指導教授：郭安妮臺灣大學：土木工程學研究所賴泰辰Lai, Tai-ChenTai-ChenLai2014-11-252018-07-092014-11-252018-07-092014http://ntur.lib.ntu.edu.tw//handle/246246/260779影響土壤的動態參數的因子有很多，如:試體密度、試體有效應力、過壓密比、 塑性…等。本研究是利用一系列動力三軸儀及剪力波原件試驗資料探討砂及砂和 粉土混合土壤的動態特性。本研究所選用的材料是石英砂及人工磨成的石英粉， 試體的配置依細料料含量的不同可分為以下三種：純砂土、5%石英粉混合土樣、 10%石英粉混合土樣。純砂土的試體配置是以乾土重模為主而混合土壤的配置方法 是使用濕搗法。所有的試驗初始是控制一定的乾密度下進行配置，接著以不同的 有效應力來進行壓密，最後再以不同的剪應變來做剪切。 根據試驗結果可以發現剪力模數會隨著剪應變的增加而降低，不過阻尼比卻 是擁有相反的趨勢，是隨著剪應變增加而下降。這個試驗結果，無論是在純砂土、 5%的混合土讓和10%的混合土壤都有一樣的趨勢。除此之外，試體的有效應力也 對動態參數也會有影響，當我們把有效應從100kPa 提升至300kPa 可以發現，正 規畫剪力摩數曲線會因有效應力的增加也有上升的趨勢，當然，阻尼比依然是相 反的趨勢，隨著應力的上升呈現下降的表現。 對於最大剪力摩數我們也有探討，細粒料的添加對於最大剪力摩數也有影響， 依剪力波原件試驗結果可以發現，細粒料的添加對於最大剪力摩數有降低的趨勢， 當然，試體有效應力上升會使得最大剪力摩數也有上升的表現。 本研究著重點著重於三個主要的影響因子，分別是：有效應力、細粒料含量 還有剪應變大小。探討這些因子對於動態摩數及阻尼比有何影響，詳細的內容皆 在以下的章節做詳細的介紹。There are many factors affecting the dynamic soil properties, including soil density, confining pressure, over-consolidation ratio, plasticity, mineralogy, and particle shape, etc. This research examined the dynamic behavior of pure sand and sand-silt mixture by a series of strain-controlled cyclic triaxial and bender element tests. Materials used in this study were pure quartz sand and sand with various percentages of quartz silt (5% and 10%). All tests were carried out under the same initial dry density. Effects of initial effective confining stress and strain amplitude are considered. From the test results, shear modulus of the mixed soil decreases as shear strain increases. However, damping ratio increases with increasing shear strain amplitude. This trend is consistent with past research on pure sand or pure clay materials. . In addition, when the initial effective confining stress increases from 100kPa to 300kPa, the mixed soil would have a higher shear modulus and become more linear (i.e. less modulus reduction and less damping). Lastly, increasing fines content would lower the shear modulus and increase the damping ratio.論文口試委員審定書 ............................................................................................... I 致謝 ......................................................................................................................... II 摘要 ........................................................................................................................ III Abstract ................................................................................................................. IV Table of Contents .................................................................................................... V List of Figures .................................................................................................... VIII List of Tables ...................................................................................................... XIII Introduction .................................................................................... 1 1.1 Motivation and Purpose ........................................................................ 1 1.2 Research Method .................................................................................. 1 1.3 Research Framework ............................................................................ 2 Literature Review ........................................................................... 4 2.1 Definition of shear modulus and damping ratio ................................... 4 2.2 Effect of void ratio on dynamic properties ........................................... 6 2.3 Effect of confining pressure on dynamic soil properties ...................... 6 2.4 Effect of plasticity on dynamic properties ............................................ 7 2.5 Effect of fines content on dynamic properties ...................................... 8 2.6 Effect of drainage condition on dynamic properties .......................... 10 2.7 Other studies based on dynamic triaxial apparatus ............................ 10 2.8 Previous studies based on bender element apparatus .......................... 11 Experimental Program ................................................................. 33 3.1 Testing material .................................................................................. 33 3.2 Testing apparatus ................................................................................ 33 3.2.1 C.K.C. Dynamic Triaxial Apparatus ........................................... 34 3.2.2 Bender Element Device .............................................................. 36 3.3 Testing Procedure ............................................................................... 37 V 3.3.1 Instrument Calibration ................................................................ 37 3.3.2 Specimen Preparing and Remolding .......................................... 37 3.3.3 Specimen Saturation ................................................................... 39 3.3.4 Specimen Consolidation ............................................................. 41 3.3.5 Cyclic Loading Test .................................................................... 41 3.3.6 Testing Data ................................................................................ 41 Test Results and Analyses ............................................................ 55 4.1 Basic soil properties ........................................................................... 55 4.1.1 Size of soil diameter ................................................................... 55 4.1.2 Specific Gravity and Relative Density ....................................... 56 4.1.3 Atterberg Limits ......................................................................... 57 4.1.4 Direct Shear Tests ....................................................................... 57 4.2 Results of Strain-Controlled Cyclic Triaxial Tests ............................. 58 4.2.1 Determination of Shear Modulus and Damping ......................... 58 4.2.2 Strain Rate and Loading Frequency ........................................... 59 4.2.3 Experimental results for pure sand ............................................. 59 4.2.4 Experimental results for mixed soil with 5% fines .................... 60 4.2.5 Experiment result for mixed soil with 10% fines ....................... 61 4.3 Results from bender element tests ...................................................... 61 4.3.1 Effect of Top Cap Direction ....................................................... 62 4.3.2 Determination of the first arrival time ........................................ 62 4.3.3 Bender element tests results for pure sand and mixture with 5% fines content .................................................................................................... 62 4.4 Data Analysis of Gmax ......................................................................... 63 4.4.1 Calculation of Shear Wave velocity ........................................... 63 4.4.2 Determination of Maximum Shear Modulus (Gmax) ................... 64 4.5 Compilation and comparison of data from cyclic triaxial tests and bender element tests ............................................................................................... 64 4.5.1 Normalized shear modulus curve ............................................... 65 4.5.2 Damping ratio curve ................................................................... 65 4.5.3 Effect of Effective Confining Stress ........................................... 66 4.5.4 Effect of Fines Content ............................................................... 67 VI 4.5.5 Effect of Number of Cycles ........................................................ 67 4.5.6 The Trend of Maximum Shear Modulus (Gmax) ......................... 67 Conclusion and Recommendation ............................................. 109 5.1 Conclusion ........................................................................................ 109 5.2 Recommendation for future research ................................................ 110 References ............................................................................................................. 11111747229 bytesapplication/pdf論文公開時間：2016/08/17論文使用權限：同意有償授權(權利金給回饋學校)剪力摩數阻尼比動力三軸試驗剪力波原件最大剪力摩數thesishttp://ntur.lib.ntu.edu.tw/bitstream/246246/260779/1/ntu-103-R01521120-1.pdf