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杭州地铁2号线某盾构区间土质主要为砂质粉土,盾构施工过程中出现了地面日沉降速率连续报警和地面沉降量过大问题。对地面沉降实测数据进行了统计分析与理论研究。结果表明:由于该地区以砂质粉土为主,渗透系数较大,导致固结沉降在盾尾通过后1周内完成;地面沉降在盾尾通过后迅速稳定,变化时间非常短(总共3～4d);由于工后固结沉降完成时间很短,一旦施工沉降较大,就容易造成日沉降速率和地面沉降量超标;引起的固结沉降量总体较小,平均值为9.7mm,但最大地面沉降值的分布范围很广,表明盾构施工水平对地面沉降的影响非常大。
The soil quality of a certain shield in Hangzhou Metro Line 2 is mainly sandy silt. During the construction of the shield, continuous alarm of ground settlement rate and excessive ground subsidence occurred. The data of ground subsidence were statistically analyzed and studied theoretically. The results show that, due to the sandy silt mainly in this area, the permeability coefficient is relatively large, resulting in the consolidation settlement being completed within 1 week after the shield tail passage. The land subsidence quickly stabilized after passing through the shield tail, and the change time was very short ~ 4d). Due to the short time after the post-construction consolidation settlement, once the construction settlement is large, the daily sedimentation rate and land subsidence will easily exceed the standard. The consolidation settlement caused by the settlement is generally small with an average value of 9.7mm The distribution of the maximum land subsidence is very wide, indicating that the impact of the shield construction level on land subsidence is very large.