細料含量對圓錐貫入試驗結果之影響

Abstract

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。然而就像其他的現場試驗一樣，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。試驗結果顯示此種砂土具有高壓縮性與破碎性，而膨脹性不高的特性。含細顆粒之砂土與級配均勻之石英乾淨砂土因礦物成份的不同導致迥異的工程性質，因此將發展自乾淨石英砂的CPT經驗公式應用於台灣西海岸的砂土之可靠性很有疑問。 研究計畫之主要目的是確認現有CPT經驗公式對雲林麥寮粉土細砂之適用性，和建立新的經驗方法來解釋在含細顆粒砂土中CPT之結果。進行一系列含不同細料的麥寮砂乾燥或飽和CPT標度試驗。本報告敘述研究之背景、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，討論並提供建議。

Because of the lack of cohesion, it is very difficult to obtain undisturbed samples 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 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 available 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, and has a less tendency to dilate. Differences in engineering properties between uniformly graded clean, quartz sand and silty sand with different mineral contents can be significant. Hence, to directly adopt the empirical CPT interpretation rules developed for clean quartz, to the sand on the West Coast of Taiwan is not desirable. The main objective of this research project is to evaluate the feasibility of the existing empirical CPT interpretation methods for Mai Liao silty sand (MLS), and establish new empirical methods for the interpretation results of CPT performed silty sand. A series of dry or saturated CPT calibration tests have been conducted in silty fine sand for Mai Liao. This thesis describes the background of the research, its objectives, 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.