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PROPOSED: METHOD STATEMENT FOR BI-DIRECTIONAL STATIC · PDF filePROPOSED: METHOD STATEMENT FOR BI-DIRECTIONAL STATIC LOAD TEST (BDSLT) (Working Piles – 1200mm Diameter) Prepared

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  • PROPOSED:

    METHOD STATEMENT

    FOR

    BI-DIRECTIONAL STATIC LOAD TEST (BDSLT)

    (Working Piles 1200mm Diameter)

    Prepared for:

    Prepared by: Hangzhou Ougan Technology Co., Ltd

    17th Floor, Wanda Plaza, Hangxing Rd, Gongshu District, Hangzhou,

    310015, P.R. China

    Tel: 86-571-28993135 Fax: 86-571-28993137

    Email: [email protected]

    www.ougangroup.com

    Date Submission Ref. Revision Prepared by

    2015-11-11 SF071015 2.00

  • Hangzhou Ougan Technology Co., Ltd

    17th Floor, Wanda Plaza, Hangxing Rd, Gongshu District, Hangzhou, 310015, P.R. China

    Tel: 86-571-28223950 Fax: 86-571-28993137

    1

    CONTENTS

    1. Introduction

    1.1 Project Information

    1.2 Test Objectives

    1.3 Applicable Standard/References

    2. Sub-surface Conditions

    3. Bi-directional Static Load Test

    3.1 Test Theory and Advantages

    3.2 Test Instrumentations

    3.3 Installation of Super Cell

    3.4 Load Test Procedures

    3.5 Loading & Unloading Sequence

    3.6Test Results Analysis And Conclusion

    4. Worksheet

    4.1 Field Responsibilities

    4.2 Equipment/materials and staff provided by contractor

    5. Risk Assessment

    Appendices

    A. Test Pile Layout

    B. Schematic Section of Test Pile & Reference pile/Reference Beam Layout

    C. Super Cell Calibration Certificate Reference

    D. Project References With Same Test Instrumentations

  • Hangzhou Ougan Technology Co., Ltd

    17th Floor, Wanda Plaza, Hangxing Rd, Gongshu District, Hangzhou, 310015, P.R. China

    Tel: 86-571-28223950 Fax: 86-571-28993137

    2

    1. Introduction

    1.1 Project Information

    Four Bi-directional Static Load Tests will be applied to four bored piles at_. The details of these

    four working test piles are as below:

    Pile Ref. No. P147 P170 P255 P208

    Borehole Log BH10 BH4 BH11 BH2

    Pile Dia.mm 1200 1200 1200 1200

    Qty 1 1 1 1

    Cut-off Level(m) -7 -7 -7 -7

    Pile Toe Level (m) -22 -22 -22 -22

    Pile Effective Length

    m 15 15 15 15

    Max. Test Load(kN) 2.24500 1.54500 1.54500 1.54500

    Super Cell Level (m) -19 -19 -19 -19

    Pile Type Working test piles

    Equilibrium Point Data Sheet

    Project

    Test Pile

    Reference P147/P170/P255/P208

    Load cell position 3m above pile toe

    Pile

    dia.(m) 1200

    Pile length

    (m) 15 Borehole No. BH10/BH4/BH11/BH2

    Soil No.

    Soil Description

    Ultimate

    Skin Friction

    qsik (kPa)

    Ultimate

    end

    bearing

    qpk

    (kPa)

    Negative

    friction

    coefficient

    a

    Thickness Li

    (m)

    Vertical

    qsik*Li

    Skin friction

    after correction

    a*qsik*Li

    1 Silty sand. Light brown,

    very dense, dry. 80 0.80 8.5 680.0 2049.8

    2

    LEAN CLAY with

    Sand.Dark brown to

    grey, hard, dry.

    90 0.80 1.8 162.0 488.3

    3 Silty sand. Light brown,

    very dense, dry. 75 0.80 1.7 127.5 384.3

    Super cell

    4 Silty sand. Light brown,

    very dense, dry. 75 2000 1.00 3.0 225.0 847.8

    Ultimate skin friction of upper pile

    2922.5

    Self-weight of upper pile

    339.1

    Ultimate uplift force of upper pile

    3261.6

    Ultimate skin friction of lower pile

    847.8

    Lower pile ultimate end bearing capacity

    2260.8

    Lower pile ultimate bearing capacity

    3108.6

    Load cell

    level

    Above pile

    toe

    3.0

    Upper pile

    length

    12.0

    Total pile

    length

    15.0

    Note: Skin friction data and end bearing data is got according to experience.

  • Hangzhou Ougan Technology Co., Ltd

    17th Floor, Wanda Plaza, Hangxing Rd, Gongshu District, Hangzhou, 310015, P.R. China

    Tel: 86-571-28223950 Fax: 86-571-28993137

    3

    1.2 Test Objectives

    a. To determine the pile ultimate compression capacity

    b. To verify related data in the geotechnical report

    1.3 Applicable Standard/References

    a. ASTM D1143: Standard Test Methods for Deep Foundations Under Static Axial Compressive Load

    b. CP4: 2003-Singapore Standard Code of Practice for Foundation

    c. BS8004: 1986-British Standard Code of Practice for Foundation

    2. Sub-surface Conditions

    P147 Borehole log

  • Hangzhou Ougan Technology Co., Ltd

    17th Floor, Wanda Plaza, Hangxing Rd, Gongshu District, Hangzhou, 310015, P.R. China

    Tel: 86-571-28223950 Fax: 86-571-28993137

    4

  • Hangzhou Ougan Technology Co., Ltd

    17th Floor, Wanda Plaza, Hangxing Rd, Gongshu District, Hangzhou, 310015, P.R. China

    Tel: 86-571-28223950 Fax: 86-571-28993137

    5

    P170 Borehole log

  • Hangzhou Ougan Technology Co., Ltd

    17th Floor, Wanda Plaza, Hangxing Rd, Gongshu District, Hangzhou, 310015, P.R. China

    Tel: 86-571-28223950 Fax: 86-571-28993137

    6

  • Hangzhou Ougan Technology Co., Ltd

    17th Floor, Wanda Plaza, Hangxing Rd, Gongshu District, Hangzhou, 310015, P.R. China

    Tel: 86-571-28223950 Fax: 86-571-28993137

    7

    P255 Borehole log

  • Hangzhou Ougan Technology Co., Ltd

    17th Floor, Wanda Plaza, Hangxing Rd, Gongshu District, Hangzhou, 310015, P.R. China

    Tel: 86-571-28223950 Fax: 86-571-28993137

    8

  • Hangzhou Ougan Technology Co., Ltd

    17th Floor, Wanda Plaza, Hangxing Rd, Gongshu District, Hangzhou, 310015, P.R. China

    Tel: 86-571-28223950 Fax: 86-571-28993137

    9

    P208 Borehole log

  • Hangzhou Ougan Technology Co., Ltd

    17th Floor, Wanda Plaza, Hangxing Rd, Gongshu District, Hangzhou, 310015, P.R. China

    Tel: 86-571-28223950 Fax: 86-571-28993137

    10

  • Hangzhou Ougan Technology Co., Ltd

    17th Floor, Wanda Plaza, Hangxing Rd, Gongshu District, Hangzhou, 310015, P.R. China

    Tel: 86-571-28223950 Fax: 86-571-28993137

    11

    3. Bi-directional Static Load Test (BDSLT)

    3.1 Test Theory and Advantages

    3.1.1 Theory of Load Cell Method

    The BDSLT method of pile load test utilizes hydraulically operated Super-Cells embedded

    inside the concrete of the pile. To determine the position of the cells the soil investigation

    report has to be studied to work out the equilibrium point. The embedded Super-Cell is

    specially designed using built in hydraulic jacks. Pressure is applied to the load cell by

    hydraulic pump on the ground through the flexible hose embedded into the pile. The

    pressure in the load cell is measured by pressure transducer and the displacements are

    measured by displacement transducers which are connected to the load cell by telltale rod

    embedded into the pile. When loaded the load cell expands, pushing the upper shaft upwards

    and the lower shaft downwards, which would mobilize the side resistance and base

    resistance of the upper and lower lengths of the pile. According to relationship between the

    movement and their corresponding S-lgt and s-lgQ curves, bearing capacities of both upper

    and lower portion of the pile can be determined. Adding up the modified side resistance of

    upward pile shaft and the base resistance of downward pile shaft makes up the total ultimate

    bearing capacity of the pile.

    3.1.2 Advantages of Load Cell Test

    a. High Test Load Capacity

    Load cell capacity can be greater than 100MN and multiple cells can be used to test a pile,

    increasing the test load capacity.

    b. Improved Safety

    No reaction system is required as for other static load test. No use of large quantities of

    girder beams and concrete blocks which could topple if the base is not well prepared.

    c. No Space or Access Problem

    Load cell test can be performed next to existing buildings, under overpasses, highway

    median strips and offshore, with much less space required compared to other static load

    test.

    d. Piles with Deep Cut Off Levels

    For basement piles, test pile can be performed below ground, eliminating the pile extension

    to ground level.

    e. Test for Working Piles

    With post test grouting techniques, testing of working piles can also be done.

    f. Time Saving

    Compared to static load test with test blocks, there is considerable time saving as no pile

    built up or strip down is necessary.

    3.2 Test Instrumentations

    3.2.1 Super Cell

    a. Ring Super Cells are applied to this project, max. stroke is 150mm. Super cell is provided with

    built in hydraulic jack (s) and flexible hose fixed to the steel cage to connect to the oil pump

    at ground level.

    The super cells are calibrated to their rated capacity by the manufacturer. A sample Super

    cell calibration certificate is included in Appendix C.

  • Hangzhou Ougan Technology Co., Ltd

    17th Floor, Wanda Plaza, Hangxing Rd, Gongshu District, Hangzhou, 310015, P.R. China

    Tel: 86-571-28223950 Fax: 86-571-28993137

    12

    Cone-shape flow-guiding mechanism

    Ring Super Cell

    3.2.2 High Pressure Pump

    The maximum pressure of the pump is 60Mpa, with gauge scale precision up to 0.5Mpa.

    3.2.3 Electronic Displacement Transducer

    Stroke: 50mm.The electronic displacement transducers are fixed onto the reference beam by

    magnetic means, each test pile i

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