纖維對納米二氧化硅 石灰改良粉土力學性質的影響

李國勛 張艷美 馬丁 畢艦心

摘 要： 山東黃泛區粉土分布廣泛，在鐵路路基填料緊缺的情況下，常用改良粉土作為路基填料。選用納米二氧化硅和石灰作為改良劑，對黃泛區粉土進行改良，并通過擊實試驗以及無側限抗壓強度試驗對其強度進行測定，發現納米二氧化硅 石灰改良粉土雖然強度有顯著提升，但也呈現出脆性較大的不良特性。為改善納米二氧化硅 石灰改良粉土的脆性，在改良粉土中加入聚丙烯纖維，并通過試驗研究了纖維摻量和長度對納米二氧化硅 石灰改良粉土強度和脆性的影響，確定纖維的最優摻量和最優長度。結果表明：纖維的加入能改善納米二氧化硅 石灰改良粉土的脆性，提高其抗壓及抗剪強度;當纖維摻量為0.4%、纖維長度為2 cm時，改良效果最好。

關鍵詞： 聚丙烯纖維;納米二氧化硅;石灰;改良粉土;抗壓強度;直剪試驗

中圖分類號：TU447? ? 文獻標志碼：A? ?文章編號：2096-6717（2020）02-0037-08

Mechanical properties of nano-silica and lime stabilized silt reinforced by fiber

Li Guoxun， Zhang Yanmei， Ma Ding， Bi Jianxin

（College of Pipeline and Civil Engineering， China University of Petroleum （Huadong），Qingdao 266580， Shandong， P.R.China）

Abstract：? In Shandong province， silt is widely distributed in the Yellow River flooding area.In the case of shortage of railway roadbed filling material， reinforced silt is commonly used as an alternative.In this study， the silt in the Yellow River floodplain area was reinforced by using nano-silica and lime as modifiers.The strength of the silt was measured by compaction test and unconfined compressive strength tests.It was found that although the strength of the silt was significantly improved， the material also showed some characteristics of brittleness.In order to overcome this disadvantage， polypropylene fibers were added to silt and then， the influences of fiber content and length on the strength and brittleness of the silt were studied through a series of experiments.The optimum fiber content and the optimum fiber content were determined.The results show that the brittleness and compressive and shear strength of the silt can be improved by adding fibers; and when the content of fibers is 0.4% and the length of fibers is 2 cm， the improvement effect is the best.

Keywords： polypropylene fiber; nano-silica; lime; improved silt; compressive strength; direct shear test

山東黃河沖積粉土覆蓋面積廣，約占全省總面積的34%，在鐵路路基填料緊缺的情況下，常用粉土作為路基填料。根據現行鐵路路基設計規范，黃泛區粉土多屬于C組鐵路路堤填料，具有結構穩定性差、壓縮性高、力學強度低等特點，必須經過改良后才可使用。

近幾十年來，納米材料迅速興起。由于納米材料尺寸的減小，使其具有一系列不同于宏觀尺度的特性，是現如今材料科學、物理、化學等領域的研究熱點[1-4]。納米二氧化硅是一種無毒、無味、無污染的無機非金屬白色粉末。……