本文選題：空心圓柱扭剪儀 + 主應(yīng)力軸旋轉(zhuǎn)　； 參考：《浙江大學(xué)》2015年碩士論文

【摘要】：砂土在含主應(yīng)力軸旋轉(zhuǎn)的復(fù)雜應(yīng)力作用下的應(yīng)力應(yīng)變特性是當(dāng)今巖土工程研究的熱點與難點,有著較高的理論價值與工程價值。盡管考慮復(fù)雜應(yīng)力作用的本構(gòu)模型研究廣受重視,但是至今國內(nèi)外仍未有一個廣受認(rèn)可的相應(yīng)的本構(gòu)模型。本文基于試驗數(shù)據(jù)分析,以Manzari臨界狀態(tài)雙面彈塑性模型為基礎(chǔ)架構(gòu),在一定的理論推導(dǎo)與假設(shè)的基礎(chǔ)上,提出了一個可以考慮主應(yīng)力旋轉(zhuǎn)作用的本構(gòu)模型。本文主要取得了如下的成果： (1)基于復(fù)雜應(yīng)力路徑作用下飽和砂土動力試驗的結(jié)果,分析了飽和砂土在不同應(yīng)力路徑(動三軸、動扭剪、圓形路徑、橢圓路徑)作用下的變形特性。其主要的規(guī)律為：動三軸加載作用下,試樣的累積變形趨勢為徑向與環(huán)向均勻壓縮,試樣軸向不斷拉伸；動扭剪荷載作用下,試樣在扭剪應(yīng)力作用平面內(nèi)均勻拉伸,而在垂直于該平面的徑向則不斷壓縮；試樣的偏差正應(yīng)力一偏差正應(yīng)變滯回曲線具有較為統(tǒng)一的形狀,應(yīng)變滯后特性不明顯,應(yīng)力與應(yīng)變幾乎同時達(dá)到峰值,扭剪應(yīng)力—扭剪應(yīng)變曲線有著相同的規(guī)律；當(dāng)有效球應(yīng)力小于某一特定值時,試樣的殘余孔壓累積速率加快,試樣的應(yīng)變發(fā)展也明顯加快,這一臨界有效球應(yīng)力近似為20kPa。 (2)對主應(yīng)力旋轉(zhuǎn)平面內(nèi)應(yīng)變增量主方向的規(guī)律進(jìn)行了較為細(xì)致的分析,得到的主要結(jié)論有：定義應(yīng)變增量主方向與主應(yīng)力方向的夾角為非共軸角(基于總應(yīng)變,而非塑性應(yīng)變),則非共軸角隨著振次的增加而不斷減��；在各應(yīng)力分量的極值處(應(yīng)力路徑的極點處),應(yīng)變增量方向幾乎與應(yīng)力路徑相切,也即應(yīng)變增量方向與應(yīng)力增量方向一致；在達(dá)到液化之前的大部分振次內(nèi),應(yīng)變增量方向與應(yīng)力增量方向都近似位于同一個象限內(nèi)；在達(dá)到液化之前,僅有很小的一段區(qū)間內(nèi),非共軸角能減小至零�；诖�,本文提出了一個非共軸角的簡化計算模型。 (3)對Manzari臨界狀態(tài)雙面彈塑性模型做了簡要的介紹,對其做了一定的修改與優(yōu)化,并且對將該模型應(yīng)用于不排水循環(huán)問題的可行性進(jìn)行了分析。提出了將該本構(gòu)模型運(yùn)用于不排水加載的變形協(xié)調(diào)迭代計算方法。基于靜力加載試驗,確定了模型的主要參數(shù)。運(yùn)用該模型對砂土的靜力三軸壓縮試驗(排水),循環(huán)三軸加載試驗(不排水)分別進(jìn)行了變形預(yù)測,驗證了該模型的適用性。 (4)在優(yōu)化的臨界狀態(tài)雙面彈塑性模型基礎(chǔ)上,增添了考慮主應(yīng)力旋轉(zhuǎn)作用的功能。運(yùn)用雙面彈塑性模型考慮正應(yīng)力增量引起的塑性變形,然后再將扭剪應(yīng)力增量引起的附加變形納入其中。扭剪應(yīng)力增量引起的附加變形采用廣義塑性理論的思想,直接根據(jù)試驗規(guī)律而給出加載強(qiáng)度、流動方向與塑性模量。附加變形分為偏應(yīng)變與體應(yīng)變,兩者的比例關(guān)系借鑒Yunming Yang所提出的公式。運(yùn)用新提出的模型預(yù)測了不同應(yīng)力路徑作用下砂土的變形趨勢,結(jié)果表明該模型能大致預(yù)測出各應(yīng)變分量及孔壓的發(fā)展趨勢,而對于試樣在較大振次時的變形預(yù)測則不甚理想,同時該模型也無法預(yù)測試樣液化后的大變形,這表明該模型具有一定的適用性,也存在一定的局限性。
[Abstract]:In the sand with the rotation of principal stress axes complex stress strain characteristics under the action of force is a hotspot and difficulty in geotechnical engineering research, has theoretical value and engineering value. Although high considering complex stress constitutive model of wide attention at home and abroad, but so far there has not been a wide approved by the corresponding constitutive model. Based on the analysis of the test data, the critical state of Manzari double elastoplastic model based architecture based on theoretical derivation and some hypotheses on the proposed one can consider the main mode should be the constitutive force of the rotating role. This paper mainly achieved the following results:
(1) complex dynamic test results of saturated sand under the action of stress path based on the analysis of the saturated sand under different stress paths (three axis, dynamic torsional shear, circular path, elliptical path) deformation characteristics under the action. Its main rule: three triaxial loading, the cumulative deformation trend test as a kind of radial and circumferential uniform axial compression, constant tensile specimen; dynamic torsional shear loads, the specimen in the shear plane uniform tensile, and radial direction perpendicular to the plane is continuously compressed; sample deviation of normal stress is a deviation strain hysteresis curve with uniform shape, strain hysteresis is not obvious, the stress and strain peak almost at the same time, shear stress and shear strain curves have the same rules; when the effective stress is less than a certain value, accelerate the accumulation rate of residual pore pressure of the specimen, the specimen strain The development is also speeded up, and the critical effective ball stress is approximately 20kPa.
(2) the main direction of incremental principal strain plane rotation law for a more detailed analysis, the main conclusions are: the definition of included angle of strain increment direction and the principal stress direction for non coaxial angle (based on the total strain and plastic strain), non coaxial angle with increasing vibration time decreases; in the extreme should force components (poles should be the path of force), strain increment and stress path direction almost tangent, i.e. strain increment and stress increment direction direction; at most before liquefaction vibration times, strain increment and stress increment direction direction approximately in the same quadrant; in just a little before liquefaction, a range of non coaxial angle can be reduced to zero. Based on this, this paper puts forward a calculation model of non coaxial angle is simplified.
(3) Manzari on the critical state of double elastoplastic model is briefly introduced. The modification and Optimization on the model, and the application of analysis on feasibility of undrained cyclic problem was put forward. The constitutive model is applied to the deformation coordination of iterative undrained loading calculation method based on the static loading test, the main parameters of the model were determined by static test. The model of sand three axial compression (drainage), cyclic loading test of three axis (undrained) of deformation prediction, verify the applicability of this model.
(4) in the optimization of the critical state of double elasto-plastic model, add considering principal stress rotation function. Using double elastoplastic model considering plastic deformation is caused by the stress increment, then the torsional shear stress increment caused by the additional deformation should be included. Torsion shearing deformation the stress increment caused by the thought of generalized plasticity theory, according to the rules given directly test loading intensity, flow direction and plastic modulus. The additional deformation is divided into partial strain and volume strain, the ratio between two reference Yunming Yang proposed a new formula. Using the model to predict the deformation trend of different stress paths under the action of sand, the results show that the model can roughly predict development trend of strain components and pore pressure, and for the prediction of deformation in large sample vibration frequency is not ideal at the same time, the model can predict the sample solution The large deformation after the transformation shows that the model has certain applicability, and there are some limitations.

【學(xué)位授予單位】：浙江大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TU441;TU411

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本文編號：1740193