本文選題：膠結結構性土　切入點：本構模型　出處：《北方工業(yè)大學》2017年碩士論文

【摘要】：膠結結構性廣泛存在于天然土中。膠結的存在使得天然土的強度較重塑土高,然而隨著變形的發(fā)展膠結會逐漸減弱。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)象不能被實際工程忽視,否則可能會增加實際工程的危險系數(shù)。因此,建立能夠考慮天然土中膠結影響的本構模型具有重要的意義。由于天然土中膠結存在較大的離散性,并且取樣過程也會使得其膠結發(fā)生變化,因此作者采用泥漿澆筑法進行膠結結構性黏土試樣的制備以模擬天然膠結結構性黏土的主要特征。使用國產(chǎn)WG(GDG)系列高壓固結儀和英國GDSTTS標準應力路徑三軸儀對其進行一維壓縮試驗和常規(guī)三軸壓縮排水剪切試驗。試驗結果表明:(a)膠結使其剪切破壞后的最終應力比高于相應重塑土;(b)膠結限制了試樣剪切時體積應變的自由發(fā)揮�；谠囼灲Y果,將p～q應力空間中靜止的臨界狀態(tài)線(CSL)擴展為動態(tài)的移動臨界狀態(tài)線(MCSL)。MCSL與CSL平行且隨著膠結減弱不斷移向CSL。根據(jù)MCSL建立了新的屈服面并依照相關聯(lián)流動準則修正了剪脹方程,將膠結考慮進結構性土 UH模型�；赟MP準則的變換應力三維化方法,將膠結結構性土UH模型擴展到三維應力空間。與原結構性土UH模型相比,本文所提模型增加了一個新的結構性參數(shù)——初始膠結應力s0,其值為p～q坐標中MCSL與CSL之間的初始水平距離,通過無側限抗壓試驗確定該參數(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)膠結結構性土的等向壓縮;(b)膠結結構性土剪切破壞后最終應力比的變化特點;(c)膠結結構性土的剪脹規(guī)律;(d)膠結結構性土真三軸剪切中應力Lode角的影響。通過將膠結結構性土的試驗數(shù)據(jù)與模型預測進行對比,表明膠結結構性土UH模型能夠較合理地對結構性土的等向壓縮、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行為進行預測。
[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.
【學位授予單位】：北方工業(yè)大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TU442

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