁隧道建设的重要环节,复杂地质条件下盾构始发端加固能保障盾构顺利掘进。依托天津地铁8号线马场道站—人民公园站区间盾构始发端垂直冻结加固工程,基于弹性薄板理论求解冻结壁理论厚度。以此为基础,确定了冻结壁实际厚度,并通过有限元软件开展了强度验算。通过布置测温孔,分析了土体冻结过程中盐水温度和测温孔温度变化规律,并根据实测温度反算冻结壁厚度和冻结壁平均温度,进而评估本工程垂直冻结加固效果。研究表明:本工程所设计的3.0 m的冻结壁厚度和-10℃的冻土设计温度满足要求。采用垂直冻结加固方案效果良好,已达到破除洞门和盾构始发的指标要求。

The starting and receiving stages of shield tunneling are critical components of subway tunnel construction.Reinforcing the starting point under complex geological conditions ensures smooth excavation.This study focuses on the vertical freezing reinforcement at the shield tunneling starting point between Machangdao Station and Renmin Park Station on Tianjin Metro Line 8.The theoretical thickness of the frozen wall was calculated using elastic thin plate theory,which provided the basis for determining the actual frozen wall thickness.Strength verification was then performed using finite element software.Temperature measuring holes were arranged to analyze temperature changes in the saline water and surrounding soil during the freezing process.Based on the measured temperatures,the thickness and average temperature of the frozen wall were calculated,allowing for an evaluation of the vertical freezing reinforcement's effectiveness.The results demonstrate that the designed 3.0 m frozen wall thickness and-10℃frozen soil design temperature meet the required standards.The vertical freezing reinforcement scheme has successfully met the requirements for breaking through the tunnel portal and initiating shield tunneling.