Load-deformation Analysis of a Pile in Expansive Soil upon Infiltration

Transcription

1 Proceeding of the 2 nd World Congre on Civil, Structural, and Environmental Engineering (CSEE 17) Barcelona, Sain Aril 2 4, 2017 Paer No. ICGRE 157 ISSN: DOI: /icgre Load-deformation Analyi of a Pile in Exanive Soil uon Infiltration Yunlong Liu, Sai K. Vanaalli, Amina W. BA Deartment of Civil Engineering, Univerity of Ottawa 161 Loui-Pateur St., Ottawa, Canada Liuyunlongzzu@hotmail.com; Vanaall@eng.uottawa.ca; Aba041@uottawa.ca Abtract - Pile are widely ued a foundation in region with exanive oil deoit to afely carry load from the uertructure to the oil without undergoing unaccetable deformation. Thee foundation are tyically deigned auming that that the oil i in a tate of aturated condition extending conventional oil mechanic rincile. However, the oil urrounding the ile in exanive oil i tyically in an unaturated tate. Due to thi reaon, the mechanical behaviour of the ile i ignificantly influenced by matric uction. In thi aer, the ile load tranfer model rooed by Zhang and Zhang (2012) i modified by taking account of the influence of matric uction on the ile-oil interface hear trength for etimating the load-deformation behaviour. In addition, an algorithm i develoed for etimating the load-deformation analyi of a ingle ile in exanive oil, taking account of infiltration condition. An examle roblem i reented for highlighting the influence of infiltration on the load ettlement behavior of a ingle ile in Regina clay, which i a tyical exanive oil from Canada. Keyword: ile, exanive oil, load tranfer, unaturated oil 1. Introduction Pile foundation are caable of carrying ignificantly large load from the uertructure to the oil below afely without tability or deformation roblem. Thee tye of foundation are alo widely ued in exanive oil, which are tyically found in an unaturated tate, with minor modification in their deign and contruction rocedure. The behaviour ile foundation in unaturated exanive oil are ignificantly influenced by matric uction. However, it i tyically ignored becaue the deign of ile foundation i baed on conventional oil mechanic auming aturated oil condition. Figure 1 illutrate the mechanical behavior of ingle ile in exanive oil before and after water or rainfall infiltration. Prior to infiltration, oitive friction develo along the entire length of the ile. The load from the uertructure i carried along the length and at the end of the ile [a hown in Figure 1 (a)]. A water infiltrate into the active zone [a hown in Figure 1 (b)], three main change that arie in the oil and ile behavior hould be given due conideration for the rational deign of ile foundation: (i) in vertical direction, volume exanion of oil caue ground heave; (ii) in the horizontal direction, retricted volume exanion contribute to the develoment of lateral welling reure, which hould be taken into account; (iii) the ile-oil interface trength roertie change due to variation in water content of the urrounding oil. Mot imortantly, due to the influence of water infiltration in the active zone, ulift friction generate along the ile a a reult of dilacement between the ile and the adjacent oil (i.e. oil well and move uward relative to the ile). The magnitude of the ulift friction can be determined from the lateral earth reure increae that arie from the contribution of lateral welling reure and the water content-deendent interface trength roertie. In the table zone (the deth below the active zone that i not influenced by water infiltration), negative friction arie when the ile move uward relative to urrounding oil in the table zone. Currently, there i limited undertanding of the comrehenive behavior of ile foundation in exanive oil [1]. For thi reaon, it i uually recommended to conduct in-itu tet [2] or erform numerical analyi to better undertand the comlexitie aociated with the ile behaviour in exanive oil [1][3][4][5]. However, in-itu ile teting i exenive and time-conuming while numerical analye require comlex contitutive relationhi, which need many oil arameter. For engineering ractice alication; a quick, imle and yet reliable and accetable aroach i required for better undertanding the ile behavior uon infiltration. In thi aer, the load tranfer curve model rooed by [6] i ICGRE 157-1

2 modified taking account of the influence of matric uction on the ile-oil interface hear trength uon infiltration. Furthermore, the traditional load tranfer method i modified to etimate the load ettlement analyi of a ingle ile in exanive oil uon infiltration. An algorithm i written for erforming the above analyi. In thi aer, an examle roblem i reented to highlight the load-deformation behavior of a ingle ile laced in Regina clay, which i a tyical examle of exanive clay from Canada, due to water infiltration. Pile head load Pile head load Change in friction direction Ground heave Active Zone Increaing Poitive Poitive Friction Friction Increaing lateral welling reure Change in interface roertie Stable Zone Poitive Friction Negative Friction Change in interface hear trength End Bearing Caacity End Bearing Caacity (A) Prior to infiltration (B) After infiltration Fig. 1: Mechanical behavior change of a ile laced in a tyical exanive oil before and after infiltration. 2. Background The load tranfer method for the analyi of ingle ile ettlement wa originally rooed by [7]. The load-ettlement curve can be reaonably etimated relating the interface hear trength roertie to the ile ettlement for ile head load. The key information in thi method i the curve relating the interface hear trength and the ile ettlement. Such load tranfer curve were develoed originally by [8]. Since then, everal other cholar have alo contributed to better undertand and etimate the load-ettlement behavior of ile from load tranfer curve. For examle, [7] and [9] reented the load tranfer curve uitable for different ituation from laboratory or field tet, or a combination of both. The load tranfer method ha gained wider accetance through decade of alication tudie [10]. In engineering ractice, the haft reitance degradation which ha been invetigated from field tet [11] [12] [13]; thee tudie ugget kin friction oftening increae which contribute to ile ettlement. However, very few aroache account for the kin friction oftening. In order to addre thi limitation, [6] rooed a imlified aroach for the nonlinear analyi of the load-dilacement reone of a ingle ile conidering haft reitance degradation and bae reitance hardening. The oftening nonlinear model of unit kin friction i hown in Fig. 2 (a). Initially, the ile haft friction increae nonlinearly with increaing ile head load. When the ile-oil relative dilacement reache S u, the unit haft friction reache a eak value u. The unit haft friction then decreae a the ile-oil relative dilacement kee increaing. The mathematical exreion of the curve hown in Fig. 2 (a) i given a Eq. (1). τ (z) τ u 1/4(b-c) τ r τ b k b2 1/a S u a/(b-2c) S (z) (a) (b) Fig. 2: (a) Relationhi between the kin friction and relative haft dilacement at the ile-oil interface (Modified after [6]); (b) Relationhi between the bae reitance and ile-end ettlement. k b1 S bu w b ICGRE 157-2

3 S ( z)[ a cs ( z)] ( z) 2 [ a bs ( z)] r u (1) (2) Where (z) i the haft hear tre at a given deth, z; S (z) i the relative dilacement along the ile-oil interface at a given deth, z; 1 1 S 1 1 u a ; 1 2 b ; c ; S u i ile-oil relative dilacement 2 u 2 u 4 u correonding to eak interface hear trength; u i the eak interface hear trength; r i the reidual interface hear trength; A erie of field tet on bored ile under comreion loading [11] [12] [13] demontrated that the value of β alied for bored ile have been found to be within the range of The bi-linear bae load-dilacement model i hown in Fig. 2 (b) and correonding mathematical exreion i given a Eq. (3). k k w w S b1 b b bu b b Sbu k ( (3) 1 b2 wb Sbu) wb Sbu Where b and w b are the unit end reitance and the ile end dilacement, reectively; k b1 and k b2 rereent the comreive rigidity of the ile-ti oil in the firt and econd tage of the load-dilacement curve, reectively; and S bu i the ile-end ettlement related to the limiting end reitance in the firt tage. A model wa rooed by [14] for the determination of k b1 a given in Eq. (4). k b1 4Gb r (1 ) 0 b (4) Where G b and b are the hear modulu and Poion' ratio of the oil below the ile bae, reectively. The value of k b2 can be aroximately calculated uing the Eq. (5) rooed by [15]. k b2 Pt kt (5) w ( P L / E A ) 1 ( k L / E A ) t t t Where P t i the increaed load on the ile head when the ettlement at the ile bae i larger than the limiting ile end ettlement of the firt tage of the b-w b curve; w t i the increaed ettlement at the ile head induced by P t; L i the ile length; E i the ile elatic modulu; A i the cro ectional area of the ile; and k t i the ratio of the load increment to the ettlement increment at the ile head, k t = P t/ w t. Baed on the rooed two model (the oftening nonlinear model of kin reitance and the bilinear bae loaddilacement model), uing load tranfer method rooed by [7], the load ettlement reone of a ingle ile can be obtained. The caacity of the rooed model i aeed by comaring the theoretical reult with the exerimental data from field meaurement of ile for different tye of oil (mud, andy ilt and clay). A atifactory agreement ha been achieved from thee comarion [6]. 3. Prooed method ICGRE 157-3

4 The load tranfer model rooed by [6] ha the ability to well imulate the relationhi between the load and ettlement of ingle ile under the alication of an axial load. Furthermore, thi relationhi i ha imle that i baed on oil arameter determined from the conventional oil tet. Thi aroach ha been uccefully alied for analyzing the load-deformation behavior of ingle ile in different kind of oil (i.e. mud, andy ilt and clay). For thi reaon, in the reent tudy, thi model ha been extended to decribe the load-deformation behaviour of ingle ile in exanive oil with neceary modification. The tre tate variable; namely, net normal tre and matric uction have a ignificant influence on the eak interface hear trength behavior of unaturated oil. The eak interface hear trength of the unaturated oil-tructure interface can be modelled uing Eq. (6) uggeted by [16]. Thi equation wa develoed after conducting a erie of interface direct hear tet between the tainle teel late and unaturated oil for different value of matric uction. u r c a ( nf uaf ) tan ( uaf uwf ) tan ( ) (6) r Where c a' i effective ile-oil interface coheion;(nf - uaf) i the net normal tre at failure, (uaf - uwf) i the matric uction at failure, ' i the effective oil internal friction angle; θ i the current volumetric water content; θr i the reidual volumetric water content; θ i the volumetric water content at a aturation of 100%. During the infiltration roce, lateral welling reure develo in exanive oil when the volume exanion of oil urrounding the ile i retricted in horizontal direction. The generation of lateral welling reure can ignificantly increae the net normal tre that act on the ile-oil interface. However, lateral welling reure i different from vertical welling reure for which tandardized teting technique and variou etimation model are available (ee the ummary by [17] [18] [19]). Reearch tudie regarding the meaurement and etimation of LSP however are relatively limited [20]. In thi tudy, the model rooed by [20] [Eq. (7)] i emloyed for the etimation of lateral earth reure (conidering the lateral welling reure) under urcharge from vertical welling reure. ( nf u af 2 (1 2 ) PS ) S 2 PS 2 1 (1 )(1 2 ) 1 E a (7) Where P i the vertical welling reure (contant volume condition); E a i the average elatic modulu with the variation uction range; σ i the urcharge tre. A emi-emirical equation [Eq. (8)] rooed by [21] i ued in Eq. (7) for redicting the variation of vertical welling reure with reect to uction reduction. It hould be noted that Eq. (8) i only uitable for the cenario of aturation oil condition. However, the water infiltration i a time deendent roce and the degree of aturation increae with an increae in initial water content (i.e. reduction of oil uction), rior to reaching full aturation condition. The lateral earth reure (conidering the lateral welling reure) during the intermediate eriod during which the degree of aturation and uction change can be calculated. For examle from ψ A (initial tate) to ψ B (ψ B i not zero), can be calculated a (P SA - P SB) uing Eq. (8). P S P S (8) 100 r 2 S 0 S ( ) Where, S r i the degree of aturation, P 0 i the intercet on the P axi at zero uction value (P 0 = 55 kpa for 0.107I comacted exanive oil), c i fitting arameter, c 0.011e d, max , d,max i the maximum denity of the oil,, I P i the index of laticity, i the oil uction. A emi-emirical model [Eq. (9)] rooed by [22] ha been ued to redict the variation of average modulu of elaticity of unaturated andy oil with reect to matric uction uing the SWCC. ICGRE 157-4

5 E unat E at 1 ( ua uw) S ( P /101.3) E [ E a ] (9) Where, E unat i modulu of elaticity under unaturated condition, E at i the aturated modulu of elaticity, α E and β E are fitting arameter, and P a i atmoheric reure (i.e kpa). Eq. (9) rooed by [23] for fine-grained oil (i.e. I P > 16%) can be extended for unaturated exanive oil to achieve a reaonable agreement uing the fitting arameter α E = 0.05 ~ 0.15 and β E = 2. Thi model can alo be extended for etimating the average elatic modulu E a in Eq. (7). E a i defined a the average value of variou E unat value calculated uing Eq. (9) over the range of matric uction variation. Limited exerimental reult from interface direct hear tet [16] [24] ugget that the reidual interface hear trength ( r), i not ignificantly influenced by the matric uction. The reaon for thi behavior can be attributed to the hearing beyond the eak trength. During thi tage of hearing (i.e. reidual condition), the air-water menici are comletely diruted which reult in a negligible trength contribution due to matric uction. However, the reidual interface hear trength doe increae with net normal tre at a given level of matric uction [21]. Extending thi hiloohy, the reidual hear trength can be given a Eq. (10). However, in Eq. (10), both the reidual effective coheion (c' ar) and the reidual interface friction angle (' r) hould be determined from exerimental tudie. The relationhi [Eq. (2)] between the eak interface hear trength and the reidual interface hear trength can alo be extended for ile-unaturated oil interface. r c ar ( u ) tan (10) nf af r Where c' ar i the reidual effective coheion; ' r i the reidual interface friction angle. The lat arameter required i the ile oil relative dilacement (S u) correonding to the eak interface hear trength ( u). A er earlier dicuion, after the eak trength, due to the oil article re-arrangement, the air-water menici are comletely diruted. Due to thi reaon, the value of (S u) i not ignificantly influenced by the matric uction. Thi view oint i uorted by variou exerimental reult [16] [24] [25]. Several factor influence the ile-oil interface behavior which include the oil tye, ile tye, conolidation condition of the oil, contruction method and environmental factor. All thee factor may oe ome influence on the value of S u and contribute to the eak unit haft friction and hence may be difficult to ae. Conidering thee difficultie, it i uggeted that S u to be determined exerimentally or from backanalyi of the field load tet reult. From a erie of field tet [11] [12] [13], [6] ummarized that the value of S u varie within a range from 5 to 25mm for bored ile with diameter from m in different kind oil (e.g., mud, clay, andy ilt, ilty clay). The load tranfer method rooed by Coyle and Reee (1966) are widely utilized to redict the load-ettlement behavior of ingle ile ubjected to axial load becaue they ugget relatively imle analytical rocedure and can be alied to any comlex comoition of oil layer with a nonlinear tre-train relationhi, nonhomogeneou medium, and any variation in the ection along a ile (Poulo and Davi 1980). The load ettlement behavior of a ingle ile in unaturated exanive oil uon infiltration can be analyzed by modifying the traditional load tranfer method, extending the following key aumtion: (i). The length ile i divided into a number of egment; (ii). Auming a mall ti movement, ρ t; the oint reitance, P t, caued by thi movement i calculated uing Eq. (3). In thi tudy the likely ituation that the ile ti ha detached with the oil i not conidered. (iii). A movement, ρ 3, at mid-height of the bottom egment i aumed (for the firt trial, it i uggeted that ρ 3=ρ t). (iv). The uction rofile kee changing during the infiltration roce. For a certain uction rofile at a certain time, a relevant load tranfer curve at a certain deth can be etimated uing the rooed method in thi tudy. (v). From the etimated load-tranfer curve, the hear trength of the oil at the deth of the egment correonding to movement ρ 3 can be obtained a 3. It hould be noted that in the active zone, the ile-oil relative dilacement hould conider the oible ground heave for rigorou analyi. The ground heave at different deth can be imly etimated uing Eq. (11) rooed by (23). (vi). The load Q 3 on the to of egment can then be calculated a Eq. (12); (vii). The elatic deformation at the midoint of the ile egment (auming a linear variation of load in the egment) i calculated uing Eq. (13); (viii). The new movement at the mid-oint of the egment i conidered a Eq. (14); (ix). The calculated ρ' 3 i comared with the etimated value of ρ 3 from te (4); (x). If the comuted ICGRE 157-5

6 movement ρ' 3 doe not agree with ρ 3 within a ecified tolerance, te (2) to te (10) are reeated and a new mid-oint movement i calculated; (xi). The next egment u i conidered after achieving convergence. Thi iteration rocedure continue until the value of ile head load (Q 0) and ile head dilacement (ρ 0) are obtained; (xii). A load-deformation curve can be achieved with reect to different bae ettlement for a certain uction rofile, following the rocedure from te (i) to te (xii). The ile head load-ettlement curve can be obtained by accumulating the ile load and ettlement at the to of each egment. (1 )(1 2 ) h h [ ] ( ua uw) E (1 ) a (11) Where h i heave of oil; h i thickne of the calculated oil layer; (u a - u w) i the uction reduction. Q Pt L (12) 3 3 3P3 Where L3 i length of egment 3; P3 i average erimeter of egment 3. Qm Pt L3 3 ( )( 2 2A E 3 ) (13) Where Q m Q3 Pt 2 ; A 3 i area of egment 3; E i elatic modulu of the ile. (14) t Examle roblem In order to better illutrate the algorithm rooed in thi aer, an examle roblem i reented in thi ection. It i aumed that a ingle ile i contructed in Regina clay, a tyical exanive oil from Canada. The load-deformation reone of the ile uon infiltration i analyed uing the rooed method. The geometry and oil roertie are derived from a cae tudy reented by [26]. Fig. 5 reent the SWCC given by [26] which wa etimated uing equation given by [27]. Proertie of Regina clay are ummarized from Vu and Fredlund (2004) are the following: Liquid limit (LL)=77%; Platic limit (PL) = 33%; Secific gravity (G) =2.82; Unit weight ( = 18.8 kn/m 3 ; Initial void ratio (e 0) = 0.962; Swelling index (C ) = 0.09; Saturated coefficient of ermeability (k at) = m/day; Saturated volumetric water content (θ ) = 0.493; Natural water content = However, hear trength roertie are not available in thi teting rogram. Intead, hear trength roertie ued in thi examle roblem are derived from the tet conducted by [28] on Regina clay. In thi examle roblem, the interface friction angle with reect to net normal tre (δ'), the interface friction angle with reect to matric uction ( b ) and interface coheion (c a') i 60% of the internal friction angle of oil with reect to net normal tre ('), oil internal friction angle with reect to matric uction ( b ) and oil coheion (c'), reectively. Thee aumtion with reect to interface roertie are baed on the concluion reented by [16]. The aumed hear trength roertie are ummarized a following: Effective internal friction angle of oil with reect to net normal tre (') = 27.9; Internal friction angle of oil with reect to matric uction( b ) = 19.8; Effective interface friction angle with reect to net normal tre (') = 16.7; Interface friction angle with reect to matric uction ( b ) = 11.9; Effective oil coheion (c' ) = 16.3kPa; Effective interface coheion (c a') = 9.8kPa. Fig. 3 how the geometry of the examle roblem. A ile (4m in length and 0.5m in diameter) i aumed to be intalled in Regina clay. In the calculation, the ile i divided into eight egment: four of thee egment are located in the active zone and the remainder four egment are in the table zone. The elatic modulu of the ile i et a 30GPa (reinforced concrete ile), the ile oil reidual hear trength i et a 60 ercent of the eak hear trength and the ile oil relative dilacement i et a (10mm) which i 1/50 of the ile diameter. The aturated elatic modulu of Regina clay ICGRE 157-6

7 i et a 5MPa and Poion' ratio i et a 0.3. The initial uction rofile given by [26], which i -888kPa at the ground urface and -12kPa at the bottom of the active zone i ued. One year after contruction, the hot water ie leakage wa detected and the oil in the active zone gradually achieved aturation condition with reect to time. Three different tate were conidered during the aturation roce for analyi in thi examle roblem. State 1 rereent the initial uction rofile before water infiltration, State 2 ignifie the uction rofile during the mid-time and State 3 mark the final teady tate. Fig. 4 how the relationhi between the ile head load and ettlement. From Fig. 4, ile how different behavior with uction decreae under different magnitude of ile head load. When the ile head load i lower than aroximately 170kN, the ile movement tend to be uward uon infiltration. However, when the ile head load i higher than thi value, the ile exerience downward movement uon infiltration. The reaon for thee behavior can be exlained a below; for ile under a head load lower than 170kN, rior to infiltration the ile haft friction i only artially mobilized (which i far le than the eak hear trength). Uon infiltration, the haft friction increae with increaing ile oil relative dilacement in the active zone. Due to thi reaon, the total ulift force outweigh the downward dragging force contributing to the uward movement of ile. However, when the ile i under a head load higher than 170kN, rior to infiltration, the haft friction contribution along the ile arie from fully mobilied eak hear trength arameter. Uon infiltration, increaing ile oil relative dilacement caue an interface hear trength decreae from eak to the reidual hear trength. The ile exerience ettlement due to decreae in the haft reitance. The ile head load of 170kN can be conidered to be a value which differentiate between the light and heavy tructure baed on the ile-oil movement uon infiltration. -888kPa -888kPa -444kPa 0 State 2 State 3 Q 0.5m Ground urface Initial ore water reure State 1 Active zone 2m 4m -12kPa Suction variation with reect to infiltration Stable zone Pile i divided into 8 egment Fig. 3: Geometry of the examle roblem. Pt Fig. 4: Pile head load ettlement relationhi. 5. Concluion The uction rofile variation aociated with infiltration ha a ignificant influence on the mechanical behavior of ier or ile foundation in unaturated exanive oil deoit. In thi aer, an algorithm i rooed baed on the traditional load tranfer method reented by [11] to tudy the ile load-deformation behavior of a ingle ile in unaturated exanive oil due to variation in uction rofile aociated with water infiltration. An examle roblem i reented in thi aer auming that a ingle ile i contructed in Regina clay, which i tyical exanive oil from Canada. The reult of the ICGRE 157-7

8 tudy indicate that for a lightly loaded ile (e.g., for light tructure), the haft friction i only artially mobilized. For uch a cenario, tyically there will be an uward ile movement. However, for heavy tructure, eak hear trength fully mobilize along the ile haft offering reitance to ile oil relative dilacement (i.e. ground heave). Once the eak hear trength value reduce to reidual value, haft friction contribution decreae raidly. A a conequence, the ile will be ubjected to a ettlement into the ground. The algorithm rooed in thi aer i romiing for reaonable etimation of the load-deformation behavior of ile in unaturated exanive oil. However, the rooed model ha to be validated againt cae tudie reult in the future for undertanding the trength and limitation of the rooed algorithm. Acknowledgement The author acknowledge the reearch funding and financial uort from the Natural Science and Engineering Reearch Council of Canada (NSERC) and China Scholarhi Council - Univerity of Ottawa Joint Scholarhi. Reference [1] J. D. Nelon, K. C. Chao, D. D. Overton, and E. J. Nelon, Foundation Engineering for Exanive Soil, John Wiley & Son, Hoboken, New Jerey, [2] Minitry of Houing and Urban-Rural Develoment of the Peole' Reublic of China (MOHURD), Technical code for building in exanive region, China Architecture & Building Pre, Beijing, [3] R. D. Ellion, E. Daolnia, and G. R. Thier, Load deformation mechanim for bored ile, J Soil Mech Fdn, ASCE., vol. 97, , [4] J. L. Juto, J. E. Rodriguez, A. Delgado, and A. Jaramillo, A finite element method to deign and calculate ier foundation in exanive oil, in Proceeding of Fifth International Conference on Exanive Soil, Adelaide, Autralia, 1984, [5] F. H. Chen, Foundation on exanive oil, Elevier, New York, [6] Q. Q. Zhang, and Z. M. Zhang, A imlified nonlinear aroach for ingle ile ettlement analyi, Canadian Geotechnical Journal, vol. 49, , [7] H. M. Coyle, and L. C. Reee, Load tranfer for axially loaded ile in clay, J.S.M.F.D, ASCE, vol. 92(SM2),. 1-26, [8] H. B. Seed, and L. C. Reee, The action of oft clay along friction ile, Tran, ASCE, vol. 122, , [9] H. M. Coyle, and I. H. Sulaiman, Skin friction for teel ile in and, J.S.M.F.D, ASCE, vol. 93(SM6), , [10] H. G. Poulo, E. H. Davi, Pile foundation analyi and deign (No. Monograh), [11] Q. Q. Zhang, Z. M. Zhang, F. Yu, and J. W. Liu, Field erformance of long bored ile within iled raft, in Proceeding of the intitution of Civil engineer: Geotechnical Engineering, vol. 163, no. 6, , [12] Z. M. Zhang, Q. Q. Zhang, and F. Yu, A detructive field tudy on the behavior of ile under tenion and comreion, Journal of Zhejiang Univerity-Science A, vol. 12, no. 4, , [13] Z. M. Zhang, Q. Q. Zhang, G. X. Zhang, and M. F. Shi, Large tonnage tet on uer-long ile in oft oil area, Chinee Journal of Geotechnical Engineering, vol. 33, no. 4, , (In Chinee) [14] M. F. Randolh, and C. P. Wroth, Analyi of deformation of vertically loaded ile, Journal of the Geotechnical Engineering Diviion, ASCE, vol. 104, no. 12, , [15] Q. Q. Zhang, Z. M. Zhang, and J. Y. He, A imlified aroach for ettlement analyi of ingle ile and ile grou conidering interaction between identical ile in multilayered oil, Comuter and Geotechnic, vol. 37, no. 7-8, , [16] T. B. Hamid, and G. A. Miller, Shear trength of unaturated oil interface, Canadian Geotechnical Journal, vol. 46, no. 5, , [17] J. D. Nelon, and D. J. Miller, Exanive oil-roblem and ractice in foundation and avement engineering. Willy, New York, [18] B. H. Rao, K. Venkataramana, and D. N. Singh, Studie on the determination of welling roertie of oil from uction meaurement, Canadian Geotechnical Journal, vol. 48, no. 3, , ICGRE 157-8

9 [19] Ö. Çimen, S. N. Kekin, and H. Yıldırım, Prediction of welling otential and reure in comacted clay, Arabian Journal for Science and Engineering, vol. 37, no. 6, , [20] Y. Liu, and S. K. Vanaalli, Influence of lateral welling reure on the geotechnical infratructure in exanive oil, Journal of Geotechnical and Geoenvironmental Engineering (acceted), [21] H. Y. Tu, and S. K. Vanaalli, Prediction of the variation of welling reure and 1-D heave of exanive oil with reect to uction uing the oil water retention curve a a tool, Canadian Technique Journal, vol. 53, no. 8, , [22] W. T.Oh, S. K. Vanaalli, and A. J. Puala, Semi-emirical model for the rediction of modulu of elaticity for unaturated oil, Canadian Geotechnical Journal, vol. 46, no. 8, , [23] H. H. Adem, and S. K. Vanaalli, "Elaticity moduli of exanive oil from dimenional analyi," Geotechnical Reearch, 60-72, vol. 1, no. 2, , [24] M. A. Hoain, J. H. Yin, Unaturated oil-cement interface behaviour in direct hear tet, Autralian Geomechanic Journal, vol. 48, no. 3, , [25] Z. H. Fan, Reearch on welling-hrinkage characteritic and ile-oil interaction of exanive oil foundation, Ph.D. thei, Central South Univerity, Changha, China, (In Chinee) [26] H. Q. Vu, and D. G. Fredlund, The rediction of one, two- and three-dimenional heave in exanive oil, Canadian Geotechnical Journal, vol. 4,. 1-25, [27] D. G. Fredlund, and A. Xing, Equation for oil-water characteritic curve, Canadian Geotechnical Journal, vol. 31, no. 3, , [28] R. H. Chowdhury, and A. Shahid, Unaturated hear trength roertie of a comacted exanive oil from Regina, Canada, Innovative Infratructure Solution, vol. 1, no. 1,. 47, ICGRE 157-9