公路路基纳米复合材料固化土试验研究
发布时间：2019-05-11 00:49
【摘要】：将淤泥质土固化处理用于道路路基,其力学性能将直接影响到道路结构层的路用性能。由于一般水泥土的强度不高、变形较大、容易开裂,在公路工程上的应用受到一定的限制。研究改善水泥固化土的力学性质,提高其作为公路路基土时的路用性能,对于改善路面结构使用状况和延长使用寿命,都具有重要意义。本文在水泥土中掺加不同比例的纳米SiO_2和纳米A12O_3,研究两种纳米材料对水泥土的固化效果及共同掺加时对水泥土的改性效果。通过室内无侧限抗压强度试验和劈裂试验,研究水泥土在不同纳米SiO_2和纳米A12O_3掺量下的力学特性。并通过扫描电镜试验来研究纳米材料改性水泥土的微观作用机理。基于Plaxis有限元分析软件,对纳米材料水泥土和纯水泥土用作道路路基时进行数值模拟分析。主要研究成果如下:(1)通过7d、14d、28d三个龄期的无侧限抗压强度试验研究发现,添加纳米材料能很好地提高水泥土的早期强度,对水泥土的后期强度也有提高。纳米SiO_2水泥土三个龄期时的抗压强度均随掺量增加而增大;纳米铝水泥土的7d抗压强度随纳米A12O_3掺量的增加而增大,但14d和28d无侧限抗压强度随纳米A12O_3掺量的增加先增大后减小,从14d和28d强度考虑,纳米A12O_3的掺量存在最佳值,最佳掺量在2%~3%之间。相同掺量下纳米硅水泥土的最终强度普遍高于纳米铝水泥土。(2)纳米SiO_2和纳米A12O_3复掺时效果优于单掺,但纳米材料掺量过大反而会使水泥土强度降低。纳米材料水泥土的抗压强度随龄期的增长而增大。(3)通过7d劈裂强度试验研究发现,纳米材料的掺加能极大地提高水泥土的劈裂强度。掺量较小和较大时,纳米硅水泥土的7d劈裂强度大于纳米铝水泥土;而掺量适中时,相同掺量下两种纳米材料单掺时水泥土的劈裂强度十分接近。两种纳米材料复掺时对水泥土劈裂强度的提高明显大于单掺。(4)纳米材料水泥土 7d劈裂强度与7d抗压强度的比值介于0.130~0. 160之间,大于纯水泥土时的比值。当纳米材料掺量增大时,σs/qu比值增大,复掺时这个比值最大。(5)扫描电镜试验结果表明,掺加纳米材料使得水泥土中的大孔隙得到填充并细化。纳米材料与水泥水化产物发生了强烈的火山灰反应,促进了水泥水化反应的进行,生成了大量的C-S-H和C-A-H絮凝状胶凝物质。它们充填在孔隙中或包裹在针柱状钙矾石晶体周围,使得网状结构更为密实,且增强了水泥石骨架之间的粘结作用。(6)借助Plaxis有限元分析软件对纳米材料水泥土和纯水泥土用作道路路基时进行数值模拟分析。数值分析结果表明,水泥土中掺加纳米SiO_2和纳米A12O_3能改善其路用性能。
[Abstract]:The mechanical properties of silt soil curing treatment in road subgrade will directly affect the road performance of road structure layer. Because the strength of cement-soil is not high, the deformation is large, and it is easy to crack, the application of cement-soil in highway engineering is limited to a certain extent. It is of great significance to improve the mechanical properties of cement solidified soil and its pavement performance as highway subgrade soil in order to improve the service condition of pavement structure and prolong the service life. In this paper, different proportion of nano-SiO_2 and nano-A12O / 3 were added to cement-soil, and the curing effect of two kinds of nanomaterials on cement-soil and the modification effect of two kinds of nano-materials on cement-soil were studied. The mechanical properties of cement-soil with different nano-SiO_2 and nano-A12O_3 content were studied by laboratory unconfined compressive strength test and split test. The micro-action mechanism of nano-material modified cement soil was studied by scanning electron microscopy (SEM). Based on Plaxis finite element analysis software, the numerical simulation analysis of nano-material cement-soil and pure cement-soil used as road subgrade is carried out. The main results are as follows: (1) through the unconfined compressive strength tests at three ages of 7 days, 14 days and 28 days, it is found that the addition of nanomaterials can improve the early strength of cement-soil and the later strength of cement-soil. The compressive strength of nano-SiO_2 cement-soil increases with the increase of content at three ages. The 7-day compressive strength of nano-aluminum cement soil increases with the increase of nano-A12O_3 content, but the unconfined compressive strength increases at first and then decreases with the increase of nano-A12O_3 content on the 14th and 28th day, considering the 14 d and 28 d strength. The content of nano-A12O_3 has the best value, and the optimum content is between 2% and 3%. At the same content, the final strength of nano-silicon cement-soil is generally higher than that of nano-aluminum cement-soil. (2) the effect of nano-SiO_2 and nano-A12O_3 is better than that of single doping, but the strength of cement-soil will be reduced when the content of nano-material is too large. The compressive strength of nano-material cement-soil increases with the increase of age. (3) through the 7-day split strength test, it is found that the addition of nano-material can greatly improve the split strength of cement-soil. When the content of nano-silicon cement-soil is small and large, the 7-day split strength of nano-silicon cement-soil is higher than that of nano-aluminum cement-soil, while when the content of nano-silicon cement-soil is moderate, the split strength of cement-soil is very close to that of the two kinds of nano-materials when the content is the same. The split strength of cement-soil was significantly improved when the two kinds of nanomaterials were mixed. (4) the ratio of 7-day split strength to 7-day compressive strength of nano-material cement-soil was 0.130 鈮，
本文编号：2474128
[Abstract]:The mechanical properties of silt soil curing treatment in road subgrade will directly affect the road performance of road structure layer. Because the strength of cement-soil is not high, the deformation is large, and it is easy to crack, the application of cement-soil in highway engineering is limited to a certain extent. It is of great significance to improve the mechanical properties of cement solidified soil and its pavement performance as highway subgrade soil in order to improve the service condition of pavement structure and prolong the service life. In this paper, different proportion of nano-SiO_2 and nano-A12O / 3 were added to cement-soil, and the curing effect of two kinds of nanomaterials on cement-soil and the modification effect of two kinds of nano-materials on cement-soil were studied. The mechanical properties of cement-soil with different nano-SiO_2 and nano-A12O_3 content were studied by laboratory unconfined compressive strength test and split test. The micro-action mechanism of nano-material modified cement soil was studied by scanning electron microscopy (SEM). Based on Plaxis finite element analysis software, the numerical simulation analysis of nano-material cement-soil and pure cement-soil used as road subgrade is carried out. The main results are as follows: (1) through the unconfined compressive strength tests at three ages of 7 days, 14 days and 28 days, it is found that the addition of nanomaterials can improve the early strength of cement-soil and the later strength of cement-soil. The compressive strength of nano-SiO_2 cement-soil increases with the increase of content at three ages. The 7-day compressive strength of nano-aluminum cement soil increases with the increase of nano-A12O_3 content, but the unconfined compressive strength increases at first and then decreases with the increase of nano-A12O_3 content on the 14th and 28th day, considering the 14 d and 28 d strength. The content of nano-A12O_3 has the best value, and the optimum content is between 2% and 3%. At the same content, the final strength of nano-silicon cement-soil is generally higher than that of nano-aluminum cement-soil. (2) the effect of nano-SiO_2 and nano-A12O_3 is better than that of single doping, but the strength of cement-soil will be reduced when the content of nano-material is too large. The compressive strength of nano-material cement-soil increases with the increase of age. (3) through the 7-day split strength test, it is found that the addition of nano-material can greatly improve the split strength of cement-soil. When the content of nano-silicon cement-soil is small and large, the 7-day split strength of nano-silicon cement-soil is higher than that of nano-aluminum cement-soil, while when the content of nano-silicon cement-soil is moderate, the split strength of cement-soil is very close to that of the two kinds of nano-materials when the content is the same. The split strength of cement-soil was significantly improved when the two kinds of nanomaterials were mixed. (4) the ratio of 7-day split strength to 7-day compressive strength of nano-material cement-soil was 0.130 鈮，
本文编号：2474128
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