本文關(guān)鍵詞：全風(fēng)化花崗巖試驗(yàn)及本構(gòu)模型研究　出處：《華南理工大學(xué)》2016年博士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 全風(fēng)化花崗巖 三軸試驗(yàn) 本構(gòu)模型 臨界狀態(tài)

【摘要】：全風(fēng)化花崗巖在我國(guó)華南地區(qū)分布十分廣泛,是工程建設(shè)中常見(jiàn)的巖土材料與工程載體。然而,由于對(duì)全風(fēng)化花崗巖沒(méi)有全面的了解以及深入、系統(tǒng)的研究,導(dǎo)致在工程建設(shè)中頻繁發(fā)生事故,對(duì)工程安全以及人民生命財(cái)產(chǎn)安全造成威脅�？梢�(jiàn),開(kāi)展對(duì)全風(fēng)化花崗巖全面、系統(tǒng)的研究工作意義重大且迫在眉睫。本文以深圳地區(qū)全風(fēng)化花崗巖為研究對(duì)象,對(duì)其展開(kāi)了全面的基本物理性質(zhì)試驗(yàn)研究以及三軸試驗(yàn)研究,并提出了適用于原狀全風(fēng)化花崗巖的修正結(jié)構(gòu)性劍橋模型以及適用于重塑全風(fēng)化花崗巖的雙邊界面模型,為相關(guān)的工程應(yīng)用提供參考和依據(jù)。基本物理性質(zhì)試驗(yàn)包括比重試驗(yàn)、含水率試驗(yàn)、界限含水率試驗(yàn)、擊實(shí)試驗(yàn)、顆粒分析試驗(yàn)、礦物成分分析試驗(yàn)以及化學(xué)成分分析試驗(yàn)。根據(jù)試驗(yàn)結(jié)果可知,土樣的礦物成分以石英和高嶺石為主,其他礦物含量較少,土體為級(jí)配不良的不均勻土,可分類為粉粘土質(zhì)砂土,風(fēng)化程度為全風(fēng)化,即土樣為全風(fēng)化花崗巖。三軸試驗(yàn)包括原狀土的各向等壓加載試驗(yàn)、固結(jié)排水試驗(yàn)以及固結(jié)不排水試驗(yàn);重塑土的各向等壓加卸載試驗(yàn)、固結(jié)排水試驗(yàn)、固結(jié)不排水試驗(yàn)、等p’剪切試驗(yàn)、不同固結(jié)狀態(tài)下(偏壓固結(jié))的不排水試驗(yàn)以及不同超固結(jié)比下的不排水試驗(yàn);摻水泥重塑土的各向等壓加載試驗(yàn)以及固結(jié)排水試驗(yàn)。重塑土三軸試驗(yàn)結(jié)果表明其應(yīng)力應(yīng)變關(guān)系特征符合臨界狀態(tài)土力學(xué)理論,故首先采用修正劍橋模型對(duì)重塑土固結(jié)不排水以及固結(jié)排水試驗(yàn)進(jìn)行模型計(jì)算。模型計(jì)算結(jié)果與試驗(yàn)曲線的對(duì)比表明,修正劍橋模型在模擬本文所研究的全風(fēng)化花崗巖重塑土力學(xué)行為時(shí)主要存在以下幾點(diǎn)不足:1)不能計(jì)算各向等壓加卸載試驗(yàn)中再加載過(guò)程土體產(chǎn)生的塑性變形;2)不能準(zhǔn)確地計(jì)算固結(jié)不排水試驗(yàn)中的孔壓,且不能模擬土樣在剪切過(guò)程中發(fā)生的相變現(xiàn)象;3)不能準(zhǔn)確地計(jì)算較高圍壓下固結(jié)排水試驗(yàn)中的體變。為此,本文基于臨界狀態(tài)理論與邊界面彈塑性土力學(xué)理論,同時(shí)考慮了狀態(tài)參數(shù)?對(duì)剪脹系數(shù)的影響,在偏應(yīng)力q-平均有效主應(yīng)力p’坐標(biāo)平面中建立了一個(gè)雙邊界面模型,并在matlab軟件中編寫(xiě)了模型代碼。模型計(jì)算結(jié)果與試驗(yàn)的對(duì)比表明,相對(duì)于修正劍橋模型而言,本文雙邊界面模型能夠準(zhǔn)確地計(jì)算各向等壓加卸載試驗(yàn)中再加載過(guò)程土體產(chǎn)生的塑性變形;能夠更準(zhǔn)確地計(jì)算固結(jié)不排水試驗(yàn)孔壓曲線,且能夠模擬剪切過(guò)程中發(fā)生的相變現(xiàn)象;能夠在一定程度上計(jì)算不同超固結(jié)比下不排水剪切試驗(yàn)應(yīng)力應(yīng)變關(guān)系曲線,比修正劍橋模型計(jì)算曲線更接近試驗(yàn)曲線。可見(jiàn),對(duì)于所研究的重塑全風(fēng)化花崗巖而言,相比于修正劍橋模型,本文提出的雙邊界面模型能更好地模擬其力學(xué)特性。原狀土與摻水泥重塑土都有著土體初始結(jié)構(gòu),為結(jié)構(gòu)性土,首先采用應(yīng)用較為廣泛的結(jié)構(gòu)性劍橋模型對(duì)其固結(jié)排水試驗(yàn)進(jìn)行模型計(jì)算。模型計(jì)算結(jié)果與試驗(yàn)曲線的對(duì)比表明,結(jié)構(gòu)性劍橋模型在模擬所研究的結(jié)構(gòu)性全風(fēng)化花崗巖力學(xué)行為時(shí)主要存在以下幾點(diǎn)不足:1)模型不能準(zhǔn)確地計(jì)算低圍壓下的峰值偏應(yīng)力,且不能較好地模擬土體在低圍壓下剪切過(guò)程中產(chǎn)生的剪脹;2)當(dāng)圍壓較高時(shí),模型計(jì)算得出的體應(yīng)變偏大,導(dǎo)致通過(guò)流動(dòng)法則計(jì)算得出的剪應(yīng)變也會(huì)偏大,以致土體在塑性階段偏應(yīng)力增量變化不大的情況下,計(jì)算得到的剪應(yīng)變?cè)隽科?模型偏應(yīng)力曲線與試驗(yàn)曲線差別較大。為此,本文在結(jié)構(gòu)性劍橋模型的基礎(chǔ)上,對(duì)其屈服函數(shù)以及塑性體應(yīng)變的計(jì)算兩個(gè)方面做了適當(dāng)?shù)男拚?將修正后的模型稱為“修正結(jié)構(gòu)性劍橋模型”,并在matlab軟件中編寫(xiě)了模型代碼。模型計(jì)算結(jié)果與試驗(yàn)曲線的對(duì)比表明,相對(duì)于結(jié)構(gòu)性劍橋模型而言,本文模型能更準(zhǔn)確地計(jì)算土體在低圍壓下的峰值偏應(yīng)力,也能更好地模擬低圍壓下產(chǎn)生的剪脹;高圍壓下的計(jì)算偏應(yīng)力曲線與體變曲線也更接近試驗(yàn)曲線�？梢�(jiàn),對(duì)于所研究的結(jié)構(gòu)性全風(fēng)化花崗巖而言,相比于結(jié)構(gòu)性劍橋模型,本文提出的模型能更好地模擬其力學(xué)特性。
[Abstract]:All weathered granite is widely distributed in the Southern China area of China. It is a common geotechnical material and engineering carrier in the construction of engineering. However, due to the lack of a comprehensive understanding of deep weathered granite and thorough and systematic research, accidents happen frequently in engineering construction, which pose a threat to engineering safety and people's life and property safety. Therefore, it is of great significance and imminent to carry out the comprehensive and systematic research on the fully weathered granite. This article takes the Shenzhen area of whole weathered granite as the object of study, carried out experimental study on basic physical properties and comprehensive experimental research on the three axis, and puts forward suitable undisturbed weathered granite modified structural model and interface model for bilateral Cambridge to reshape the whole weathered granite, and provide reference for the related engineering applications. The basic physical properties tests include specific gravity test, moisture content test, limiting moisture content test, compaction test, particle analysis, mineral composition analysis and chemical composition analysis. According to the test results, the mineral composition of the soil samples is mainly composed of quartz and kaolinite, and the other minerals are few. The soil is uneven soil with poor gradation. It can be classified as silty clay sand. The weathering degree is totally weathered, namely the soil sample is completely weathered granite. Three axis test including undisturbed soil under isotropic loading test, consolidation test and consolidated undrained test; isotropic loading test, consolidation test, consolidation of remolded soil undrained tests, P shear test, different consolidation conditions (consolidated undrained test) and different overconsolidation ratios under undrained test; cement remolded the isotropic loading test and consolidation test. The results of three axis test of remolded soil show that the relationship between stress and strain is in accordance with the theory of critical state soil mechanics. First, the modified Cambridge model is applied to calculate the consolidation and drainage of remolded soil and consolidation drainage test. Compared the calculation results of the model and experimental curve, the whole weathered granite of remolded soil mechanical behavior research in the simulation of the modified Cambridge model mainly exist the following problems: 1) could not calculate the isotropic loading and unloading tests in the loading process of soil produced by plastic deformation; 2) cannot accurately calculate the consolidated undrained test the pore pressure, phase transition and cannot simulate the soil in the cutting process; 3) cannot be accurately calculated under high confining pressure consolidation test in volume change. Therefore, the theory and the boundary surface elasto-plastic critical state soil mechanics based on the theory, considering the state parameters? Of dilatancy coefficient, the deviatoric stress q- effective mean principal stress of P 'coordinate plane to establish a bilateral interface model, and compile the code model in MATLAB software. Compared with the calculation results of the model test, compared with the modified Cambridge model, the bilateral interface model can accurately calculate isotropic loading and unloading tests in the loading process of soil produced by plastic deformation; able to accurately calculate the consolidated undrained test pore pressure curve, and can simulate the phase transition phenomenon occurs in the shearing process; to a certain extent, calculating different overconsolidation ratios under undrained shear test stress-strain curve, than the modified Cambridge model is more close to the calculated curve test curve. It can be seen that for the studied remolded fully weathered granite, compared with the modified Cambridge model, the bilateral interface model proposed in this paper can better simulate its mechanical properties. The original structure of undisturbed soil and cement mixed remolded soil has the initial structure of soil. For the structured soil, the model of the consolidation and drainage test is firstly calculated by the widely used structural Cambridge model. Compared the calculation results of the model and experimental curve, the structural model of Cambridge in the simulation of structural mechanical behavior of weathered granite mainly exist the following problems: 1) model can not accurately calculate the peak under low confining pressure and deviatoric stress, can better simulate soil dilatancy under low confining pressure generated under the shearing process; 2) when the confining pressure is higher, the volume strain model calculation is too large, resulting in the shear strain calculated by flow rule will be too large, so that the soil in the plastic stage of deviatoric stress increment is not the case, the calculated shear strain increment is too large, the model should be partial the force curve and test curve difference. For this reason, based on the structural Cambridge model, this paper corrections the yield function and the calculation of plastic strain in two aspects. The modified model is called the modified structural Cambridge model, and the model code is compiled in MATLAB software. Compared the calculation results of the model and experimental curve, relative to the Cambridge structural model, this model can accurately calculate the soil under low confining pressure under peak deviatoric stress, also can better simulate the low confining pressure under the dilatancy; partial stress curve and the volume change curve is closer to the test curve of high confining calculation of pressure. It can be seen that, for the structural fully weathered granite, compared with the structural Cambridge model, the model proposed in this paper can better simulate its mechanical properties.
【學(xué)位授予單位】：華南理工大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2016
【分類號(hào)】：TU45

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本文編號(hào)：1347347