共查询到19条相似文献,搜索用时 62 毫秒
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针对某金矿破碎、易风化的围岩支护难度大等特点,采用湿喷混凝土技术实施机械化施工。研究了水泥掺量、纤维掺量、水灰比及砂率对湿喷混凝土可泵性及强度的影响。并通过正交试验方法,讨论了掺合料对湿喷混凝土坍落度、扩展度、抗压与抗折强度的影响规律。结果表明:增加水灰比能显著提高湿喷混凝土的坍落度,纤维用量增大对强度变化不明显但其对扩展度影响较大;砂率增大虽然能够增大混凝土的流动性但是强度呈下降趋势;通过极差分析结果得出了影响混凝土强度的显著因素及最优配合比,该配合比成功应用于实际工程。 相似文献
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湿喷是喷射混凝土发展的必然趋势 ,是解决粉尘和回弹、提高混凝土品质的根本措施。中铁一局机械工业有限公司研制的HBP - 0 1型泵式湿喷机(见图 1) ,可广泛用于铁路、公路、水利、煤炭工程施工中隧道、地下工程、护坡等 ,作为临时和永久支护的理想机具。图 11 喷射混凝土的 相似文献
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就湿喷钢纤维混凝土的施工方法,从适用范围、原材料及机具设备、准备工作、湿喷机的操作、喷射钢纤维的施工过程、施工中的注意事项等方面进行了论述。证明了采用湿喷钢纤维混凝土方法施工,不仅解决了关键性技术问题,而且提高了混凝土的抗裂能力,改善了延展性,使之被广泛地应用于地下工程中。 相似文献
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以乌鞘岭特长隧道为例,从施工准备、喷射作业等方面阐述了湿喷混凝土的施工工艺,并提出了一些施工注意事项,对其效果进行了分析。 相似文献
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结合具体的工程实践,阐述了钢纤维湿喷混凝土的性能,从材料选用、配合比设计、施工技术等多个方面,介绍了钢纤维湿喷混凝土在隧道施工中的应用。 相似文献
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文中研究了花岗岩石粉的掺加比例对C35、C40、C45新拌混凝土坍落度的影响。试验结果表明:花岗岩石粉掺加比例不超过10%时,C35、C40、C45新拌混凝土的坍落度及坍落度损失满足要求,流动性、粘聚性、保水性均有明显改善,经工程应用效果良好。 相似文献
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通过利用新拌混凝土综合性能测试仪(FCT101)检测出新拌混凝土塌落度、水灰比、温度并预测其28d强度,与实际数据对比,拟合出相关函数关系式,以期用于实际工程中混凝土强度的早期评定。 相似文献
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选择低碱性速凝、早强物质,采用外加剂复配的方法,通过对水泥凝结时问,强度检验的手段。进行了正交试验,确定了一种喷射混凝土用低碱性速凝外加剂的配方。通过试验结果可以得出,Al2(SO4)3掺量在2%~4%之间时,随着掺量增大,初凝时间和终凝时间变短,掺量为4%时,初凝为14分,终凝25分;K2SO4掺量在2%~4%之间可以缩短水泥凝结时间,掺量为4%时,初凝为12分,终凝23分,当其掺量超过4%时,后期强度会下降;NaF的速凝效果十分显著,当掺量只有0.2%时就可以使水泥的初凝时间控制在5分钟,终凝控制在10分钟。与传统的高碱性外加剂不同,低碱性速凝剂可显著提高喷射混凝土早期强度,1天强度可达9.6MPa,而且后期强度发展良好,28天强度达到45.5MPa。 相似文献
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Anders Ansell 《Tunnelling and Underground Space Technology incorporating Trenchless Technology Research》2004,19(6):587-596
A criterion for how close, in time and distance, to young shotcrete blasting can take place will be an important tool in planning for safe and economical tunnelling projects. As a first step, in situ tests with young, plain un-reinforced shotcrete have been conducted in a Swedish mine. Shotcrete panels were projected on tunnel walls and exposed to vibrations from explosive charges detonated inside the rock at shotcrete ages between 1 and 25 h. The shotcrete was tested to investigate growth of compressive strength and also to determine final compressive and adhesive strengths. The response of the rock was measured with accelerometers, giving signals that were later numerically integrated to particle vibration velocities. An average scaling relation of distance between explosive charges and the point of observation and weight of explosives was also derived. The recorded vibration levels showed that the shotcrete had withstood high particle velocity vibrations without being seriously damaged, even when the rock material was fragmented and ejected. Drumminess of shotcrete appeared, indicating that the major failure mechanism was sudden loss of adhesion at the shotcrete–rock interface. No differences in performance between shotcrete of different ages were observed. It was, thus, confirmed that young shotcrete without reinforcement can also survive high vibration levels without being seriously damaged. 相似文献
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This study investigates early age bond strength of shotcrete (sprayed concrete), in the case of shotcrete sprayed on hard rock. Shotcrete differs from ordinary, cast concrete through the application technique and the addition of set accelerators which give immediate stiffening. The bond between shotcrete and rock is one of the most important properties. During the very first time after spraying the physical properties and the bond to the rock depend on the set accelerator and the micro structure that is formed. In this work a laboratory test method for measuring early bond strength for very young or early age shotcrete is presented. The newly developed method was tested and evaluated and proved that it can be used for bond strength testing already from a couple of hours after shotcreting. 相似文献
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喷射混凝土的抗渗性能与喷射混凝土的使用年限、承受水压力、喷射混凝土的龄期等因素密切相关。以喷射混凝土的渗水高度作为其抗渗性能的评价指标,通过室内试验研究了基于复合胶凝材的喷射混凝土渗水高度与加压时间、承受水压力、混凝土龄期的相关关系;并进一步研究了喷射混凝土回弹率、吸水率等,以及这些指标与抗渗性能的相关性。通过研究得到,掺加复合胶凝材对提高喷射混凝土的抗渗性能有显著作用;加压时间和水压力量值对渗水高度的影响很大,加压时间与渗水高度呈正比关系,水压力大小与渗水高度成近似正比关系;随着龄期的增加,渗水高度逐步减小,28 d龄期后渗水高度趋于稳定;单掺复合胶凝材的喷射混凝土吸水率低于掺加复合胶凝材和聚丙烯纤维的喷射混凝土,抗渗性更好一些;但是加入聚丙烯纤维后,与只掺加复合胶凝材的混凝土比较,其回弹率大大降低。 相似文献