本文選題：靜載試驗 + 剛性基礎(chǔ)　； 參考：《西南交通大學(xué)》2017年碩士論文

【摘要】：隨著我國基礎(chǔ)設(shè)施建設(shè)的蓬勃發(fā)展,各種建筑物拔地而起,然而所有的建筑的安全建設(shè)與運營都離不開穩(wěn)固的地基,因此地基土的變形特性是一個重要的研究內(nèi)容。本文依托"中國鐵路總公司科技研究開發(fā)計劃課題"《超深大截面沉井基礎(chǔ)設(shè)計理論及關(guān)鍵技術(shù)研究》,通過室內(nèi)模型靜載試驗為主,數(shù)值模擬為輔的研究方法,設(shè)計制作了試驗槽和3個不同尺寸的混凝土模型及對應(yīng)的剛性底板,開展了 5組不同基礎(chǔ)寬度和不同埋深條件下的靜載試驗,通過位移計和土壓力傳感器監(jiān)測整個試驗加載過程中基礎(chǔ)沉降數(shù)據(jù)和土中附加應(yīng)力數(shù)據(jù),對砂土地基在不同基礎(chǔ)寬度、不同埋深剛性基礎(chǔ)作用下,地基土的破壞過程,加載過程中的基底應(yīng)力分布及變化規(guī)律,土中的應(yīng)力分布及變化規(guī)律,加載至破壞后卸載回彈變形規(guī)律以及重復(fù)加載時土體承載特性進行研究。得到以下結(jié)論:(1)通過靜載試驗和數(shù)值模擬計算發(fā)現(xiàn),砂土地基的破壞具有明顯漸進破壞特征�；讘�(yīng)力隨著地基土的漸進破壞出現(xiàn)顯著的重分布。在荷載施加初期,基底應(yīng)力分布均為均勻增長;隨著加載過程的進行,當(dāng)荷載增加到比例界限時,5組試驗均出現(xiàn)了基底邊緣應(yīng)力不再因荷載增加而上升,說明基底邊緣土體發(fā)生破壞,失去承載能力,隨著荷載的繼續(xù)增加到極限荷載,基底應(yīng)力峰值由基礎(chǔ)外圍向基礎(chǔ)中心移動,說明破壞范圍逐漸增大,此時承載力主要由基礎(chǔ)中心附近土體提供。(2)在加載初期,土中的豎向附加應(yīng)力基本成均勻增長;當(dāng)各組試驗加載到比例界限時,由于基底邊緣土體破壞,基底實際發(fā)揮承載能力土體的面積減小,基礎(chǔ)中心下方土體的豎向附加應(yīng)力大幅高于基底邊緣位置土體,距基底較遠的土體規(guī)律相似,但變化幅度不如基底附近土體。(3)在加載初期,土中的水平附加應(yīng)力基本成均勻增長,土中水平應(yīng)力的峰值最先在上部出現(xiàn),隨著荷載的增加逐漸向下移動,加載到極限荷載時,基礎(chǔ)邊緣位置下方土中的水平附加應(yīng)力峰值出現(xiàn)在基底以下1倍基礎(chǔ)寬度的位置;基礎(chǔ)邊緣向外0.5倍基礎(chǔ)寬度位置下方土中的水平附加應(yīng)力峰值出現(xiàn)在基底以下1.5倍基礎(chǔ)寬度的位置。(4)根據(jù)土中豎向附加應(yīng)力圖分析計算可得,試驗條件下,基底豎向附加應(yīng)力擴散角θ為18.4°026.6°,與《建筑地基基礎(chǔ)設(shè)計規(guī)范》(GB50007-2011)規(guī)定相符。(5)5組試驗所得卸載回彈曲線非常平緩,總體回彈量在10mm左右且大部分回彈變形發(fā)生在卸載的最后階段。基礎(chǔ)寬度和埋深對地基回彈變形有影響,對比不同基礎(chǔ)寬度時發(fā)現(xiàn),在卸荷比相同時,基礎(chǔ)寬度越大回彈量越小;對比不同埋深時發(fā)現(xiàn),卸荷比相同時,零埋深組的回彈量小于兩組有埋深組,但0.5倍基礎(chǔ)寬度埋深和1倍基礎(chǔ)寬度埋深卸載回彈規(guī)律基本相同。(6)重復(fù)加載時發(fā)現(xiàn),地基在發(fā)生整體破壞之后依然具有承載能力,且承載能力較初次加載時有大幅度提高,土的壓縮模量比初次加載時提高了 1.84～2.25倍,基礎(chǔ)寬度和埋深對地基土壓縮模量有影響,不同基礎(chǔ)寬度的對比分析中可知,隨著基礎(chǔ)寬度的增加,壓縮模量比逐漸增大,且基本呈線性增長;不同埋深的對比分析中可知,隨著基礎(chǔ)埋深的增加,壓縮模量比逐漸增大,且呈非線性增長,基礎(chǔ)埋深越大,壓縮模量比增長越快。
[Abstract]:With the rapid development of our country's infrastructure construction, various buildings have sprung up, but the safety of construction and operation of all buildings all cannot do without a solid foundation, so the deformation characteristics of the foundation soil is an important research topic. This paper is based on China railway company of science and technology research and development program "< ultra deep caisson section the basic design theory and key technology research", the static load test with the indoor model, numerical simulation, research methods, design of rigid plate test groove and 3 different sizes and the corresponding concrete model, carry out the static load test of 5 groups of different base width and different depth conditions, through the data and additional stress in soil foundation settlement monitoring data displacement meter and soil pressure sensor test whole loading process of sand foundation in different base width, different depth of rigid foundation. Next, the failure process of foundation soil, substrate loading process of stress distribution and variation of soil stress distribution and variation of load to the unloading deformation and damage after repeated loading when the soil bearing was investigated. Get the following conclusions: (1) through static load tests and numerical simulation calculation the destruction, sandy soil has obvious characteristics of progressive failure. The base stress of foundation soil with progressive failure appeared significant redistribution. In the early days of the applied load, the stress distribution is uniform basal growth; with the loading process, when the load increased to proportional limit, 5 groups were the basal edge stress no longer due to the load increased, indicating the substrate edge soil damage, loss of bearing capacity, continue to increase with the load to the limit load, the stress of the base peak by the basic foundation of the periphery to the center, said The damage range increases, the bearing capacity of foundation soil is mainly provided by near the center. (2) in the early stage of loading, vertical additional stress in soil basically uniform growth; when the load test were proportional to the limit, due to the destruction of the edges of the foundation soil, the actual use of the bearing capacity of soil basal area decreased, vertical base center the soil under the additional stress is significantly higher than the basal edge position of soil, soil from the base rules far similar, but the change range is less than the soil near the base. (3) in the early stage of loading, the soil level of additional stress of the soil into a uniform growth peak in the horizontal stress in the upper part of the first, with the load the increase gradually moving down, loaded into the ultimate load, foundation soil in the edge position below the level of additional stress peak in the basement below 1 times the width of foundation base edge position; outward 0.5 times the foundation The width of soil in the position below the level of additional stress peak in the basement below 1.5 times the width of the foundation position. (4) according to the analysis of additional stress can be calculated from vertical soil, under the condition of test, the basal vertical additional stress diffusion angle theta is 18.4 degrees 26.6 degrees, and < > (code for design of building foundation GB50007-2011) conformity. (5) 5 groups of tests of the unloading curve is very flat, the overall springback at around 10mm and most of springback deformation in the final stages of unloading. The foundation width and depth of influence on the deformation of foundation rebound, compared different base width, the unloading ratio is the same, the greater the width of foundation springback is smaller; comparison of different depth when the unloading ratio is the same, the springback zero depth group less than two group depth group, but 0.5 times the width of the foundation depth and 1 times the width of the foundation depth unloading rule base (6) repeat the same. When loading, the bearing capacity of foundation in the overall destruction is still, and the bearing capacity of a first load is greatly increased, the compression modulus of the soil than the initial load is increased by 1.84 to 2.25 times, the base width and the depth of the foundation soil compression modulus influence, unknown compared with the width of the foundation of with the increase of the width of the foundation, the compression modulus ratio increases gradually, and the linear growth; the comparative analysis of different depth, with the depth increasing, the ratio of compression modulus increases gradually, and nonlinear growth, the foundation depth greater than the compression modulus of the faster growth.

【學(xué)位授予單位】：西南交通大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TU470

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本文編號：1763005