飽和砂土中圓錐貫入引發之音射特性; Using Acoustic Cone Penetration Test on Acoustic Emission Characteristics in saturated sand.

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題名:	飽和砂土中圓錐貫入引發之音射特性;Using Acoustic Cone Penetration Test on Acoustic Emission Characteristics in saturated sand.
作者:	林盈宏;Ying-Hung Lin
貢獻者:	土木工程研究所
關鍵詞:	頻譜分析;音射發生率;均方根音壓;錐尖阻抗;acoustic emission rate;frequency spectrum;cone resistance;root mean square of sound pressure
日期:	2003-06-24
上傳時間:	2009-09-18 17:13:26 (UTC+8)
出版者:	國立中央大學圖書館
摘要:	圓錐貫入試驗在工程上的應用主要有土壤分類、推求土壤工程性質與相關參數及評估土層支承力與液化等，其中以土壤分類與土層研判為最常應用的項目。本研究在貫入圓錐錐頭部分裝置微型麥克風，量測土壤在貫入過程所產生的音射訊號，藉由音波的反應來改進量測的準確度。本研究針對在不同覆土壓力及相對密度之條件下的飽和砂土貫入實驗，同時量測錐尖阻抗與音射訊號，分別就錐尖阻抗及均方根音壓、頻譜分析於貫入之反應進行探討。試驗結果顯示，於飽和砂土中，錐尖阻抗會隨著深度的增加而持續上升。而不同相對密度與覆土壓力之各組試驗，當相對密度或覆土壓力愈大，所得之錐尖阻抗與均方根音壓亦愈大。將此結果與王志偉(2002)所進行之乾砂反應相比較，發現在飽和砂土中之錐尖阻抗、均方根音壓及音射發生率都比乾砂低。頻譜分析中，福隆砂、峴港砂與西螺砂之頻譜，主要頻率分佈於2~4kHz之間，而音壓約在0.1~0.25Pa之間。音射分析中，隨著相對密度與覆土壓力的增加，音射發生率會有提高的趨勢。 Cone Penetration Tests (CPT) are usually applied to the investigation of soil classification, determination of soil parameters, estimation of bearing capacity of soil and judgement of liquefaction. This research installed a mini microphone into the cone tip to measure acoustic signal during cone penetration into soil. So the accuracy of testing results will be improved by using this high sensitivity of acoustic signal. This research measured the cone resistance and acoustic signal in saturated sand to study the response of cone resistance, root mean square of sound pressure and frequency spectrum in cone penetration tests. The results mean that the cone resistance in the saturated sand will increase continuously with depth. It is also shown that the cone resistance, RMS of sound pressure and AE rate of the saturated sand would be increased with the increase of relative density and overburden pressure. Take these results to compare with that of dry sand measured by Wang(2002), it can be found that the cone resistance, root mean square of sound pressure and acoustic emission rate of the saturated sand is lower than that of the dry sand. The analysis of frequency spectrum of Fulong Sand, Danang Sand and Shiluo Sand showed that the major frequency distributions of these tests are located at the range of 2kHz~4kHz, and the sound pressures are about 0.1Pa to 0.25Pa. The rate of acoustic emission count rate increased with the relative densities and overburden pressures.
顯示於類別:	[土木工程研究所] 博碩士論文

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