【摘要】：本文針對以鋼纖維混凝土損傷破壞問題,從細(xì)觀角度出發(fā),采數(shù)值計算方法,建立鋼纖維混凝土細(xì)觀數(shù)值模型,對鋼纖維混凝土的損傷破壞過程進(jìn)行模擬計算,從宏觀和細(xì)觀的角度對破壞過程進(jìn)行深入分析,獲得了鋼纖維混凝土力學(xué)性質(zhì)同各影響因素之間的關(guān)系,揭示了鋼纖維混凝土細(xì)觀損傷破壞規(guī)律。首先,依據(jù)混凝土配合比理論和實際鋼纖維混凝土配合比,利用MATLAB數(shù)學(xué)軟件,建立鋼纖維混凝土二維幾何模型;針對建模過程中鋼纖維與鋼纖維相交判斷和鋼纖維與骨料相交判斷問題,引入矢量算法,減少了計算工作量,提高了建模質(zhì)量和速度;將矢量相交判斷方法與掃描排序算法相結(jié)合,提高了骨料、鋼纖維投放數(shù)量和投放速度;依托MATLAB中的GUI平臺,編制了鋼纖維混凝土二維建模軟件,依托界面操作窗口,能夠簡潔、迅速地生成鋼纖維混凝土平面模型;在骨料與鋼纖維滿足隨機(jī)分布的幾何模型上,依據(jù)隨機(jī)力學(xué)參數(shù)模型,建立了力學(xué)參數(shù)滿足Weibull分布的鋼纖維混凝土細(xì)觀數(shù)值模型。其次,開展了鋼纖維拔出物理試驗,獲得了不同長度、不同形狀鋼纖維的荷載-位移曲線,在此基礎(chǔ)上依據(jù)彈脆性損傷本構(gòu)模型,對鋼纖維拔出過程進(jìn)行數(shù)值模擬;引入界面破壞量閥值,認(rèn)為當(dāng)界面的破壞量超過此值后鋼纖維進(jìn)入滑移階段,對滑移階段界面單元的彈性模量進(jìn)行重新賦值,依據(jù)實際拔出試驗中鋼纖維滑移段的荷載曲線,用界面單元的彈性變形模擬鋼纖維的剛體滑移,用彈性力模擬滑動摩擦力,取得了較好的模擬效果;開展了不同長度的單根鋼纖維拔出試驗的數(shù)值模擬研究,獲得了鋼纖維界面應(yīng)力傳遞規(guī)律;將鋼纖維拔出物理試驗獲得的位移-荷載曲線與數(shù)值模擬得到的位移-荷載曲線進(jìn)行對比分析,結(jié)果表明,無論從峰值荷載、滑移荷載還是荷載變化規(guī)律上,數(shù)值計算結(jié)果均與物理試驗結(jié)具有很好的一致性,驗證了本文提出數(shù)值模型的準(zhǔn)確性。第三,以鋼纖維水泥砂漿數(shù)值模型為基礎(chǔ),依據(jù)彈脆性損傷本構(gòu)模型,開展了鋼纖維砂漿試件單軸拉伸、單軸壓縮數(shù)值模擬。在此基礎(chǔ)上研究了端部摩擦約束、鋼纖維幾何形狀、鋼纖維含量對模擬結(jié)果的影響。從宏觀力學(xué)特性、細(xì)觀裂紋演化、細(xì)觀單元損傷破壞發(fā)展三個方面進(jìn)行深入分析,建立了鋼纖維砂漿試件在典型荷載下的宏觀力學(xué)響應(yīng)與細(xì)觀單元損傷之間的聯(lián)系,揭示了鋼纖維在試件損傷破壞過程中的內(nèi)力變化規(guī)律,獲得了鋼纖維對試件增強(qiáng)、增韌、阻裂效果與鋼纖維角度、鋼纖維尺寸和鋼纖維含量之間的關(guān)系。最后,以骨料、鋼纖維位置隨機(jī)分布的鋼纖維混凝土二維數(shù)值模型為基礎(chǔ),應(yīng)用隨機(jī)力學(xué)參數(shù)模型,基于彈脆性損傷本構(gòu)理論,模擬了鋼纖維混凝土試件在典型單軸拉伸、單軸壓縮荷載作用下?lián)p傷破壞的全過程。分別模擬了不同基體強(qiáng)度、不同骨料形狀以及含孔隙的鋼纖維混凝土試件的單軸壓縮全過程。結(jié)果表明,在幾何參數(shù)不變的情況下,隨著基體強(qiáng)度的提高,鋼纖維混凝土試件的抗壓強(qiáng)度隨之提高,試件在破壞時的脆性特性越明顯,骨料的損傷破壞量越大;在滿足鋼纖維分布情況相同,骨料投放面積相同的情況下僅改變骨料的形狀,表明對CF80高強(qiáng)鋼纖維混凝土而言,骨料形狀對試件力學(xué)特性的影響較小;含有孔隙缺陷的鋼纖維混凝土試件的損傷破壞過程更加復(fù)雜,抗壓強(qiáng)度下降較為明顯,裂紋發(fā)展不再遵循簡單順序,隨機(jī)性更強(qiáng),更符合實際鋼纖維混凝土特點。研究表明,本文建立的細(xì)觀數(shù)值模型能夠有效地模擬鋼纖維混凝土試件的損傷破壞過程,實現(xiàn)了從細(xì)觀角度研究鋼纖維混凝土裂紋萌生、演化、發(fā)展,為研究鋼纖維混凝土損傷破壞問題提供了一種新的手段。
文內(nèi)圖片：
圖片說明：骨料切面示意圖
[Abstract]:In this paper, based on the damage of steel fiber concrete, the numerical calculation method of steel fiber concrete is set out from the micro-point of view, and the damage and destruction process of steel fiber concrete is simulated. The relationship between the mechanical property of the steel fiber concrete and the influence factors is obtained from the macroscopic and the micro-scale angle, and the damage rule of the steel fiber concrete meso-damage is revealed. First, according to the concrete mix ratio theory and the actual steel fiber concrete mix ratio, the two-dimensional geometric model of the steel fiber concrete is established by using the MATLAB mathematical software, and the vector algorithm is introduced aiming at the intersection judgment of the steel fiber and the steel fiber and the intersection judgment of the steel fiber and the aggregate during the modeling process, the calculation workload is reduced, the modeling quality and the speed are improved, the vector intersection judgment method and the scanning sequencing algorithm are combined, the quantity and the throwing speed of the aggregate and the steel fiber are improved, and the two-dimensional modeling software of the steel fiber concrete is prepared on the basis of the GUI platform in the MATLAB, Based on the interface operation window, the steel fiber concrete plan model can be generated in a simple and rapid manner; on the geometric model of the random distribution of the aggregate and the steel fiber, the micro-numerical model of the steel fiber concrete satisfying the Weibull distribution is established according to the random mechanical parameter model. Secondly, the physical test of steel fiber pull-out is carried out, and the load-displacement curve of steel fiber with different lengths and different shapes is obtained. Based on the constitutive model of the elastic brittle damage, the numerical simulation of the steel fiber pull-out process is carried out, and the threshold value of the interface failure amount is introduced. it is considered that when the damage amount of the interface exceeds this value, the steel fiber enters the sliding stage, the elastic modulus of the interface unit of the sliding stage is re-assigned, the rigid body of the steel fiber is simulated by the elastic deformation of the interface unit according to the load curve of the steel fiber sliding section in the actual extraction test, The elastic force is used to simulate the sliding friction force, and a good simulation effect is obtained; the numerical simulation of the single steel fiber pull-out test with different lengths is carried out, and the stress transmission law of the steel fiber interface is obtained; The displacement-load curve obtained by pulling out the steel fiber out of the physical test and the displacement-load curve obtained by the numerical simulation are compared and analyzed, and the results show that no matter the peak load, the slip load or the load change rule, The numerical results are consistent with the physical test, and the accuracy of the numerical model is verified. Thirdly, based on the numerical model of steel fiber cement mortar, the uniaxial tension and single-axis compression of steel fiber mortar test piece are simulated according to the constitutive model of the elastic brittle damage. The effects of end friction, steel fiber geometry and steel fiber content on the simulation results are studied. The relationship between the macro-mechanical response of the steel fiber mortar test piece under the typical load and the damage of the micro-unit is established from the three aspects of the macro-mechanical property, the micro-crack evolution and the damage development of the micro-unit. The relationship between steel fiber and steel fiber angle, steel fiber size and steel fiber content is obtained. At last, based on the two-dimensional numerical model of the steel fiber concrete which is randomly distributed at the position of the aggregate and the steel fiber, a random mechanical parameter model is applied to simulate the typical uniaxial tension of the steel fiber concrete test piece based on the elastic brittle damage constitutive theory. The whole process of damage damage under the action of uniaxial compression load. The whole process of uniaxial compression of steel fiber concrete specimen with different base strength, different aggregate shape and pore-containing steel fiber was simulated respectively. The results show that, with the change of the geometric parameters, with the increase of the strength of the matrix, the compressive strength of the steel fiber concrete test piece is increased, the more obvious the brittle character of the test piece when the test piece is damaged, the more the damage and the damage amount of the aggregate are, and in the case that the steel fiber distribution is satisfied, the shape of the aggregate is changed only under the condition that the aggregate throwing area is the same, indicating that the influence of the aggregate shape on the mechanical property of the test piece is small for the CF80 high-strength steel fiber concrete, and the damage and destruction process of the steel fiber concrete test piece containing the pore defect is more complicated, The compressive strength is obviously lower, and the crack development is no longer in the simple sequence, the randomness is stronger, and the concrete characteristics of the steel fiber concrete are more practical. The study shows that the micro-numerical model established in this paper can effectively simulate the damage and damage process of the steel fiber concrete specimen, and the crack initiation, evolution and development of the steel fiber concrete are studied from the micro-angle. In order to study the damage of steel fiber concrete, a new method is provided.
【學(xué)位授予單位】：中國礦業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TU528.572

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