考虑颗粒组成与含水率的冰碛体成拱规律研究

Study on Arching Effect of Moraine Considering Grain Composition and Moisture Content

为分析隧道穿越冰碛体地层时冰碛体的成拱效应,对各地区冰碛体特性进行调研,并基于普氏理论推导冰碛体围岩平衡应力拱轴线的方程。然后通过研发的拱效应套筒试验装置测量冰碛体在不同颗粒级配与含水率下的成拱高度,分析其对成拱特性的影响。研究结果表明:(1)冰碛体围岩平衡应力拱轴线的方程为二次函数;(2)塌落物质量、成拱高度与粒径大小大致呈反比关系,散粒体自由下落时,锥形是摩擦剪胀自稳的终极形态;(3)颗粒级配的不均匀性越大、粒径越小,成拱高度越高、越不稳定;(4)不同级配下,高跨比随相对粒径的增大而减小,但随着小于2 mm的细颗粒含量增加,高跨比反而减小;(5)含水率在一定范围内时,随着含水率的增加,高跨比逐渐减小,且减小的速率越来越小。

To analyze the arching effect of moraines when tunnels pass through moraine layers,this study investigated the characteristics of moraines in various regions and derived the equation for the equilibrium stress arch axis of the moraine surrounding rock based on the Protodyakonor′s theory.Then,using a developed arching effect sleeve test apparatus,the arching height of the moraine was measured under different particle gradations and moisture contents to analyze their influence on arching characteristics.The study results indicate:(1)The equation for the equilibrium stress arch axis of the moraine surrounding rock is a quadratic function;(2)The mass of debris and the arching height are inversely proportional to particle size.During the free fall of granular material,the ultimate shape of frictional dilatancy self-stabilization is conical;(3)The greater the non-uniformity of the particle gradation and the smaller the particle size,the higher and less stable the arching height;(4)Under different gradations,the heightspan ratio decreases with the increase of relative particle size,but decreases with the increase in fine particles smaller than 2 mm;(5)Within a certain range,as moisture content increases,the height-span ratio gradually decreases,and the rate of decrease becomes smaller.