Analytical modeling and field assessment of embankment stabilized with vertical drains and vacuum preloading

摘要: ABSTRACT: This study presents an analytical model of radial drainage with vacuum preloading using compressibility indices and varying horizontal permeability considers the influence linearly distributed pressure along drain. An so-lution based on Cylindrical Cavity Expansion theory is used to evaluate extent smear zone drain length predict performance embankment stabilized vacuum-assisted prefabricated vertical drains at New Bangkok Interna-tional Airport (NBIA). Here, a significantly reduced height sand surcharge could be applied because excess pore was re-duced by preloading. The evaluated under different vac uum conditions during which suction head not maintained in field due probable air leaks. In analysis, therefore, magnitude ap-plied measurements adjusted accordingly. settlem ent predictions writers’ solutions were compared agreed available data. results also indicate that efficiency de-pends zone, distribution leak protection pro-vided field. RESUME : Cette etude presente un modele analytique de systeme par prechargement le vide utilisant des indi-ces compressibilite et une permeabilite horizontale var iable examine l’influence la lineaire pression long du Une solution basee sur theorie d’Expansion Cavite Cylindrique est utilisee pour evaluer l’etendue souillure toute longueur predit d’un remblai stabilise l’aide verticaux prefabri-ques sous site Nouvel Aeroport International Ici, pourrait utiliser hauteur sable considerablement reduite fait que amoindri l’excedent interstitielle. La perfor-mance ete evaluee differentes pendant lesquelles d’aspiration ne pouvait etre maintenue terrain cause probables fuites d’air. Dans l’analyse, niveau appliquee etait donc base mesures ajuste en consequence. Les tassement basees les donnees auteurs ont comparees aux notre disposition confirmees. resultats indiquent aussi l’efficacite depend souillure, l’ampleur vide, ainsi l’importance contre d’air disponible site. 1 INTRODUCTION A system probably most successful ground improvement technique for low-lying soft clays where objective accelerate consolida-tion shortening path. use mandrel driven (geosynthetics) (PVD) now economical. During installation, surround-ing soil remoulded near lateral will estab-lished: can determined large-scale consolidation tests (Indraratna Redana, 1998). Vacuum pre-loading increase per-formance. Negative surface further speed up consolidation, perform as additional surcharge, therefore em-bankment achieve same degree consolidation. practical effects has been discussed Qian al. (1992), Chu (2000) In-draratna (2005a) among others, application vac-uum load but without any modeled Mohamedelhassan Shang (2002). revised coefficients. analyse pile driving, tunneling testing (Pestana al., 2002), ex-tent modified Cam-clay (MCC). preconsolidation pressure, magni-tude variation are examined through associated consoli-dation settlement. Finally, settlement cen-terline measure-ments taken from plates. 2 SITE CONDITIONS proposed (Suvarnab-humi Airport) located Samut Prakan Province Bangkok. Located lowland area very problematic, so techniques have designed implemented overcome potential problems re-lated ground, land subsidence tight construction timelines. fairly uniform sub-soil consists thin weath-ered clay crust (about 2.0 m thick) overlying approximately 11 thick. stiff layer lying beneath extends 20-24 below while water (piezometric surface) level about 0.5m sur-face. adopted parameters subsoil layers Asian Institute Technology listed Table (AIT, 1995). Several test embankments built clay, few PVDs. this paper,