凍風(fēng)積土的塑性損傷閾值及演化規(guī)律
本文選題:道路工程 切入點(diǎn):塑性損傷閾值 出處:《公路交通科技》2017年09期
【摘要】:為了獲取凍風(fēng)積土在循環(huán)逐級(jí)加載過程中發(fā)生的動(dòng)力損傷特征,通過對(duì)不同負(fù)溫、圍壓及振動(dòng)頻率條件下的凍風(fēng)積土試樣進(jìn)行動(dòng)三軸試驗(yàn),測(cè)得其動(dòng)應(yīng)力-應(yīng)變曲線。按照凍風(fēng)積土發(fā)生各向同性損傷及塑性應(yīng)變?cè)隽看怪庇谇娴幕炯僭O(shè),利用塑性勢(shì)函數(shù)F(Y,D,σ)相關(guān)聯(lián)流動(dòng)法則并按照R-O硬化定律建立了凍風(fēng)積土加載過程中塑性損傷演化模型(P模型)。利用文中提出的有效應(yīng)力分析方法對(duì)試驗(yàn)所測(cè)得總動(dòng)應(yīng)變中所包含的累積塑性變形部分進(jìn)行分離,實(shí)現(xiàn)了對(duì)P模型中參數(shù)擬合的目標(biāo);根據(jù)一、三主應(yīng)力對(duì)D-P屈服邊界進(jìn)行劃分以確定加載過程中彈塑性變形特征。通過分析裂隙發(fā)展規(guī)律研究?jī)鲲L(fēng)積土內(nèi)部塑性損傷演化過程,將累積塑性變形變化率曲線的拐點(diǎn)作為凍風(fēng)積土發(fā)生塑性損傷的閾值,給出了確定初始發(fā)生塑性損傷的理論依據(jù)。研究結(jié)果表明:P模型與相關(guān)文獻(xiàn)模型確定的塑性損傷變量變化規(guī)律具有一致性,為凍風(fēng)積土路基或基礎(chǔ)的動(dòng)力災(zāi)害防治研究提供理論基礎(chǔ)。
[Abstract]:In order to obtain the dynamic damage characteristics of frozen aeolian soil during cyclic progressive loading, dynamic triaxial tests were carried out on frozen aeolian soil samples under different negative temperature, confining pressure and vibration frequency. According to the assumption that isotropic damage of frozen aeolian soil occurs and plastic strain increment perpendicular to yield surface, the dynamic stress-strain curves are obtained. The plastic damage evolution model of frozen aeolian soil during loading is established by using the associated flow rule of plastic potential function FKY D, 蟽) and according to R-O hardening law. The total motion measured by the effective stress analysis method proposed in this paper is obtained by using the effective stress analysis method proposed in this paper. The cumulative plastic deformation part contained in the strain is separated, The objective of parameter fitting in P model is achieved, D-P yield boundary is divided according to the first and third principal stresses to determine the elastoplastic deformation characteristics during loading. The evolution process of plastic damage in frozen aeolian soil is studied by analyzing the law of fracture development. The inflection point of the curve of cumulative plastic deformation rate is used as the threshold of plastic damage of frozen aeolian soil. The theoretical basis for determining the initial plastic damage is given. The research results show that the variation law of plastic damage variables determined by the proportion P model is consistent with that of the related literature model. It provides a theoretical basis for the study of dynamic disaster prevention of frozen aeolian soil subgrade or foundation.
【作者單位】: 遼寧工程技術(shù)大學(xué)土木工程學(xué)院;
【基金】:國(guó)家自然科學(xué)基金項(xiàng)目(51504125) 高等學(xué)校博士學(xué)科點(diǎn)專項(xiàng)科研基金聯(lián)合項(xiàng)目(20112121110004)
【分類號(hào)】:U416.1
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