【摘要】：我國是一個(gè)地震多發(fā)國家,地震所造成的砂土液化問題一直是巖土工程界研究的重點(diǎn)和熱點(diǎn)之一。目前針對(duì)砂土液化影響因素、影響機(jī)理的研究已取得很多成果,并得到了廣泛認(rèn)可。在地震荷載作用下土體內(nèi)部會(huì)產(chǎn)生超孔隙水壓力,而實(shí)際地層中不同位置的土體受相鄰?fù)翆訚B透性質(zhì)的影響會(huì)導(dǎo)致不同的排水條件,排水條件不同對(duì)超孔隙水壓力產(chǎn)生、消散和重分布有重要影響。目前關(guān)于液化問題的研究大多假定為不排水條件,而場地實(shí)際排水條件對(duì)土體液化特性的影響一直沒有得到充分認(rèn)識(shí)。基于此,本文通過室內(nèi)動(dòng)三軸試驗(yàn)對(duì)不同排水及粉土夾層條件下飽和砂土的液化特性進(jìn)行了試驗(yàn)研究。(1)設(shè)計(jì)了可控制滲透系數(shù)大小的排水夾層裝置,該裝置放置在試樣頂部,實(shí)現(xiàn)了對(duì)試樣不同排水條件的控制,為后續(xù)試驗(yàn)工作提供了依據(jù)。(2)利用動(dòng)三軸儀進(jìn)行了不同排水條件下飽和砂土動(dòng)三軸試驗(yàn),獲得了不同排水和加載模式條件下飽和砂土試樣的超孔隙水壓發(fā)展和應(yīng)力應(yīng)變關(guān)系曲線。試驗(yàn)結(jié)果表明:隨著滲透系數(shù)比的增加,飽和砂土試樣孔隙水壓增長速度減緩;雙向荷載相較與同幅值的單向荷載作用試樣產(chǎn)生的塑性變形大,孔隙水壓發(fā)展速率快,試樣更容易發(fā)生液化。試驗(yàn)條件下,滲透系數(shù)比大于0.54時(shí)飽和砂土試樣不液化,小于0.17時(shí)試樣液化。(3)開展了粉土夾層條件下飽和砂土動(dòng)三軸試驗(yàn),獲得了不同夾層間距比、不同排水條件下飽和層狀砂土試樣的超孔隙水壓發(fā)展和應(yīng)力應(yīng)變關(guān)系曲線。試驗(yàn)結(jié)果分析表明:飽和層狀砂土試樣,孔隙水壓積累速率隨著粉土夾層間距比的增大而減小,試樣抗液化強(qiáng)度增加;排水條件和雙向荷載對(duì)飽和層狀砂土試樣的液化強(qiáng)度影響與均勻砂土試樣相似,超孔隙水壓在滲透系數(shù)比較大和雙向加載條件下發(fā)展速率快,試樣更容易液化。(4)開展了飽和砂土試樣液化后剪切試驗(yàn),獲得了液化后飽和砂土試樣在不同排水條件下的超孔隙水壓力消散和變形曲線。試驗(yàn)結(jié)果分析表明:液化后飽和砂土試樣的剪切模量隨著滲透系數(shù)比的增大而增大,即排水條件的提高而增加,相應(yīng)的液化后試樣體積剪縮量減小,而剪切吸水效應(yīng)增強(qiáng),試樣抗剪強(qiáng)度折減率增大。
[Abstract]:China is an earthquake-prone country. The liquefaction of sandy soil caused by earthquake has always been one of the focal points and hot spots in geotechnical engineering. At present, a lot of achievements have been made on the influencing factors and mechanism of sand liquefaction, which have been widely recognized. Under the action of earthquake, the excess pore water pressure will be produced in the soil body, but the different positions of soil in the actual stratum will be affected by the permeability of adjacent soil layer, which will lead to different drainage conditions, and the different drainage conditions will produce the excess pore water pressure. Dissipation and redistribution have important effects. At present, most of the researches on liquefaction are assumed to be undrained conditions, but the influence of actual drainage conditions on soil liquefaction characteristics has not been fully understood. Based on this, the liquefaction characteristics of saturated sand under different drainage and silt intercalation conditions are studied by dynamic triaxial test in laboratory. (1) A drainage interlayer device with controllable permeability coefficient is designed. The device is placed at the top of the sample, which realizes the control of different drainage conditions of the sample, and provides the basis for the subsequent test work. (2) the dynamic triaxial test of saturated sand under different drainage conditions is carried out by using the dynamic triaxial apparatus. The overpore water pressure development and stress-strain relationship curves of saturated sand samples under different drainage and loading modes were obtained. The experimental results show that with the increase of permeability coefficient ratio, the pore water pressure growth rate of saturated sand samples slows down. Compared with the unidirectional load with the same amplitude, the bidirectional load produces larger plastic deformation, faster development rate of pore water pressure, and the sample is more prone to liquefaction. Under the experimental conditions, the saturated sand samples do not liquefy when the permeability coefficient ratio is greater than 0.54, and when the permeability coefficient ratio is less than 0.17. (3) the dynamic triaxial tests of saturated sandy soils under silt intercalation conditions are carried out, and the different interlayer spacing ratios are obtained. Superpore water pressure development and stress-strain curves of saturated layered sand samples under different drainage conditions. The experimental results show that the pore water pressure accumulation rate decreases with the increase of the interlayer spacing ratio, and the liquefaction strength of the sample increases. The influence of drainage conditions and bidirectional loads on the liquefaction strength of saturated layered sand samples is similar to that of homogeneous sand samples, and the excess pore water pressure develops rapidly under the condition of high permeability coefficient and biaxial loading. (4) the shear tests of saturated sand samples after liquefaction were carried out, and the excess pore water pressure dissipation and deformation curves of saturated sand samples after liquefaction were obtained under different drainage conditions. The experimental results show that the shear modulus of saturated sand increases with the increase of permeability coefficient ratio, that is, with the increase of drainage conditions, the volume shear shrinkage decreases and the shear water absorption effect increases after liquefaction. The shear strength reduction rate of the specimen increases.
【學(xué)位授予單位】：中國礦業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TU441

【參考文獻(xiàn)】

相關(guān)期刊論文 前10條

1 王剛;張建民;魏星;劉彥玲;;剪脹性砂土地震后流滑的機(jī)理和模擬[J];巖土工程學(xué)報(bào);2015年06期

2 陳龍偉;袁曉銘;孫銳;;2011年新西蘭M_w6.3地震液化及巖土震害述評(píng)[J];世界地震工程;2013年03期

3 黃雨;于淼;BHATTACHARYA Subhamoy;;2011年日本東北地區(qū)太平洋近海地震地基液化災(zāi)害綜述[J];巖土工程學(xué)報(bào);2013年05期

4 石杰;王毅;樊殷莉;李鯤;熊楊;;粗細(xì)�；旌贤亮W(xué)特性研究[J];西北水電;2013年01期

5 路德春;程星磊;杜修力;;飽和砂土的漸近狀態(tài)力學(xué)特性試驗(yàn)研究[J];防災(zāi)減災(zāi)工程學(xué)報(bào);2013年01期

6 楊永香;胡金虎;賈敏才;黃志全;;粉粒夾層對(duì)飽和砂土液化特性影響的試驗(yàn)研究[J];地下空間與工程學(xué)報(bào);2012年06期

7 黃博;汪清靜;凌道盛;丁浩;陳云敏;;飽和砂土三軸試驗(yàn)中反壓設(shè)置與抗剪強(qiáng)度的研究[J];巖土工程學(xué)報(bào);2012年07期

8 張建民;;砂土動(dòng)力學(xué)若干基本理論探究[J];巖土工程學(xué)報(bào);2012年01期

9 周健;陳小亮;楊永香;賈敏才;;飽和層狀砂土液化特性的動(dòng)三軸試驗(yàn)研究[J];巖土力學(xué);2011年04期

10 侯龍清;徐紅梅;曹振中;袁曉銘;;汶川地震液化土層類型驗(yàn)證及土性分析[J];巖土力學(xué);2011年04期

相關(guān)會(huì)議論文 前2條

1 張建民;;地震液化后地基側(cè)向變形對(duì)樁基礎(chǔ)的影響[A];中國土木工程學(xué)會(huì)第八屆土力學(xué)及巖土工程學(xué)術(shù)會(huì)議論文集[C];1999年

2 張國平;王洪瑾;周克驥;;內(nèi)外室壓力不等的空心圓柱扭剪儀的研制[A];中國土木工程學(xué)會(huì)第七屆土力學(xué)及基礎(chǔ)工程學(xué)術(shù)會(huì)議論文集[C];1994年

相關(guān)博士學(xué)位論文 前2條

1 王維銘;場地液化特征研究及液化影響因素評(píng)價(jià)[D];中國地震局工程力學(xué)研究所;2013年

2 王富強(qiáng);自然排水條件下砂土液化變形規(guī)律與本構(gòu)模型研究[D];清華大學(xué);2010年

，

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