本文選題：加筋土 + 筋土界面　； 參考：《上海大學》2013年碩士論文

【摘要】：加筋土技術從20世紀60年代問世以來，因其技術經濟效益十分顯著，可節(jié)約工程造價25％~65％，施工快速、外形美觀、節(jié)約土地等優(yōu)點，得到了廣泛應用。筋土界面的相互作用特性直接影響著加筋土結構的穩(wěn)定性，界面強度參數對加筋土工程結構的設計起著至關重要的作用。本文通過室內大型直剪試驗，對幾種工程中常用的土工合成材料與砂土填料的界面特性進行了較為詳細的研究，，主要工作如下： 1.為了研究填土與土工合成材料相互作用時筋土界面的抗剪強度以及剪脹特性，采用三種不同級配的砂土分別與土工格柵和土工織物進行了室內大型直剪試驗。研究了不同顆粒級配、密實度、筋材種類以及豎向應力對界面剪切特性的影響，并對界面剪脹系數進行了分析。結果表明：粗砂和細砂與筋材的界面剪切強度要明顯大于粗細混合砂；松砂剪切過程中只有剪縮效應的存在，但密實砂土表現(xiàn)出了明顯的剪脹過程；當豎向應力較大時，筋土界面達到峰值剪切強度所需的剪切位移比低應力水平時大；粗砂與土工格柵作用時達到峰值剪切強度所需的剪切位移比與土工織物作用時大，而細砂則相反。 2.采用室內大型直剪試驗，系統(tǒng)地分析了格柵橫肋與縱肋以及格柵幾何尺寸對于筋土界面強度特性的影響。試驗結果表明：格柵的橫肋與縱肋在界面強度中均發(fā)揮了較大的作用，兩者表現(xiàn)為不同的作用機理，當剪切位移較小時格柵橫肋的被動阻力和縱肋的摩阻力起到共同承擔荷載的作用；而隨著剪切位移的增大，橫肋的被動阻力進一步提升，縱肋則發(fā)揮了較為顯著的提高筋材剛度的框架作用。因此，格柵的縱橫肋需要協(xié)調作用才能發(fā)揮出較大的筋土界面強度。 3.為了研究砂土與土工合成材料相互作用的動力特性，進行了一系列室內大型界面循環(huán)剪切與單調剪切試驗。研究了不同豎向應力、循環(huán)剪切幅值、剪切次數等因素對于界面抗剪強度以及剪脹性的影響，并與單調剪切試驗條件下的試驗結果對比，分析了循環(huán)后的界面特性。試驗結果表明：豎向應力的值越大，循環(huán)剪切強度的增長幅度越平緩，即低應力下循環(huán)剪切強度的增幅較為明顯；界面剪脹剪縮性能隨著剪切幅值的增加而增強；隨著循環(huán)次數的增加，界面的強度有了一定的提高，同時豎向位移變化也較大。 4.在試驗基礎上提出了一種能夠描述筋土界面力學性能的組合本構模型，該模型包含四個關系式：(1)峰值、殘余強度包絡線；(2)強度峰值前的雙曲線模型；(3)強度峰值后的位移軟化模型；(4)反映剪脹特性的界面剪脹模型。該組合模型的預測結果與驗證試驗的結果能夠較好的吻合，表明所提模型是合理的。
[Abstract]:Since the advent of reinforced earth technology in the 1960s, it has been widely used because of its remarkable technical and economic benefits, the advantages of saving engineering cost by 25 and 65, rapid construction, beautiful appearance and saving land. The interaction characteristics of the reinforced soil interface directly affect the stability of the reinforced soil structure, and the interface strength parameters play an important role in the design of the reinforced soil engineering structure. In this paper, the interfacial characteristics of geosynthetics and sand fillers, which are commonly used in engineering, are studied in detail through large direct shear tests. The main work is as follows: 1. In order to study the shear strength and shear dilatancy of reinforced soil interface under the interaction of fill and geosynthetics, three kinds of sand with different gradation, geogrid and geotextile were used in the laboratory direct shear tests. The effects of particle gradation, compactness, reinforcement type and vertical stress on the interfacial shear properties were studied, and the shear expansion coefficient of the interface was analyzed. The results show that the interfacial shear strength of coarse sand and fine sand and steel bar is obviously greater than that of coarse sand, the shear shrinkage effect exists only in loose sand shear process, but the shear expansion process is obvious in dense sand, and when the vertical stress is large, The shear displacement required to reach the peak shear strength of the reinforced soil interface is larger than that of the low stress level, and the shear displacement required to reach the peak shear strength between coarse sand and geogrid is greater than that of geotextile, whereas the shear displacement of fine sand is opposite to that of geotextile. In this paper, the influence of transverse rib, longitudinal rib and geometric size of grid on the strength characteristics of reinforced soil interface is systematically analyzed by large direct shear test. The experimental results show that the transverse rib and longitudinal rib play a significant role in the interfacial strength, and the two play different mechanisms. When the shear displacement is small, the passive resistance of the transverse rib and the friction resistance of the longitudinal rib bear the load together, but with the increase of the shear displacement, the passive resistance of the transverse rib increases further. Longitudinal ribs play a more significant role in improving the stiffness of steel frame. Therefore, the longitudinal and transverse ribs of the grille need to be coordinated in order to play a larger reinforced soil interface strength. 3. In order to study the dynamic characteristics of the interaction between sand and geosynthetics, a series of laboratory tests on cyclic shear and monotone shear were carried out. The effects of different vertical stress, cyclic shear amplitude and shear times on the shear strength and dilatancy of the interface were studied. Compared with the experimental results under monotonic shear test, the characteristics of the interface after cycling were analyzed. The experimental results show that the increasing amplitude of cyclic shear strength is more gentle with the increase of vertical stress, that is, the increase of cyclic shear strength is obvious under low stress, and the expansion and shrinkage properties of interfacial shear increase with the increase of shear amplitude. With the increase of cycle times, the strength of the interface increases to a certain extent, and the vertical displacement changes greatly. 4. 4. On the basis of experiments, a combined constitutive model is proposed, which can describe the mechanical properties of the interface between reinforcement and soil. The model consists of four relations: (1) peak value, envelope of residual strength, (2) hyperbolic model before peak strength; (3) displacement softening model after peak strength and (4) interfacial shear dilatation model reflecting shear dilatancy. The prediction results of the combined model are in good agreement with the results of the verification test, which indicates that the proposed model is reasonable.
【學位授予單位】：上海大學
【學位級別】：碩士
【學位授予年份】：2013
【分類號】：TU41

【參考文獻】

相關期刊論文 前10條

1 楊廣慶,楊春玲;土工格柵拉拔試驗影響因素分析[J];地下空間;2004年01期

2 周志剛,李文勝,宋勤德;大型直剪儀試驗的尺寸效應[J];長沙交通學院學報;1999年01期

3 崔偉,李華鑾,穆乃敏;土工織物與土的直剪摩擦試驗研究[J];地質與勘探;2002年05期

4 雷勝友;臺階式加筋土擋墻的原型試驗研究[J];工程地質學報;2001年01期

5 吳夢軍,趙明階;CAT筋帶加筋土工程特性試驗研究[J];公路;2002年11期

6 岳紅宇,陳功,陳加付;土工格柵工程特性的試驗分析及其在處理公路路基中的應用[J];公路交通科技;2004年06期

7 竇寶松;加筋土擋墻的試驗研究[J];華北水利水電學院學報;1998年03期

8 陳福全;韓鈞;;高頻循環(huán)剪切下結構與松砂接觸面的土體特性[J];土木建筑與環(huán)境工程;2011年04期

9 羅書學;填料中的細粒含量對加筋土擋墻的影響[J];勘察科學技術;2000年06期

10 岳祖潤,趙維鈞,張興明,馬培德;粉煤灰中的筋條拉拔試驗[J];石家莊鐵道學院學報;1994年02期

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