福州软土地区土压平衡盾构隧道地表沉降特性分析

Analysis on the Characteristics of Ground Surface Settlement Caused by EPB Shield Tunnelling in Fuzhou Soft Ground

  • 摘要: 文章依托福州软土地区地铁2号线某土压平衡盾构区间隧道,对盾构施工地表沉降监测数据和掘进参数进行分析,总结了地表沉降的特点。结合沉降实测值,给出了地面沉降修正双曲线预测公式的参数。分析结果表明:无论是福州软土地区土压平衡盾构施工引起的地层损失沉降、固结沉降,还是考虑固结沉降的长期沉降均符合Peck公式;盾构掘进时可影响到刀盘前方3D~5D范围,产生少量隆起(沉降);地面沉降主要为盾尾脱离后3~5 d 内的地层损失沉降和扰动土体的固结沉降,测量期间分别约占总沉降的65%和32%,实际上固结沉降占比较之更大;修正后的双曲线模型可为福州软土地层类似土压平衡盾构隧道工程条件下隧道中心轴线地面沉降预测提供一定的借鉴,参数a,b和c取值范围分别为-0.14~-0.67 mm/d,-0.028~-0.042 mm-1和-0.89~7.67 mm。

     

    Abstract: Based on a EPB shield running tunnel of Fuzhou metro line 2 in soft ground, it summarized the charac? teristics of ground settlement by analyzing the monitoring data and driving parameters during shield construction,and proposed the parameters of modified hyperbolic model for predicting ground settlement with consideration of the measured settlements. The analysis results indicate that the settlements caused by ground loss and consolidation during EPB shield construction in soft ground as well as the long-term horizontal settlements in transverse direction conform to the results by Peck equation; the affected scope during shield driving is 3D-5D ahead of the cutterhead and it results in small amount of heaving(settlement); the ground settlements are mainly the ground loss induced settlement and consolidation settlement of disturbed soil mass within 3-5 d after passing shield tail, with the percentages of 65% and 32% of the total settlement respectively in the course of measuring, and actually the percentage of final consolidation settlement is larger; the modified hyperbolic model can be used to predict ground settlements at central axis caused by EPB shield driving in soft ground of Fuzhou, and the ranges of parameter values of a, b, c are -0.14~0.67 mm/d, -0.028~0.042 mm-1 and -0.89~7.67 mm respectively.

     

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