ASCE GSP 258-2016 Advances in Pavement Engineering and Ground Improvement.pdf

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1、Advances in Pavement Engineering and Ground ImprovementGeotechnical Special Publication No. 258Edited byHadi Khabbaz, Ph.D. Zahid Hossain, Ph.D. Boo Hyun Nam, Ph.D. Xianhua Chen, Ph.D.Selected Papers from the Proceedings of the Fourth Geo-China International ConferenceSEGEOTECADVANLECTED GEGeo-PHNIC

2、ALGEOCES INGRPAPERS O-CHINAShandoChineInstitute oublished bSPECI-CHPAVEMOUND IFROM THINTERNJuly 2ShanSPONShandong DeparUniversise Nationf the AmeEDHadi KZahid HBoo HyXianhuby the AmerAL PUBINAENT EMPROVE PROCEATIONA527, 201dong, ChinSORED BYng Univertment of Tty of Oklahal Sciencerican SocieITED BY

3、habbaz, Phossain, Phun Nam, Pa Chen, Phican SocietyLICATIO20NGINEEEMENTEDINGS L CONFE6 a sity ransportathoma Foundatioety of Civi.D. .D. h.D. .D. of Civil EnON NO.16 RING ANT OF THE FRENCE ion n l Engineergineers 258 ND OURTHs Published by American Society of Civil Engineers 1801 Alexander Bell Driv

4、e Reston, Virginia, 20191-4382 www.asce.org/publications | ascelibrary.org Any statements expressed in these materials are those of the individual authors and do not necessarily represent the views of ASCE, which takes no responsibility for any statement made herein. No reference made in this public

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9、y locating a title in ASCEs Civil Engineering Database (http:/cedb.asce.org) or ASCE Library (http:/ascelibrary.org) and using the “Permissions” link. Errata: Errata, if any, can be found at http:/dx.doi.org/10.1061/9780784480014 Copyright 2016 by the American Society of Civil Engineers. All Rights

10、Reserved. ISBN 978-0-7844-8001-4 (PDF) Manufactured in the United States of America. Preface This Geotechnical Special Publication (GSP) contains 18 papers that were accepted and presented at the 4thGeoChina International Conference on Sustainable Civil Infrastructures: Innovative Technologies for S

11、evere Weathers and Climate Changes, held in Shandong, China on July 25-27, 2016. Major topics covered in this GSP are: Engineering Issues in Ground Subsidence Geophysical Testing in Civil and Geological Engineering Ground Improvement, and Chemical / Mechanical Stabilization for Pavement and Geotechn

12、ical Applications Asphalt Mix-Design, HMA Testing, Yuan Chang Deng2; Teng Ruei You3; and Hao Shiang Hsu41Professor, Dept. of Civil Engineering, National Central Univ., No. 300, Jhongda Rd., Jhongli, Taoyuan, Taiwan. E-mail: 2Ph.D. Candidate, Dept. of Civil Engineering, National Central Univ., No. 3

13、00, Jhongda Rd., Jhongli, Taoyuan, Taiwan. E-mail: 3Ph.D. Candidate, Dept. of Civil Engineering, National Central Univ., No. 300, Jhongda Rd., Jhongli, Taoyuan, Taiwan. E-mail: 943202029cc.ncu.edu.tw 4Master, Dept. of Civil Engineering, National Central Univ., No. 300, Jhongda Rd., Jhongli, Taoyuan

14、, Taiwan. E-mail: Abstract: One of the viaducts of the High Speed Railway in Taiwan has suffered significant structural cracks in its piers. This has raised serious public concern. The damage was conjectured to have resulted from ground settlement due to regional water pumping. The paper proposed a

15、 practical methodology to investigate the downdrag behavior of the pile foundations of the viaduct. A fictitious settlement controlled layer beneath the pile foundation was used to control the ground surface settlement due to deep water pumping. A three-dimensional finite difference mesh including t

16、he soil profile and the pile foundation was established with the geotechnical investigation report and design data. By varying the ground surface settlement, the variations of the pile settlement, ground settlement, and downdrag force with depth for each pile can be reasonably simulated. The results

17、 show an obvious pile group effect, which shows the minimum downdrag force in the interior pile and maximum force in the corner pile. There also exists a critical surface ground settlement at which the drag force reaches the maximum value. The simulated differential settlement was close to the measu

18、red value, however this was not enough to have caused the structural cracks in the piers. The cracks are more likely caused by other engineering events. INTRODUCTION The Taiwan High Speed Railway (HSR) was constructed along Taiwans western coastal alluvial plain in 2006 and began operating in 2007.

19、Figure 1 shows its route and the site under study. Nowadays, it is a very important transportation artery. The western coastal plain has suffered from regional ground subsidence for many years owing to *HR Kai Yao2; Xiaomeng Zhang3; Xiuguang Song4; Teng Ma5; and Xianghong Pan61Professor, School of C

20、ivil Engineering, Shandong Univ., 17923 Jingshi Rd., Jinan, Shandong 250061, P.R. China. E-mail: zhanyong- 2Ph.D. Student, Dept. of Civil and Environmental Engineering, National Univ. of Singapore, 1 Engineering Dr. 2, Singapore, 117576 Singapore (corresponding author). E-mail: 3Ph.D. Student, Scho

21、ol of Civil Engineering, Shandong Univ., 17923 Jingshi Rd., Jinan, Shandong 250061, P.R. China (corresponding author). E-mail: 4Professor, School of Civil Engineering, Shandong Univ., 17923 Jingshi Rd., Jinan, Shandong 250061, P.R. China. E-mail: 5Master Student, School of Civil Engineering, Shand

22、ong Univ., 17923 Jingshi Rd., Jinan, Shandong 250061, P.R. China. E-mail: 6Consultant, China Construction Bank, 22 Donghai Xilu, Qingdao, Shandong 266000, P.R. China. E-mail: Abstract: A physical model for expressway foundation with cement mixing piles was established according to the similarity t

23、heory. The effect of pile length, area replacement ratio and surcharge load on foundation settlement was studied. The pile length was varied from 40 cm to 100 cm while the area replacement ratio was changed from 0.023 to 0.093. Test results show that the foundation settlement will decrease as the in

24、crease of pile length at the same area replacement ratio and surcharge load. As the surcharge load increases, the settlement difference between foundation with longer pile and shorter pile will also increase. When the pile length is certain, bigger area replacement ratio will lead to smaller foundat

25、ion settlement. INTRODUCTION The Yellow River alluvial plain is 1/3 of the whole area of Shandong Province in China. Silt is the main constituent of soils in this kind of area, which will cause big or even non-uniform settlement for expressway foundation without ground improvement 1-2. The foundatio

26、n with cement mixing piles has been widely used for ground improvement to decrease settlement and increase the capacity of foundation. This kind of technology will mix soft soils with cement, lime or a combination of both in situ to form hardened columns with a certain machine 3-5. Numerous studies

27、have been done in the past on the foundation with cement mixing piles, most of which focused on the properties of cement stabilized soil, bearing capacity or stability of the combined foundations. However, there are still many uncertainties in the settlement calculation or prediction for foundation

28、with cement mixing piles. Moreover, the design parameters of foundation with cement mixing piles should be based on quite many factors, such as the soil type and surcharge load. 6-11. As the in-situ test is not easy to control, it is of great importance to do physical model test to study the factors

29、 influencing foundation settlement, including area replacement ratio, pile length and surcharge load. *HR shear failure and/or downward movement (settlement) or upward movement (expansion). The downward pressure from the foundation is extremely high at the immediate vicinity of the contact line betw

30、een soil and foundation and decreases below the foundation to a depth equal to half or full the width of the foundation or even two times the foundation width within the influence zone of the pressure. Numerous methods were suggested by previous researchers to predict the safe bearing *HR Terzaghi (

31、1943), Meyerhof (1963), Hansen (1970), Vesic (1973, 1975), DeBeer and Martens (1957), Mayne and Poulos (1999), Burland and Burbidge (1985) and others. Expansive soils expand when hydrated, and shrink when dried. This soil movement causes extensive damage to buildings, roads, pipelines, and other str

32、uctures. The repair costs are estimated to be in billion dollars annually (Shamrani, et al. 2010). The construction on problematic soil needs special precautions and detailed examinations of the ability of the soil to swell/consolidate under the design load. The well-known physical tests to predict

33、the upward and downward movement of the soil are: swelling and consolidation test; respectively. The swelling pressure is defined as the pressure required to suppress the expansion and it can be measured directly through the swelling test. The estimation of the shallow foundation settlements is a ro

34、utine process in geotechnical investigations. Foundation settlements can be categorized into two components elastic settlement (Se) and consolidation settlement (Sc) or short term and long term settlements; respectively. For foundations supported by silty/clayey soil within the influence zone of the

35、 pressure, the total settlement (ST) can be evaluated as the sum of Seand Sc.According to Bowles (1997), both types of settlement analyses are in the form of: +=1iiHHsiiEqHH The total settlement is the summation obtained from all n layers of soil (Bowles 1997). To estimate the elastic settlement, th

36、e modulus of elasticity Esiis defined as )21)(1()1(1+=strvsEmE where vm is the coefficient of volume change (m2/kN), is Poissons ratio and strE is modulus of elasticity obtained from Triaxial Test. One of the most important parameters of the consolidation test is the coefficient of consolidation (Cv

37、). Sridharan and Nagaraj (2000) suggested the following correlation between the coefficient of consolidation and the coefficient of volume change from Triaxial Test: )/(.2smmkCwvv= K is the hydraulic conductivity (m/s) and w is the unit weight of pure fluid (kN/m3) In this study 17 boreholes were dr

38、illed to 15m, 20m, and 30m below existing ground level in order to ascertain the subsurface condition and its ability to sustain infrastructure facilities. A generalized soil profile of the drilled boreholes is created in order to summarize the soil design properties. An estimation of the uplift for

39、ce has been carried out through swelling test and the expected settlement has been predicted through consolidation test. From the consolidation test, the coefficient of consolidation (Cv) is estimated and by using Sridharan and Nagaraj (2000) formulation, the coefficient of volume change (mv) can be

40、 calculated in order to estimate the value of elastic modulus (Es) by using the formula suggested by (Bowles 1997). The long and short term settlement can be calculated using the elastic modulus and via the software package (CED V.200). The software that executes settlement analysis according to the

41、 Hooke equation: *HR&KLQD*63 $6&()SHEiiZi i Xi Yiin=+= 1Hiis the thickness of the i layer, Ei is the Young modulus of the i layer, iis the Poisson ratio (equal to 0.33 in drained conditions), Ziis the increment of vertical stress induced by the applied load, Xi and Yiare the increments of the horizo

42、ntal stresses induced by the applied load. The computation of the overstresses z, x, y, induced by an applied pressure 0is carried out considering the set of equations proposed by Ohde, using the Frlich coefficient ( = 1+ 1/) to compute overstresses in cohesive soils. The calculation of the settleme

43、nt (extension of the sum from i to n subdivision) is interrupted when the increment of vertical stress zis lower than the 10% of the effective vertical pressure. A site in Khartoum showed typical swelling problems. Seventeen boreholes were drilled in order to ascertain the subsurface condition and i

44、ts ability to sustain infrastructure facilities. MATERIAL AND SITE CONDITIONS The subsurface soil conditions within the site indicated a very stiff to hard silty clay with sand continuing throughout the investigated depth of 30 meters. Groundwater was encountered at 17 m depth. Disturbed and undistu

45、rbed soil samples were extracted from the drilled boreholes and multitudes of physiochemical testing were carried out (classification, UCS, compaction, CBR, chemical analysis, consolidation and swelling tests). The swelling tests were carried out in accordance with ASTM D4546 (Method A). The reporte

46、d swelling is 17.4% and the swelling pressure was reported as 25kPa for an initially wet sample. The consolidation tests carried out indicated compressibility index of 0.328 with initial void ratio of 0.623 and pre-consolidation pressure of 60kPa. The coefficient of consolidation (Cv) was measured a

47、s 0.042cm2/min. The gradation, hydrometer and Atterberg limit tests showed high percentages of fine materials (Silt/Clay) with high plasticity values along the borehole depths. The plasticity values for some tested samples are summarized in Table 1. Table 1. Subsurface soil index properties BH No. S

48、ample depth (m) % Passing from Sieve No.200 Liquid limit (%) Plasticity Index BH-01 9.00 39 80 44 BH-01 12.00 29 52 29BH-02 15.00 26 52 27 BH-05 18.00 37 42 17BH-12 3.00 65 71 50 BH-14 3.00 89 70 47BH-15 10.50 19 44 32 BH-17 4.50 89 60 41*HR&KLQD*63 $6&(By plotting these values in the plasticity chart (Fig. 1) as shown below, this value was located within the A-Line, with a medium/very high risk of swelling. Fig. 1 Plasticity Chart TEST RESULTS AND DISCUSSION Swelling and consolidation tests were carried out on undisturbed samples