iosr-JMCE   International Conference on Innovations in Civil Engineering (ICICE 2014)

Abstract: The Rural public transportation is insufficient, accessibility is very much required in countries like India for the movement of passenger and goods .to nearby towns with in aspects of public participation, for overall development. Rural areas are suffering from transport problems such as inadequate transport facilities in terms of shortage of buses and non-availability of services. Present study focused to increase the public transport accessibility in safe and efficient way and also meeting future demand up to 2018 for study area.
Keywords -Accessibility, Public Transport, Questionnaires, Rural Regions and Surveys

[1] C. V. Phani Kumar, Debasis Basu, and Bhargab Maitra. Modeling Generalized Cost of Travel for Rural Bus Users: A Case Study, Journal of Public Transportation, Vol. 7, No. 2, 2004, PP: 59 – 72.
[2] Danang parikesit and La Ode Muhammad magribi, Development of a dynamic model for investigating the Interaction between rural transport and development, Journal of the Eastern Asia Society for Transportation Studies. Vol. 6, 2005, PP: 2747 – 2761.
[3] Mairead Cantwell, Brian Caulfield, Margaret O'Mahony, Examining the Factors that Impact Public Transport Commuting Satisfaction, Journal of Public Transportation, Vol. 12, No. 2, 2009, PP :1 - 21 .
[4] Ar Anuj Jaiswal, Ashutosh Sharma, Jigyasa Bisaria, Estimation of Public Transport Demand in Million Plus Indian Cities based on Travel Behavior, ISSN: 2249 – 8958, Volume-2, Issue-1 , 2012, PP :249 - 259.
[5] Amiruddin Ismail, Mohammad Ganji, Mohammad Hesam Hafezi, Foad Shokri and Riza Atiq, An Analysis of Travel Time in Multimodal Public Transport, Australian Journal of Basic and Applied Sciences, ISSN 1991-8178, 2012, PP: 165-172.

Abstract: The present paper describes a study carried out to check the improvements in the properties of Black Cotton (BC) soil with a non traditional stabilizer. The collected soil samples were treated with a commercially available bio enzyme and the treated soil samples were cured for different curing periods as 0, 7 and 28 days. The engineering properties obtained for different mix proportions of soil and the stabilizer are studied. The results of Consistency limits, Compaction test, Free swell index (FSI), Unconfined Compressive Strength (UCS), California Bearing Ratio (CBR), Durability tests such as Wet Dry (WD) and Freeze Thaw (FT) and Permeability test obtained for different curing periods under soaked and unsoaked conditions have been studied and discussed. Tests were also conducted to determine the chemical composition of untreated and treated soils to understand the mechanism of stabilization. Test results indicate that properties of BC soil, which are important for pavement construction, get enhanced by bio enzyme stabilization. Keywords – Bio enzyme, CBR, Durability test, Free swell index, Permeability, UCS.

[1] R Wright Fox, J. G. Macfarlane, and R. F. Bibbens, Alternate Chemical Soil Stabilizers, Minor Research Report. CalTrans. 1993.
[2] B.M. Lekha, A.U. Ravi Shankar, and S. Goutham, Fatigue and Engineering Properties of Chemically Stabilized Soil for Pavements, Indian Geotechnical Journal, Volume 43, Issue 1, 2013, 96-104
[3] R. Brazetti, and S. R. Murphy, General usage of Bio-Enzyme stabilizers in Road Construction in Brazil, 32ndAnnual Meeting on Paving Brazil, October 2000.
[4] R. Andrew, S. M. Fadi, E. Nicholos, and M. Elahe. An Evaluation of Strength change on Subgrade soils stabilized with an Enzyme Catalyst solution using CBR and SSG comparisons, Report submitted to University Transportation Centre South Carolina State University Orangeburg, SC, USA, 2003.
[5] A. U. Ravi Shankar, H. K. Rai, and I. R. Mithanthaya, Bio-Enzyme Stabilized Lateritic Soil as a Highway Material, Journal of the Indian Roads Congress, Paper No. 553, 2009, 143-151.
[6] C. Venkatasubramanian, and G. Dhinakaran, Bio-Enzymatic Stabilization on Unconfined Compressive Strength and California Bearing Ratio, Journal of Engineering and Applied Sciences, 6(5), 2011, 295-298.

Abstract: Stone Matrix Asphalt (SMA) is a gap graded bituminous mixture with comparatively higher concentration of coarse aggregates and binder mastic. The higher concentration of mastic (bitumen and filler) may cause drain down in these mixtures and to prevent it, suitable stabilizing additive is used. In this investigation, it was aimed to eliminate the use of additional stabilizing material, by modifying the aggregates and bitumen with suitable chemicals. Modification of aggregates was done by treating them with a chemical named Terrasil and bitumen modification was achieved by the addition of another chemical called Zycosoil. Effect of these chemicals was determined from testing the SMA mixtures for volumetric and Marshall properties, tensile strength and rutting behaviour. Samples were prepared in Superpave Gyratory Compactor (SGC) for testing. From the results it was observed that proper usage of these chemicals eliminates the necessity of stabilizing additive. Also it was seen that chemical treatment with aggregates is a better method to improve the overall performance of SMA mixtures compared to bitumen modification.
Keywords –Drain down, Stone Matrix Asphalt, Stone on stone contact, Superpave Gyratory Compactor, Terrasil, Zycosoil.

[1] E.R. Brown, and J.E. Haddock, A method to ensure stone-on-stone contact in Stone Matrix Asphalt paving mixtures, NCAT Report 97-02, NCAT, Auburn, Alabama, US, 1997.
[2] Y.F. Qiu, and K.M. Lum, Design and performance of Stone Mastic Asphalt, Journal of Transportation Engineering, 132(12),ASCE, 2006, 956–963.
[3] AASHTO,Report on the 1990 European asphalt tour, AASHTO Report, Washington DC, US, 1990.
[4] E.R. Brown, J.E. Haddock, R.B. Mallick, and T.A. Lynn, Development of a mixture design procedure for Stone Matrix Asphalt." Journal of Association of Asphalt Paving Technologists, 66, 1977, 426–457.
[5] B.D. Prowell, D.E. Watson, G.C. Hurley, and E.R. Brown,Evaluation of Stone Matrix Asphalt (SMA) for airfield pavements,Final Report, No: AAPTP 04-04, Airfield Asphalt Pavement Technology Program, Auburn University, Alabama, US, 2009.

Abstract: Thermal Power Plants (TPPs) which generate more than 60% of the electricity in India are responsible for generation of huge quantity of CCRs. Fly ash and bottom ash the two main by-products of TPPs are mixed along with water and the resulting slurry is carried to ash ponds through drains which contains trace metals like As, Cr, Zn, Cd and sometimes radioactive elements like U, Th etc. Three pond ash samples were collected from three different ash ponds situated around Kolaghat Thermal Plant in West Bengal, India. The leaching potentials of different elements and total leachable concentration of those elements present in the three pond ash samples were assessed by Sequential Extraction procedure. TCLP was carried out on the same pond ash samples to assess the hazardous nature of the samples to the environment. According to the results obtained from Sequential Extraction, toxic elements showed potential of getting leached varying from moderate to high ranges of concentrations. Radioactive elements like U and Th could also be detected. Results of Sequential Extraction indicate high possibility of contamination of the surrounding soil and groundwater around the ash ponds. TCLP results indicate that the pond ash samples are hazardous in nature.
Keywords – CCRs, SEP, TCLP, TPPs, USEPA, WHO, RCRA

[1] Pappu A., Saxena M. and Asolekar S.R. Solid wastes generation in India and their recycling potential in building materials. Building and Environment, 42(6), 2007, 2311-2320.
[2] Shivpuri K.K., Lokeshappa B., Kulkarni D.A., Dikshit A.K. Metal Leaching Potential in Coal Fly Ash. American Journal of Environmental Engineering, 1(1), 2011, 21-27.
[3] Mandal A. and Sengupta D. Radionuclide and trace element contamination around Kolaghat Thermal Power Station, West Bengal –Environmental implications. Current Science, 88(4), 2005, 617-624.
[4] Shan X., Chen B. Evaluation of sequential extraction for speciation of trace metals in model soil containing natural minerals and humic acid, Anal. Chem., 65(6), 1993, 802–807.
[5] Chang C. F., Wang C. F., Mui D. T. and Chiang H. L. Application of methods (sequential extraction procedures and high-pressure digestion method) to fly ash particles to determine the element constituents: A case study for BCR 176. Journal of Hazardous Materials, 163(2-3), 2009, 578-587.

Abstract: In the present study a investigation on the performance of a multi-outrigger structure subjected to seismic loads has been carried out. A three dimension model has been developed using the software ETABS. The relative height of the outrigger is varied and the performance of outrigger is then studied based on lateral displacement, storey drift, shear force and bending moment in the core wall for different values of relative axial rigidity (ratio of axial rigidity of the columns to the axial rigidity of core wall). When the displacement criteria is considered, a significant reduction in lateral displacement at top has been observed for the multi-outrigger structure for a relative height of 1.5 when compared with a structure without outrigger. When bending moment criteria is taken into account, there has been a considerable reduction in bending moment when the multi-outrigger structure with a relative height of 6.67 is compared with a model without outrigger .
Keywords- Bending Moment, Lateral Displacement, Multi-outrigger, Relative Axial Rigidity, Relative Height.

[1]. Z. Bayati, M. Mahidikhani and A. Rahaei, Optimized Use of Multi-outrigger System to Stiffen Tall Buildings, The 14th World Conference on Earthquake Engineering, Beijing China, October 2008, 12-17.
[2]. N. Herath, N. Haritos, T. Ngo and P. Mendis, Behaviour of Outrigger Beams in High-Rise Buildings Under Earthquake Loads, Proceedings of Australian Earthquake Engineering Society Conference, 2009.
[3]. Kiran Kamath, N. Divya and Asha U. Rao, A Study on Static and Dynamic Behaviour of Outrigger Structural System for Tall Buildings, Bonfring International Journal of Industrial Engineering and Management, Vol 2, No. 4, December 2012,15-20.
[4]. J. R. Wu and Q. S. Li, Structural Performance of Multi-Outrigger Braced Tall Buildings, The Structural Design of Tall and Special Buildings, Volume 12, 2003, 155-176.
[5]. Rob J. Smith and Michael R. Willford, The Damped Outrigger Concept for Tall Buildings, The Structural Design of Tall and Special Buildings 16, November, 2007, 501-507.

Abstract: Earthquake vulnerability analysis is a fertile area of research which needs more input from seismologists and engineers. This paper focuses on the generation of fragility curves for a five-story reinforced concrete (RC) flat-slab building structure in the central United States. Fragility curve is a statistical tool representing the probability of exceeding a given damage state to the earthquake intensity. For the development of fragility curves asset of earthquake records selected from PEER data base .Inelastic time history analysis was performed to anlyse the structure subjected to the earthquake records in terms of spectral acceleration in ETABS V 9.7.3. To improve the seismic performance of the structure retrofitting was done by the addition of shear walls. Then fragility curves were also developed for retrofitted structure. The fragility curves developed from this study were used to compare the seismic performance of retrofitted and unretrofitted structure.
Keywords - Fragility Curves, PEER Data Base, Flat Slab Structure, Time History Analysis, Spectral Acceleration, Damage State

[1] Erbiric, M. (2000), "Fragility Curves for Reinforced Concrete Structures in Skopje (Macedonia) Region," Soil Dynamics and Earthquake Engineering, 19, 455-466.
[2] Jisra, J.O. and Kreger, M. (1989), "Recent Research on Repair and Strengthening of Reinforced Concrete Structures," Proceedings, ASCE Structures Congress, San Francisco, CA, 1, 679-688.
[3] Lombard, j., Humar, J.L. and Cheung, M.S. (2000), "Seismic Strengthening and Repair of Reinforced Concrete Shear Walls," Proc., 12th world Conference on Earthquake Engineering, Auckland, New Zealand (CD-Rom).
[4] Mary, Beth, Hueste, D. and Jong, Wha, Bai. (2007). "Seismic Retrofit of a Reinforced Concrete Flat Slab Structure: Part II- Seismic Fragility Analysis" Engineering Structures, 29, 1178-1188.
[5] Wen, Y.K. and Wu, C.L. (2001), "Uniform Hazard Ground Motions for Mild-America's Cities," Earthquake Spectra, 17, (2), 359-384.

Abstract: Seismic response of steel tank depends however on complex fluid structure interaction that results in global overturning moments and base shear induced by horizontal inertial forces, overturning moment causes an increase of vertical stresses in the tank wall and even uplift of the base plate, while base shear can lead to relative displacements between base plate and foundation. The responses of cylindrical steel tank under seismic effect is analyzed by means of finite element software package ANSYS which make use of modal analysis and response spectrum analysis . In this study, the seismic analysis of fuel storage tank with diameter of 10m and height 11m under four different liquid filling levels ( 25 %, 50%, 75%,100%) is considered. Tanks were designed according to American Petroleum institute (API) 650-2007. The seismic analysis of fuel storage tanks were calculated using IS 1893:2002 (Part 2 )and dependence of various parameters on different aspect ratios were analyzed. Using ANSYS software package, modal analysis was carried out on all four tanks considered. Response spectrum analysis was also carried out on fuel storage tanks to study the effect of fluid level on tank behavior. Next the response spectrum analysis is done. The results of the normal stress in Y-direction are presented and found that normal stress in Y-direction of tank 1, tank 2, tank 4 have higher normal stress which exceeds the minimum yield strength(240MPa) of plate material A 516 M. Only the tank 3 (75% filling level) is safe under seismic effect.
Keywords – Base shear, Modal analysis , Normal stress ,Overturning moment , Response spectrum analysis

[1] Al Zeiny, "Simplified Modeling of Liquid-Structure Interaction in the Seismic Analysis of Cylindrical Liquid Storage Tanks", 13th World Conference on Earthquake Engineering Vancouver, B.C., Canada August 1-6, 2004, Paper No. 1914.
[2] American Petroleum Institute (API) 650-2007, Welded Steel Tanks for Oil Storage, 11th Edition, August 2011.
[3] Carluccio and Fabbrocino, "Fem Seismic Analysis of Steel Tanks For Oil Storage In Industrial Facilities", The 14th World Conference on Earthquake Engineering October, 2008,12-17 .
[4] Cho KH, Kim MK, Lim YM, Cho SY,"Seismic response of base isolated liquid storage tanks considering fluid–structure-soil interaction in time domain". Soil Dynamics and Earthquake Engineering, 2006,839–52.
[5] Cooper, T. W. "A Study of the Performance of Petroleum Storage Tanks during Earthquakes, 1933– 1995", NIST No. GCR 97-720, U.S. Dept. of Commerce, National Institute of Standards and Technology, Gaithersburgh,1997

Abstract: Chimneys are tall structures and an effective means of air pollution control. Current Indian code follows the Working Stress Design (WSD) approach, assuming elastic behavior of materials and use of permissible stresses on cracked section. For solid circular sections, necessary charts are available to compute flexural strength in presence of axial loads as per Limit State Design (LSD) .Currently there are no charts available for designing hollow circular sections by limit state design method. The 'interaction curve' is a complete graphical representation of the design strength of a chimney of given proportions. Each point on the curve corresponds to the design strength values of P and M. Percentage of reinforcement can be obtained directly from chart when openings are present. Longitudinal steel design is very tedious and involves lengthy calculations. Formulas give only strength for openings at particular location. We have to assume openings symmetrically and this gives conservative results. Furthermore if there are many openings of varying sizes at one particular section an accurate design becomes very difficult. This paper presents a method of designing by dividing the section in to a number of trapezoidal strips of equivalent area and developing the interaction curve. Using design interaction curve - for a given chimney section, quick judgment as to whether or not the section is safe can be made.
Keyword - Equivalent area, Interaction curve, LSD ,Trapezoidal strips, Ultimate bending moment, Ultimate force.

[1] Durgesh C Rai,Kamlesh Kumar,Ultimate Flexural Strength Of Reinforced Concrete Circular Hollow Sections, Journal Of The Indian concrete journal 2010,30-45
[2] K. S. Babu Narayan ,Subhash C. Yaragal ,Interaction Envelopes For Limit State Design Of Chimneys,The fourth international symposium on computational wind engineering 2006,439-442
[3] Bhairav K Thakkar , Analyses and design of reinforced concrete circular cross section, Journal of ACI Structural, 2001 ,85-95.
[4] Manohar, S.N (1985), Tall Chimneys - Design and Construction, Tata McGraw-Hill Publishing Company Limited, New Delhi.
[5] Pinfold,G M,Reinforced Concrete Chimney and Tower, Viewpoint Publication, C and CA,UK,1975
[6] S Unnikrishna pillai and Devadas Menon,Reinforced Concrete Design, Tata McGraw-Hill Publishing Company Limited, NewDelhi.
[7] IS 456:2000, "Plain and Reinforced Concrete", Bureau of Indian Standards, New Delhi.
[8] SP 16: 1980, "Design Aids for Reinforced Concrete to IS: 456-1978", Bureau of Indian Standards, New Delhi

Abstract: Earthquake is a sudden violent shaking of the ground and can cause destruction of structures. The behavior of a structure under earthquake forces depends not only on its stiffness but also on the supporting foundation and soil. The phenomenon in which the response of the soil influences the motion of the structure and the motion of structure influences the response of the soil is termed as soil structure interaction (SSI). In conventional studies, structure is assumed as resting on rigid soil and SSI effect is neglected. However, for the realistic analysis of structure, the soil and foundation are to be considered as an integral part of the structure. For the present study a plane frame structure subjected to earthquake is analyzed considering SSI effect so as to investigate the effects of SSI on the response of a structure subjected to earthquakes. The structure is subjected to four earthquake ground accelerations and the response of the structure obtained from the analysis without considering SSI is compared with the response obtained from the analysis considering SSI.
Keywords – acceleration, base shear, bending moment, earthquakes, soil structure interaction

[1] J. Bielak, Dynamic behavior of structures with embedded foundations, International Journal of Earthquake Engineering and Structural Dynamics, 3(3), 1974, 259–274.
[2] J.P. Stewart, G.L. Fenves, and R.B. Seed, Seismic Soil–Structure Interaction in Buildings. I: Analytical Method, Journal of Geotechnical and Geoenvironmental Engineering, 125(1), 1999, 26–37.
[3] J.P. Stewart, R.B. Seed and G.L. Fenves, Seismic Soil–Structure Interaction in Buildings. II: Empirical Findings, Journal of Geotechnical and Geoenvironmental Engineering, 125(1), 1999, 38–48.
[4] J. Zheng, T. Takeda, Effects of soil-structure interaction on seismic response of PC cable-stayed bridge. Soil Dynamics and Earthquake Engineering 1995, 14:427-437.
[5] Y.K. Tang, H.T. Tang, J.C. Kasssawara, Validation of soil-structure interaction methods using earthquake data in lotung, Taiwan. 9th Word Conference on Earthquake Engineering, Tokyo – Kyoto, Japan 1988.
[6] M.R. Kianoush, and A.R. Ghaemmaghami, The effect of earthquake frequency content on the seismic behavior of concrete rectangular liquid tanks using the finite element method incorporating soil-structure interaction, Engineering structures ,33, 2011, 2186-2200
[7] Milos Novac, Hisham Mitwally, Transmitting boundary for axisymmetrical dilation problems, Journal of Engineering Mechanics, Vol.114, No.1, 1988, 181-186.

Abstract:Earthquakes are most devastating natural hazards in terms of life and property of any region. The behavior of the structure greatly depends on size, shape and geometry of that structure in addition to how the earthquake forces are carried to the supporting ground. Irregularity in building attracts forces which lead to stress concentration at the point of irregularity; subsequently it leads to localized failure of that structure. The present study focuses on seismic performance of irregular RC frames in elevation. For this purpose ETABS a finite element software has been used. Here 2-D RC frames with four bays are considered. The irregularity is gradually increased from regular frame to highly irregular frame. Roof displacement; Base shear carried; performance points; number of hinges formed are the parameters used to quantify the performance of the structure.
Keywords: Irregular frames, Pushover analysis, Performance point, Plastic Hinges.

[1] Pradip Sarkar, A. Meher Prasad and Devdas Menon, "Vertical Geometry irregularity in stepped building frames", Engineering Structures, Vol. 32, 2010, pp. 2175-2182.
[2] Athanassiadou C. J., "Seismic performance of RC plane frames irregular in elevation", Science Direct Journal", Engineering Structures , Vol .30, 2008, pp.1250-1261.
[3] Chopra A.K and Goel R.K., "Capacity-Demand Diagram Methods for estimating seismic deformation of inelastic structure" SDOF Systems, PEER Report 1999/02, Pacific earthquake Engineering Research Centre, University of California,Berkley,2001.
[4] Kadid A. and Boumrkik A., (2008), "Pushover Analysis of Reinforced Concrete Frame Structures", Asian Journal of Civil Engineering (Building and Housing) Vol. 9, No. 1, 2008, pp. 75-83.
[5] IS1893, Indian seismic code, Part 1, Criteria for Earthquake Resistant Design of Structures, General Provisions and Buildings (Bureau of Indian Standards, New Delhi, 2002).

Abstract: The present study focuses on the effect of a provision of concentric bracings on the seismic performance of the steel frames. In the present study two different types of concentric bracings (viz. X and inverted-V type bracing) have been considered for the different storey levels. For this purpose, ETABS, Finite Element software has been used and the comparison between the performances of 1- bay X and inverted–V type and unbraced frames is made using pushover curves. Base shear carried, roof displacement generated and the number of hinges formed are the parameters used to identify the seismic performance of the frames. It is inferred that the effect of a provision of bracing will increase the strength of the steel frames and roof displacement undergone by the frame gets reduced considerably in braced frame.
Keywords: Concentric bracings, Inverted-V braces, Pushover analysis, Steel Frame, X braces.

[1] Tafheem Z. and Khusru S., Structural behavior of steel building with concentric and eccentric bracing: A comparative study, International Journal of Civil and Structural Engineering, vol 4, No 1, 2013, pp 12-19.
[2] Luigi Di Sarno and Amr S. Elnashai, Bracing system for seismic retrofitting of steel frames, 13th World Conference on Earthquake Engineering, Vancouver, Canada, 2004.
[3] Madhusudan, G. K., Prasad S. K., and Srikanta Prasad S., Pushover analysis for seismic strengthening of steel frames with bracings , Fifth CUSAT National Conference on Recent Advances in Civil Engineering, Nov 29 – Dec 01, Kochi, India, 2012.
[4] P. Poluraju, Pushover Analysis of Reinforced Concrete Frame Structure using SAP 2000,International Journal of Earth Sciences and Engineering, vol. 4, no. 6, 2011, pp. 684–690.
[5] Krawinkler H and Seneviratna G. D. P. K., Pros and cons of pushover analysis of seismic Performance evaluation, Engineering Structures, Vol. 20, No. 4.6,1998, pp. 452 – 464.
[6] ATC-40, Seismic Evaluation and Retrofit of Concrete Buildings (Applied Technical Council, California Seismic Safety Commission, Redwood City, California, 1996).
[7] FEMA 356, Prestandard and Commentary for the Seismic Rehabilitation of Buildings (Federal Emergency Management Agency, Washington (DC), 2000).
[8] Agawal P. and Shrikhande M., Earthquake Resistant Design of Structures (Prentice-Hall of India Private Limited, New Delhi, India, 2006).
[9] Subramanian N., Design of steel structures (Oxford university press, New Delhi, India, 2008).

Abstract: Many times the structures are constructed on soft consolidating soils which has low bearing capacity, excessive settlement characteristics and long duration for consolidation. Determination of settlement of footing constructed on these soils is one of the major problems of geotechnical engineering. In this paper a footing supported by piles on soft consolidating soil is analysed using finite element method. In this method pore pressure and displacement in soil are coupled and resulting equations are solved to obtain the displacements and pore-pressure at various time intervals from beginning till the end of consolidation. Behaviour of soil is considered as nonlinear and a cam clay model is used to simulate the behaviour of soil. The settlement of the footing resting on pile foundation is compared with the settlement of foundation without piles and it is found that the time required for consolidation for the footing on piles is considerably less than that of the foundation without piles.
Keywords – Cam clay model, Consolidation, Finite element method, Footing on piles.

[1] M.A. Biot General theory of three dimensional consolidation, Journal of Applied Physics, 12, 1941, 155-164.
[2] J.M. Duncan , V.R. Schaefer, Finite element consolidation analysis of embankments. Comput Geotech, 6(2),1988, 77–93.
[3] M.F. Bransby, S.M. Springman, 3-D finite element modelling of pile groups adjacent to surcharge loads. Comput Geotech, 19(4), 1996, 301–24.
[4] P.K. Woodward, A.P. Berenji, Advanced numerical investigation of Terzaghi's superposition theory. Adv Eng Softw 2001, 32(10–11), 797–804.
[5] D.T. Bergado, A.S. Balasubramaniam , R.J. Fannin, D. Holtz, Prefabricated vertical drains (PVDs) in soft Bangkok clay: a case study of the new Bangkok International Airport project. Can Geotech J, 2002, 39, 304–315.