本文選題：自密實混凝土　切入點：堆石混凝土　出處：《清華大學(xué)》2014年博士論文　論文類型：學(xué)位論文

【摘要】：堆石混凝土是一種基于自密實混凝土的新型大體積混凝土施工技術(shù)，具有施工速度快、節(jié)能減排等諸多優(yōu)勢，已經(jīng)在全國40多個工程中得到應(yīng)用。然而，在堆石混凝土研究與應(yīng)用中仍存在兩個核心問題：自密實混凝土能否有效填充堆石體內(nèi)部孔隙；堆石混凝土獨特的施工工藝和大粒徑塊石的應(yīng)用是否會影響塊石/漿體的界面特性。目前有關(guān)這兩個問題的研究還局限于工程經(jīng)驗和宏觀試驗，缺乏機理性的研究。本文旨在通過一系列基礎(chǔ)試驗，探索這兩大問題的作用機理，分析相關(guān)因素的影響，為堆石混凝土工程中方案設(shè)計、參數(shù)選取及工程安全評價提供理論與試驗依據(jù)。 本文采用了多尺度方法來研究自密實混凝土的填充性能。利用自主設(shè)計的試驗裝置，本文首先研究了自密實凈漿、自密實砂漿在堆石體中的流動和填充過程。利用流體阻塞模型和顆粒阻塞模型對自密實凈漿和自密實砂漿在堆石體中的填充性能和阻塞機理進行了分析和討論，得出了兩種阻塞模型各自的適用范圍，并研究了石子尺寸、漿體流動性等相關(guān)因素對填充性能的影響。在此基礎(chǔ)上，結(jié)合Roussel提出的顆粒阻塞概率模型，利用改進的試驗裝置，本文對自密實混凝土的通過性能進行了試驗研究，根據(jù)試驗結(jié)果對Roussel的模型進行了補充，使其更適用于堆石混凝土工程。本文提出了一種研究自密實混凝土在堆石體中填充性能的新方法——多孔介質(zhì)填充法，通過理論分析建立了漿體屈服應(yīng)力與填充結(jié)果的關(guān)系，并通過自密實砂漿填充多孔介質(zhì)模型試驗驗證了方法的可行性。最后，，對自密實混凝土充隙能力及相關(guān)影響因素進行了初步的試驗研究。 另一方面，為了研究堆石混凝土的界面微觀特性，論文首先對當(dāng)前有關(guān)水泥基材料界面微觀特性的研究方法進行了整理和比較，選出最有效的兩種微觀試驗方法：背散射電子圖像分析和納米壓痕。本文以模型堆石混凝土試件為樣本，選取多個試樣在相同位置進行背散射電子圖像分析和納米壓痕試驗，對試驗結(jié)果進行擬合，建立了孔隙率與彈性模量的量化關(guān)系。在此基礎(chǔ)上，本文利用自密實凈漿和自密實砂漿填充堆石體形成的模型堆石混凝土試件，分別對凈漿/石子界面和砂漿/石子界面進行了背散射電子圖像分析，得到了兩種模型堆石混凝土的的孔隙率和微觀彈性模量。利用界面孔隙率結(jié)果，本文分析了各試驗參數(shù)對界面微觀結(jié)構(gòu)的影響，并通過與傳統(tǒng)混凝土的界面特性研究成果進行比較，得出了堆石混凝土界面的新特點。
[Abstract]:Rockfill concrete is a new mass concrete construction technology based on self-compacting concrete. It has many advantages such as fast construction speed, energy saving and emission reduction, and has been applied in more than 40 projects in China. There are still two core problems in the research and application of rockfill concrete: whether self-compacting concrete can effectively fill the internal pores of rockfill; Whether the unique construction technology of rockfill concrete and the application of large-size block stone will affect the interfacial characteristics of mass stone / slurry, the current research on these two problems is limited to engineering experience and macroscopic test. The purpose of this paper is to explore the action mechanism of these two problems through a series of basic tests, to analyze the influence of related factors, and to design the scheme for the rockfill concrete engineering. Parameter selection and engineering safety evaluation provide theoretical and experimental basis. In this paper, a multi-scale method is used to study the filling performance of self-compacting concrete. Flow and filling process of self-compacting mortar in rockfill. The filling performance and blocking mechanism of self-compacting mortar and self-compacting mortar in rockfill are analyzed and discussed by using fluid blocking model and particle blocking model. The respective applicable ranges of the two blocking models are obtained, and the effects of stone size, slurry fluidity and other related factors on the filling performance are studied. On this basis, combining with the particle blocking probability model proposed by Roussel, the improved test device is used. In this paper, the passing performance of self-compacting concrete is studied experimentally, and the model of Roussel is supplemented by the experimental results. In this paper, a new method to study the filling performance of self-compacting concrete in rockfill is presented. The relationship between the yield stress of slurry and the filling result is established by theoretical analysis. The feasibility of the method is verified by the model test of self-compacting mortar filled with porous media. Finally, the filling capacity of self-compacting concrete and related influencing factors are preliminarily studied. On the other hand, in order to study the microcosmic characteristics of the interface of rockfill concrete, the present research methods of the interface micro-characteristics of cement-based materials are sorted out and compared in this paper. Two most effective microcosmic test methods were selected: back scattering electron image analysis and nano indentation. In this paper, several samples were selected for back scattering electron image analysis and nano indentation test in the same position. The quantitative relationship between porosity and elastic modulus is established by fitting the test results. On this basis, the model rockfill concrete specimens formed by self-compacting mortar and self-compacting mortar filled with rockfill are used in this paper. The porosity and elastic modulus of the two kinds of model rockfill concrete were obtained by using the back scattering electronic image analysis of the clean slurry / stone interface and the mortar / stone interface, respectively. The results of the interfacial porosity were used. In this paper, the influence of test parameters on the microstructure of the interface is analyzed, and the new characteristics of the interface of rockfill concrete are obtained by comparing with the research results of the interface characteristics of traditional concrete.
【學(xué)位授予單位】：清華大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2014
【分類號】：TV431

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