Mesostructural character and numerical simulation of mechanical properties of soil-rock mixtures

Abstract

Soil-rock mixture is a kind of inhomogeneous material; for the difficulty of in-situ sampling and the underdevelopment of large-scale laboratory soil test, at present the study of the soil-rock mixture's mechanical properties is still at initial stage. With the quick development of digital image processing method, digital image processing has been successfully used in many kinds of fields. Based on the digital image processing, the microstructural model of soil-rock mixture by taking into account the actual material inhomogeneity is constructed. The structural character of the distribution of blocks is studied statistically; and it is shown that the confusion is only the external performance of the soil-rock mixtures. In fact, soil-rock mixtures have a good character of self-comparability in statistics. Using geometry transformation, the model of soil-rock mixtures under dual digital image has been translated into a document format which can be received by finite element software. By this step, the numerical simulation of actual microstructures of soil-rock mixture is carried out. The numerical simulation of the large-scale direct shear test indicates that the blocks obviously influence the stress field of soil-rock mixtures, and then influence the deformation and fracture type. Three kinds of possible failure propagation routes in soil-rock mixtures are put forward.

土石混合體是一種非常復雜的不連續介質。隨著數字圖像處理理論的飛速發展,數字圖像處理技術已經成功地應用于多種學科領域。通過利用數字圖像處理技術建立土石混合體細觀結構“概念模型”,并對其內部塊體分布的結構特征進行統計分析研究,研究結果表明土石混合體的“混亂”狀態只是其外在表現,其內部塊體的分布具有良好的統計自相似性特點。利用幾何矢量轉換技術,將二元數字圖像下土石混合體的概念模型轉換為有限元軟件可以接受的矢量格式,從而為土石混合體細觀結構數值模擬提供基礎。土石混合體大尺度直接剪切試驗的數值模擬結果表明,土石混合體中的塊石對其內部應力場具有明顯的影響,從而影響了其相應的變形破壞形式。提出了內部塑性區擴展可能存在的3種模式。