本文選題：土力學(xué)　切入點：粉質(zhì)黏土　出處：《巖石力學(xué)與工程學(xué)報》2017年06期

【摘要】：凍融循環(huán)是凍土地區(qū)路基填料性能劣化的主要因素之一。以壓實度和凍融循環(huán)次數(shù)為主要變量,對青藏高原粉質(zhì)黏土力學(xué)性質(zhì)的變化規(guī)律進(jìn)行三軸試驗研究。試驗結(jié)果表明:初始壓實度對粉質(zhì)黏土力學(xué)性質(zhì)的凍融效應(yīng)具有顯著影響。不同壓實度試樣的應(yīng)力 應(yīng)變曲線形式隨凍融次數(shù)的增加趨于接近,并由應(yīng)變軟化型向硬化型過渡。封閉系統(tǒng)中試樣的水分遷移會引起含水率的增減分區(qū)分布,低壓實度有利于增大水分遷移量和含水率增高區(qū)的分布范圍。凍融過程對高壓實試樣的破壞強度以降低為主,對低壓實度試樣則相反。在最優(yōu)含水率附近,土體抗剪強度隨含水率呈非線性變化規(guī)律,因此試樣內(nèi)部水分重分布也可能會導(dǎo)致強度的改變,且其作用效果受壓實度影響具有不確定性,壓實度較高時會導(dǎo)致試樣黏聚力減小,壓實度較低時則相反;不同壓實度下內(nèi)摩擦角均呈現(xiàn)增大的趨勢,且壓實度越低,變化幅度越大。凍融過程中,土體干密度和含水率變化對力學(xué)性質(zhì)的影響是同時存在的,由于初始壓實度和凍融次數(shù)的不同,對強度變化起主導(dǎo)作用的因素也不同。水分重分布是不同壓實度土體力學(xué)性質(zhì)凍融循環(huán)效應(yīng)的整體趨勢和具體過程呈現(xiàn)多樣化的原因之一。
[Abstract]:Freeze-thaw cycle is one of the main factors for the deterioration of the performance of subgrade fillers in permafrost regions. The compaction degree and the number of freeze-thaw cycles are the main variables. The variation of mechanical properties of silty clay in Qinghai-Xizang Plateau is studied by triaxial test. The experimental results show that initial compaction has a significant effect on the freeze-thaw effect of silty clay. With the increase of freeze-thaw times, the form of strain curve tends to be close. And the transition from strain softening type to hardening type. The moisture migration of the sample in the closed system will cause the increase or decrease of the distribution of water content. Low compaction is beneficial to increase the distribution range of water migration and water content increase. The failure strength of freeze-thaw high pressure specimen is mainly decreased, while the low compaction sample is opposite, near the optimal moisture content, the failure strength of freeze-thawing process is mainly reduced to that of high pressure solid sample, while the low compaction degree is opposite. The shear strength of the soil changes with the moisture content, so the distribution of moisture in the sample may cause the change of the strength, and the influence of the compaction on the shear strength is uncertain. When the compaction degree is high, the cohesion of the specimen will decrease, but when the compaction degree is low, the internal friction angle will increase, and the lower the compaction degree, the greater the change. The influence of soil dry density and moisture content on mechanical properties exists simultaneously, because of the difference of initial compaction and freeze-thaw times. The distribution of water redistribution is one of the reasons why the freeze-thaw cycle effect of different compaction degree soil mass is varied.
【作者單位】： 北京交通大學(xué)土木建筑工程學(xué)院;青海省交通科學(xué)研究院;
【基金】：國家自然科學(xué)基金資助項目(51378057,41371081) 國家重點基礎(chǔ)研究發(fā)展計劃(973)項目(2012CB026104)~~
【分類號】：TU41

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本文編號：1681921