本文關(guān)鍵詞： 顆粒尺度效應(yīng) 數(shù)字圖像處理 多尺度 胞元體 內(nèi)稟長度　出處：《華南理工大學(xué)》2014年博士論文　論文類型：學(xué)位論文

【摘要】：土體介質(zhì)在復(fù)雜多變的條件下形成了以固相、液相和氣相等物質(zhì)為基本成分的組合物。固相物質(zhì)在經(jīng)歷風(fēng)化、搬運(yùn)、沉積和沖刷等自然作用力后形成了大小差異明顯的顆粒材料，，包括小至微米級的黏粒、大至數(shù)十厘米以上的卵石、塊石，顆粒尺度跨越了6~7個數(shù)量級。不同尺度土顆粒的無序空間排列形成了土體介質(zhì)承受自身重力及外力荷載的顆粒骨架，對土體介質(zhì)復(fù)雜的物理力學(xué)特性產(chǎn)生關(guān)鍵性的影響。土體的各粒徑顆粒以不同的組合形成的土體微細(xì)觀結(jié)構(gòu)，其物理力學(xué)特性受到顆粒的尺寸、形狀和級配等顆粒特征強(qiáng)烈的影響，呈現(xiàn)顯著的顆粒尺度效應(yīng)。為了解決傳統(tǒng)連續(xù)介質(zhì)力學(xué)無法對顆粒尺度效應(yīng)現(xiàn)象進(jìn)行解釋的問題，通過建立具有多尺度特征的土體胞元模型，闡述各尺度土體顆粒相互作用的力學(xué)機(jī)理，引入刻畫土體微結(jié)構(gòu)特征的材料內(nèi)稟長度參數(shù)，建立宏觀力學(xué)性質(zhì)與微觀結(jié)構(gòu)特征相互關(guān)聯(lián)的力學(xué)模型。 本文完成的理論與試驗(yàn)研究工作及其結(jié)論有以下幾個方面： (1)通過數(shù)字圖像處理技術(shù)對加強(qiáng)顆粒的幾何特征進(jìn)行測定，獲得了顆粒粒度特征的分布規(guī)律。測試結(jié)果表明，對具有同一巖性和生產(chǎn)工藝的不同粒徑加強(qiáng)顆粒，其二維投影的形狀參數(shù)具有相似的分布規(guī)律；顆粒短軸具有明顯的對稱性，呈典型的標(biāo)準(zhǔn)正態(tài)分布，方形篩孔對顆粒短軸有良好的篩分性。 (2)基于土體的多尺度模型，分析顆粒加強(qiáng)土體的力學(xué)模型。根據(jù)不同粒徑顆粒的作用力類型，劃分基體材料與加強(qiáng)顆粒；計算協(xié)調(diào)微裂紋密度與平均應(yīng)變梯度，獲得顆粒加強(qiáng)土體流動應(yīng)力的計算方法。分析結(jié)果表明顆粒加強(qiáng)土體的強(qiáng)度由基體材料的性質(zhì)和加強(qiáng)顆粒的粒度特征共同決定，協(xié)調(diào)微裂紋的萌生與發(fā)展對應(yīng)變能的消耗作用表現(xiàn)為土體力學(xué)性能的提高，顆粒加強(qiáng)土體強(qiáng)度的尺度效應(yīng)由土體胞元的強(qiáng)化引起。 (3)研究基體水理性質(zhì)與加強(qiáng)顆粒粒度特征對土體顆粒尺度效應(yīng)的影響及其機(jī)理。根據(jù)試驗(yàn)結(jié)果分析，基體液性指數(shù)的減小強(qiáng)化了土體顆粒間的作用，削弱了水分子對接觸顆粒的潤滑力；加強(qiáng)顆粒含量的增加使得土體胞元數(shù)量隨著增加，提高了胞元體對土體的強(qiáng)化作用；加強(qiáng)顆粒粒徑的減小加劇了單位體積土體對剪切應(yīng)變能的消耗；顆粒加強(qiáng)土體的流動應(yīng)力與顆粒體表面積呈近似的線性關(guān)系。 (4)基于顆粒加強(qiáng)土體的流動應(yīng)力計算方法，分析了可變內(nèi)稟長度的影響因素。由分析結(jié)果可知，土體的內(nèi)稟長度反映了基體材料與加強(qiáng)顆粒的物理力學(xué)性質(zhì)，揭示了兩種材料耦合程度對力學(xué)性能的影響，刻畫了土體內(nèi)部非均質(zhì)微胞元的結(jié)構(gòu)特征尺寸。土體內(nèi)稟長度的表達(dá)式不僅包含了加強(qiáng)顆粒的粒度特征與基體的剪切強(qiáng)度性質(zhì)，還綜合反映了基體的能量儲存與釋放的能力、抗剪特征、受力變形的非線性和塑性特征。 (5)基于可變內(nèi)稟長度的試驗(yàn)研究結(jié)果，分析內(nèi)稟長度的變化規(guī)律及其影響因素的敏感性。分析結(jié)果表明，可變內(nèi)稟長度隨應(yīng)變的增加而趨于穩(wěn)定值；內(nèi)稟長度隨液性指數(shù)的增加呈先增加后減小的變化規(guī)律；內(nèi)稟長度隨加強(qiáng)顆粒含量的增加而呈非線性增長，增幅亦隨加強(qiáng)顆粒含量的增加而增加；內(nèi)稟長度隨加強(qiáng)顆粒粒徑的減小以非線性的規(guī)律減小，加強(qiáng)顆粒含量越大則非線性越明顯。
[Abstract]:The soil medium in complex conditions formed by solid phase, liquid phase and gas composition of equal material as the basic component of the solid material handling. After weathering, erosion, deposition and other natural forces after the formation of the granular material size difference is obvious, including small micron clay, to tens of centimeters above the pebble. Stone size across the 6~7 orders. The disordered spatial arrangement of different scales of soil particles formed skeleton soil under their own gravity and external load, the soil physical and mechanical properties of complex production key. The effects of soil fine soil particles formed by the combination of different views the structure, physical and mechanical properties by the particle size, shape and gradation and particle characteristics of strong, showing remarkable grain size effect. In order to solve the traditional continuum mechanics without Method to explain the problem of particle size effects, soil cell model through the establishment of the multi-scale feature, describes the mechanical mechanism of the scale of soil particle interaction, the characterization of soil microstructure of the material length scale parameter, the mechanics model is established in macroscopic mechanical properties and microstructure characteristics related to each other.
The theoretical and experimental research work completed in this paper and its conclusions are as follows:
(1) to strengthen the geometric characteristics of particles were measured by digital image processing technology, the distribution of particle size characteristics. The test results show that with the same lithology and production process of different size particles strengthen, its shape parameter 2D projection has similar distribution; with obvious symmetry short particle axis, was typical of the standard normal distribution, square sieve on particle short axis has good screening.
(2) multiscale model of soil based on the mechanical model of soil particles. According to the analysis of strengthening the different particle types of force, division of matrix material and strengthening particles; coordination of micro crack density and average strain gradient, particle strengthening the soil flow stress calculation method. Analysis results show that the strength of soil particle strengthening is determined by the properties of matrix material and strengthen the particle size characteristics, coordination of micro crack initiation and development of the strain energy consumption performance for improving the mechanical properties of soil particles, strengthen the scale effect of soil strength caused by soil cell enhancement.
(3) on the base of water physical properties and enhance the particle size characteristics influence on the scale effect of soil particles and its mechanism. Based on the analysis of the test results, the matrix liquid index decreased to strengthen the soil particle particle interactions, weaken the lubricating capacity of water molecule on the contact of particles; particle content increased the number of soil cell with the increase, improve the strengthening effect of the cell element of soil; strengthen the decrease of the particle size increased the unit volume consumption of soil shear strain energy; soil flow is a linear relationship of the approximate surface area and particle strengthening.
(4) to strengthen the soil particle flow stress calculation method based on the analysis of the influence factors in the intrinsic variable length. The analysis result shows that the intrinsic length of soil reflects the base material and strengthen the physical and mechanical properties of particles, reveals the influence of two kinds of materials on the mechanical properties of the coupling degree, describe the soil the heterogeneous characteristics of micro cellular structure element size. The expression length in soil contains not only the shear strength properties of reinforced particles and matrix grain size characteristics, but also reflects the ability of energy storage and release matrix, shear characteristics, nonlinear deformation and plastic characteristics.
(5) results in variable length based on sensitivity variation and influence factors analysis in length. The analysis results show that the intrinsic variable length with the increase of strain tends to a stable value; showed a trend of first increase and then decrease with the increase of the length of the intrinsic liquid index; intrinsic length with the increase of reinforcement particle content and nonlinearly increase with increasing growth, also strengthen the content of particles increases; the intrinsic length increases with the decrease of the particle size in order to strengthen the rule of nonlinear decreases, the reinforcement particle content greater nonlinear is more obvious.

【學(xué)位授予單位】：華南理工大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2014
【分類號】：TU43

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