长沙典型地层土压平衡盾构掘进参数及表现预测

Excavation parameters and performance prediction of earth pressure balance shield in typical strata of Changsha

为对长沙典型地层土压平衡盾构的掘进表现进行预测,基于实际工程采集的砾岩、砂卵石和泥岩地层盾构施工记录数据,对主要施工参数在3类地层中的分布及变化特征进行统计分析。研究贯入度、场切入指数和掘进比能三者间的变化关系,并讨论地层可掘性问题。根据贯入度、场切入指数和掘进比能分类提出考虑地层条件的净掘进速率预测方法及经验模型,并用于4类地层的盾构掘进表现预测分析。研究结果表明:贯入度的最小和最大平均值分别出现在泥岩和砂卵石地层中;刀盘扭矩在砂卵石和泥岩地层中变化幅度较大,而在泥岩地层中平均值最大;砂卵石地层的总推进力比其他2类地层的总推进力高30%左右,3类地层的总推进力对刀盘扭矩影响特征有所差异;贯入度、场切入指数和掘进比能三者间相关性较好,可作为表征地层可掘性的指标。所提出的净掘进速率预测模型对4类地层盾构掘进表现的预测效果较好,具有一定的适用性。

In order to predict the excavation performance of earth pressure balance shield in typical strata of Changsha,the earth pressure balance shield excavation recorded data of conglomerate,sandy gravel and mudstone strata were collected based on the actual project.The distribution and variation characteristics of the main excavation parameters in three types of strata were statistically analyzed.The relationship among penetration,field penetration index and specific energy of excavation was studied,and the problem of stratum boreability was discussed.According to the classification of penetration,field penetration index and specific energy,the prediction method and empirical model of net penetration rate considering stratum conditions were put forward and applied in the prediction of tunneling performance of earth pressure balance in four strata.The results show that the minimum and the maximum mean values of penetration appear in mudstone and sandy gravel strata respectively.The torques of cutter head vary greatly in sandy gravel and mudstone strata,and the mean value of mudstone strata is the largest.Total thrust of sandy gravel formation is about 30%higher than that of other two types of strata,and the influence of total thrust on the torque is different due to the difference of the geological conditions.The correlation among penetration,field penetration index and specific energy is good,which can be used as an indicator to express the stratum boreability.The prediction model of net penetration rate proposed in this paper has good prediction effect on the performance of earth pressure balance shield tunneling in four types of strata,and has certain applicability.