【摘要】：泥炭質(zhì)土是一種具有明顯區(qū)域性的特殊土。通過(guò)一系列不同圍壓、固結(jié)比、加載頻率等條件下的分級(jí)加載動(dòng)三軸試驗(yàn),研究了昆明泥炭質(zhì)土在循環(huán)荷載作用下的動(dòng)變形特性。從動(dòng)骨干曲線、應(yīng)力-應(yīng)變滯回曲線和動(dòng)彈性模量等方面重點(diǎn)分析了圍壓、固結(jié)比、加載頻率對(duì)泥炭質(zhì)土變形特性的影響。試驗(yàn)結(jié)果表明:泥炭質(zhì)土的動(dòng)應(yīng)變隨動(dòng)應(yīng)力幅值非線性增長(zhǎng),且存在某一臨界動(dòng)應(yīng)力,當(dāng)動(dòng)應(yīng)力幅值達(dá)到臨界動(dòng)應(yīng)力值后,應(yīng)變急劇增長(zhǎng),土體結(jié)構(gòu)發(fā)生破壞;圍壓對(duì)泥炭質(zhì)土動(dòng)變形的影響最為顯著,固結(jié)比次之,加載頻率最小;固結(jié)比對(duì)泥炭質(zhì)土動(dòng)變形的影響程度依賴于圍壓,圍壓越大,固結(jié)比的影響越明顯;相同循環(huán)振級(jí)下,泥炭質(zhì)土的彈性變形隨圍壓和固結(jié)比增大而減小,加載頻率愈低,土體的彈性變形愈大;隨著循環(huán)振次的增加和振級(jí)水平的提高,泥炭質(zhì)土剛度逐漸下降,塑性變形產(chǎn)生并累積增長(zhǎng),圍壓和固結(jié)比越大,加載頻率越低,泥炭質(zhì)土的塑性變形越大。
[Abstract]:Peat soil is a special soil with obvious regional features. Based on a series of dynamic triaxial tests under different confining pressure, consolidation ratio and loading frequency, the dynamic deformation characteristics of Kunming peat soil under cyclic loading were studied. The influences of confining pressure, consolidation ratio and loading frequency on the deformation characteristics of peat soil were analyzed in the following key curves, stress-strain hysteretic curves and dynamic elastic modulus. The experimental results show that the dynamic strain of peat soil follows the nonlinear growth of dynamic stress amplitude, and there exists a certain critical dynamic stress. When the amplitude of dynamic stress reaches the critical dynamic stress value, the strain increases sharply and the soil structure is destroyed. The effect of confining pressure on the dynamic deformation of peat soil is the most significant, the consolidation ratio is the second, and the loading frequency is the least, the influence of consolidation ratio on the dynamic deformation of peat soil depends on the confining pressure, the greater the confining pressure is, the more obvious the effect of consolidation ratio is. Under the same cyclic vibration level, the elastic deformation of peat soil decreases with the increase of confining pressure and consolidation ratio, and the lower the loading frequency, the greater the elastic deformation of soil. With the increase of cyclic vibration times and the increase of vibration level, the stiffness of peat soil decreases gradually, the plastic deformation occurs and accumulates, the larger the confining pressure and consolidation ratio, the lower the loading frequency, the greater the plastic deformation of peat soil.
【作者單位】： 中南大學(xué)土木工程學(xué)院;昆明理工大學(xué)建筑工程學(xué)院;長(zhǎng)沙市軌道交通集團(tuán)有限公司;
【基金】：國(guó)家自然科學(xué)基金項(xiàng)目(No.51108461,No.51308270) 國(guó)家重點(diǎn)基礎(chǔ)研究發(fā)展計(jì)劃項(xiàng)目(973計(jì)劃)(No.2011CB013802)~~
【分類號(hào)】：TU447

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