以數值方法探討卵礫石層的力學行為

Abstract

Gravel formation involves the mixture of hard gravel and a soil matrix. Knowing the integrated mechanical characteristics of gravel formation is beneficial for engineering constructions and disaster prevention. This study adopts the software PFC2D, which is based on the discrete element method, to investigate the mechanical behavior of gravel formations. First, simulation is carried out through a biaxial test to adjust the micro parameters in PFC2D, and then multiple regression analysis is performed to establish the relationship between macro and micro parameters. Furthermore, with the reasonable micro parameters obtained, the particle size and content of gravel can changed to investigate how they influence mechanical behavior. The results show that the bigger particle size and the greater the content of gravel, the higher the values of shear strength, elastic modulus, Poisson’s ratio and friction angle, but the lower the value of cohesion. In other words, this kind of material has higher shear strength and stronger deformation resistance. These findings correspond with previous research results.卵礫石層是混合堅硬卵礫石與基質土壤之綜合體，了解卵礫石層整體力學性質，對工程建設與災害防治有極大幫助。本研究以台灣中部卵礫石層為對象，運用分離元素法為基礎之軟體PFC2D 探討卵礫石材料力學行為。首先進行雙軸試驗之模擬，校正PFC2D 微觀參數，接著利用複迴歸分析 (multiple regression model)建立宏觀參數與微觀參數間之關係。另外，以得到的合理微觀參數，改變卵礫石粒徑大小與含量，探討粒徑大小和含量對力學性質的影響。結果顯示當卵礫石粒徑越大與含量越多，其剪力強度、彈性模數、柏松比、摩擦角也會越大，但凝聚力略為下降。表示卵礫石粒徑大、含量高之材料，其抗剪強度大，變形性小，此結果與前人研究結果相符