本文選題：黃土 + 各向異性　； 參考：《蘭州交通大學(xué)》2015年碩士論文

【摘要】：通過室內(nèi)應(yīng)變控制式三軸儀,測定蘭州榆中縣王家溝隧道水平方向與豎直方向上的抗剪強(qiáng)度各向異性,用軸向壓裂的方法測定水平與豎直方向上抗拉強(qiáng)度各向異性,測定蘭州九州重塑黃土在不同干密度不同含水量下的抗剪、抗拉強(qiáng)度,測定王家溝隧道與定西北二十里鋪隧道重塑黃土抗剪、抗拉強(qiáng)度。詳細(xì)對(duì)比分析黃土抗剪各向異性以及抗拉強(qiáng)度各向異性,含水量、干密度、粘聚力、內(nèi)摩擦角、孔隙比、飽和度等對(duì)黃土抗拉強(qiáng)度的影響,通過TanleCuver3D三維數(shù)據(jù)處理軟件,討論含水量與干密度、粘聚力與內(nèi)摩擦角、孔隙比與飽和度等雙重因素共同作用下對(duì)黃土抗拉強(qiáng)度的影響,通過對(duì)軸向壓裂法測定土體抗拉強(qiáng)度及試樣破壞模式進(jìn)行力學(xué)機(jī)理分析,討論傳統(tǒng)軸向壓力法計(jì)算黃土抗拉強(qiáng)度公式的適用性,針對(duì)黃土遇水結(jié)構(gòu)性減弱的特點(diǎn),分析黃土隧道開挖過程中易發(fā)生塌方事故的作用機(jī)理,探討黃土抗拉強(qiáng)度在隧道塌方事故中的應(yīng)用。結(jié)果表明:豎直方向上的無側(cè)限抗壓強(qiáng)度、抗拉強(qiáng)度以及抗剪強(qiáng)度均高于水平方向上,且提出黃土各向異性強(qiáng)度簡化幾何模型。黃土豎直最大偏差應(yīng)力與水平向最大偏差應(yīng)力比在低圍壓下較大,達(dá)到1.35左右,高圍壓下比值較小,僅有1.03左右,說明黃土各向異性在低圍壓下受影響較大,且低圍壓時(shí)黃土偏差應(yīng)力與應(yīng)變關(guān)系表現(xiàn)為應(yīng)變軟化,高圍壓時(shí)表現(xiàn)為應(yīng)變硬化規(guī)律,且水平向的塑性比豎直向的強(qiáng)。對(duì)傳統(tǒng)E-P模型進(jìn)行修正,將黃土試樣剪切破壞過程分為線彈性階段、彈塑性應(yīng)力峰值階段和塑性破壞階段,得出適合于有峰值出現(xiàn)的應(yīng)變軟化的模型,由試驗(yàn)結(jié)果按照硬化規(guī)律可將黃土分為強(qiáng)硬化、硬化、弱硬化、弱軟化、軟化、強(qiáng)軟化六類。黃土抗拉強(qiáng)度隨含水量的增大而減小,且成二次多項(xiàng)式形式,隨干密度的增大而增大,拉應(yīng)力達(dá)到抗拉強(qiáng)度時(shí)的軸向貫入深度在相同干密度條件下隨含水量的增大先減小后增大,在相同含水量條件下隨干密度增大先增大后減小。無側(cè)限抗壓強(qiáng)度與抗拉強(qiáng)度呈線性關(guān)系,且相關(guān)性較好,拉壓強(qiáng)度比的最大值出現(xiàn)在最優(yōu)含水量和最大干密度附近,最小值則出現(xiàn)在干密度最小處,含水量最大處。粘聚力與內(nèi)摩擦角正切值的乘積分別于抗拉強(qiáng)度與無側(cè)限抗壓強(qiáng)度呈冪指數(shù)關(guān)系�？估蜔o側(cè)限抗壓強(qiáng)度均隨空隙比、飽和度的增大而減小,飽和度和孔隙比分別對(duì)抗拉和無側(cè)限抗壓強(qiáng)度呈二次多項(xiàng)式關(guān)系。將抗拉幾何模型簡化為三類,第一,高干密度低含水量;第二,含水量和干密度居中;第三,低干密度高含水量。綜合影響因素對(duì)抗拉強(qiáng)度的結(jié)果表明:黃土抗拉強(qiáng)度受含水量、干密度雙重因素影響,含水量對(duì)抗拉強(qiáng)度的影響程度高于干密度,受飽和度與空隙比雙重因素影響,且飽和度對(duì)抗拉強(qiáng)度的影響高于空隙比,粘聚力和內(nèi)摩擦角方面,抗拉強(qiáng)度受粘聚力影響較大,受內(nèi)摩擦角影響較小。通過對(duì)抗拉強(qiáng)度力學(xué)特性分析可知,抗拉強(qiáng)度與粘聚力及無側(cè)限抗壓強(qiáng)度之間存在線性關(guān)系,由試驗(yàn)結(jié)果驗(yàn)證可知,無側(cè)限抗壓強(qiáng)度與抗拉強(qiáng)度之比接近13.8,抗拉強(qiáng)度與粘聚力之比接近0.22。隧道塌方分為淺埋整體塌方和深埋局部塌方,前者滿足摩爾-庫倫理論或廣義摩爾-庫倫理論,即塌方由抗剪強(qiáng)度不足引起,后者滿足最大伸長拉伸線應(yīng)變理論,即塌方由抗拉強(qiáng)度不足引起。
[Abstract]:The shear strength anisotropy in horizontal direction and vertical direction of Wangjia Gou tunnel, Yuzhong County, Lanzhou, is measured by three axis strain control instrument, and the anisotropy of tensile strength in horizontal and vertical direction is measured by axial fracturing, and the shear strength and tensile strength of Lanzhou Jiuzhou remolded loess under different dry density and different water content are measured. The shear resistance and tensile strength of the Wangjia tunnel and the northwest twenty Li Pu tunnel are determined. The influence of the shear anisotropy and the anisotropy of the tensile strength, water content, dry density, cohesive force, internal friction angle, pore ratio, saturation and so on on the tensile strength of loess are analyzed in detail, and the TanleCuver3D 3D data processing software is used to discuss the effect of the Loess The effects of water content and dry density, cohesive force and internal friction angle, pore ratio and saturation on tensile strength of loess are discussed. The mechanical mechanism of tensile strength of soil and failure mode of specimen is analyzed by axial fracturing method, and the applicability of traditional axial compression method to calculate the tensile strength formula of Loess is discussed. According to the characteristics of the structural weakening of the loess, the mechanism of the collapse accident in the excavation of the loess tunnel is analyzed, and the application of the tensile strength of the Loess in the tunnel collapse is discussed. The results show that the unconfined compressive strength in the vertical direction, the tensile strength and the shear strength are all higher than the horizontal direction, and the Loess anisotropy is put forward. The maximum deviations stress ratio of loess vertical maximum deviation stress and horizontal maximum deviation stress ratio under low confining pressure is larger, about 1.35, the ratio of high confining pressure is smaller, only about 1.03, indicating that the anisotropy of loess is greatly influenced by low confining pressure, and the relationship between stress and strain of loess is strain softening under low confining pressure. The high confining pressure is characterized by strain hardening law, and the horizontal plasticity is stronger than the vertical direction. The traditional E-P model is modified. The shear failure process of the Loess specimen is divided into linear elastic stage, the peak stage of elastoplastic stress and the stage of plastic failure, and the strain softening model suitable for peak occurrence is obtained, and the test results are in accordance with the hardened test results. The law can divide loess into six kinds: strong hardening, hardening, weak hardening, weak softening, softening, and strong softening. The tensile strength of loess decreases with the increase of water content, and becomes two polynomial form, which increases with the increase of dry density. The axial penetration depth of tensile stress reaches the same dry density and decreases with the increase of water content in the same dry density condition. In the same water content, it increases first and then decreases with the increase of dry density under the same water content. The unconfined compression strength is linear with the tensile strength, and the correlation is good. The maximum value of the tensile compression strength ratio appears near the optimal water content and the maximum dry density. The minimum value appears at the minimum dry density and the maximum water content. Cohesion and internal strength. The product of the tangent value of the friction angle has a power exponent relationship with the tensile strength and the unconfined compression strength respectively. The tensile and unconfined compressive strength decreases with the increase of the void ratio, the saturation and the void ratio, respectively. The tensile geometric model is simplified to the three class, the first and the high. Dry density is low water content, second, water content and dry density are middle, third, low dry density and high water content. The results of comprehensive influence factors on tensile strength show that the tensile strength of loess is influenced by water content and dry density, and the influence of water content on tensile strength is higher than that of dry density, and it is influenced by double factors of saturation and void ratio, and The influence of saturation on the tensile strength is higher than the void ratio, the cohesion and the internal friction angle, the tensile strength is greatly influenced by the cohesive force and less influenced by the internal friction angle. Through the analysis of the mechanical characteristics of the tensile strength, it is known that there is a linear relationship between the tensile strength and the cohesive force and the unconfined compression strength. The ratio of compressive strength to tensile strength is close to 13.8, and the ratio of tensile strength to cohesive force is close to 0.22. tunnel collapse divided into shallow buried whole collapse and deep buried local collapse. The former satisfies the Moore Kulun theory or the generalized Moore Kulun theory, that is, the collapse is caused by the lack of shear strength, and the latter satisfies the maximum elongation tension line strain theory, that is, the landslide. It is caused by the lack of tensile strength.

【學(xué)位授予單位】：蘭州交通大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：U452.11

【參考文獻(xiàn)】

相關(guān)博士學(xué)位論文 前1條

1 孫萍;黃土破裂特性試驗(yàn)研究[D];長安大學(xué);2007年

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本文編號(hào)：1892197