細顆粒對砂土性質的影響:儀器之改良與結果之分析

Abstract

由經驗得知當砂土含有細顆粒時,其工程性質與均勻級配之砂土有很大不 同.在相同的相對密度之下,均勻級配砂土可能是膨賬性,如有細顆粒則可 變成收縮性.細顆粒對現場土壤實驗,比如錐貫入實驗也可能有很大影響. 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,於1993年2月展開一系列的研究,包括實驗室之砂 土實驗與不連續變形法之數值模擬.試驗儀器之研發與試驗程序之設定,已 於1994年6月完成.本研究的主要目的是:改良本研究所用之土壤試驗儀器, 並進行中空扭剪試驗來瞭解細顆粒對砂土性質的影響.本論文報告儀器改 良之細節與現有實驗結果之分析. 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. 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 in February of 1993, to enchance our understanding related to the effects of fines on the behavior of sands. These activities include nemerical simulation, using discontinus deformation analysis method and laboratory experiments on sands. A soil testing apparatus and testing procedure were developed as of June 1994. The objetives of this research are : modify the soil testing apparatus, perform a series of hollow cylinder torsional simple shear tests, and evaluate the effects of fines on the test results. The thesis describes the details of the apparatus modification and analysis of the available test results.