本文選題：膠結(jié)結(jié)構(gòu)性土　切入點(diǎn)：本構(gòu)模型　出處：《北方工業(yè)大學(xué)》2017年碩士論文

【摘要】：膠結(jié)結(jié)構(gòu)性廣泛存在于天然土中。膠結(jié)的存在使得天然土的強(qiáng)度較重塑土高,然而隨著變形的發(fā)展膠結(jié)會逐漸減弱。因此,天然土的模量在加載初期較重塑土大但最終會趨近于重塑土的模量。這種現(xiàn)象不能被實(shí)際工程忽視,否則可能會增加實(shí)際工程的危險(xiǎn)系數(shù)。因此,建立能夠考慮天然土中膠結(jié)影響的本構(gòu)模型具有重要的意義。由于天然土中膠結(jié)存在較大的離散性,并且取樣過程也會使得其膠結(jié)發(fā)生變化,因此作者采用泥漿澆筑法進(jìn)行膠結(jié)結(jié)構(gòu)性黏土試樣的制備以模擬天然膠結(jié)結(jié)構(gòu)性黏土的主要特征。使用國產(chǎn)WG(GDG)系列高壓固結(jié)儀和英國GDSTTS標(biāo)準(zhǔn)應(yīng)力路徑三軸儀對其進(jìn)行一維壓縮試驗(yàn)和常規(guī)三軸壓縮排水剪切試驗(yàn)。試驗(yàn)結(jié)果表明:(a)膠結(jié)使其剪切破壞后的最終應(yīng)力比高于相應(yīng)重塑土;(b)膠結(jié)限制了試樣剪切時(shí)體積應(yīng)變的自由發(fā)揮�；谠囼�(yàn)結(jié)果,將p～q應(yīng)力空間中靜止的臨界狀態(tài)線(CSL)擴(kuò)展為動(dòng)態(tài)的移動(dòng)臨界狀態(tài)線(MCSL)。MCSL與CSL平行且隨著膠結(jié)減弱不斷移向CSL。根據(jù)MCSL建立了新的屈服面并依照相關(guān)聯(lián)流動(dòng)準(zhǔn)則修正了剪脹方程,將膠結(jié)考慮進(jìn)結(jié)構(gòu)性土 UH模型�；赟MP準(zhǔn)則的變換應(yīng)力三維化方法,將膠結(jié)結(jié)構(gòu)性土UH模型擴(kuò)展到三維應(yīng)力空間。與原結(jié)構(gòu)性土UH模型相比,本文所提模型增加了一個(gè)新的結(jié)構(gòu)性參數(shù)——初始膠結(jié)應(yīng)力s0,其值為p～q坐標(biāo)中MCSL與CSL之間的初始水平距離,通過無側(cè)限抗壓試驗(yàn)確定該參數(shù)。模型的演化規(guī)律表明本文所提模型能夠光滑、連續(xù)地描述:(a)膠結(jié)結(jié)構(gòu)性土的等向壓縮;(b)膠結(jié)結(jié)構(gòu)性土剪切破壞后最終應(yīng)力比的變化特點(diǎn);(c)膠結(jié)結(jié)構(gòu)性土的剪脹規(guī)律;(d)膠結(jié)結(jié)構(gòu)性土真三軸剪切中應(yīng)力Lode角的影響。通過將膠結(jié)結(jié)構(gòu)性土的試驗(yàn)數(shù)據(jù)與模型預(yù)測進(jìn)行對比,表明膠結(jié)結(jié)構(gòu)性土UH模型能夠較合理地對結(jié)構(gòu)性土的等向壓縮、一維壓縮、排水/不排水常規(guī)三軸剪切、等p排水三軸剪切及真三軸剪切等力學(xué)行為進(jìn)行預(yù)測。
[Abstract]:The cementation structure exists widely in natural soil.The strength of natural soil is higher than that of remolded soil due to the existence of cement, but the cementation will weaken gradually with the development of deformation.Therefore, the modulus of natural soil is larger than that of remolded soil at the beginning of loading, but will eventually approach the modulus of remolded soil.This phenomenon can not be ignored by practical engineering, otherwise it may increase the risk coefficient of actual engineering.Therefore, it is of great significance to establish a constitutive model which can take into account the effect of cementation in natural soil.Because of the large dispersion of cementation in natural soil and the change of cementation in the sampling process,The experimental results show that the final stress ratio after shear failure is higher than that of the corresponding remolded soil.A new yield surface is established according to MCSL and the shear expansion equation is modified according to the associated flow criterion. The cementation is considered in the structural soil UH model.The UH model of cemented structural soil is extended to three dimensional stress space based on SMP criterion.The evolution of the model shows that the model presented in this paper is smooth.By comparing the experimental data of cemented structural soil with the model prediction, it is shown that the UH model of cemented structural soil can reasonably compress the structural soil in isotropic direction, one dimensional compression and conventional triaxial shear of drainage / undrained soil.The mechanical behaviors of isop drainage triaxial shear and true triaxial shear are predicted.
【學(xué)位授予單位】：北方工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TU442

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