本文選題：道路工程 + 加筋土��； 參考：《中國公路學(xué)報》2017年05期

【摘要】：針對循環(huán)剪切作用對Sandwich形加筋土界面剪切特性影響研究不足的狀況,采用室內(nèi)大型直剪儀對Sandwich形加筋土進(jìn)行了一系列循環(huán)直剪試驗。試驗所用的筋材為土工格柵,砂為福建標(biāo)準(zhǔn)砂,黏土為含水率為28%的重塑黏土,分別在豎向應(yīng)力為30,60,90kPa,剪切位移幅值為3,6,9mm,剪切速率為1,2,5,10mm·min~(-1),薄砂層厚度分別為4,6,8,10,12,14mm時,研究了剪切速率、薄砂層厚度、循環(huán)剪切幅值和豎向應(yīng)力等因素對Sandwich形加筋土筋土界面循環(huán)剪切特性的影響。試驗結(jié)果表明:在薄砂層厚度由2mm增加到14mm的過程中,界面的峰值剪應(yīng)力呈現(xiàn)出先增大后減小的現(xiàn)象,峰值剪應(yīng)力先由54.3kPa增加到67.9kPa,然后又減小到59.4kPa,薄砂層厚度為8mm時筋土界面峰值剪應(yīng)力達(dá)到最大值67.9kPa;當(dāng)剪切速率為1 mm·min~(-1)時,筋土界面主要表現(xiàn)出剪切硬化現(xiàn)象,且在前幾個循環(huán)周次,峰值剪應(yīng)力增幅較大,隨著循環(huán)周次的增加,增幅逐漸減小;當(dāng)剪切速率大于1 mm·min~(-1)時,筋土界面表現(xiàn)出剪切軟化現(xiàn)象,且剪切速率越大,軟化現(xiàn)象越明顯;在剪切幅值從3mm增加到9mm的過程中,循環(huán)剪切時筋土界面的剪脹、剪縮交替現(xiàn)象越來越明顯,并且剪切幅值越大,界面最終剪縮量也越大;豎向應(yīng)力為30,60,90,120kPa時,筋土界面對應(yīng)的峰值剪應(yīng)力分別為32.6,43.2,60.4,82.9kPa,表明隨著豎向應(yīng)力的增加,筋土界面的峰值剪應(yīng)力也隨之增加。
[Abstract]:In view of the insufficient research on the effect of cyclic shear on the interfacial shear characteristics of Sandwich reinforced soil, a series of circular direct shear tests on Sandwich reinforced soil were carried out by using a large direct shear apparatus in the laboratory. The steel bar used in the test is geogrid, the sand is Fujian standard sand, and the clay is remolded clay with moisture content of 28%. The shear rate is studied when the vertical stress is 30 ~ 600 ~ 90kPa, the shear displacement amplitude is 3 ~ 6 ~ 6mm, the shear rate is 1 ~ 2 ~ 2 ~ 10 mm / min ~ (-1), and the thickness of thin sand layer is 4 ~ 6 ~ 8 ~ 10 ~ 1 ~ 12 ~ (14 mm), respectively. The influence of thickness of thin sand layer, cyclic shear amplitude and vertical stress on cyclic shear characteristics of Sandwich reinforced soil interface. The experimental results show that the peak shear stress of the interface increases first and then decreases when the thickness of the thin sand layer increases from 2mm to 14mm. The peak shear stress increases from 54.3kPa to 67.9 KPA and then decreases to 59.4 KPA. When the thickness of the thin sand layer is 8mm, the peak shear stress of the interface reaches the maximum value of 67.9 KPA, and when the shear rate is 1 mm / min ~ (-1), the shear hardening is mainly observed at the interface of the reinforced soil. In the first few cycles, the increase of peak shear stress is larger, and with the increase of cycle, the increase decreases gradually, and when the shear rate is more than 1 mm / min ~ (-1), the shear softening occurs at the interface of the reinforced soil, and the shear rate increases with the increase of the cycle. In the process of increasing shear amplitude from 3mm to 9mm, the shear dilatation and shear-shrinkage alternations of the reinforced soil interface become more and more obvious during cyclic shear, and the larger the shear amplitude, the greater the final shear shrinkage of the interface, and when the vertical stress is 30 ~ 60,90,120kPa, The peak shear stress corresponding to the reinforced soil interface is 32. 6 脳 43.2 / 60.4 / 82.9 KPA, respectively, indicating that the peak shear stress of the interface increases with the increase of vertical stress.
【作者單位】： 上海大學(xué)土木工程系;
【基金】：國家自然科學(xué)基金項目(51478255,51678352) 上海市自然科學(xué)基金項目(14ZR1416100)
【分類號】：U416
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本文編號：1868085