本文選題：紅黏土 + 側(cè)限條件　； 參考：《東華理工大學(xué)》2017年碩士論文

【摘要】：土是非連續(xù)、非均勻、各向異性體,它是在各種復(fù)雜地質(zhì)環(huán)境中經(jīng)過(guò)漫長(zhǎng)的地質(zhì)作用而孕育形成的,外界環(huán)境的變遷會(huì)使其物理力學(xué)性質(zhì)發(fā)生質(zhì)的變化。對(duì)于工程建設(shè)而言,土的承載力是最普遍、最重要的力學(xué)參數(shù),實(shí)驗(yàn)室內(nèi)通常借助壓縮試驗(yàn)來(lái)研究土體強(qiáng)度及變形特性。在自然界中,埋藏在地表深部的巖土體通常處于全圍壓受力狀態(tài),從側(cè)限角度上講即處于全側(cè)限受壓狀態(tài)。除此之外,自然界中以及工程建設(shè)中還分布著處于各種不同的側(cè)限受壓條件下的巖土體,參照臨空面的數(shù)量和相對(duì)位置關(guān)系可將側(cè)限受壓工況劃分為:(1)無(wú)側(cè)限受壓工況;(2)單面?zhèn)认奘軌汗r;(3)鄰面?zhèn)认奘軌汗r;(4)對(duì)面?zhèn)认奘軌汗r;(5)三面?zhèn)认奘軌汗r;(6)完全(四面)側(cè)限6種受壓工況。然而,現(xiàn)有的試驗(yàn)條件只能模擬無(wú)側(cè)限受壓和完全側(cè)限受壓工況下巖土體強(qiáng)度、變形特征,而無(wú)法適用于其他側(cè)限工況下巖土體的試驗(yàn)測(cè)試需求。基于此,本文以國(guó)家自然科學(xué)基金項(xiàng)目“極端降雨作用下紅壤土坡響應(yīng)試驗(yàn)與災(zāi)變機(jī)理研究”(項(xiàng)目編號(hào):41462011)為依托,以江西省南昌市典型的第四系紅黏土為研究對(duì)象,通過(guò)自主研發(fā)一種側(cè)限可調(diào)節(jié)式巖土體豎向壓縮輔助試驗(yàn)裝置,將其與液壓伺服壓力機(jī)相結(jié)合,分別開(kāi)展不同基本物理力學(xué)性質(zhì)、不同側(cè)限條件下紅黏土的豎向壓縮試驗(yàn)。著重研究了重塑紅黏土試樣對(duì)部分側(cè)限條件的力學(xué)響應(yīng)特征,并借助先進(jìn)的數(shù)值模擬試驗(yàn)手段構(gòu)建計(jì)算模型,以期從豎向應(yīng)力與應(yīng)變、及剪切應(yīng)變率的發(fā)展演化等角度全面分析不同側(cè)限工況下巖土體受壓過(guò)程中所表現(xiàn)出的差異性。通過(guò)室內(nèi)側(cè)限豎向壓縮試驗(yàn)和FLAC3D數(shù)值模擬試驗(yàn)相結(jié)合,經(jīng)對(duì)比分析,較為準(zhǔn)確地分析了紅黏土在各種復(fù)雜工況下的變形及強(qiáng)度特征。該研究將為進(jìn)一步豐富巖土工程地下空間的利用開(kāi)發(fā)理論提供有益的借鑒。本文的主要工作與研究成果如下:(1)在江西省南昌市經(jīng)濟(jì)開(kāi)發(fā)區(qū)某段公路施工處采集到大量紅黏土試樣,對(duì)紅黏土進(jìn)行室內(nèi)基本物理力學(xué)性質(zhì)試驗(yàn),從而獲取紅黏土的顆粒級(jí)配、塑限WP、液限WL、黏聚力c、內(nèi)摩擦角φ等基本物理力學(xué)參數(shù)。(2)通過(guò)對(duì)不同初始含水率、不同最終含水率和不同干密度的紅黏土開(kāi)展六種側(cè)限工況下的豎向壓縮試驗(yàn),并對(duì)各類側(cè)限條件下的紅黏土應(yīng)力-應(yīng)變關(guān)系發(fā)展演化特征進(jìn)行了階段性劃分,剖析了其變化機(jī)理。(3)隨著最終含水率的增加,無(wú)側(cè)限、單面、對(duì)面和四面?zhèn)认藜t黏土峰值強(qiáng)度均呈現(xiàn)出先升高后降低的規(guī)律。當(dāng)最終含水率一定時(shí),紅黏土殘余強(qiáng)度在各側(cè)限條件的大小關(guān)系為:無(wú)側(cè)限單面?zhèn)认迣?duì)面?zhèn)认捺徝鎮(zhèn)认奕鎮(zhèn)认蕖＜t黏土的峰值強(qiáng)度、殘余強(qiáng)度、峰值應(yīng)變和壓縮模量總體上均隨干密度的增大而增大。(4)對(duì)室內(nèi)紅黏土側(cè)限豎向壓縮試驗(yàn)進(jìn)行FLAC3D數(shù)值模擬試驗(yàn),針對(duì)紅黏土立方體試樣及試驗(yàn)條件的實(shí)際受壓工況,采用正六面體模型,實(shí)現(xiàn)模擬立方體在無(wú)、單面、鄰面、對(duì)面、三面以及四面?zhèn)认逘顟B(tài)下的響應(yīng)機(jī)理試驗(yàn)研究,通過(guò)對(duì)數(shù)值模擬和室內(nèi)試驗(yàn)的試驗(yàn)結(jié)果進(jìn)行對(duì)比分析,發(fā)現(xiàn)數(shù)值模擬和室內(nèi)試驗(yàn)的結(jié)果一致性較好,證明了數(shù)值模擬方法的可靠性和有效性,也較好例證了當(dāng)室內(nèi)外試驗(yàn)條件難以達(dá)到時(shí)借助FLAC3D數(shù)值模擬手段來(lái)完成試驗(yàn)分析的可行性。
[Abstract]:Soil is a non continuous, nonuniform, anisotropic body, which is conceived by a long geological process in various complex geological environments. The changes in the external environment will make the physical and mechanical properties change qualitatively. For engineering construction, the soil bearing capacity is the most common and most important mechanical parameter, usually in the laboratory with the aid of compression. The soil strength and deformation characteristics are studied in the experiment. In nature, the rock and soil buried in the deep surface of the earth are usually in the state of full confining pressure. From the lateral point of view, the rock and soil are in the state of the full lateral pressure. In addition, in nature and in the construction, the rock and soil under the different lateral confinement conditions are also distributed in the engineering construction. The relationship between the number and relative position of the plane can be divided into: (1) unconfined compression conditions; (2) unilateral side limited compression conditions; (3) side limited compression working conditions of adjacent surface; (4) face side limited pressure condition; (5) three side side limit compression conditions; (6) completely (four sides) side limit 6 compression conditions. However, the existing test conditions can only simulate the unconfined limit. The strength and deformation characteristics of rock and soil soil under compression and full lateral confinement can not be applied to the test and test requirements of rock and soil under other conditions. Based on this, this paper is based on the National Natural Science Foundation Project "response test and catastrophe mechanism study of red soil slope under extreme rainfall" (project number: 41462011), and Jiangxi The typical Quaternary red clay in Nanchang province is the research object. By independently developing a side limited adjustable rock soil vertical compression auxiliary test device, it is combined with the hydraulic servo press to carry out the vertical compression test of red clay under different basic physical and mechanical properties and different side limits. The emphasis is on the study of remolding red viscosity. The mechanical response characteristics of the soil specimen to some side limit conditions and the advanced numerical simulation test method are used to construct the calculation model in order to analyze the difference in the rock and soil compression process under the different side limit conditions from the angle of vertical stress and strain and the development and evolution of shear strain rate. The deformation and strength characteristics of red clay under various complex conditions are analyzed accurately by the combination of test and FLAC3D numerical simulation test. This study will provide useful reference for further enriching the theory of underground space utilization and development of geotechnical engineering. The main work and research results of this paper are as follows: (1) in the south of Jiangxi Province A large number of red clay samples were collected at a section of highway construction in Changshi Economic Development Zone, and the basic physical and mechanical properties of red clay were tested, and the basic physical and mechanical parameters, such as particle size distribution of red clay, plastic limit WP, liquid limit WL, cohesive C, internal friction angle, etc. were obtained. (2) different water cut rates and no final water content were obtained by different initial water content. The vertical compression test of the red clay with the same dry density was carried out under six side limit conditions, and the evolution characteristics of the stress strain relationship of red clay under different side conditions were divided and the change mechanism was analyzed. (3) with the increase of the final water content, the peak strength of the unconfined, single side, opposite and four sides of the red clay was all present. When the final water content is certain, the relationship between the residual strength of the red clay at all side limits is that the side limit of the unconfined single side side limits the side limit of the side limit of the opposite side of the three side side limits. The peak strength, the residual strength, the peak strain and the compressive modulus of the red clay increase with the increase of the dry density. (4) to the room The vertical compression test of red clay side limit is carried out by FLAC3D numerical simulation test. In view of the actual compression conditions of red clay cubes and test conditions, the positive hexahedron model is adopted to study the response mechanism of the simulated cube under the condition of no, single, adjacent, opposite, three and four sides, through the numerical simulation and the indoor test. The experimental results are compared and analyzed. It is found that the results of the numerical simulation and the laboratory test are in good agreement, which proves the reliability and effectiveness of the numerical simulation method. It also exemplifies the feasibility of completing the test analysis with the help of FLAC3D numerical simulation when the test conditions are difficult to reach in the room.

【學(xué)位授予單位】：東華理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TU446

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