【摘要】：將淤泥質(zhì)土固化處理用于道路路基,其力學(xué)性能將直接影響到道路結(jié)構(gòu)層的路用性能。由于一般水泥土的強(qiáng)度不高、變形較大、容易開裂,在公路工程上的應(yīng)用受到一定的限制。研究改善水泥固化土的力學(xué)性質(zhì),提高其作為公路路基土?xí)r的路用性能,對(duì)于改善路面結(jié)構(gòu)使用狀況和延長(zhǎng)使用壽命,都具有重要意義。本文在水泥土中摻加不同比例的納米SiO_2和納米A12O_3,研究?jī)煞N納米材料對(duì)水泥土的固化效果及共同摻加時(shí)對(duì)水泥土的改性效果。通過室內(nèi)無側(cè)限抗壓強(qiáng)度試驗(yàn)和劈裂試驗(yàn),研究水泥土在不同納米SiO_2和納米A12O_3摻量下的力學(xué)特性。并通過掃描電鏡試驗(yàn)來研究納米材料改性水泥土的微觀作用機(jī)理。基于Plaxis有限元分析軟件,對(duì)納米材料水泥土和純水泥土用作道路路基時(shí)進(jìn)行數(shù)值模擬分析。主要研究成果如下:(1)通過7d、14d、28d三個(gè)齡期的無側(cè)限抗壓強(qiáng)度試驗(yàn)研究發(fā)現(xiàn),添加納米材料能很好地提高水泥土的早期強(qiáng)度,對(duì)水泥土的后期強(qiáng)度也有提高。納米SiO_2水泥土三個(gè)齡期時(shí)的抗壓強(qiáng)度均隨摻量增加而增大;納米鋁水泥土的7d抗壓強(qiáng)度隨納米A12O_3摻量的增加而增大,但14d和28d無側(cè)限抗壓強(qiáng)度隨納米A12O_3摻量的增加先增大后減小,從14d和28d強(qiáng)度考慮,納米A12O_3的摻量存在最佳值,最佳摻量在2%~3%之間。相同摻量下納米硅水泥土的最終強(qiáng)度普遍高于納米鋁水泥土。(2)納米SiO_2和納米A12O_3復(fù)摻時(shí)效果優(yōu)于單摻,但納米材料摻量過大反而會(huì)使水泥土強(qiáng)度降低。納米材料水泥土的抗壓強(qiáng)度隨齡期的增長(zhǎng)而增大。(3)通過7d劈裂強(qiáng)度試驗(yàn)研究發(fā)現(xiàn),納米材料的摻加能極大地提高水泥土的劈裂強(qiáng)度。摻量較小和較大時(shí),納米硅水泥土的7d劈裂強(qiáng)度大于納米鋁水泥土;而摻量適中時(shí),相同摻量下兩種納米材料單摻時(shí)水泥土的劈裂強(qiáng)度十分接近。兩種納米材料復(fù)摻時(shí)對(duì)水泥土劈裂強(qiáng)度的提高明顯大于單摻。(4)納米材料水泥土 7d劈裂強(qiáng)度與7d抗壓強(qiáng)度的比值介于0.130~0. 160之間,大于純水泥土?xí)r的比值。當(dāng)納米材料摻量增大時(shí),σs/qu比值增大,復(fù)摻時(shí)這個(gè)比值最大。(5)掃描電鏡試驗(yàn)結(jié)果表明,摻加納米材料使得水泥土中的大孔隙得到填充并細(xì)化。納米材料與水泥水化產(chǎn)物發(fā)生了強(qiáng)烈的火山灰反應(yīng),促進(jìn)了水泥水化反應(yīng)的進(jìn)行,生成了大量的C-S-H和C-A-H絮凝狀膠凝物質(zhì)。它們充填在孔隙中或包裹在針柱狀鈣礬石晶體周圍,使得網(wǎng)狀結(jié)構(gòu)更為密實(shí),且增強(qiáng)了水泥石骨架之間的粘結(jié)作用。(6)借助Plaxis有限元分析軟件對(duì)納米材料水泥土和純水泥土用作道路路基時(shí)進(jìn)行數(shù)值模擬分析。數(shù)值分析結(jié)果表明,水泥土中摻加納米SiO_2和納米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，

本文編號(hào)：2474128