EFPI的地层关联性与复杂地层盾构掘进参数的演化规律分析

Stratigraphic Correlation of EFPI and Evolution Regularity of Shield Tunneling Parameter In Complex Stratum

盾构掘进参数的演化规律是复杂地层盾构施工中地层感知和大数据分析研究的基础,福州地铁某区间沿线穿越淤泥质土、黏土、碎卵石、强风化和中风化硬岩等16种地层,针对该工程地层复杂的特点,提出考虑土舱压力影响的有效比推力指标EFPI用于表征地层条件的变化,并对依托工程盾构掘进参数的演化规律进行分析,得到如下结果:1)复杂地层中,EFPI在评估盾构切削围岩的难易程度,区分土层和强风化硬岩上的效果方面优于目前常用的FPI指标。2)EFPI与地层标贯击数呈线性正相关,土—风化岩交互的复杂地层施工中可采用Log(EFPI)=2.3作为划分土层和强风化硬岩地层的判断依据。3)Log(EFPI)和Log(TPI)正相关,Log(EFPI)和掘进速度v反相关,且土层中特征点的离散性很大;而强风化硬岩、强—中风化硬岩过渡段的特征点离散性较小,拟合得到强风化硬岩和强—中风化硬岩过渡段Log(EFPI)和Log(TPI)、Log(EFPI)和v的函数关系。4)Log(EFPI)≤2.3时,建议掘进速度控制以保持土舱压力稳定为主;Log(EFPI)>2.3时,建议根据EFPI数值采用合理的掘进速度以提高掘进效率。

The regularity of tunneling data is the foundation of stratigraphic perception and big data analysis during shield tunneling in composite strata.A section of Fuzhou metro passes through 16 kinds of strata such as muddy soil,clay,broken pebble,strongly weathered,and moderately weathered hard rocks.According to the characteristic of complex strata for the metro section,the effective field penetration index(EFPI)which considers the effect of chamber earth pressure is proposed,and the regularity of tunneling parameter is analyzed.The results show the following.(1)The EFPI works better than the field penetration index(FPI)in evaluating the difficulty of surrounding rock cutting by TBM and distinction of soil and strongly weathered hard rock.(2)EFPI is proportionally and linearly correlation to the strata standard penetration number,and when tunneling in the soil-weathered rock strata,Log(EFPI)=2.3 can be used as the dividing standard of soil and strong weathered rock.(3)Log(EFPI)is positively correlated to Log(TPI),while Log(EFPI)is negatively correlated to the propulsion speed v.The characteristic points in soil layer are with great discreteness,while the characteristic points in the transitional section of strong to moderately weathered hard rock are with small discreteness.Function relationship among Log(EFPI),Log(TPI),Log(EFPI)and v in the transitional section of strong to moderately weathered hard rock is obtained by fitting.(4)If Log(EFPI)≤2.3,the excavation control should be focused on keeping the stability of earth pressure;if Log(EFPI)>2.3,the tunneling speed should be adjusted according to the value of EFPI to improve tunneling efficiency.