高含氣量濕噴混凝土性能與組成設計方法研究
發(fā)布時間：2018-10-30 19:02
【摘要】：濕噴混凝土因具有改善施工作業(yè)環(huán)境、便于混凝土集中生產(chǎn)及質(zhì)量控制、有利于發(fā)展成高性能噴射混凝土等優(yōu)越性而備受關注，但其可壓送性與可噴性難以協(xié)調(diào)、組成設計無章可循，可壓送性差、一次噴射厚度小、回彈率高、液體速凝劑摻量大等缺陷極大限制了它在當今基礎設施建設中的廣泛應用。本文就普通濕噴混凝土與高含氣量濕噴混凝土的工作性及硬化特性、組成設計方法進行了系統(tǒng)研究，主要做了下列工作： （1）優(yōu)化了新拌濕噴混凝土一次噴射厚度、回彈率等性能測評方法，提出了用椎體貫入新拌混凝土深度表征濕噴混凝土稠度、用直剪法測試新拌濕噴混凝土內(nèi)聚力的新方法。 （2）將入濕噴機坍落度≮50mm且相對壓力泌水率S10≯40%作為普通濕噴混凝土可壓送性的評價指標，研究了組成材料對普通濕噴混凝土可壓送性的影響。結(jié)果表明，新拌濕噴混凝土的壓力泌水率比易于滿足要求，影響新拌濕噴混凝土可壓送性的主要因素為流動性。 （3）提出了高含氣量濕噴混凝土引氣劑類型優(yōu)選方法，揭示了組成材料對高含氣量濕噴混凝土工作性的影響規(guī)律。結(jié)果表明，摻量為0.02%AES引氣劑與摻量為0.5%聚羧酸減水劑復合配制的新拌混凝土含氣量達18%左右，流動性大、穩(wěn)定性好，噴射后新拌濕噴混凝土含氣量降至6%以下，不摻速凝劑的一次噴射厚度達170mm以上，解決了濕噴混凝土可壓送性與可噴性難以統(tǒng)一的矛盾。 （4）利用直剪法試驗，借助XRD圖譜，采用正交設計方法分析了組成材料對新拌混凝土內(nèi)聚力的影響規(guī)律，得出了影響新拌混凝土內(nèi)聚力的主次因素及排序結(jié)果。根據(jù)材料力學橫力彎曲理論，建立了一次噴射厚度力學模型，分析了一次噴射厚度的受力特點，確立了一次噴射厚度與濕噴混凝土內(nèi)聚力的關系，驗證了力學模型的有效性。 （5）剖析了混凝土稠度、工作風壓、噴射厚度、組成材料對回彈率的影響規(guī)律，基于Armelin建立的干噴混凝土的回彈判定準則，探析了濕噴混凝土的回彈機理。結(jié)果表明：工作風壓存在理想值；回彈率隨混凝土流動性降低有增大趨勢，隨噴射厚度增大逐漸降低，達50mm時，趨于穩(wěn)定；高含氣量濕噴混凝土較普通濕噴混凝土回彈率降低約5%左右，摻入粉煤灰可改善濕噴混凝土的可噴性。 （6）對比了高含氣量濕噴混凝土與普通濕噴混凝土噴射后的抗壓強度及抗凍性能，研究了濕噴混凝土水化物的SEM形貌與強度生長機理，分析了組成材料對強度與抗凍性的影響。結(jié)果表明，高含氣量濕噴混凝土噴射后28d抗壓強度達34.4MPa，，滿足設計強度C25要求，抗凍等級滿足F300技術要求。 （7）利用計算法、簡易試驗法綜合確定混合骨料緊裝堆積空隙體積，基于Dennis等建立的管徑與潤滑層厚度關系計算潤滑層體積，由混合骨料緊裝堆積空隙體積和潤滑層體積確定最小膠漿體積，提出了高含氣量濕噴混凝土組成設計方法，并在隧洞的斜井與仰坡工程中進行了應用，對1m3濕噴混凝土的經(jīng)濟成本對比分析表明，高含氣量濕噴混凝土具有明顯的價格優(yōu)勢。
[Abstract]:As the wet shotcrete has the advantages of improving the construction work environment, facilitating the production and quality control of the concrete, and being beneficial to the development of the advantages of high-performance sprayed concrete and the like, the wet shotcrete has the advantages of difficult coordination of pressure delivery and sprayability, no rule-based design, poor pressure delivery, The defects of small injection thickness, high rebound rate and large amount of liquid accelerator have greatly restricted its wide application in infrastructure construction today. In this paper, the working properties and hardening characteristics of ordinary wet shotcrete and high gas content wet shotcrete are studied systematically, and the following work is done mainly: (1) Optimizing the performance evaluation of one-time injection thickness and rebound rate of new wet shotcrete In this paper, the consistency of wet shotcrete is characterized by the penetration of the vertebral body into the new mixed concrete, and the new method is used to test the new wet shotcrete. Methods: (2) The wet spraying machine was used as the evaluation index for the pressure delivery of the ordinary wet shotcrete, and the relative pressure and the water yield of S10 to 40% were used as the evaluation index for the pressure delivery of the common wet shotcrete. The results show that the pressure and water ratio of the new wet sprayed concrete is higher than that of the new wet shotcrete. The preferred method for the type of air entraining agent with high gas content wet shotcrete is put forward, and the wet shotcrete with high content of air is revealed. The results show that the content of the new mixed concrete is about 18%, the fluidity is large, the stability is good, the air content of the newly mixed wet shotcrete after injection is reduced to below 6%, and the thickness of the non-mixing accelerator is less than 6%. Up to 170mm, the pressure delivery and sprayability of wet shotcrete are solved. It is difficult to unify the contradiction. (4) By means of the direct shear test, by means of the XRD pattern, the influence law of the composition material on the new mixed concrete is analyzed by means of the orthogonal design method, and the influence on the cohesion of the new mixed concrete is obtained. Based on the theory of transverse force bending of material mechanics, a mechanical model of injection thickness is established, the stress characteristics of primary injection thickness are analyzed, and the relationship between primary injection thickness and wet shotcrete is established. The effectiveness of mechanics model was validated. (5) The effect of concrete consistency, working air pressure, spray thickness, composition material on rebound rate was analyzed, and the criterion of rebound determination of dry-sprayed concrete based on Armelin was analyzed. In this paper, the springback mechanism of wet shotcrete is discussed. The results show that the ideal value exists in the working air pressure, the rebound rate decreases with the decrease of the fluidity of the concrete, decreases with the increase of the injection thickness, and tends to be stable when it reaches 50mm. The high gas content wet shotcrete is more common. The rebound rate of shotcrete is reduced by about 5%, and the mixed powder Coal ash can improve the sprayability of wet shotcrete. (6) Compared with the compressive strength and frost resistance of wet shotcrete and ordinary wet shotcrete, the SEM morphology and strength growth mechanism of wet shotcrete are studied. The effect of composition materials on strength and frost resistance was analyzed. The results showed that the compressive strength of 28d after injection of wet shotcrete with high content of air was 34.4MPa, and the design strength was satisfied. According to the requirements of F300 technical requirements, the frost resistance level meets the technical requirements of F300. (7) By means of the calculation method, the simple test method comprehensively determines the void volume of the mixed aggregate, calculates the volume of the lubricating layer based on the relationship between the pipe diameter established by Dennis and the like and the thickness relation of the lubricating layer, and is tightly packed by the mixed aggregate. The volume of void volume and the volume of lubricating layer are determined, and the design method of high gas content wet shotcrete is put forward, and the economic cost contrast analysis table of 1m3 wet shotcrete is applied in inclined shaft and inverted slope engineering of tunnel.
【學位授予單位】：長安大學
【學位級別】：博士
【學位授予年份】：2014
【分類號】：U414
[Abstract]:As the wet shotcrete has the advantages of improving the construction work environment, facilitating the production and quality control of the concrete, and being beneficial to the development of the advantages of high-performance sprayed concrete and the like, the wet shotcrete has the advantages of difficult coordination of pressure delivery and sprayability, no rule-based design, poor pressure delivery, The defects of small injection thickness, high rebound rate and large amount of liquid accelerator have greatly restricted its wide application in infrastructure construction today. In this paper, the working properties and hardening characteristics of ordinary wet shotcrete and high gas content wet shotcrete are studied systematically, and the following work is done mainly: (1) Optimizing the performance evaluation of one-time injection thickness and rebound rate of new wet shotcrete In this paper, the consistency of wet shotcrete is characterized by the penetration of the vertebral body into the new mixed concrete, and the new method is used to test the new wet shotcrete. Methods: (2) The wet spraying machine was used as the evaluation index for the pressure delivery of the ordinary wet shotcrete, and the relative pressure and the water yield of S10 to 40% were used as the evaluation index for the pressure delivery of the common wet shotcrete. The results show that the pressure and water ratio of the new wet sprayed concrete is higher than that of the new wet shotcrete. The preferred method for the type of air entraining agent with high gas content wet shotcrete is put forward, and the wet shotcrete with high content of air is revealed. The results show that the content of the new mixed concrete is about 18%, the fluidity is large, the stability is good, the air content of the newly mixed wet shotcrete after injection is reduced to below 6%, and the thickness of the non-mixing accelerator is less than 6%. Up to 170mm, the pressure delivery and sprayability of wet shotcrete are solved. It is difficult to unify the contradiction. (4) By means of the direct shear test, by means of the XRD pattern, the influence law of the composition material on the new mixed concrete is analyzed by means of the orthogonal design method, and the influence on the cohesion of the new mixed concrete is obtained. Based on the theory of transverse force bending of material mechanics, a mechanical model of injection thickness is established, the stress characteristics of primary injection thickness are analyzed, and the relationship between primary injection thickness and wet shotcrete is established. The effectiveness of mechanics model was validated. (5) The effect of concrete consistency, working air pressure, spray thickness, composition material on rebound rate was analyzed, and the criterion of rebound determination of dry-sprayed concrete based on Armelin was analyzed. In this paper, the springback mechanism of wet shotcrete is discussed. The results show that the ideal value exists in the working air pressure, the rebound rate decreases with the decrease of the fluidity of the concrete, decreases with the increase of the injection thickness, and tends to be stable when it reaches 50mm. The high gas content wet shotcrete is more common. The rebound rate of shotcrete is reduced by about 5%, and the mixed powder Coal ash can improve the sprayability of wet shotcrete. (6) Compared with the compressive strength and frost resistance of wet shotcrete and ordinary wet shotcrete, the SEM morphology and strength growth mechanism of wet shotcrete are studied. The effect of composition materials on strength and frost resistance was analyzed. The results showed that the compressive strength of 28d after injection of wet shotcrete with high content of air was 34.4MPa, and the design strength was satisfied. According to the requirements of F300 technical requirements, the frost resistance level meets the technical requirements of F300. (7) By means of the calculation method, the simple test method comprehensively determines the void volume of the mixed aggregate, calculates the volume of the lubricating layer based on the relationship between the pipe diameter established by Dennis and the like and the thickness relation of the lubricating layer, and is tightly packed by the mixed aggregate. The volume of void volume and the volume of lubricating layer are determined, and the design method of high gas content wet shotcrete is put forward, and the economic cost contrast analysis table of 1m3 wet shotcrete is applied in inclined shaft and inverted slope engineering of tunnel.
【學位授予單位】：長安大學
【學位級別】：博士
【學位授予年份】：2014
【分類號】：U414
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相關期刊論文 前10條
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