扬州瘦西湖隧道全黏土地层泥水盾构施工开挖面稳定性研究

扬州瘦西湖隧道地处全黏土地层,在该类地层中使用泥水盾构施工的案例较少,全黏土地层在盾构施工下的土体力学性质与变形规律尚未得到充分研究。为了解决全黏土地层在盾构施工下开挖面稳定性与各项盾构参数之间的关系问题,采用室内试验与计算模拟相结合的方法对瘦西湖隧道泥水盾构施工停机状态下的开挖面稳定性进行研究分析。研究结果表明:1)盾构停机时,随着停机时间的增长,泥水不断浸入开挖面前方土体,开挖面附近土体应力表现出一定的拱效应,导致开挖面稳定性不断降低;2)在泥水浸润时间相同的条件下,随膨胀土膨胀力取值的增高,开挖面极限支护压力呈现增长趋势;3)根据开挖面失稳原因,提出了开挖面稳定性控制措施,并通过模型计算进行验证。

Study on Stability of Full Clay Excavation Face in Boring of Slurry Shield

Slender West Lake Tunnel in Yangzhou of China is located in full clay strata. However, so far there are few cases of slurry shield boring in full clay strata. Therefore, the mechanical properties and deformation law of full clay strata during shield boring need further study. In order to obtain the relationship between the excavation face stability and the various parameters during shield boring in clay strata, the author studies the stability of the excavation face of Slender West Lake Tunnel by means of laboratory tests and simulations. The results showed that: 1) When the shield boring is suspended, the slurry infiltrates into the soil mass in front of the excavation face constantly, the soil stress near the excavation face has certain arching effect, which leads to the continuous reduction of the stability of the excavation face; 2) Under the same slurry infiltration time, the ultimate support pressure for the excavation face has an increase tendency as the expansion force of the expansive soil increases; 3) Measures to stabilize the excavation face are proposed according to the causes for the excavation face failure and are also verified by model calculations. 