本文選題：季凍區(qū) + 過濕土��； 參考：《吉林建筑大學(xué)》2017年碩士論文

【摘要】：本文依托《過濕土公路地基處理技術(shù)研究》科技項目,針對吉舒高速公路實際工程應(yīng)用技術(shù),開展了過濕土路基生石灰處治技術(shù)的研究,取得如下成果:1.石灰處治土的液塑限隨著石灰摻入比的增大而增加,而塑性指數(shù)的變化規(guī)律正好相反。土中摻入石灰后,土顆粒比重呈逐漸增長趨勢,其顆粒粒徑大小發(fā)生了明顯變化。隨著石灰摻量的增加,土中粉粒與粘粒的含量均呈減小的趨勢,但粘粒的變化更加明顯。2.隨著石灰摻量的增加,石灰處治土的最佳含水率呈逐漸增大的趨勢,而最大干密度呈現(xiàn)逐漸減小的趨勢。石灰處治土的抗剪強(qiáng)度隨著石灰摻量以及壓實度的增大呈現(xiàn)出比較明顯的增長趨勢。3.在路基路面力學(xué)結(jié)構(gòu)體系中,構(gòu)建了過濕土路基頂面石灰處治土加強(qiáng)層結(jié)構(gòu),通過分析加強(qiáng)層對土基強(qiáng)度、土基頂面壓應(yīng)力分布、土基內(nèi)動力偏應(yīng)力以及路面結(jié)構(gòu)力學(xué)響應(yīng)的影響規(guī)律得出:土基加強(qiáng)層的厚度與模量,對土基強(qiáng)度提高作用顯著,但在土基強(qiáng)度較差的情況下,一味地增加加強(qiáng)層的厚度或模量,并不能很好的改善土基的強(qiáng)度。鋪筑加強(qiáng)層的過濕土路基,其頂面壓應(yīng)力減小,壓應(yīng)力分布更加平緩。隨著加強(qiáng)層厚度及模量的增加,土基表面壓力應(yīng)力與土基內(nèi)動力偏應(yīng)力均呈現(xiàn)逐漸減小的趨勢,同時路面基層與底基層底部彎拉應(yīng)力與彎拉應(yīng)變逐漸減小,且厚度與模量越大,其減小的幅度越大。終上所述,增加生石灰處治過濕土加強(qiáng)層厚度與模量有利于延長路面結(jié)構(gòu)使用壽命。4.隨著石灰摻量的增加,石灰處治土的高度與體積凍脹率呈現(xiàn)減小而逐漸趨于穩(wěn)定的趨勢,石灰的摻入能夠有效提高路基的整體抗凍性。經(jīng)若干次凍融循環(huán)作用后,石灰處治土的強(qiáng)度雖有所衰減,但仍遠(yuǎn)大于素土強(qiáng)度;無論是素土還是石灰處治土,隨著壓實度的增大,其凍融前后的強(qiáng)度均有所增加,說明提高土基的壓實度,是保證路基整體強(qiáng)度與穩(wěn)定性的最經(jīng)濟(jì)、最有效的措施之一。提高路基的壓實度,亦可以改善凍融后土基的CBR值,從而確保凍融后路基的承載能力�？紤]經(jīng)濟(jì)方面的因素,研究認(rèn)為石灰摻入比控制在3~5%比較理想。5.從吉舒高速公路路基水溫狀況監(jiān)測數(shù)據(jù)可以看出,路基內(nèi)部的溫度隨著大氣溫度的變化而變化。且深度愈大,其變化幅度愈小,即路基內(nèi)部溫度受大氣溫度影響愈小。通過比較日溫差變化可以發(fā)現(xiàn),5%生石灰處治路基內(nèi)部日溫差變化幅度小于換填山皮石路基,說明石灰處治土路基具有更好的保溫性能,其路基最大凍結(jié)深度小。另外,同一埋置深度下,5%生石灰處治路基體積含水量變化幅度小于換填山皮石路基,說明其具有一定的隔水性能。研究表明,在吉舒高速公路,采用生石灰處治過濕土修筑路基在技術(shù)上是可行的。
[Abstract]:In this paper, based on the project of "Research on Foundation treatment Technology of overwet soil Highway", aiming at the practical engineering application technology of Jishu Expressway, the research on the treatment technology of quicklime for overwet soil subgrade has been carried out, and the following results have been obtained: 1.The liquid-plastic limit of lime treated soil increases with the increase of lime ratio, but the change of plasticity index is just the opposite.When lime was added into the soil, the specific gravity of soil particles increased gradually, and the particle size changed obviously.With the increase of lime content, the content of silt and clay in soil decreased, but the change of clay was more obvious.With the increase of lime content, the optimum moisture content of lime treated soil increases gradually, while the maximum dry density decreases gradually.The shear strength of lime treated soil shows an obvious increasing trend with the increase of lime content and compaction degree.In the mechanical structure system of roadbed and pavement, the structure of lime treating soil strengthened layer on top of overwet soil subgrade is constructed. The strength of strengthening layer to soil foundation and the distribution of compressive stress on top surface of soil foundation are analyzed.The influence of dynamic deflection stress in soil foundation and the mechanical response of pavement structure shows that the thickness and modulus of strengthening layer of soil foundation have a significant effect on improving the strength of soil foundation, but when the strength of soil foundation is poor,Only increasing the thickness or modulus of the strengthening layer can not improve the strength of soil foundation.The compressive stress of overwetted soil subgrade is reduced and the distribution of compressive stress is more gentle.With the increase of the thickness and modulus of the strengthening layer, the surface pressure stress of the soil foundation and the dynamic deflection stress of the soil foundation gradually decrease, and the bending tension stress and the bending tension strain at the bottom of the pavement base and the bottom of the base gradually decrease, and the thickness and modulus increase.The greater the extent of the decrease.In the end, increasing the thickness and modulus of the strengthening layer of quicklime treatment of overwetted soil is beneficial to prolong the service life of pavement structure .4.With the increase of lime content, the frost heave ratio of lime treated soil decreases and tends to be stable gradually. Lime mixing can effectively improve the overall frost resistance of roadbed.After several freeze-thaw cycles, the strength of lime treated soil decreases, but it is still much larger than that of plain soil, and the strength of lime treated soil increases with the increase of compaction degree.It shows that increasing the compaction degree of soil foundation is one of the most economical and effective measures to ensure the overall strength and stability of subgrade.Increasing the compaction degree of roadbed can also improve the CBR value of soil foundation after freeze-thaw, so as to ensure the bearing capacity of roadbed after freeze-thaw.Considering the economic factors, it is considered that the lime blending ratio should be controlled at 3 ~ 5%.From the monitoring data of subgrade water temperature in Jishu Expressway, it can be seen that the temperature inside the subgrade changes with the change of atmospheric temperature.The greater the depth, the smaller the variation, that is, the temperature inside the roadbed is less affected by atmospheric temperature.By comparing the daily temperature difference, it can be found that the range of daily temperature difference within the subgrade treated with 5% quicklime is smaller than that of replacing the embankment with rock filling, which indicates that the lime treatment of soil subgrade has better thermal insulation performance, and the maximum freezing depth of the roadbed is small.In addition, the change range of volume water content of subgrade treated with 5% quicklime at the same buried depth is smaller than that of replacement embankment, which indicates that it has certain water insulation performance.The research shows that it is technically feasible to use quicklime to construct roadbed on Jishu Expressway.
【學(xué)位授予單位】：吉林建筑大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：U416.1

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