近幾年全球氣候異常，夯實後之林口紅土之含水量不斷改變，因而影響其吸力、勁度及強度等工程性質。因此，乾濕化行為下基質吸力與土壤波速對夯實紅土力學性質之影響應是一值得探討之課題。本研究以靜壓夯實製作三種不同初始狀態之試體，分別為乾側、最佳含水量(OMC)與濕側，並利用環境模擬設備改變試體內部含水量及基質吸力。再依循土壤水分特性曲線來達到設定之目標基質吸力，然後再分別進行彎曲元件試驗、超音波試驗與不飽和無圍壓縮等試驗，並根據試驗結果探討基質吸力、土壤波速與無圍壓縮強度的相互關係。
試驗結果顯示，試體經飽和後乾化，在同一吸力下不論是土壤波速或是土壤模數均以乾側試體最低、OMC次之、濕側最高。雖然OMC與濕側試體吸力特性相近，但因OMC試體飽和後，體積膨脹量與乾密度下降量均比濕側大，因此工程性質弱化程度也較濕側大。研究成果也顯示無論採用基質吸力或是壓力波速所建立之土壤模數迴歸方程式，具有良好的預測能力。另一方面，壓力波速與不飽和無圍壓縮強度之關係圖顯示，隨著吸力增加，壓力波速與無圍壓縮強度兩者呈線性成長。由於各側試驗結果以線性迴歸後約略相互平行，經由座標轉換後，可建立一正規化迴歸方程式，此式可以壓力波速來推估無圍壓縮強度，頗具工程應用潛能。

In recent years, global warming leads to abnormal weather conditions, causing continuous change of the water content of compacted Linkou lateritic soils. As a result, matric suction and engineering properties such as soil modulus, shear strength, etc. may be affected. Therefore, the effect of matric suction and soil velocity on the mechanical properties of compacted lateritic soils upon drying and wetting is an interesting issue. Soil specimens were compacted at three different initial water contents including the dry side, the optimum moisture content (OMC), and the wet side. They were then subjected to designated water content and matric suction using the environmental simulation apparatus. Subsequently, following the SWCC to reach the target matric suction, then a series of laboratory tests were conducted including the bender element test, the ultrasonic test, and the unconfined compression test. Based on the test results, the relationship among matric suction, soil velocity, and unconfined compression strength was studied.
Test results demonstrated that the soil compacted at dry side exhibits the lowest soil velocity and soil modulus. Although the suction characteristic of OMC and the wet side is similar, the OMC shows larger volume expansion and dry density decrease, thus the weakening of engineering properties is more significant when compared with soils compacted at the wet side. Test results also illustrate that the regression function can predict the soil modulus reasonably based on matric suction or p-wave velocity. On the other hand, the results of the p-wave velocity and the unconfined compression strength show that the unconfined compression strength increases linearly with the p-wave velocity as matric suction increases. Because the regression lines for all compacted sides are approximately parallel to each other, a normalized regression function can be established using the coordinate conversion. This normalized function can be used to estimate the unconfined compression strength using the p-wave velocity and it has a good application potential for geotechnical engineering.

1.王正君，「乾、濕化路徑與夯實狀態對土壤基質吸力之影響」，碩士論文，國立台灣科技大學營建工程研究所，2008。
2.李豪智，「乾濕化路徑下基質吸力對不飽和夯實紅土應變相依土壤模數之影響」，碩士論文，國立台灣科技大學營建工程研究所，2016。
3.林保延，「利用彎曲元件試驗推估砂土動態性質之探討」，碩士論文，國立台灣科技大學營建工程研究所，2004。
4.拱祥生，「降雨對不飽和土壤邊坡穩定性之影響研究」，碩士論文，國立台灣科技大學營建工程研究所，1999。
5.拱祥生，「不飽和紅土基質吸力行為及其在工程之應用」，博士論文，國立台灣科技大學營建工程研究所，2011。
6.廖志穎，「不飽和路基土壤濕化及剪力模數研究」，碩士論文，國立台灣科技大學營建工程研究所，2007。
7.Chan, C. M., “Bender Element Test in Soil Specimens: Identifying the Shear Wave Arrival Time”, Electronic Journal of Geotechnical Engineering, 15, pp. 1263-1276, (2010).
8.Ching, M., and Phoon, K. K., “Reducing the Transformation Uncertainty for the Mobilized Undrained Shear Strength of Clays”, Journal of Geotechnical and Geoenvironmental Engineering, 141(2), (2014).
9.Duncan, J. M., “Factor of Safety and Reliability in Geotechnical Engineering”, Journal of Geotechnical and Geoenvironmental Engineering , 126(4), 307-316, (2000).
10.Dyvik, R. and Madshus, C., “Lab Measurements of Gmax Using Bender Element”, Advances in the Art of Testing Soils under Cyclic Conditions, ASCE, New York, 186-196, (1985).
11.Ercikdi, B., Yılmaz, T., and Külekci, G., “Strength and Ultrasonic Properties of Cemented Paste Backfill”, Ultrasonics, 54(1), 195-204, (2014).
12.Fredlund, D.G., Morgenstern, N.R., and Widger, R.A., “The Shear Strength of Unsaturated Soils” Canadian Geotechnical Journal, 15(3), 313-321, (1978).
13.Fredlund, D. G., “Appropriate Concepts and Technology for Unsaturated Soils”, Canadian Geotechnical Journal, 16 (1), 121-139, (1978).
14.Fredlund, D. G. and Rahardjo, H., Soil Mechanics for Unsaturated Soils, John Wiley, N.Y., (1993).
15.Fredlund, D. G and Xing, A., “Equation for the Soil-Water Characteristic Curve”, Canadian Geotechnical Journal, 31(3), 521-532, (1994).
16.Fredlund, M. D., Wilson, G. W. and Fredlund, D. G., “Use of Grain- size Distribution for the Estimation of the Soil-water Characteristic Curve”, Canadian Geotechnical Journal, 39(5), 1103-1117, (2002).
17.Harr, M. E., ‘‘Reliability-based Design in Civil Engineering.’’ 1984 Henry M. Shaw Lecture, Dept. of Civil Engineering, North Carolina State University, Raleigh, N.C., (1984).
18.Senthilmurugan, T. and Ilamparuthi, K., “Study on Compaction Characteristics and Strength through Ultrasonic Method”, Advances in Pavement Engineering, (2005).
19.Inci, G., Yesiller, N. and Kagawa, T., “Experimental Investigation of Dynamic Response of Compacted Clayey Soils”, Geotechnical Testing Journal, 26(2), (2003).
20.Khandelwal, M. and Singh, T. N., “Correlating Static Properties of Coal Measures Rocks with P-wave Velocity”, International Journal of Coal Geology, 79(1), 55-60, (2009).
21.Krahn, J. and Fredlund, D. G., “On Total, Matric and Osmotic Suction”, Journal of Soil Science, 114(5), 339-348, (1972).
22.Kulhawy, F. H., ‘‘On the Evaluation of Soil Properties’’, ASCE Geotech. Spec. Publ. No. 31, 95-115, (1992).
23.Lacasse, S., and Nadim, F., ‘‘Uncertainties in Characterizing Soil Properties’’, Publ. No. 201, Norwegian Geotechnical Institute, Oslo, Norway, 49-75, (1997).
24.Lambe, T.W., “The Structure of Compacted Clay”, Journal of the Soil Mechanics and Foundations Division, ASCE, 84(SM2), 1654-1 to 1654-34, (1958a).
25.Lambe, T.W., “The Engineering Behavior of Compacted Clay”, Journal of the Soil Mechanics and Foundations Division, ASCE, 84(SM2), 1655-1 to 1655-35, (1958b).
26.Lewis, C. D., Industrial and Business Forecasting Method, Butterworth Scientific Publishers, London, (1982).
27.Likos, W. J., and Lu, N., “On the Filter Paper Technique for the Measurement of Total Soil Suction”, 81th Annual Meeting of Transportation Research Board, CD-ROM. National Research Council, Washington, D.C., (2002).
28.Lin, H. D., Kung, J. H. S., and Wang, C. C., “Matric Suction and Shear Modulus of Unsaturated Compacted Lateritic Soil Subjected to Drying and Wetting”, 6th Japan-Taiwan Workshop on Geotechnical Hazards from Large Earthquakes and Heavy Rainfall, 12-15, (2014).
29.Lin, H. D., Wang, C. C., and Kung, J. H. S., “Wetting and Drying on Matric Suction of Compacted Cohesive Soil”, Proceedings, ISOPE-2015, the 25th International Ocean and Polar Engineering Conference (with CD-ROM), 2, 1069-1075, Kona, Big Island, Hawaii, USA, (2015).
30.Mendoza, C. E. and Colmenares, J. E., “Influence of the Suction on the Stiffness at Very Small Strains”, Proc. 4th Int. Conf. on Unsaturated Soils, Carefree, AZ, 2-6, 529-540, (2006).
31.Miller, C. J., Yesiller, N., Yaldo, K., and Merayyan, S., “Impact of Soil Type and Compaction Conditions on Soil Water Characteristic”, Journal of Geotechnical and Geoenvironmental Engineering, 128(9), 733-742, (2002).
32.Yesiller, N., Inci, G., and J. Miller, J. C., “Ultrasonic Testing for Compacted Clayey Soils”, Advances in Unsaturated Geotechnics, (2000).
33.Nyunt, T. T., Leong, E. C., and Rahardjo, H., “Stress-Strain Behavior and Shear Strength of Unsaturated Residual Soil from Triaxial Tests”, Conference on Unsaturated Soils: Theory and Practice, 221-226, (2011).
34.Rao, S. M., and Revanasiddappa, K., “Role of Soil Structure and Matric Suction on Collapse of Compacted Soils”, Geotechnical Testing Journal, 26, 102-110, (2003).
35.Sawangsuriya, A., Bosscher, P. J., and Edil, T. B., “Alternative Testing Techniques for Modulus of Pavement Bases and Subgrades”, Proceedings of the 13th Annual Great Lakes Geotechnical and Geoenvironmental Engineering Conference, ASCE, Geotechnical Practice Publication, No.3, Milwaukee, WI, 108-121, (2005).
36.Shirley, D. J. and Hampton, L. D., “Shear-Wave Measurements in Laboratory Sediments”, Journal of Acoust.Soc.Am.63, No. 2, 607-613, (1978).
37.Singh, G. and R. Siddique., “Effect of Waste Foundry Sand (WFS) as Partial Replacement of Sand on the Strength, Ultrasonic Pulse Velocity and Permeability of Concrete”, Construction and Building Materials, 26(1), 416-422, (2012).
38.Terzaghi, K., “The Shear Resistance of Saturated Soils”, Proceedings, 1st International Conference on Soil Mechanics and Foundation Engineering, 1, Cambridge, (1936).
39.Vanapalli, S.K., Fredlund, D.G., Pufahl, D.E., and Clifton, A.W., “Model for The Prediction of Shear Strength with Respect to Soil Suction”, Canadian Geotechnical Journal, 33(3), 379-392, (1996).
40.Vasanelli, E., Colangiuli, D., Calia, A., Sileo, M., and Aiello, M.A., “Ultrasonic Pulse Velocity for the Evaluation of Physical and Mechanical Properties of a Highly Porous Building Limestone”, Ultrasonics, 60, 33-40, (2015).
41.Vasconcelos, G., Lourenco, P.B., Alves, C.A.S., and Pamplona, J., “Ultrasonic Evaluation of the Physical and Mechanical Properties of Granites”, Ultrasonics, 48(5), 453-466, (2008).
42.Viggiani, G. and Atkinson, J. H., “Interpretation of Bender Element Tests”, Geotechnique, 45(1), 149-154, (1995).