地工離心機(geotechnical centrifuge)高速旋轉時，若要確實得知詴體內部之土層性質，需藉由詴驗方式進行模型地盤調查之動作。本研究以壓電彎曲元件(bender elements)量測離心模型於高g重力場下的土壤剪力波波速(shear wave velocity)，以得知砂土模型在不同應力場模擬狀況下的土壤剪力波波速，以觀察剪力波波速剖面，了解詴體之土層性質。 於不同圍壓狀態的模型詴體中量測剪力波波速，可推估該覆土應力狀態下之最大剪力模數(Gmax)；另外，剪力波波速亦可進行土壤液化潛能評估之應用。本研究更開發於土壤詴體振動中量測剪力波波速之方法，以壓電彎曲元件量得詴體振動期間剪力波波速的變化，與孔隙水壓計量測超額孔隙水壓相比，探討動態超額孔隙水壓與剪力波波速演化之關係。 研究結果顯示，本研究有效的利用壓電彎曲元件，在飽和離心模型詴體於高g離心重力場下進行波傳詴驗，了解模型砂土層之性質；並於80g離心重力場下驅動離心振動台振動砂土模型詴體，觀察土層受振後之性質變化，以及檢核剪力波波速液化評估法於本研究環境中之適用性。本研究亦成功於土壤詴體振動中以及超額孔隙水壓消散期間，量測剪力波波速隨時間之演化，藉以探討砂土層之動態反應。 In this research, a bender elements system and the related software have been developed for evaluating the in-flight shear wave velocity in dynamic centrifuge tests. The in-flight shear wave velocity and the calculated maximum shear modulus profiles of the models were obtained. Before and after seismic events shear wave velocity profile can also be determined, and the profile is used to evaluate the change of dynamic soil property and the liquefaction potential of soil bed based soil resistance criteria in terms of shear wave velocity. During earthquakes the shear modulus would change with time. The developed bender element system is capable of measuring the evolution of shear wave velocity on the model during shaking as well. The test result shows that the shear wave velocities decrease with the increase of excess pore water pressure during shaking, while the shear wave velocities gradually increase as the excess pore water pressure dissipates after stop of shaking.
