隧道开挖跨度对隧道围岩分级的影响分析  

Influence analysis on different tunnel span conditions to rock grade classification

作　　者：付素蓉 高伟 王硕 梁秋花 左建平[2] Fu Surong;Gao Wei;Wang Shuo;Liang Qiuhua;Zuo Jianping(Shenzhen Integrated Geotechnical Investigation&Surveying Co.,Ltd.,Shenzhen 518029,China;China University of Mining and Technology(Beijing),Beijing 100083,China)

机构地区：[1]深圳市建设综合勘察设计院有限公司,广东深圳518029 [2]中国矿业大学(北京),北京100083

出　　处：《工程勘察》2025年第3期35-41,共7页Geotechnical Investigation & Surveying

摘　　要：工程实例表明,隧道跨度增加可能会导致围岩性质弱化,按照《公路隧道设计规范》(JTG D70-2004)中的[BQ]修正公式计算,会使隧道围岩的质量评价和分级可能与实际产生一定的误差。为了进一步准确分析隧道开挖时不同跨度尺寸对围岩分级所带来的影响,从工程实际的角度出发,运用非连续变形分析方法(DDA)开展相应数值分析,得到不同隧道洞室跨度影响下围岩弱化特征,并据此建立岩体完整性系数相同情况下不同岩石抗压强度的BQ指标修正模型,经过模拟、计算、统计,给出常见的五类围岩在不同尺寸跨度下的修正指标值(K4)。分析认为:当隧道跨度不超过10m时,跨度对围岩的等级划分几乎无影响;岩石的单轴抗压强度越大,则在更大的开挖跨度情况下才对围岩等级划分产生影响。以深圳某工程为例,验证了大跨度隧道工程围岩分级时考虑跨度修正系数是适宜的,对其它类似工程具有一定的参考意义。Practical engineering cases show that big tunnel span may lead to the weakness of surrounding rocks,so it may cause its grade deviation if the basic quality of rock(BQ)is calculated directly according to the revised formulation from the"Code for design of road tunnel"(JTG D70-2004).In order to further accurately analyze the influence of different span size on surrounding rock’s stability and grade during tunnel excavation,based on practical engineering,the corresponding numerical analysis is carried out by using DDA(Discontinuous Deformation Analysis)method.The weakness characteristics of tunnel surrounding rock under the influence of different tunnel spans are discussed.Based on the characteristics,the model for BQ index refinement under different tunnel spans with the same Kv(integrity coefficients of rock mass)but different Rc(uniaxial compressive strength of rock)is proposed.The parameter(K4)to further refine rock quality is proposed and approached by means of systematically testing and analyzing the 5 types of rocks with different grades.It is shown that the influences can be neglected on surrounding rock grade under small span size conditions(less than 10 meters).In case of larger excavation span sizes,the grading values of rocks with higher strengths start to be influenced and changed.Taking certain engineering case in Shenzhen as the example,it is proved that considering the span revise coefficient is appropriate for surrounding rock grading of tunnel engineering with big span,which can provide the reference for the similar engineering projects.

关 键 词：围岩等级 隧道跨度 数值分析 DDA BQ 

分 类 号：TU45[建筑科学—岩土工程]