本文關(guān)鍵詞： 低溫共振柱試驗(yàn) 季節(jié)凍土 動(dòng)剪切模量 阻尼比 負(fù)溫 含水率 凍融循環(huán) 土層地震反應(yīng)分析　出處：《中國(guó)地震局工程力學(xué)研究所》2016年博士論文　論文類型：學(xué)位論文

【摘要】：隨著國(guó)家經(jīng)濟(jì)建設(shè)程度的提高,“一帶一路”戰(zhàn)略的布局,寒區(qū)交通網(wǎng)絡(luò)與房屋建筑工程日益增多,建設(shè)中面臨著很多季節(jié)凍土相關(guān)的地基振動(dòng)分析以及地震災(zāi)害風(fēng)險(xiǎn)評(píng)價(jià)等問(wèn)題,以往關(guān)注較少的凍土動(dòng)力學(xué)性能逐漸受到重視;由于受研究條件的限制,以往通過(guò)低溫動(dòng)三軸試驗(yàn)獲得的凍土動(dòng)剪切模量阻尼比參數(shù),其可靠性有待提高。本文以國(guó)內(nèi)首臺(tái)低溫共振柱儀為試驗(yàn)平臺(tái),對(duì)低溫共振柱試驗(yàn)技術(shù)進(jìn)行了摸索;對(duì)粘土、粉土及砂土三種典型土類進(jìn)行了一系列不同溫度、含水率及凍融循環(huán)次數(shù)的共振柱試驗(yàn),并總結(jié)其動(dòng)剪切模量阻尼比參數(shù)的變化模式及規(guī)律;初步研究了Ⅰ、Ⅱ類理想含季節(jié)凍土場(chǎng)地工況中的地震反應(yīng)。試驗(yàn)技術(shù)從圍壓介質(zhì)入手,經(jīng)過(guò)方案比較,將氯丁橡膠膜與硅油作為圍壓介質(zhì);通過(guò)實(shí)測(cè)結(jié)果與前人成果,選擇凍結(jié)時(shí)長(zhǎng)為24h,而凍結(jié)溫度則按照不同土類進(jìn)行選擇。按這套技術(shù)進(jìn)行低溫共振柱試驗(yàn),測(cè)試結(jié)果離散性小且可靠性高。使用先進(jìn)可靠的低溫共振柱試驗(yàn)技術(shù),研究負(fù)溫下三種典型土類動(dòng)剪切模量阻尼比變化的基本模式,并提出溫度修正系數(shù)及其計(jì)算方法。結(jié)果表明,無(wú)論何種土類,負(fù)溫對(duì)其初始剪切模量、剪切模量比和阻尼比都有重要影響,相應(yīng)的溫度修正系數(shù)按Boltzmann與指數(shù)函數(shù)變化,均在0℃到-6.0℃快速變化之后趨于平緩,但變化程度和修正公式中的參數(shù)均與土類有關(guān)。開展對(duì)不同含水率、負(fù)溫的三種典型土類試樣的低溫共振柱試驗(yàn),研究了負(fù)溫及含水率對(duì)修正系數(shù)的影響,給出了考慮含水率修正系數(shù)及計(jì)算方法。結(jié)果表明,對(duì)某一種土,雙因素(含水率和負(fù)溫)的修正系數(shù)曲面形態(tài)主要受負(fù)溫項(xiàng)控制,含水率項(xiàng)影響較小;而對(duì)不同土類,曲面形態(tài)相近但數(shù)值不同。在含圍壓環(huán)境下對(duì)三種土類試樣進(jìn)行凍融循環(huán),測(cè)試它們的低溫動(dòng)剪切模量和阻尼比,研究其凍融循環(huán)修正系數(shù)的變化規(guī)律。結(jié)果表明,修正系數(shù)變化規(guī)律與土類有關(guān);不論哪一種土,凍融循環(huán)對(duì)其剪切模量阻尼比均有弱化作用,工程上需要采取措施減輕這種弱化作用。建立Ⅰ、Ⅱ類場(chǎng)地含凍土層理想土層模型,使用國(guó)內(nèi)廣泛使用的等效線性化程序進(jìn)行計(jì)算。結(jié)果表明,多數(shù)情況下凍土層對(duì)Ⅰ、Ⅱ類場(chǎng)地有減震作用,而且隨著凍深的增厚,減震效果更加顯著;Ⅰ類場(chǎng)地低烈度下一些工況中凍土層會(huì)增強(qiáng)地震動(dòng),這與德都地震群震害現(xiàn)象有類同之處。
[Abstract]:With the improvement of national economic construction, the layout of "Belt and Road" strategy, the traffic network and housing construction projects in cold areas are increasing day by day. In the process of construction, many problems such as foundation vibration analysis and seismic hazard risk assessment are faced with. The dynamic performance of frozen soil, which has been paid less attention in the past, has been paid more and more attention because of the limitations of the research conditions. The reliability of the damping ratio of dynamic shear modulus of frozen soil obtained by triaxial test at low temperature needs to be improved. In this paper, the experimental technology of low temperature resonant column is explored with the first low temperature resonance column instrument as the test platform, and the clay, clay, clay, clay, clay, clay, clay, clay, clay, clay, clay, clay, clay, clay, A series of resonance column tests with different temperature, moisture content and freeze-thaw cycle times were carried out for silt and sandy soils, and the variation model and regularity of the damping ratio parameters of dynamic shear modulus of silt and sandy soil were summarized. The seismic response of type 鈪，

本文編號(hào)：1545123