圓錐貫入試驗在粉砂中之標定

Abstract

中文摘要 由於缺乏凝聚力，砂土的非擾動性試樣很難取得，為量測砂土的工程性質，現場試驗 是常用的方法。圓錐貫入試驗（cone penetration test, CPT）是一種廣泛使用的現場試 驗方法。然而，如同其他的現場試驗，圓錐貫入試驗的結果多靠經驗公式來分析，經驗公 式大多根據試驗室中的標度試驗結果，經由一些理論的推導而來；現有的經驗公式多來自 歐美，根據在級配均勻之乾淨砂土中所做之標度試驗推導得來。台灣西海岸的砂土，包括 雲林麥寮之台塑六輕工地，含粉土（silt）量相當高，實驗結果顯示此種砂土具有高壓縮 性與破碎性，膨脹性不高的特性。含細顆粒的砂土與級配均勻的乾淨砂土在工程性質上有 相當大的差異因此將來自歐美的 CPT經驗公式應用於台灣西海岸砂土之可靠性很有疑問。 研究計畫之主要目的是建立一套經驗的方法來解釋在含細顆料砂土中 CPT之結果。本 方法將可直接應用於台塑六輕工地，考慮細顆粒含量和因土壤改良而改變的側向土壓力等 因素，並對土壤受動力夯實改良後超額孔隙水壓之消散速率建立一個比較精確的估計方法 。 現已完成全部之基本物理試驗與三軸試驗。標度槽已架設，並完成一系列的CPT標度試 驗。 本論文敘述研究之背景、目的、進行步驟、CPT標度試驗之程序與試驗結果資料。對 於在粉砂中 CPT結果進行分析，提出新的經驗公式。 關鍵詞： 現場試驗，膨脹性，橫向應力，砂土強度，圓錐貫入標度試驗 Abstract Because of the lack of cohesion, it is very difficult to obtain undisturbe dsamples for sand. In situ tests are often used to determine the engineering properties of sand. The cone penetration test (CPT) is a popular in situ test method. As in many other types of in situ test methods, the interpretation of CPT data is mostly empirical. These empirical interpretation rules are mostly developed based on chamber calibration tests in the laboratory, and limited theoretical considerations. Most of the availle empirical rules came from Europe or Northern America, based on tests in uniformly graded, clean sand. The sand on the West Coast of Taiwan, including that at the 6th Naptha project site in Mai Liao, Yuen Lin, contains significant amount of silt. Experiments have indicated that this type of sand is compressible and crushable, but has a less tendency to dilate. The difference between a uniformly graded clean sand and a silty sand can be significant. Hence, to directly adopt the empirical CPT interpretaon rules developed in the West, to the sand on the West Coast of Taiwan is not desirable. The main objective of this research project is to establish an empirical method for the interpretation results of CPT performed silty sand. This method applied directly to the soils at the 6th Naptha project site in Mai Liao, considering the effects of high fines content and the effects of soil improvement. Experiments to determine the basic physical properties and triaxial tests have been completed. The calibration chamber system has been established. A seies of cone penetration tests have been perford in this chamber system. This thesis describes the background of the research, its objetives, research approach, procedures of the CPT calibration tests and test results. The CPT data are analyzed and a new empirical rule is proposed specifically for CPT in silty sand. Keywords : in situ test, dilatancy, horizontal stress, shear strength of sand , calibration of cone penetration test