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http://dx.doi.org/10.12989/gae.2014.7.5.477

Behaviour of micropiles in collapsible loess under tension or compression load  

Qian, Zeng-Zhen (School of Engineering and Technology, China University of Geosciences)
Lu, Xian-Long (China Electric Power Research Institute)
Yang, Wen-Zhi (China Electric Power Research Institute)
Cui, Qiang (China Electric Power Research Institute)
Publication Information
Geomechanics and Engineering / v.7, no.5, 2014 , pp. 477-493 More about this Journal
Abstract
This study examines the behaviour of single micropiles subjected to axial tension or compression load in collapsible loess under in-situ moisture content and saturated condition. Five tension loading tests and five compression loading tests on single micropiles were carried out at a typical loess site of the Loess Plateau in Northwest China. A series of laboratory tests, including grain size distribution, specific gravity, moisture content, Atterberg limits, density, granular components, shear strength, and collapse index, were carried out during the micropile loading tests to determine the values of soil parameters. The loess at the test site poses a severe collapse risk upon wetting. The tension or compression load-displacement curves of the micropiles in loess, under in-situ moisture content or saturated condition, can generally be simplified into three distinct regions: an initial linear, a curvilinear transition, and a final linear region, and the bearing capacity or failure load can be interpreted by the L1-L2 method as done in other studies. Micropiles in loess should be considered as frictional pile foundations though the tip resistances are about 10%-15% of the applied loads. Both the tension and compression capacities increase linearly with the ratio of the pile length to the shaft diameter, L/d. For micropiles in loess under in-situ moisture content, the interpreted failure loads or capacities under tension are 66%-87% of those under compression. However, the prewetting of the loess can lead to the reductions of 50% in the tensile bearing capacity and 70% in the compressive bearing capacity.
Keywords
loess; micropile; load test; ultimate load; skin friction;
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  • Reference
1 Chen, Y.J. and Fang, Y.C. (2009), "Critical evaluation of compression interpretation criteria for drilled shafts", J. Geotech. Geoenviron. Eng., 135(8), 1056-1069.   DOI   ScienceOn
2 Derbyshire, E., Meng, X.M. and Wang, J.T., Zhou, Z.Q. and Li, B.X. (1995), "Collapse loess on the loess plateau of China", Genesis, properties of Collapsible Soils, (Derbyshire E., Dijkstra T. and Smalley I.J. Eds.), Kluwer, Dordrecht, The Netherlands, pp. 267-293.
3 Chen, Y.J., Chang, H.W. and Kulhawy, F.H. (2008), "Evaluation of uplift interpretation criteria for drilled shaft capacity", J. Geotech. Geoenviron. Eng., 134(10), 1459-1468.   DOI   ScienceOn
4 CLC (2008), Technical code for building pile foundations, Chinese Local Code JGJ 94-2008, China Architecture and Building Press, Beijing, China. [In Chinese]
5 CNC (2011), Code for design of building foundations, Chinese National Code GB50007-2011, China Architecture and Building Press, Beijing, China. [In Chinese]
6 Feda, J. (1988), "Collapse of loess upon wetting", Eng. Geol., 25(2-4), 263-269.   DOI
7 Gao, G.R. (1988), "Formation and development of the structure of collapsing loess in china", Eng. Geol., 25(2-4), 235-245.   DOI
8 Gibbs, H.J. and Holland, W.Y. (1960), "Petrographic and engineering properties of loess", Engineer Monograph No. 28, U.S. Bureau of Reclamation, Denver, CO, USA, 37 p.
9 Han, J. and Ye, S.L. (2006), "A field study on behavior of micropiles under compression or tension", Can. Geotech. J., 43(1), 19-29.   DOI
10 Hirany, A. and Kulhawy, F.H. (1988), "Conduct and interpretation of load tests on drilled shaft foundations: Detailed guidelines", Report No. EPRI EL-5915, Electric Power Research Institute, Palo Alto, CA, USA, pp. 272-273.
11 Hirany, A. and Kulhawy, F.H. (1989), "Interpretation of load tests on drilled shafts. II: Axial uplift", Foundation Engineering: Current Principles and Practices, (Kulhawy FH Eds.), ASCE, New York, (GSP 22), pp. 1150-1159.
12 Lim, Y.Y. and Miller, G.A. (2004), "Wetting-induced compression of compacted Oklahoma soils", J. Geotech. Geoenviron. Eng., 130(10), 1014-1023.   DOI
13 Hirany, A. and Kulhawy, F.H. (2002), "On the interpretation of drilled foundation load test results", Deep foundations, (O'Neill M.W. and Townsend F.C. Eds.), ASCE, Reston, VA, (GSP 22), pp. 1018-1028.
14 Jeon, S.S. and Kulhawy, F.H. (2001), "Evaluation of axial compression behavior of micropiles", Proceedings of Foundation and Ground Improvement, (Brandon T.L. Eds.), ASCE, Reston, VA, (GSP 113), pp. 460-471.
15 Lawton, E.C., Fragaszy, R.J. and Hardcastle, J.H. (1989), "Collapse of compacted clayey sand", J. Geotech. Geoenviron. Eng., 115(9), 1252-1267.   DOI
16 Lizzi, F. (1980), The Use of Root Pattern Piles in the Underpinning of Monuments and Old Buildings and in the Consolidation of Historic Centres, L'Industria delle Costruzioni, Volume 110, p. 25.
17 Makarchian, M. and Poulos, H.G. (1996), "Simplified method for design of underpinning piles", J. Geotech. Geoenviron. Eng., 122(9), 745-751.   DOI
18 Nouaouria, M.S., Guenfoud, M. and Lafifi, B. (2008), "Engineering properties of loess in Algeria", Eng. Geol., 99(1-2), 85-90.   DOI
19 Qian, Z.Z and Lu, X.L. (2011), "Behavior of micropiles in soft soil under vertical loading", Adv. Mater. Res., 243-249, 2143-2150.   DOI
20 Qian, Z.Z., Lu, X.L. and Yang, W.Z. (2014), "Axial uplift behavior of drilled shafts in Gobi gravel", Geotech. Test. J., 37(2), 205-217.
21 Akbas, S.O. and Kulhawy, F.H. (2009), "Axial compression of footings in cohesionless soils. I: Load-settlement behavior", J. Geotech. Geoenviron. Eng., 135(11), 1562-1574.   DOI
22 Anil, M., Chen, C.H. and Oberoi, R. and Kleiber, A. (2004), "Simplified analysis method for micropile pullout behavior", J. Geotech. Geoenviron. Eng., 130(10), 1024-1033.   DOI
23 Assallay, A.M., Rogers, C.D.F. and Smalley, I.J. (1996), "Engineering properties of loess in Libya", J. Arid Environ., 32(4), 373-386.   DOI
24 ASTM (2011), Standard practice for classification of soils for engineering purposes (Unified Soil Classification System), ASTM D2487-11, American Society for Testing and Materials; ASTM International, West Conshohocken, PA, USA.
25 Basma, A.A. and Tuncer, E.R. (1992), "Evaluation and control of collapsible soils", J. Geotech. Eng. Div., 118(10), 1491-1504.   DOI
26 ASTM (1995), Standard test method for individual piles under static axial tensile load, ASTM D3689-90(1995), American Society for Testing and Materials; ASTM International, West Conshohocken, PA, USA.
27 ASTM (2003), Standard test method for measurement of collapse potential of soils, ASTM D5333 - 2003, American Society for Testing and Materials; ASTM International, West Conshohocken, PA, USA.
28 ASTM (2007), Standard test method for particle-size analysis of soils, ASTM D422-63, American Society for Testing and Materials; ASTM International, West Conshohocken, PA, USA.
29 Briaud, J.L. (2007), "Spread footings in sand: Load settlement curve approach", J. Geotech. Geoenviron. Eng., 133(8), 905-920.   DOI   ScienceOn
30 Bruce, D.A. (1989), "Aspects of minipiling practice in the United States", Ground Eng., 22(1), 35-39.
31 Bruce, D.A., Dimillio, A.F. and Juran, I. (1995), "Introduction to micropiles: An international perspective", Foundation Upgrading and Repair for Infrastructure Improvement, (William F.K. and John M.T. Eds.), ASCE, New York, GSP(50), pp. 1-26.
32 CEI/IEC (1996), Overhead lines-Testing of foundation for structures, CEI/IEC 1773, Commission Electrotechinque Internationale / International Electrotechnical Commission, Bureau central de la Commission Electrotechnique Internationale 3, Geneva, Switzerland.
33 Chen, Y.J. and Chu, T.H. (2012), "Evaluation of uplift interpretation criteria for drilled shafts in gravely soils", Can. Geotech. J., 49(1), 70-77.   DOI   ScienceOn
34 Armour, T., Groneck, P., Keeley, J. and Sharma, S. (2000), "Micropile design and construction guidelines implementation manual priority technologies program (PTP) project", Rep. No. FHWA-SA-97-070, Department of Transportation Federal Highway, Washington, D.C., USA, pp. 32-33.