【摘要】：作為一種由松散顆粒積聚而成的多孔介質(zhì),天然狀態(tài)下的土體極易發(fā)生不可恢復(fù)的塑性變形。在很多情況下,這種變形不僅僅是由于外部荷載的改變引起,同時(shí)還和吸力及溫度變化密切相關(guān)。尤其是在一些特殊的巖土工程中,這種表現(xiàn)更為突出。例如,在地?zé)豳Y源開(kāi)發(fā)、高放廢物地質(zhì)處置、城市垃圾填埋場(chǎng)建設(shè)運(yùn)營(yíng)以及埋熱管道建設(shè)等眾多工程領(lǐng)域中,相應(yīng)的巖土材料都同時(shí)受到外部荷載、水以及熱的共同作用,這一特殊環(huán)境使得土體的變形特性變得更為復(fù)雜。 為了更好地認(rèn)識(shí)土體在熱-水-力耦合作用下的變形行為,并對(duì)其進(jìn)行定量化的描述,本文基于蔡國(guó)慶(2012)所建立的非飽和土熱-水-力耦合本構(gòu)模型對(duì)非等溫條件下非飽和土的變形特性進(jìn)行了模擬。通過(guò)開(kāi)展大量的文獻(xiàn)調(diào)研,首先綜述了溫度對(duì)非飽和土基本性質(zhì)影響的相關(guān)研究,包括試驗(yàn)研究和本構(gòu)模型,通過(guò)對(duì)現(xiàn)有研究成果進(jìn)行總結(jié),指出了現(xiàn)有研究存在的問(wèn)題和不足：隨后,對(duì)蔡國(guó)慶(2012)模型進(jìn)行了進(jìn)一步推導(dǎo)論證,給出了相應(yīng)的屈服條件、硬化規(guī)律及流動(dòng)法則,并完成了增量本構(gòu)方程的推導(dǎo)建立;最后,通過(guò)編制Fortran計(jì)算程序,實(shí)現(xiàn)了模型的預(yù)測(cè)功能,并利用試驗(yàn)數(shù)據(jù)對(duì)模型進(jìn)行了驗(yàn)證。 主要研究成果包括： (1)基于非飽和土熱-水-力耦合本構(gòu)模型,對(duì)各向同性條件下吸力和溫度對(duì)非飽和土變形性質(zhì)的影響進(jìn)行了預(yù)測(cè)和分析�；诮⒌目紤]溫度影響的非飽和土增量本構(gòu)方程,重點(diǎn)考察模型的固相變形部分,利用Fortran語(yǔ)言編制計(jì)算程序,對(duì)各向同性條件下非飽和土變形特性進(jìn)行預(yù)測(cè)。結(jié)果表明：在某一確定溫度下,吸力增加引起土體的屈服應(yīng)力的增大,當(dāng)溫度升高時(shí),吸力對(duì)土體的強(qiáng)化作用依然存在：在某一確定吸力下,溫度增加引起土體屈服應(yīng)力的減小,當(dāng)吸力增加時(shí),溫度對(duì)土體的弱化作用依然存在。通過(guò)模型預(yù)測(cè)與試驗(yàn)數(shù)據(jù)的對(duì)比,驗(yàn)證了本文所提模型在等向壓縮條件下的適用性。 (2)基于非飽和土熱-水-力耦合本構(gòu)模型,對(duì)三軸剪切條件下吸力和溫度對(duì)非飽和土變形性質(zhì)的影響進(jìn)行了預(yù)測(cè)和分析�；谏鲜霰緲�(gòu)模型,利用Fortran的語(yǔ)言編制計(jì)算程序,對(duì)三軸剪切條件下非飽和土變形特性進(jìn)行預(yù)測(cè)。結(jié)果表明,屈服應(yīng)力隨溫度的增加而減小,隨吸力的增加而增大。因此,溫度的升高對(duì)土體有軟化作用,吸力的增加對(duì)土體有硬化作用。另外,溫度越高,土體體積收縮越顯著,同樣,吸力的增加,也會(huì)導(dǎo)致土體體積的收縮更加顯著。通過(guò)模型預(yù)測(cè)與試驗(yàn)數(shù)據(jù)的對(duì)比,驗(yàn)證了本文所提模型在三軸剪切條件下的適用性。
[Abstract]:As a porous medium formed by the accumulation of loose particles, the soil in natural state is prone to irrecoverable plastic deformation. In many cases, the deformation is not only caused by the change of external load, but also closely related to the variation of suction and temperature. Especially in some special geotechnical engineering, this performance is more prominent. For example, in many engineering fields, such as geothermal resources development, high-level radioactive waste geological disposal, construction and operation of municipal solid waste landfills, and construction of buried heat pipelines, the corresponding geotechnical materials are subjected to the combined effects of external loads, water and heat at the same time. This special environment makes the deformation characteristics of soil more complex. In order to better understand the deformation behavior of soil under thermal-hydro-mechanical coupling, the deformation behavior of soil is described quantitatively. Based on the thermo-hydro-mechanical coupled constitutive model of unsaturated soil established by Cai Guoqing (2012), the deformation characteristics of unsaturated soil under non-isothermal condition were simulated. Based on a large number of literature studies, this paper first summarizes the relevant studies on the effects of temperature on the basic properties of unsaturated soils, including experimental studies and constitutive models, and summarizes the existing research results. The problems and shortcomings of the existing research are pointed out. Then, the Cai Guoqing (2012) model is further deduced and demonstrated, the corresponding yield condition, hardening law and flow rule are given, and the incremental constitutive equation is established. The prediction function of the model is realized by programming the Fortran program, and the model is verified by the experimental data. The main research results are as follows: (1) based on the thermo-hydro-mechanical coupling constitutive model of unsaturated soil, the effects of suction and temperature on the deformation properties of unsaturated soil under isotropic conditions are predicted and analyzed. Based on the incremental constitutive equation of unsaturated soil considering the influence of temperature, the solid deformation part of the model is investigated, and the deformation characteristics of unsaturated soil under isotropic condition are predicted by using Fortran language. The results show that under a certain temperature, the increase of suction causes the increase of yield stress of soil. When the temperature increases, the reinforcement of soil by suction still exists: under a certain suction, The soil yield stress decreases with the increase of temperature, and the weakening effect of temperature on soil remains when the suction increases. The applicability of the proposed model under the condition of isotropic compression is verified by comparing the model prediction with experimental data. (2) based on the thermo-hydro-mechanical coupling constitutive model of unsaturated soil, The effects of suction and temperature on the deformation properties of unsaturated soils under triaxial shear are predicted and analyzed. Based on the above constitutive model, the deformation characteristics of unsaturated soil under triaxial shear conditions are predicted by using Fortran language. The results show that the yield stress decreases with the increase of temperature and increases with the increase of suction. Therefore, the increase of temperature can soften the soil, and the increase of suction can harden the soil. In addition, the higher the temperature, the more significant the volume shrinkage of soil, the same, the increase of suction will lead to more significant shrinkage of soil volume. The applicability of the proposed model under triaxial shear condition is verified by comparing the model prediction with experimental data.
【學(xué)位授予單位】：北京交通大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類(lèi)號(hào)】：TU43

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