湿喷混凝土的回弹机理试验研究
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摘要
为解决湿喷混凝土回弹率较高的问题,从混凝土中粗骨料的回弹机理角度出发研究降低湿喷混凝土回弹率的措施。通过石子贯入砂浆层试验模拟湿喷混凝土中粗骨料贯入混凝土的过程,研究石子贯入砂浆深度与石子的初速度、质量的关系,并在现场进行湿喷试验验证降低回弹率的效果。由石子贯入试验得到砂浆层的回弹阻尼平均值和初始喷砂浆层的厚度。研究发现,石子贯入砂浆深度与石子的初速度、质量均呈正相关,在岩面初喷适当厚度砂浆层再喷射混凝土的措施可以降低回弹率。因此提出,当石子较小时,可适当增加风压机风压,以得到较快喷射速度;当石子较大时,可适当降低风压机风压,以得到较慢喷射速度的措施来降低回弹率。研究结果表明,从回弹机理角度出发,先喷射砂浆再喷射混凝土的方法或调整喷射速度的措施能降低湿喷混凝土回弹率。
In response to the problem of high rebound rate of wet-sprayed concrete, the countermeasures were explored from the perspective of the rebound mechanism of coarse aggregate in concrete. Through the experiment of stone penetration into the mortar layer, the process of penetration of coarse aggregate into the concrete was simulated in wet-sprayed concrete, probing into the relationship between the penetration depth of the stone and the initial velocity, mass of the stone, and carrying out the wet-sprayed test on site to verify the rebound rate effect. The mean value of the rebound damping of the mortar layer and the thickness of the initial mortar layer were obtained from the stone penetration test. The study has indicated that the penetration depth of the stone into the mortar is positively correlated with the initial velocity and mass of the stone. It is found that the rebound rate can be reduced by initially spraying the appropriate thickness of the mortar layer and then spraying concrete. It is also proposed that the stone being small, the wind pressure of the wind press can be appropriately increased to obtain a faster injection speed, while the stone being large, the wind pressure of the wind press can be appropriately reduced to obtain a slower injection speed to reduce the rebound rate. The research results show that from the point of view of rebound mechanism, the method of spraying mortar and then spraying concrete or adjusting the spraying speed can reduce the rebound rate of wet-sprayed concrete.
In response to the problem of high rebound rate of wet-sprayed concrete, the countermeasures were explored from the perspective of the rebound mechanism of coarse aggregate in concrete. Through the experiment of stone penetration into the mortar layer, the process of penetration of coarse aggregate into the concrete was simulated in wet-sprayed concrete, probing into the relationship between the penetration depth of the stone and the initial velocity, mass of the stone, and carrying out the wet-sprayed test on site to verify the rebound rate effect. The mean value of the rebound damping of the mortar layer and the thickness of the initial mortar layer were obtained from the stone penetration test. The study has indicated that the penetration depth of the stone into the mortar is positively correlated with the initial velocity and mass of the stone. It is found that the rebound rate can be reduced by initially spraying the appropriate thickness of the mortar layer and then spraying concrete. It is also proposed that the stone being small, the wind pressure of the wind press can be appropriately increased to obtain a faster injection speed, while the stone being large, the wind pressure of the wind press can be appropriately reduced to obtain a slower injection speed to reduce the rebound rate. The research results show that from the point of view of rebound mechanism, the method of spraying mortar and then spraying concrete or adjusting the spraying speed can reduce the rebound rate of wet-sprayed concrete.
引文
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[16] 陈文耀,李文伟.湿喷混凝土速凝剂选择及配合比设计方法探讨[J].水利水电技术,2006,37(12):33.
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[2] 关宝树.隧道及地下工程喷混凝土支护技术[M].北京:人民交通出版社,2009.
[3] 杜扬柱.湿喷工艺在新安煤矿的应用技术实践[J].煤矿现代化,2014(4):21.
[4] 宁逢伟,丁建彤,白银,等.湿喷混凝土回弹率影响因素的研究进展[J].水利水电技术,2018,49(1):149.
[5] 陶坤.长深高速公路承德段长逢沟隧道初期支护湿喷混凝土施工关键技术研究[D].西安:长安大学,2014.
[6] 刘康.低回弹喷射混凝土技术研究[D].天津:河北工业大学,2015.
[7] 姜波.湿喷混凝土回弹率影响因素[J].辽宁工程技术大学学报(自然科学版),2016,35(3):270.
[8] BURNS D.Characterization of wet-mix shotcrete for small line pumping[D].Quebec:University of Laval,2008.
[9] ARMELIN H S.Rebound and toughening mechanisms in steel fiber reinforced dry-mix shotcrete[D].Vancouver:The University of British Columbia,1997.
[10] PARKER H W,FERNANDEZ-DELGADO G,LORIG L J.A practical new approach to shotcrete rebound losses[C]//Shotcrete for Ground Support.New York:American Society of Civil Engineers,1977:149.
[11] MELBYE T,DIMMOCK R,GARSHOL K F.Sprayed concrete for rock support[M].9th ed.Zurich:MBT International Underground Construction Group,Division of MBT,2001:183.
[12] 王飞.巷道支护混凝土潮式喷射喷头优化设计及实验研究[D].济南:山东科技大学,2017.
[13] 王斌.降低锚喷巷道喷射混凝土回弹率技术探究[J].山东工业技术,2015(20):37.
[14] 王璞东,李远,邵大明,等.湿法喷射混凝土回弹率控制技术[J].东北水利水电,2018,36(2):18.
[15] 李俊均.基于机械手施工的隧道湿喷混凝土质量主要影响因素研究[J].公路交通技术,2017,33(3):82.
[16] 陈文耀,李文伟.湿喷混凝土速凝剂选择及配合比设计方法探讨[J].水利水电技术,2006,37(12):33.
[17] 张雪刚.湿喷混凝土在市政硬岩隧道中的应用[J].建筑技术开发,2018,45(14):83.
[18] 国家质量监督检验检疫总局,国家标准化管理委员会.建设用砂GB/T 14684—2011[S].北京:中国标准出版社,2011.
[19] 中华人民共和国住房和建设部.砌筑砂浆配合比设计规程JGJT 98—2010[S].北京:中国建筑工业出版社,2010.