摘要
隧道设计理论认为较完整的岩体可以发挥岩体的自支撑能力,而对于松散体,普遍认为其完全没有自承能力,不可利用,只能当作重力荷载作用在结构上。为探究松散体的自承能力,进行原型堆载试验,结果表明:随着堆载体高度的变化,监测得到的支护结构拱顶压力值小于松散荷载理论计算值,进一步结合数值模拟方法,也发现拱顶压力值小于理论值。通过分析松动压力产生的原因,并采用数值模拟分别对裸洞模型、劣化围岩+支护模型、散体+支护模型进行研究,得到拱顶压力沿竖直方向的变化规律,主要结论如下:(1)松散体重力并不完全作用于支护结构上,而是松散体与支护结构分担;(2)松散体在支护结构的支撑与组织作用下,其内部也可形成承载拱,岩体的重力荷载通过承载拱传递,使得围岩主应力方向发生偏转,竖向应力逐渐转化为沿拱轴线上的切向应力;(3)原型堆载试验表明,堆载高度为10 m时仅71%的自重荷载作用于支护结构,说明承载拱分担了上方岩体的部分重力,分担比例由围岩和支护的刚度决定,呈形变压力特征。因此,松散体也存在与支护的相互作用,考虑其承载能力可使设计更加经济。
Tunnel design theory holds that relatively intact rock masses can exert their self-supporting ability,while loose materials are conventionally considered to possess no self-supporting ability at all and cannot be utilized,only serving as gravitational loads acting on structures.To explore the self-supporting ability of loose materials,prototype surcharge loading tests were conducted.The results showed that with the variation in surcharge height,the measured arch pressure of the support structure was lower than the theoretical calculated value of the loose material load.Combined with numerical simulation methods,it was found that the arch pressure value was less than the theoretical value.By analyzing the causes of loose pressure,and using numerical simulation to study the unsupported tunnel model,deteriorated surrounding rock+support model,and loose material+support model,the distribution pattern of the arch pressure along the vertical direction was obtained.The main conclusions are as follows:(1)The gravity of the loose materials does not completely act on the support structure,but is shared between the loose materials and the support structure.(2)Under the supporting and structuring effects of the support structure,the loose materials can form a loadbearing arch internally,and the gravitational loads of the rock masses are transmitted through the load-bearing arch.This causes the principal stress direction of the surrounding rock to deviate,and the vertical stress is gradually converted into tangential stress along the arch axis.(3)The prototype surcharge loading test shows that when the surcharge height is 10 m,only 71%of the self-weight load acts on the support structure,indicating that the load-bearing arch shares part of the gravity of the overlying rock masses,and the sharing proportion is determined by the stiffness of the surrounding rock and the support,showing deformation-pressure characteristics.Therefore,loose materials have interaction with the support,and considering their load-bearing capacity can make the design more economical.
作者
罗元成
谌勇
仇文革
陈吉辉
段东亚
罗杰
LUO Yuancheng;SHEN Yong;QIU Wenge;CHEN Jihui;DUAN Dongya;LUO Jie(Guizhou Road and Bridge Group Co.,Ltd.,Guiyang 550001,China;Chengdu Tianyou Tunnelkey Co.,Ltd.,Chengdu 610031,China;Key Laboratory of Transportation Tunnel Engineering,Ministry of Education,Southwest Jiaotong University,Chengdu 610031,China)
出处
《铁道标准设计》
北大核心
2025年第7期120-129,共10页
Railway Standard Design
基金
贵州省交通运输厅科技项目(2022-122-025)。
关键词
隧道工程
支护
堆载
拱顶压力
松散荷载
承载拱效应
形变压力
tunnel engineering
support
surcharge load
arch pressure
loose load
bearing arch effect
deformation pressure
