初期支护设计方法优化及二次衬砌施作时机研究

发布时间：2018-04-15 09:10

本文选题：喷射混凝土 + 龄期　；参考：《石家庄铁道大学》2014年硕士论文

【摘要】：隧道施工所采用的喷射混凝土是一种龄期类材料。在喷射混凝土施作完成后，需要几天甚至是几十天的时间才能使其强度和弹性模量达到最终值。而目前大多数设计者在进行初期支护计算模拟时往往不考虑喷射混凝土这一硬化特性。本文使用FLAC3D软件通过对喷射混凝土支护参数进行循环赋值，实现了初期支护中喷射混凝土支护参数随龄期变化的模拟。通过数值模拟对初期支护中考虑喷射混凝土硬化特性和不考虑喷射混凝土硬化特性两种情况进行对比分析，得出两种情况对围岩的变形和塑性区的范围的影响无明显差别，而两种情况下初期支护的应力相差很大，在隧道初期支护设计时需要考虑喷射混凝土硬化特性。并以埋深为100m的V级围岩衬砌为例，通过对比分析，阐述了在初期支护的设计时考虑喷射混凝土硬化特性可以使得设计更加合理并且可以避免工程材料的浪费。对于二次衬砌而言，，合理确定二次衬砌施作时机是保证隧道工程施工阶段和长期运营阶段安全性的关键。本文使用ANSYS软件对IV、V级围岩条件下150m、200m、250m、300m埋深的隧道分别进行数值模拟计算，通过比较初期支护拱顶相对下沉速度恰满足铁路隧道施工规范时距离开挖掌子面的距离与拱脚水平相对净空变化速度恰满足规范规定时距离开挖掌子面的距离，得到初期支护拱脚水平相对净空变化速度先于拱顶相对下沉速度满足铁路隧道施工规范的要求。通过对二次衬砌安全性和抗裂性的检算，以及与二次衬砌极限变形值的比较，最终得到在不干扰前方隧道开挖支护施工的情况下，二次衬砌的合理施作时机。
[Abstract]:The shotcrete used in tunnel construction is a kind of age material.It takes a few days or even tens of days to reach the final value of the strength and elastic modulus of the sprayed concrete.At present, most designers do not consider the hardening characteristics of shotcrete in the initial support calculation simulation.In this paper, FLAC3D software is used to simulate the variation of shotcrete support parameters with the age of the initial support through the cyclic assignment of the parameters of the shotcrete support.Through numerical simulation, the effects of shotcrete hardening characteristics and not shotcrete hardening characteristics on the deformation of surrounding rock and the range of plastic zone of surrounding rock are analyzed and compared by numerical simulation, and the results show that there is no obvious difference between the two conditions on the deformation of surrounding rock and the range of plastic zone.However, the stress of initial support is very different between the two conditions, and the hardening characteristics of shotcrete should be considered in the design of initial support of tunnel.Taking the V-class surrounding rock lining with a depth of 100m as an example, through comparison and analysis, it is expounded that considering the hardening characteristics of shotcrete in the design of initial support can make the design more reasonable and avoid the waste of engineering materials.For secondary lining, it is the key to ensure the safety of tunnel construction stage and long-term operation stage.In this paper, ANSYS software is used to numerically simulate the tunnel with a buried depth of 250m ~ 300m under the condition of class V surrounding rock.By comparing the relative subsidence speed of the initial supporting arch roof with the distance between the excavation face and the relative clearance speed of the arch foot, the distance from the excavation face to the excavation face is exactly satisfied when the relative subsidence speed of the supporting arch roof meets the construction specifications of the railway tunnel.It is obtained that the relative clearance speed of the arch foot in the initial support is prior to the relative subsidence velocity of the arch roof to meet the requirements of the construction code of the railway tunnel.Through checking and calculating the safety and crack resistance of the secondary lining and comparing with the limit deformation value of the secondary lining, the reasonable timing of the secondary lining can be obtained without interfering with the excavation and supporting construction of the tunnel in front.
【学位授予单位】：石家庄铁道大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U455

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