【摘要】：在季凍區(qū),由于特殊氣候的影響,道路普遍會受到凍融作用的影響而產(chǎn)生病害,但是對于道路路基病害的研究還沒有引起國內(nèi)研究人員的足夠重視。為了弄清凍融作用下季凍區(qū)路基土的強度性能的變化,選擇黑龍江省3條有代表性的等級公路,冬季前后分別調(diào)查路基土含水率,研究其隨季節(jié)變化情況,判斷路基的干濕狀況；取土樣進行室內(nèi)不同條件下路基土凍融強度試驗,研究凍融作用下路基土強度的變化規(guī)律；采用電鏡掃描研究凍融后路基土的微觀變化機理。 調(diào)查發(fā)現(xiàn)春季凍土融化后路基土含水率較冬季凍結(jié)前的含水率有所增大,并且大多數(shù)調(diào)查路段路基處于干燥或中濕狀態(tài)。室內(nèi)試驗表明：在凍融循環(huán)次數(shù)相同時,土體的回彈模量隨壓實度的降低而減小,隨含水率的降低而增大,且壓實度越低,含水率對土體回彈模量的影響系數(shù)越大,在含水率和壓實度條件相同時,凍融作用能夠使土體的回彈模量降低,且凍融循環(huán)次數(shù)越多,回彈模量衰減值越大,6次凍融之后,其模量降低基本穩(wěn)定：凍融循環(huán)作用使土體的黏聚力降低,內(nèi)摩擦角增大,其中粉質(zhì)粘土的黏聚力受凍融作用的影響最大；隨著壓實度的增加,各類土的黏聚力和內(nèi)摩擦角值都有不同程度的增加,其中砂性土黏聚力變化最為明顯；隨著含水率的增加,土體的黏聚力和內(nèi)摩擦角都會降低,而粉質(zhì)粘土的黏聚力和內(nèi)摩擦角受含水率的影響最大。微觀電鏡掃描發(fā)現(xiàn)土體在經(jīng)過凍融循環(huán)作用后內(nèi)部結(jié)構(gòu)發(fā)生改變,顆粒之間的孔隙得以發(fā)育,顆粒之間相互接觸變得比較松散,導致土的力學性能下降。
[Abstract]:Due to the influence of special climate, the road will be affected by freeze-thaw process, but the research of road roadbed disease has not been paid enough attention to by domestic researchers. In order to find out the change of strength performance of subgrade soil in freeze-thaw region, three representative grade highways in Heilongjiang Province were selected. The moisture content of subgrade soil was investigated before and after winter, and the variation of soil moisture with seasons was studied. To judge the dry and wet condition of roadbed, to test the freeze-thaw strength of subgrade soil under different indoor conditions, and to study the change rule of roadbed soil strength under freeze-thaw action, and to study the microcosmic change mechanism of roadbed soil after freeze-thaw by electron microscope scanning. It is found that the moisture content of subgrade soil after frozen soil thawing in spring is higher than that before freezing in winter, and the subgrade of most sections of investigation is in dry or medium wet state. The results of laboratory tests show that when the number of freeze-thaw cycles is the same, the elastic modulus of soil decreases with the decrease of compaction degree, and increases with the decrease of moisture content, and the lower the compaction degree, the greater the influence coefficient of moisture content on the resilience modulus of soil. Under the same conditions of moisture content and compaction, the springback modulus of soil can be reduced by freeze-thaw action, and the more times of freeze-thaw cycle, the greater the attenuation value of springback modulus is after 6 times freeze-thaw. Its modulus is basically stable: freezing and thawing cycle makes the cohesive force of soil decrease and the angle of internal friction increases, among which the cohesion of silty clay is most affected by freezing and thawing, and with the increase of compaction, The cohesive force and internal friction angle of all kinds of soils are increased to some extent, among which the cohesion of sandy soil is the most obvious, and with the increase of water content, the cohesive force and internal friction angle of soil will decrease. The cohesion and internal friction angle of silty clay are most affected by moisture content. It was found by SEM that the internal structure of soil changed after freeze-thaw cycle, the pores between particles developed, and the contact between particles became loose, which resulted in the decline of mechanical properties of soil.
【學位授予單位】：東北林業(yè)大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：U416.1

【參考文獻】

相關(guān)博士學位論文 前1條

1 韓春鵬;石灰處治土路基凍融作用特性研究[D];東北林業(yè)大學;2011年

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本文編號：2151200