Design of Anchored-Strengthened Sheet Pile Wall: A Case Study

Transcription

1 Design of Anchored-Strengthened Sheet Pile Wall: A Case Study Ümit Gökkuş* 1, Yeşim Tuskan 2 1 Prof.Dr., Department of Civil Engineering, Celal Bayar University, İzmir, Turkey ( umit.gokkus@cbu.edu.tr Phone: 90(236) ) 2 Res.Asst., Department of Civil Engineering, Celal Bayar University, İzmir, Turkey ( yesim.tuskan@cbu.edu.tr Phone: 90(236) ) *Corresponding Address: Dept.of Civil Eng, Celal Bayar University, Sehit Prof.Dr.Ilhan Varank Campus, ,Yunusemre-Manisa/TURKEY Abstract: The design of a m high anchored-strengthened steel sheet pile, effective on building foundations, staged excavations and earth retention, is presented in this study. Sheet piling with a single anchor was considered. Wall deformations, bending moments, wall shear forces and anchor forces were investigated for the conditions studied. An evolution of the safety provided by classical limit equilibrium method for anchored sheet pile wall is investigated. Investigation of the stabilization problems that are mentioned above was observed with the determination of the design parameters such as anchors, box pile wall profile and interaction of these parameters which effects the deformations into the ground during the stabilization studies. Moments of inertia were gradually changed and strengthened parts of profile were placed considering shelves. Keywords: Sheet Pile Wall, Anchorage of Sheet Pile Wall, Strengthened Sheet Pile Profile, Structural Analysis of Retaining Walls 1. Introduction Brinch-Hansen (1953) developed a design method with plastic hinges for sheet pile wall and ever since this method has formed the basis for the current Danish design practice (Brinch et al.1953). Retaining walls are used to maintain a difference in the elevation of the ground surface. The retaining wall can be classified as rigid or flexible walls according to system rigidity. A wall is considered to be rigid if it moves as a unit in rigid body and does not experience bending deformations like most of gravity walls. However, flexible walls are the retaining walls that undergo bending deformations in addition to rigid body motion. Steel sheet pile wall is the most common example of the flexible walls because it can tolerate relatively large deformations. A continuously interlocked pile segments embedded in soils were used to resist horizontal pressures. Steel is the most common material used for sheet pile walls due to its resistance to high driving stresses, relatively lightweight, and long service life (Bowles 1988). In recent years, Choudhury et al.(2006) presented a paper concerning with the lateral earth pressure on sheet pile against earthquake motion. Soils with high groundwater tables or soils with low bearing capacity are ideal sites for the application of sheet piling (Tan et al. 2008). The anchored sheet pile walls used as either permanent or temporary lateral earth support system in various civil engineering projects are one of the most reliable methods of structure protection (Bilgin et al.2009). They proposed the response of a sheet pile retaining wall with a single anchor to improve the sloping ground conditions. The advantage of decreasing the cut and fill operations of slope was presented for a 12 m high slope. After that, Ramsden et al (2010) 92

2 investigated the load carrying capacity of the sheet pile wall by examining the lateral wall deflection and examined the cross-section lost due to the corrosion. The rehabilitation of an 11 m high offshore sheet pile wall is studied (Ramsden et al.2010). Zhang et al. (2011) studied the feasibility of concrete sheet pile retaining wall as vertical shoring. Finite element analysis was carried out to define earth pressure, settlement, and horizontal displacement of shoring structure and the pile s stress and strain variation by simulating the design conditions (Zhang et al.2011). Within last five years, Isobe et all.(2014) used the sheet pile wall made of steel pipes to reinforce the caisson foundation in their studies. Armanyous et al.,(2016) studied experimentally in double sheet-walls replaced intervally. Gazetas et al. (2016) also worked especially for tall and anchored sheet-pile wall under seismic loads as mentioned in Choudhury et al.(2006). They studied on wall composed of I and V shaped sheet piles. In this study, it is aimed that tall and anchored sheet pile wall are strengthened by using sheet piles varying sections from the bottom to top of wall. On a case study considering this strengthened sheet pile, the calculation procedures taking into account the uniform surcharge loads and lateral earth pressure stated clearly. 2. Methodology The wall movement from active earth pressure towards the passive conducted the horizontal pressure distributions around the sheet pile wall. The simple triangular pressure distribution is adopted for an ideal conservative solution with lower earth pressures and smaller bending moments in the wall. For the effectiveness of the anchorage system location, outside of the potential active failure zone must be selected behind a sheet pile wall. The anchorage system length is designed to provide sufficient resistance to movement under limit state conditions. The slip circle of overall stability is also considered for the length of the tie rod system. Steel sheet piles are used in many aggressive environments and consequently corrosion protection or factor influencing effective life must be considered. There are several design methods for sheet pile walls. The simplified method is slightly more conservative than the full method and gradual method with the benefit of simplicity on the traditional system of equations (Padfield et al.1984). The main advantage of an anchored sheet pile wall, against those cantilevered, is the ability to reduce the embedment depth by increasing the excavation depth. Initially the total pressure coefficients for active and passive conditions were calculated in presence of earthquake magnitude by the following equations: = ± 1 + " = ± 1 +!! For retaining structures restrained by anchors equivalent horizontal seismic coefficient and vertical seismic coefficient were presented in the equations: # $ = 0.3( + 1) * (3) # + = 2# $ 3 (4) Effective ground acceleration coefficient, A 0, was selected 0.4 for seismic zone 1 in Turkey, building importance factor, I, was selected 1.00 for the standard buildings. 93 (2) (1)

3 3. Case Study A wall is built to support a retained height of 16 m with the ties acting at 3.8m below ground level. The simplified method for a fixed earth analysis assumes that the point of contra-flexure in bending moment diagram occurs at the level where the active pressure equals the passive pressure. The length of sheet pile is found by moments about the 1.67 m below the low ground level and forces equilibrium. Then the depth below the point of contra-flexure is increased by 20% to give the pile penetration. Zero shear occurs at 3.8 m and m below the ground level. The backfill behind the sheet pile wall has a dry unit weight of about 18 kn/m 3, a saturated unit weight of 20 kn/m 3 and shear strength parameter of φ = 40. Additional features, such as the ground water height H w and surcharge load q are shown in Figure 1 as a typical cross-section with the maximum design wall height. A surcharge load of 17 kn/m 2 was applied for traffic loading. The total active and passive pressure coefficients were summarized in Table 1. for saturated and natural unit weight conditions with ground water level (Kip et al.1999). The calculated horizontal pressures and the calculated values of horizontal equivalent forces were depicted in Figure 2. The distance between the contra flexure point and the dredged level with the pressure value of point, P c2 are calculated by the following equations:.! = / ! (5) 3 = (6) Bending moments about the point B were calculated and D 1 was founded by the moment equilibrium then the forces equilibrium was carried out to obtain the anchor load, T. Section PSp 1117 with height of 1117 mm and width of 460 mm second moment of inertia Ix= cm 4, section modulus ωx=44860 cm 3,allowable stress = kn/cm 2 were selected according to ASTM A328 was selected in the Sheet Piling Handbook (2010) and the section is shown in Figure 3. The total deflection exhibited by a retaining wall comprises a component based on the deflection of the section as a result of the applied loads and a component based on compression of the soil as the active/passive pressure regime is established. The calculations of shear forces and bending moments are set out in Figure 4. with the parametric study of SAP2000 and were compared with the results obtained by effective stress distribution. The ability of large size construction is carried out with reinforcement. An anchored-strengthened sheet pile wall cross-section is shown in Fig.5. It is possible to enhance the strength of overlap parts for different layers. Joints of sheet pile wall were strengthened in presence of suitable overlap length. Piling energy of sheet pile wall should be increased for additional profiles. The strengthened parts may also be located on beam flanges of sheet pile wall. 94

4 4. Conclusion In this study, efforts were made to develop an anchored sheet pile wall system to satisfy successfully external and internal stability of the retaining wall. Results show that the proposed method can capture the displacements and bending moments of retaining wall for quite deep excavations. Deep-seated Failure and rotational failure due to inadequate pile penetration were prevented to improve soil stability. The designed sheet-pile wall with anchor system enabled the stability to carry out earth and foundation work safely. References Armanyous,A.M., Ghoraba,S.M., Rashwan,I.M.H., Dapaon,M.A.,(2016) A Study on Control of Contaminant Transport through the Soil Using Equal Double Sheet Piles, Ain Shams Engineering Journal, Vol:7, pp Bilgin, O. and Erten, B. (2009). Anchored Sheet Pile Walls Constructed on Sloping Ground, International Foundation Congress and Equipment Expo Bowles, J. E. (1988). Foundation Analysis and Design. 4th Ed., McGraw-Hill, New York. Brinch Hansen, J., (1953). Earth pressure calculation, PhD Thesis, University of Cophenagen. Choudhury,D., Chatterjee,S.,(2006), Dynamic Active Earth Pressure on Retaining Structures, Sadhana, Vol. 31, Part 6, pp Gazetas,G., Garini,E., Zafeirakos,A.,(2016), Seismic analysis of tall anchored sheet-pile walls, Soil Dynamics and Earthquake Engineering, Vol:91, pp Isobe,K.,Kimura,M.,Ohtsuka,S.,(2014),Design Approach to a Method for Reinforcing Existing Caisson Foundation Using Steel Pipe Sheet Piles, Soils and Foundations, The Japanese Geotechnical Society, Vol: 54 (2), pp , Kip, F. and Kumbasar, V. (1999). Problems in Soil Mechanics, Caglayan Publishing, Istanbul (in Turkish) Padfield, C. J. and Mair, R. J. (1984). Design of retaining walls embedded in stiff clay, CIRIA Report 104. Ramsden, M.R., Griffiths, T.F., (2010). Steel Sheet Pile Wall Wale Rehabilitation, Ports, pp State of New York,(2015), Geotechnical Design Procedure: Geotechnical Design Procedure for Flexible Wall Systems,GDP-11,Revision #4, Geotechnical Bureau, Department of Transportation, NY Sheet Piling Handbook (2010), 3rd Edition, Hoesch Spundwand und Profil-A Member of the Salzgitter Group and Peiner Trager-A Member of the Salzgitter Group, ThyssenKrupp GfT Bautechnik Tan, Y. and Paikowsky S. G. (2008). Performance of sheet pile wall in peat, Journal of Geotechnical and Geoenvironmental Engineering, Vol 134, No.4, Technical Standarts for Port and Harbour Facilities in Japan. (1980). Bureau of Ports and Harbours, Ministry of Transport Port and Harbour Research. United States Steel Corporation, (1984), Steel Sheet Piling Design Manual, U. S.Department of Transportation /FHWA Zhang, L., Zhang, F. And Hua, M. (2011). Application of Sheet Pile Wall in a Channel to Upgrade Water ways, Slope Stability and Earth Retaining Walls:

5 Figures Fig. 1 Anchored sheet pile wall Fig. 2 (a)horizontal effective stress distribution (b) Horizontal equivalent forces with tie rod force 96

6 International Journal of Scientific Research rch aand Innovative Technology ISSN: Vol. Vo 4 No. 3; March 2017 Fig.3 Sheet Pile Wall Box Section Fig. 4 Shear ear Force Forces and Bending Moments of the Sheet Pile Wall System 97

7 Fig. 5 Strengthened Cross-Section of Sheet Pile Wall Table Table 1 The total active and passive pressure coefficients Total Pressure Coefficient K at, MAX (above water table) K at, MAX (below water table) K pt, MAX (above water table) K pt, MAX (below water table)