本文選題：巖石-混凝土界面 + 界面裂縫��； 參考：《大連理工大學(xué)》2014年碩士論文

【摘要】：建立在巖石基礎(chǔ)上的混凝土大壩,由于基巖-混凝土界面開裂問題,易引發(fā)壩體失穩(wěn)等安全事故�；炷翂闻c基巖的薄弱界面在荷載、水流及溫度變化等作用下極易產(chǎn)生裂縫并沿建基面不斷擴展,直至壩體潰決。因此,壩踵處壩體與基礎(chǔ)巖石的開裂可歸結(jié)于基巖-混凝土界面開裂問題。然而,巖石和混凝土兩種材料本身具有的非均質(zhì)性與各向異性等屬性加深了界面裂縫問題的復(fù)雜程度。因此,對巖基與混凝土壩體的界面斷裂性能及其裂縫擴展問題進(jìn)行研究,對大壩的安全使用具有重大意義�；诨鶐r-混凝土界面裂縫問題研究的必要性,本文開展了如下的研究工作： (1)人工切槽界面斷裂特性試驗研究 均采用一半為巖石一半為混凝土的界面復(fù)合試件,對巖石表面進(jìn)行人工切槽處理,對尺寸為500mm×100mm×100mm的復(fù)合試件進(jìn)行了三點彎曲斷裂試驗,同時進(jìn)行了軸向拉伸與劈裂試驗。試驗結(jié)果表明,隨著界面粗糙度的增加,巖石-混凝土界面的抗拉強度、斷裂韌度及斷裂能均有大幅度提高,可以通過增加界面粗糙度的方式來提高界面的抗彎及抗裂性能。 (2)自然界面斷裂特性試驗研究 通過三點彎曲加載試驗使巖石形成自然斷面,并將其與另一半混凝土結(jié)合制成復(fù)合試件,按預(yù)制裂縫設(shè)計5種初始縫高北a0/D,對尺寸為500mm×100mm×100mm界面試件進(jìn)行三點彎曲試驗。試驗結(jié)果表明,隨著a0/D的增加,試件的起裂荷載和最大荷載逐漸減小,抗折強度逐漸增大；試件的起裂韌度的和斷裂能不隨a0/D變化,認(rèn)為是與a0/D無關(guān)的斷裂參數(shù)。 (3)界面拉伸軟化本構(gòu)關(guān)系的確定及數(shù)值應(yīng)用 采用改進(jìn)的J積分法,通過試驗獲得的荷載-加載點位移(P-δ)曲線,進(jìn)而根據(jù)裂縫擴展過程中的能量損耗,建立與Hillerborg提出的粘聚力模型下的能量平衡關(guān)系,確定了界面軟化本構(gòu)關(guān)系。采用本文得到的軟化本構(gòu)關(guān)系,并引入Ⅰ型裂縫擴展準(zhǔn)則,對巖石-混凝土界面裂縫擴展全過程進(jìn)行數(shù)值模擬。研究表明,試驗結(jié)果與數(shù)值計算結(jié)果吻合良好,從而驗證了界面軟化本構(gòu)關(guān)系的正確性。
[Abstract]:Concrete dam based on rock is liable to lead to dam instability and other safety accidents due to the crack between bedrock and concrete interface. The weak interface between concrete dam and bedrock is easy to produce cracks and expand along the foundation surface under the action of load, water flow and temperature change, until the dam body collapses. Therefore, the cracking between the dam body and the foundation rock at the dam heel can be attributed to the crack between the bedrock and concrete interface. However, the heterogeneity and anisotropy of rock and concrete increase the complexity of interfacial crack problem. Therefore, it is of great significance to study the interface fracture performance and crack propagation of rock foundation and concrete dam. Based on the necessity of the research on the interfacial crack between bedrock and concrete, the following research work has been carried out in this paper: (1) the experimental research on the fracture characteristics of the interface between the artificial cut groove and the concrete interface is carried out by using the composite specimen which is half rock and half concrete. Three point bending fracture tests were carried out for the composite specimens with the size of 500mm 脳 100mm 脳 100mm, and the axial tensile and splitting tests were carried out at the same time. The experimental results show that the tensile strength, fracture toughness and fracture energy of the rock-concrete interface increase greatly with the increase of the interfacial roughness. The flexural and crack resistance of the interface can be improved by increasing the roughness of the interface. Combined with the other half of concrete, the composite specimen was designed according to the precast crack, and five kinds of initial joint height (a _ 0 / D) were designed. The three-point bending test was carried out on the 500mm 脳 100mm 脳 100mm interface specimen. The experimental results show that with the increase of a _ 0 / D, the initiation load and maximum load of the specimen decrease gradually, and the flexural strength increases, and the initial fracture toughness and fracture energy of the specimen do not change with a _ 0 / D. It is considered to be a fracture parameter independent of a _ 0 / D. The determination and numerical application of tensile softening constitutive relation at the interface are obtained by using the improved J-integral method and the load-loading point displacement (P- 未) curves obtained by experiments. Furthermore, according to the energy loss during crack propagation, the energy balance relationship under the cohesive force model proposed by Hillerborg is established, and the constitutive relation of interface softening is determined. Based on the softening constitutive relation obtained in this paper and the model I crack propagation criterion, the whole process of crack propagation at the rock-concrete interface is numerically simulated. It is shown that the experimental results are in good agreement with the numerical results, which verifies the correctness of the constitutive relation of interface softening.
【學(xué)位授予單位】：大連理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TV642;TV313

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