標度槽邊界控制之研發

Abstract

由於砂土缺乏凝聚力,所以砂土的不擾動試樣很難取得.為量測砂土的工程 性質,現地試驗是常用的方法.圓錐貫入試驗是一種廣泛使用的現場試驗方 法.然而圓錐貫入試驗的結果多靠經驗公式來分析,經驗公式大多經由試驗 室中的標度試驗而來.標度試驗的重要缺陷是它的邊界效應.標度槽中的試 體其橫向邊界可以應力或應變控制,這兩種邊界都無法模擬介於兩者之間 的真正現地情況.有人提出以修正係數的方法來抵消邊界效應,但是修正係 數方法的正確性與邊界影響之機制至今 都尚未得到證實.論文包括了矽膠 膜之製作,邊界位移量測系統之製作,系統安裝與標 節的描述.最後以傳統 之CPT標度槽試驗,來完成此一新標度槽系統的初步測試. Due to the lack of cohesion,it is difficult to obtainisturbed samples for sand.In-site testing is often used to determine the engineering properties for sands.The cone penetration test(cpt) is a popular in-site test method.However ,as for many other in- site test methods,we rely on empirical equations to interpret CPT data.A significant part of these empirical equations came from laboratory chamber calibration tests.An important drawback of the calibration chamber is its boundary effects.The lateral boundary of the sand specimem in a calibration chamber is either stress controlled or rigid. Neither of these two boundary conditions can truly duplicate the field conditions which lies somewhere in between.Correction factors have been proposed to account for these boundary effects.However,the validity of the use of correction factors and the mechanisms of boundary efffects have not been independently verified.The thesis describes details of making silicone rubber membranes for the chamber cell,instrumentation and monitoring of the lateral boundary displacement,system set up and calibration,and available test results.