覆跨比对地铁隧道洞室围岩稳定性影响分析  

Analysis of the Influence of Coverage Span Ratio on the Stability of Surrounding Rock in Subway Tunnel Chambers

作　　者：朱朋刚 ZHU Penggang(China Railway 20th Bureau Group 3rd Engineering Co.Ltd.,Chongqing 400065,China)

机构地区：[1]中铁二十局集团第三工程有限公司,重庆400065

出　　处：《铁道建筑技术》2024年第2期36-40,共5页Railway Construction Technology

基　　金：重庆市科技厅科技研发项目(cstc2020 kqjscx-phxm0183)。

摘　　要：由于受地形条件限制和使用功能需要,地下工程埋深和跨度往往存在较大变化,研究覆跨比对洞室围岩稳定性影响意义重大。本文结合太沙基围岩压力理论推导表征围岩压力随覆跨比变化规律的理论公式,并采用基于网格自适应划分技术的有限元模拟方法,从地表极限承载力、位移响应、应力响应及围岩塑性区等方面,对不同覆跨比矩形洞室围岩稳定性进行系统研究。结果表明:在Ⅳ级围岩条件下,矩形洞室围岩压力随覆跨比增大而增大,当覆跨比H/D=2之后,围岩压力开始逐渐趋于稳定;当覆跨比H/D<2时,矩形洞室在极限状态下易发生贯穿至地表的垮塌破坏;当覆跨比H/D>2时,洞室拱顶上方出现压力拱效应。故覆跨比H/D=2可作为Ⅳ级围岩条件下深浅埋洞室分界线参考值。Due to the limitation of topographic conditions and the need of function,the buried depth and span of underground engineering often vary greatly,so it is of great significance to study the influence of the ratio of cover to span on the stability of surrounding rock of tunnel.This paper deduced a formula of surrounding rock pressure by combining with Terzaghi theory and used the finite element simulation method based on mesh adaptive partition technology to systematically study the stability of surrounding rock of rectangular caverns with different coverage span ratio from the aspects of surface ultimate bearing capacity,displacement response,stress response and surrounding rock plastic zone.The results show that:under the condition of gradeⅣsurrounding rock,the surrounding rock pressure of rectangular cavern increases with the increase of span ratio,when the coverage span ratio H/D reaches 2,the surrounding rock pressure gradually tends to be stable.When the coverage span ratio H/D is less than 2,the collapse failure of the rectangular cavern is easy to occur to the ground surface in the limit state.When the coverage span ratio H/D is greater than 2,the pressure arch effect appears above the cavern vault.Therefore,the ratio between depth and span equaling to 2 can be used as a reference standard to divide the depth of deep and shallow buried caverns under gradeⅣsurrounding rock conditions.

关 键 词：地下洞室 覆跨比 有限元 太沙基理论 压力拱效应 

分 类 号：U451.2[建筑科学—桥梁与隧道工程]