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
