隧道拱部衬砌混凝土浇筑结束控制标准研究

Research on the Control Standard for the End of Concrete Pouring of Tunnel Arch Lining

研究目的:铁路具有"运量大、速度快、成本低"的显著特点,是我国重要的基础设施和大众化交通工具。铁路运输安全一直是人们关注的焦点,隧道作为铁路的重要组成部分,由于其"复杂性高、隐蔽性强",因此隧道的安全问题更为重要。据不完全统计分析,铁路隧道拱墙衬砌混凝土质量缺陷风险比例最高,约为61.7%,其中拱墙衬砌混凝土空洞风险比例最大,约为所有隧道运营风险的28.8%,因此,提升隧道衬砌混凝土质量是消除铁路隧道运营安全风险的关键。隧道衬砌混凝土质量缺陷产生的原因很多,影响因素十分复杂,其中衬砌混凝土浇筑结束控制标准是众多影响因素中最关键的一个,为提高隧道衬砌质量水平,需要研究隧道拱部衬砌混凝土浇筑结束控制标准。研究结论:(1)隧道拱部衬砌混凝土采取有压浇筑方式,可以提高衬砌混凝土的浇筑质量,避免衬砌混凝土背后出现空洞;(2)浇筑压力控制和防脱空预警控制都能实现衬砌混凝土的有压浇筑,现场可结合实际情况,至少选择一种方法作为隧道拱部衬砌混凝土浇筑结束标准,混凝土用量对比方法可作为选用方法使用;(3)结合目前我国铁路隧道衬砌设计,浇筑压力宜采用20 kPa浇筑终压作为控制标准;(4)防脱空预警控制标准为所有声光报警器处于预警状态,继续浇筑混凝土3~5 min,并结合混凝土用量、排气管出浆情况等综合判断混凝土是否浇筑饱满;(5)混凝土用量对比控制标准为实际浇筑混凝土量=理论浇筑混凝土量+1~3 m^(3);(6)本研究成果可在隧道衬砌施工中推广应用。

Research purposes:Railway is an important infrastructure and popular means of transportation in China,which is characterized by large volume,high speed and low cost.Railway transportation safety has always been the focus of people’s attention.As an important part of the railway,tunnel safety is more important because of its"high complexity and strong concealment".According to incomplete statistical analysis,the risk ratio of quality defects of arch wall lining concrete of railway tunnel is the highest,which is about 61.8%.Among them,the risk ratio of tunnel lining concrete cavity is the largest,accounting for 28.8%of all tunnel operation risks.Therefore,improving the quality of tunnel lining concrete is the key to eliminate the risk of railway tunnel operation safety.There are many reasons for the quality defects of tunnel lining concrete,and the influencing factors are very complex.Among them,the control standard for the end of lining concrete pouring is one of the most critical factors.In order to improve the quality level of tunnel lining,it is necessary to study the control standard for the end of concrete pouring of lining in tunnel arch.Research conclusions:(1)The tunnel arch lining concrete is cast with pressure,which can improve the quality of lining concrete and avoid the cavity behind the lining concrete.(2)Both the pouring pressure control and the anti void early-warning control can realize the pressure pouring of the lining concrete.At least one method can be selected as the end standard of lining concrete pouring according to the actual situation.The comparison method of concrete dosage can be used as the selection method.(3)Combined with the design of railway tunnel lining in China,the pouring pressure should be 20 kPa as the control standard.(4)The control standard of anti void early warning control is that all sound and light alarms are in the early warning state,continue to pour concrete for 3~5 min,and comprehensively judge whether the concrete is full by combining with the amount of concrete and the grouting situation of exhaust pipe.(5)The contrast control standard of concrete dosage is that the actual pouring concrete amount is equal to the theoretical pouring concrete amount increasing by 1~3 m^(3).(6)The research results can be widely used in tunnel lining construction.