本文選題：道路工程 + 路基　； 參考：《長安大學學報(自然科學版)》2017年04期

【摘要】：季節(jié)性凍土區(qū)活動層土體在寒季的凍結(jié)會引起與凍脹相關(guān)的工程病害,如埋設(shè)在凍土中的地基會隨凍脹的發(fā)展發(fā)生凍拔等。針對該問題,寒區(qū)工程一般選用螺旋樁來減輕影響。采用COMSOL Multiphysics軟件建立有限元模型,模擬單向凍結(jié)條件下螺旋樁-地基土系統(tǒng)的響應�？紤]水分、溫度、應力3種物理場的順序耦合,即自定義水分-溫度耦合計算模塊,在理查德方程中考慮冰水相變、冰對水分遷移的阻抗作用等,得到某時刻的全局體積含冰量分布,根據(jù)半經(jīng)驗模型建立凍脹量與體積含冰量、溫度之間的關(guān)系,用以計算應力場中凍脹、凍拔變形,得到應力與位移分布,最終實現(xiàn)水分、溫度、應力3個物理場的順序耦合。根據(jù)幾何對稱性,建立二維軸對稱計算模型。比選了3類螺旋樁(多葉片螺旋樁、寬葉片雙螺旋樁、窄葉片雙螺旋樁),并設(shè)置1組直線形樁作對照。計算結(jié)果表明:邊界溫度設(shè)為-15℃,經(jīng)過7d凍結(jié),土體凍深超過了樁的埋設(shè)深度,3種螺旋樁的凍拔位移小于直線形樁,證明了其減輕凍拔的作用;此時,螺旋樁底層葉片將承擔最多的應力,樁身可以傳遞更多的冷量到下部土層,促使樁周土體凍結(jié);通過對比不同樁形,總結(jié)出葉片布設(shè)的主要幾何參數(shù),即螺距、葉片寬度與數(shù)量及頂層葉片位置等對螺旋樁-地基土系統(tǒng)的凍拔響應會產(chǎn)生較大影響,并初步探索了寒區(qū)工程中一種基礎(chǔ)的抗凍拔措施。
[Abstract]:The freezing of active layer soil in seasonal frozen soil region will cause engineering diseases related to frost heaving, such as the foundation buried in frozen soil will be frozen and pulled out with the development of frost heave. In view of this problem, spiral pile is generally used to alleviate the influence in cold area engineering. A finite element model was established by using COMSOL Multiphysics software to simulate the response of spiral pile-soil system under unidirectional freezing. Considering the sequential coupling of moisture, temperature and stress, namely the self-defined water-temperature coupling calculation module, the ice water phase transition and the impedance of ice to water migration are considered in Richard's equation. The distribution of global volume ice content at a certain time is obtained. The relationship between frost heaving quantity and volume ice content and temperature is established according to the semi-empirical model, which can be used to calculate frost heaving and freezing drawing deformation in stress field, obtain stress and displacement distribution, and finally realize moisture content. The sequential coupling of three physical fields, temperature and stress. According to geometric symmetry, a two-dimensional axisymmetric model is established. Three kinds of spiral piles (multi-blade spiral pile, wide-blade double-helical pile, narrow blade double-helical pile) were compared and a group of linear piles were set as control. The calculation results show that the boundary temperature is -15 鈩，

本文編號：2023229