小應變中空扭剪試驗局部變形監測

Abstract

土壤單元力學試驗時應該使用試體內局部之變形監測，此一觀念已被國際間大地工程界廣為接受。但現有局部變形監測之技術大多適用於線型移動監測，例如量測三軸試驗中試體軸向之變形，對於例如中空扭剪試驗中試體扭轉量測之技術非常有限。

本研究目的是研發能夠做局部應變量測之中空扭剪試驗儀器，以此研發完成之中空扭剪試驗設備配合剪力波元件剪力波速量測，針對不同細粒料含量之麥寮砂，進行一系列應變控制往復式不排水中空扭剪試驗以驗證本試驗系統之功能並藉以瞭解在中低應變範圍情況下麥寮砂剪力模數、阻尼比、孔隙水壓與應變之關係以及此關係受細料含量之影響。

The concept of using local displacement measurement for soil element testing has been well accepted by the international geotechnical engineering community. The available techniques however, are mostly developed for monitoring linear displacement such as the axial deformation in a triaxial test. Methods to provide local rotational displacement measurement in a hollow cylinder torsional simple shear test are rare. The main objective of this research is to develop a practical method to monitor the specimen rotational displacement locally, in a hollow cylinder torsional simple shear test. Coupled with beneder elelment, the new technique was used in a series of cyclic tests on a silty sand with various fines contents. The effects of fines contents on the correlations among shear modulus, damping ratio, pore pressure development and shear strain were then studied based on these tests.