复杂地质或环境条件下盾构施工整体筹划中的问题分析

Problem Analysis for Overall Planning of Shield Tunnel Construction in Complex Geological and Environmental Conditions

以深圳市城市轨道交通7号线为例,阐述复杂地质或环境条件下盾构施工整体筹划中应重点考虑施工勘察加密到位、盾构机的新旧程度与区间条件的适应性、盾构掘进指标的合理选择、换刀方案的综合确定4个方面的问题,并依据工程实际数据对各问题进行了具体分析。分析结果表明:确定不良地质的范围后应通过钻机取芯确认,在场地条件允许时按勘探点间距5 m左右加密勘察,对不良地质段提前处理;宜选用新购盾构或掘进使用寿命50%以下的盾构;应按掘进指标比建设标准的平均进度降低约50%左右来考虑工期要求。

Taking the No.7 line of Shenzhen urban rail transit as an example,this paper proposed four problems for overall planning of shield tunnel construction which could be taken into consideration under complex geological or environmental conditions including the appropriate encrypting of construction investigation,the adaptability between the depreciated degree of shield machine and the interval geological condition,the reasonable selection of shield tunneling indexes,the comprehensive determination of cutter replacement scheme,and these problems were analyzed in detail according to the actual data of the project.Results indicate that the scope of poor geology should be conf irmed by drilling rig coring,encrypting investigation should be implemented according to the exploration point spacing of 5 m and the bad geological section should be treated ahead of time if site conditions permit,the new shield machine or shield machine with a service life less than 50%should be used,and the project time schedule should be considered based on the fact that the tunneling index is about 50%lower than the average progress of construction standard.