盾构隧道内机械法修建废水泵房技术研究

为解决采用传统矿山法修建废水泵房存在工期长、风险大等问题以及在机械法联络通道内修建废水泵房作业空间狭小、二次拆除管片风险大等问题，提出采用机械法在盾构隧道内修建废水泵房，明确上部接口和下部封底2项关键技术，并通过数值模拟分析地层水压力对封底混凝土力学性能的影响，最后将该修建技术应用到北京地铁17号线望—勇区间隧道中。研究结果表明： 1）考虑安全系数不小于1.4的情况下，1.0 m厚C30混凝土封底水压可用于不超过0.3 MPa水压的地层条件； 2）封底混凝土与外盾相连接的角部为薄弱部位，其破坏模式呈异形“八”字分布； 3）盾构隧道内采用机械法修建废水泵房能有效保障施工质量，泵房容积大，可有效减少潜水泵的启停次数，降低维修时间和成本，减少对线路运营的影响。

Mechanized Construction of Wastewater Pump Room in Shield Tunnel

The wastewater pump room constructed by conventional mining method has disadvantages of long construction period and high risk, and the wastewater pump room in connection gallery constructed by mechanized method is limited by small operation space and high risk of secondary segment dismantling. Accordingly, mechanized construction method is proposed for wastewater pump room in shield tunnel, and two essential techniques of upper joint and bottom sealing are clarified. Then, numerical simulation method is conducted to analyze the influence of ground water pressure on mechanical properties of sealing concrete. The results of the techniques have been applied in wastewater pumping station in a shield tunnel of Wangjingxi station Yongshiying station tunnel section of Beijing metro line 17. The resalts show that: (1) Under the condition that the safety factor larger than 1.4, the bottom sealing water pressure of 1.0 m thick C30 sealing concrete can be used for the formation condition that does not exceed 0.3 MPa water pressure. (2) The corner of the connection between the bottom sealing concrete and the outer shield is weak, and its failure mode shows a gable slope shape distribution. (3) The mechanized construction of wastewater pump room with large volume in shield tunnel can effectively control the construction quality, reduce the stop time of submerged pump, the maintaining time and cost, and influence on line operation.