pile and pile group

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PILE AND PILE GROUP : 

PILE AND PILE GROUP MUHAMMAD JAVED AKHTAR 07-MS- GEO-22

PILES AND PILE GROUP : 

PILES AND PILE GROUP INTRODUCTION OF PILES AND PILE GROUP BEARING CAPACITY OF PILES AND PILE GROUP REHABILITATION OF PILES

PILES CAP : 

PILES CAP

PILES IN GROUP : 

PILES IN GROUP

Introduction of piles in group : 

Introduction of piles in group Piles in groups are use in bridges silos and industrial buildings After casting the piles pile cap is placed on the top of piles for uniform distribution of load on piles Pile cap Is either kept some distance above the ground (for expansive soils )or on the ground.

BEARING CAPACITY OF PILE AND PILE GROUP : 

BEARING CAPACITY OF PILE AND PILE GROUP Bearing capacity of piles is found by dynamic formulae ( SPT, meyerhoff) Empirical methods (SPT, MPT, CPT) Pile load test

BEARING CAPACITY OF PILES IN GROUP : 

BEARING CAPACITY OF PILES IN GROUP The bearing capacity of piles in a group is generally less then sum of individual piles in a group. GROUP EFFICIENCY is a term used for ratio Of capacity of a pile group to the sum of capacities of a single pile at same depth in same soil deposit .in evaluating the performance of a pile group in compression settlement is the major consideration.

PILE GROUP : 

PILE GROUP Evaluation of group of shaft in cohesive soil shall be consider the presence of cap with ground surface and spacing between adjacent shaft's or a shaft with a cap in firm contact with Ground quilt may be computed the lesser of 1)sum of individual capacities of each shaft in group 2)capacity of an equivalent pier defined in the perimeter area of group . For equivalent pier Shear strength of soil shall not be reduced by any factor .to determine qs component of qult,t he total area of e equivalent pier shall be used to determine qt component of qult.. E value for cohesive soils is taken as 0.67 for c/c of 3B And 1.0 for c/c spacing of 6B. For cohesionless soil max of 8B.

PILES : 

PILES Group in strong soil overlaying weaker soils found by Qe=q equivalent lo+(h/10b1)(qup-qlo)<pup Low =ultimate tip capacity of equal vent shaft Qup=ultimate unit tip capacity B1=least width of shaft H=distance from tip to top of weak soil layer

4. Load carrying capacity of Pile based on standard penetration test : 

4. Load carrying capacity of Pile based on standard penetration test The basis of the ‘static’ or soil machines method of calculating the ultimate carrying capacity of a pile is that the ultimate carrying capacity is equal to the sum of the ultimate resistance of the base of the pile and the ultimate skin friction over the embedded shaft of the pile. This is expressed by the Equation Qu = Qb + Qs, (4.1) Where Qb = base resistance, Qs = shaft resistance.

Slide 13: 

Bearing Capacity of Pile in Cohesionless Soil Knowing the angle of shearing resistance of the soil at base level, Qb can be calculated from Terzaghi’s general equation (2.2) in Section 2.0. Because the diameter of the pile is small in relation to its depth the term 0.4BN can be neglected. Therefore Net unit base resistance, qnf = qf = pd (Nq – 1) and so Net total base resistance, Qb = Abpd (Nq – 1), (4.2) where pd = effective overburden pressure at pile base level. The total ultimate skin friction on the pile shaft is given by the general expression Unit skin friction, f = Kspd tan , (4.3) Where Ks = an earth pressure coefficient,  = angle of wall friction.

Slide 14: 

The failure load of the pile, Qu, is equal to the load at failure applied to the pile, Q´u, plus the weight of the pile, Wp. Q´u = Qu – Wp = Qb + Qs = Abpd (Nq - 1 ) + Qs (from equation (4.2)) = AbpdNq – Abpd + Qs. Since the weight of the concrete in the pile is not much greater than the weight of soil displaced by the pile, then for all practical purposes Wp and Abpd are roughly equal for straight-sided or moderately tapered piles. Therefore Q´u = AbpdNq + Qs = AbpdNq + Kspd tan  As, (4.4) Where As = embedded surface area of pile, Pd = average effective overburden pressure over embedded depth of pile.

Slide 15: 

Base Resistance Nq factor in base resistance can be determined from the graph shown in the Fig with the help of Angle of shearing resistance and D / B ratio. It is same that the penetration depth 10 to 20 pile diameters maximum base resistance is reached.

Slide 16: 

Broms has related the values of Ks and  to the effective angle of shearing resistance of cohesionless soils for various pile materials and relative densities as shown in Table ‘A’. Broms used the effective angle Ø’ instead of the undrained angle Ø as Table ‘A’ Values of Ks and  Value of Ks Pile Material  Low relative density High relative density Steel 20o 0.5 1.0 Concrete 3/4Ø 1.0 2.0 Wood 2/3Ø 1.5 4.0

Slide 17: 

Broms has related the values of Ks and  to the effective angle of shearing resistance of cohesionless soils for various pile materials and relative densities as shown in Table ‘A’. Broms used the effective angle Ø’ instead of the undrained angle Ø as Table ‘A’ Values of Ks and  Value of Ks Pile Material  Low relative density High relative density Steel 20o 0.5 1.0 Concrete 3/4Ø 1.0 2.0 Wood 2/3Ø 1.5 4.0

Slide 18: 

Case - 1 The highest adhesion factors are obtained in Case 1 in which piles are driven through sands or sandy gravels into a clay. The gap which tends to form between the pile and clay is filled with dragged-down granular material and no skin friction is lost. The greater the penetration into the clay the less becomes the effect of the granular material with consequent reduction in adhesion factor. Case - 2 The reverse is true for case of soft clay over the stiff clay where the dragged-down soft clay skin has a weakening effect on skin friction. The smaller the penetration depth into the stiff clay the greater is the proportionate reduction in skin friction. Case – 3 In case of piles driven into a firm to stiff clay without different overlying strata a gap forms around the upper part of the pile and no skin friction is mobilized. The smaller the penetration and the stiffer the clay the greater is the effect of the gap.

Slide 20: 

Pile Subjected To Horizontal Loads / Structural Design of Pile To find out the maximum reaction, pile is subjected to different combination of loading as per prevailing ASSHTO Specification. Maximum moment will be developed at the point of fixity as shown in the figure.

NEGATIVE SKIN FRICTION : 

NEGATIVE SKIN FRICTION If driven or bored piles are installed in compressible fill or any soil showing appreciable consolidation under its own weight, a load additional to the working load on the head of the pile is transmitted in skin friction, i.e. ‘Negative Skin Friction’, to the pile surface. Negative Skin Friction must be allowed for when considering the safety factor on the ultimate carrying capacity of the pile, in the shape of Ultimate carrying capacity Working load + negative skin friction

REHABILITATION : 

DEFINITION: Rehabilitation" means the repair, renovation, alteration or reconstruction of any building or structure” “Repair" means the restoration to a good or sound condition of materials, systems and/or components "Renovation" means the removal and replacement or covering of existing interior or exterior finish, trim, doors, windows, or other materials "Alteration" means the rearrangement of any space by the construction of walls or partitions REHABILITATION

REHABILITATION : 

REHABILITATION DEFINITION: Rehabilitation" means the repair, renovation, alteration or reconstruction of any building or structure” “Repair" means the restoration to a good or sound condition of materials, systems and/or components "Renovation" means the removal and replacement or covering of existing interior or exterior finish, trim, doors, windows, or other materials "Alteration" means the rearrangement of any space by the construction of walls or partitions

REHABILITATION : 

REHABILITATION DEFINITION: Rehabilitation" means the repair, renovation, alteration or reconstruction of any building or structure” “Repair" means the restoration to a good or sound condition of materials, systems and/or components "Renovation" means the removal and replacement or covering of existing interior or exterior finish, trim, doors, windows, or other materials "Alteration" means the rearrangement of any space by the construction of walls or partitions

TYPES OF REHABILITATION OF PILES : 

TYPES OF REHABILITATION OF PILES CORR-JACK PILE ENCASEMENT FORM Five Star Pile Rehabilitation & Repair System Pile rehabilitation by PVC Rehabilitation of steel H-piles

The Corr-Jack forms innovative double wall corrugated design that makes it the only form on the market that provides impact protection absorption to the structural member being rehabilitated Corr-Jack can be used to rehabilitate timber, concrete and steel piles above and below the water. 1. CORR-JACK PILE ENCASEMENT FORM

Slide 27: 

Corr jack form

THE CORR-JACK ADVANTAGE : 

THE CORR-JACK ADVANTAGE One Piece Construction Reduces Installation Time No Alignment Problems Durable, Easy To Cut, Light Weight & Chemical Resistant Easily Extendable Corrugations Provide Impact Protection Low Cost

PHYSICAL PROPERTIES : 

PHYSICAL PROPERTIES

2. FIVE STAR PILE REPAIR & REHABILITATION SYSTEM : 

2. FIVE STAR PILE REPAIR & REHABILITATION SYSTEM Pilings located in or near salt water are subject to deterioration caused by chemical attack, wave action and collision with ships. Five Star Pile Jacket Grout System is formulated to be an encapsulation grout for repair and rehabilitation of these pilings, used in conjunction with a pile jacket. The grout is formulated to be installed underwater with superior bonding to concrete, steel and wood piles.

Slide 31: 

FIVE STAR PILE REHABILITATION SYSTEM

ADVANTAGES : 

ADVANTAGES It has excellent chemical resistance to a variety of chemicals including oils, fuels, salts and solvents.

3. PILE GRADE REHABILITATION BY PVC : 

3. PILE GRADE REHABILITATION BY PVC The PILE-GRADE method is to encircle the piles with polyvinyl chloride (PVC) wraps stiffened by rigid longitudinal pole pieces. The wraps are provided with water tight seals at the top and the bottom of the module and further secured to the pile with metal bands.

Slide 34: 

PILE GRADE REHABILITATION BY PVC

CLOSER VIEW : 

CLOSER VIEW

PILE GRADE ADVANTAGES : 

PILE GRADE ADVANTAGES Time Tested Quality Components and Construction Economical To Install Compatible H-Pile, Square Pile or Round Pile Longest Service Life In the Industry Positive Closure Durable, UV Resistant Low Cost

4. REHABILITATION OF STEEL H-PILES : 

4. REHABILITATION OF STEEL H-PILES During an underwater inspection of the bearing piles supporting electric power transmission towers in Baltimore Harbor, it was discovered that most of the steel 'H' piles had badly corroded from a point approximately one foot below the cap to a depth of four to five feet. The rehabilitation process began by surface preparation of the piles. The FRP jackets were moulded to fit the piles in translucent material to enable the progression of the encapsulation grout to be monitored.

Slide 38: 

STEEL H-PILES

REFERENCES : 

REFERENCES FOUNDATION DESIGN AND CONSTRUCTION BY TOMLINSON FOUNDATION ANALYSIS AND DESIGN BY JOSEPH E BOWLES FOUNDATION ENGINEERING BY BRAJA M. DAS FOUNDATION ENGINEERING BY G.A LEONARDS www.barrierimp.com/pile_rehabilitation.cfm www.madconcorp.com/projects_inland.htm

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