發(fā)布時間：2018-05-13 19:11

  本文選題：核磁共振 + SHPB　； 參考：《江西理工大學(xué)》2016年碩士論文

【摘要】：本文主要研究沖擊荷載作用下離子型稀土風(fēng)化層花崗巖損傷演化規(guī)律,課題源于國家自然科學(xué)青年基金項目(編號51404111)。論文主要采用室內(nèi)試驗與理論分析的研究手段,結(jié)合核磁共振技術(shù)與SHPB試驗裝置系統(tǒng)開展了以下工作:(1)對試樣進(jìn)行了單軸抗壓強(qiáng)度試驗、超聲波波速測試試驗、NMR孔隙試驗,分析了巖石波速與天然孔隙之間的關(guān)系、靜荷載作用下的應(yīng)力-應(yīng)變曲線特征以及單軸抗壓強(qiáng)度與波速的關(guān)系。(2)基于核磁共振技術(shù),對離子型稀土礦山風(fēng)化層花崗巖孔隙結(jié)構(gòu)進(jìn)行了測量,得出原始巖樣的核磁共振2T分布、譜面積分布特征、孔隙度以及核磁共振成像等信息,結(jié)果顯示天然巖樣的2T分布包含5個波峰,內(nèi)部孔隙結(jié)構(gòu)分布主要以微小尺寸孔隙為主。(3)對不同初始孔隙度的巖石進(jìn)行了沖擊破壞實驗,與靜荷載相比動荷載作用下應(yīng)力應(yīng)變曲線沒有壓密過程的下凹段;巖石在沖擊荷載作用下破壞模式多樣,如壓剪破壞、拉應(yīng)力破壞等,其破碎程度并不取決于試樣所吸收的絕對能量,而是與所吸收能量占臨界破壞能的比值相關(guān)聯(lián)。(4)結(jié)合核磁共振技術(shù)與SHPB試驗裝置系統(tǒng)對離子型稀土風(fēng)化層花崗巖在應(yīng)力波作用下的損傷演化規(guī)律進(jìn)行了研究,得到了沖擊前后巖石的2T譜分布、孔隙度、2T譜面積、核磁共振成像的變化特征與巖石內(nèi)部孔隙結(jié)構(gòu)分布的變化。結(jié)果表明巖石在動荷載作用下的孔隙度增加主要來源于孔隙的擴(kuò)張、貫通以及新生孔隙,各個類型尺寸孔隙在循環(huán)沖擊下其分布將越趨于均勻化,表明巖石內(nèi)部的損傷是具有一定方向性的。(5)采用核磁共振成像技術(shù),對經(jīng)歷SHPB桿沖擊后的同一塊巖樣進(jìn)行成像分析,獲得了沖擊前后的巖石的孔隙結(jié)構(gòu)分布圖,直觀的展示了巖石內(nèi)部結(jié)構(gòu)在沖擊前后變化特征,將沖擊荷載下巖石內(nèi)部微觀結(jié)構(gòu)的損傷演化規(guī)律進(jìn)行了可視化。
[Abstract]:This paper mainly studies the damage and evolution law of granite in the ion type rare earth weathering layer under impact load. The project is derived from the National Natural Science Youth Fund Project (No. 51404111). The paper mainly adopts the research means of indoor test and theoretical analysis, and carries out the following work in combination with the nuclear magnetic resonance technology and the SHPB test device system: (1) the test The samples were tested by uniaxial compression strength test, ultrasonic wave velocity test and NMR pore test. The relationship between rock wave velocity and natural pores, the stress-strain curves under static load and the relationship between uniaxial compression strength and wave velocity. (2) on the basis of nuclear magnetic resonance technology, the pores in the weathered layer of the ion type rare earth mine are porous. The structure is measured and the NMR 2T distribution, spectral area distribution, porosity and magnetic resonance imaging of the original rock samples are obtained. The results show that the 2T distribution of the natural rock samples contains 5 peaks, and the distribution of the internal pore structure is mainly small size pores. (3) the rock of different initial porosity is impacted and destroyed. The stress strain curve under the action of dynamic load does not have the lower concave section of the compaction process compared with the static load; the failure modes of rock under the impact load are varied, such as the shear failure, the tensile stress damage and so on. The degree of breakage does not depend on the absolute energy absorbed by the specimen, but is related to the ratio of the absorbed energy to the critical failure energy. (4) Combined with nuclear magnetic resonance and SHPB test system, the damage evolution law of the ionic rare-earth weathered granite under stress wave is studied. The distribution of 2T spectrum, porosity, 2T spectrum area, the change characteristics of nuclear magnetic resonance imaging and the distribution of pore structure in rock and rock are obtained before and after the impact. The increase of porosity of stone under dynamic load mainly comes from the expansion of pores, through through and new pores. The distribution of each type of pore size will tend to homogenization under cyclic impact, which indicates that the damage in the rock is of certain direction. (5) the same block after the impact of SHPB rod is used by the technique of nuclear magnetic resonance imaging. The formation of rock pore structure before and after the impact is obtained by imaging analysis of rock samples, and the changes of the internal structure of rock before and after the impact are visually displayed, and the damage evolution law of the internal microstructure of rock under the impact load is visualized.

【學(xué)位授予單位】：江西理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2016
【分類號】：TD315

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