細顆粒對砂土性質之影響:儀器之研發與實驗程序之設定

Abstract

由經驗得知當砂土中含有細顆粒時，其工程性質與均勻級配之砂土有很大 不同。在相等的相對密度下，均勻級配的砂土可能是膨脹性 (dilatant) ，如有細顆粒則可變成收縮性 (contractive)。細顆粒對現場土壤試驗， 比如錐貫入試驗也有很大的影響。數值模擬顯示砂土中之細小的顆粒在受 圓錐貫入試驗的影響下所受的應力(stress)要比大顆粒高。我們對於細顆 粒如何影響砂土之工程性質所知有限。為了進一步了解細小顆粒對砂土性 質之影響，我們展開一系列的研究，包括用不連續變形法之數值模擬與實 驗室中之砂土實驗。本論文所敘述的研究是有關砂土實驗方面啟始的工作 。研究的主要目的是︰研發一套多功能之土壤實驗裝置以滿足未來實驗所 需､建立實驗所用砂土的基本資料及確立砂土實驗之方法與程序和檢測實 驗方法與程序之可行性與重複性。論文報告多功能之土實驗裝置之研發， 砂土實驗過程與現有的實驗結果。 Experience has indicated that the engineering properties of a graded sand with fines are significantly different from those of a uniform sand. Under a given relative density , a uniform sand could be dilatant while a graded sand with fines could be contractive. Fines can influence the results of in-situ tests such as the cone penetration tests. Numerical simulations , show that finer particles tend to experience higher stress induced by the penetration of a cone. There is a lack of fundamental understanding as to how the fines affect the behavior of a granular material. A series of research activities were initiated to enhance our understanding related to the effects of fines on the behavior of sands. These activities include numerical simulations using Discontinuous Deformation Analysis (DDA) method ,and laboratory experiments on sands. The objectives of the research are :development of a multiple purpose soil testing apparatus to meet the need of future research work , establish basic engineering properties , testing method and procedures for the sand to be used in the future , and evaluate the feasibility and repeatability of the testing procedure. The thesis describes details of the multiple purpose soil testing apparatus , and results of preliminary experiments.