基于分形理论的地铁荷载下采空区覆岩损伤特征  

Damage Characteristics of Overburden Rock in Goaf Under Subway Load Based on Fractal Theory

作　　者：田书广 TIAN Shuguang(China Railway 15th Bureau Group Co.Ltd.,Shanghai 200070,China)

机构地区：[1]中铁十五局集团有限公司,上海200070

出　　处：《铁道建筑》2024年第11期124-130,共7页Railway Engineering

摘　　要：以乌鲁木齐1号线穿越急倾斜煤层采空区为原型,借助物理相似试验引入分形理论开展荷载下采空区覆岩动态演化规律及其质量评价研究。结果表明:随着采场推进,覆岩最大应力增加且伴随升维现象;利用双重分形定量描述覆岩裂隙状态变化,荷载0.20~0.35 MPa时产生新裂隙,且原有裂隙会闭合;裂隙条数分形维数与地表最大下沉量及侧壁围岩最大离层量呈非线性相关,荷载0.20 MPa时均有较大跳跃,变化趋势一致;建立基于岩体完整性系数和岩体损伤程度的岩体质量评价方法,对采动和地铁荷载工况下覆岩岩体质量进行评价,发现RMR(Rock Mass Rating)值随分维数增大呈线性递减趋势,并量化表征了岩体力学参数和岩体质量的弱化程度。研究结果可为穿越采空区的路基稳定性评价提供科学依据。Urumqi Subway Line No.1 crossing the steeply inclined and extra-thick seam mined-out subsidence area was selected as an engineering background.The dynamic evolution and quality evaluation of the overburden rock with mining and loading was studied by similar simulation experiment and fractal theory.The results show that,fractal dimension and maximum stress of overburden rock increases with the increase of the mining.The fracture state of the overburden is quantitatively described with the load applied based on double fractal.The load is 0.20~0.35 MPa,new cracks are generated and the original cracks are closed.Fractal dimension is nonlinearly correlated with the maximum subsidence of the surface and the maximum amount of separation of sidewall surrounding rock.When the load is 0.20 MPa,these have a large change and the trend is consistent.In addition,a comprehensive evaluation method,considering the degree of rock damage and the rock integrity coefficient,was established based on the fractal damage.The quality of rock mass under mining and subway loading was respectively evaluated.The Rock Mass Rating decreases linearly with the increase of the fractal dimension.The weakening degree of rock mechanics parameters and rock mass quality are quantitatively characterized.The research results provide scientific basis for the stability evaluation of Subgrade.

关 键 词：地铁 损伤特征 模型试验 采空区覆岩 分形维数 岩体质量 

分 类 号：U451.2[建筑科学—桥梁与隧道工程]