Thuyết minh biện pháp thí nghiệm cọc khoan nhồi (Method Statement For Testing Pile) (English Version)

Biện Pháp mô tả đầy đủ chi tiết các bước thí nghiệm cọc khoan nhồi.

3 KEY PERSONNELS FOR THE BID 4

4 EQUIPMENTS FOR TESTING WORKS 4

5 VERTICAL COMPRESSIVE STATIC LOADING TEST 5

5.3.2 Process the head of the test piles 7

5.3.3 Installing the hydraulically jacks 7

5.3.4 Reinforced base, installation floor systems 7

5.3.5 Install monitoring system 7

5.3.6 Testing: 7

5.4Testing Report 7

5.5Table of Testing Procedure 8

6 PILE INTEGRITY TEST 9

6.2PIT test application standards 10

6.3Contents of PIT small strain experiment 10

6.4Experimental equipment 11

6.5Pit test procedure 12

6.5.1 Preparation of the experiment 12

6.5.2 Installation of measuring equipment 13

1.GENERAL DESCRIPTION

1.1Project Information

The project road connects Tbong Khmum district to Kratie Province of the Cambodia,stretching along the northern, to Kratie province The road passes on a comfortable alignmentthrough flat/wavy terrain along the toe of hilly land Four (4) rather sharp curves along the roadare considered non-critical due to adequate super-elevation of the road way and appropriatesignage The traffic on the road is a medium mix of private cars and quite heavy trucks thatcontribute mainly to the road wear The PR.377 and PR377A of RCIP are located in Kratieprovince The length of the PR377 is 35.00 km and the PR377A is 13.593km The location ofthe packages is shown in Figure-1.1

Figure 1.1 Location of Contract Package on CW-3(PR377 & PR377A)

1.2Purpose of the Test

(a) Single pile compression static load test:

+ Determine single pile vertical compression ultimate bearing capacity of test piles;+ Determine maximum settlement deformation and rebound deformation of test piles

(b) Pile Integrity Test (PIT Method)

Purpose of the test: Determine the location and degree of defects (if any) of the bored pilebased on the reflected wave recorded on the top of the pile

Test load(ton)

1 Static Load Test: Vertical Compressive Static Loading Test

D500Pile Required by the

2.ORGANIZATION CHART

Organization Chart is as follow:

POLY CHANDA ENGINEERING CO., LTD

ROAD MANAGER

Mr.WEI JAING

Material Engineer

Mr LAI DE SEN

AMP Manager

Mr.LIN ZHI HUI

Design Engineer

Mr LAI DUY TRUNG

QA/QCManager

Mr XU CHENG HUI

Safety & EnvironmentalManager

Mr LIN JIN HAO

3.KEY PERSONNELS FOR THE BID

Key personnels for testing shall submit separate document

4.EQUIPMENTS FOR TESTING WORKS

A For testing load is 320 tons

B For Pile Integrity Test

5.VERTICAL COMPRESSIVE STATIC LOADING TEST

5.1Introduction:

 Static loading test provides the relationship between loads - settlement of the pile to determinethe axis bearing capacity of the pile working in the land Piles are tested by the method loadingeach level up to 200% design loading

 Testing standard application: Standard test method for pile under axial compressive load Thisstandard is also consistent with the standards of advanced countries such as American standard(ASTM-D1143) standard British (BS 8004)

 Static loading test is conducted in accordance with the standard testing regulations Loading onthe head pile is made by a specialized hydraulic system through a hydraulic pump andcontrolled by the pressure meter for the whole system

 Load used for reaction loading test is the steel floor system above has specialized concreteblocks to ensure the total load greater than 120% highest load Floor beam system includeprimary and secondary beam system

 Pile settlement is monitored by meter system at two or four positions on the head pile,matching symmetric through the pile center The meters are mounted on the stand independentto testing pile

 Horizontal beam system using sub-beams of I steel, 12 meters long The beam is strengthenedforming a solid floor The sub-beams are placed directly and perpendicular to the main beam.The head sub-beams are also put on the concrete in order ton ensure stability and safety duringtesting procedure.

 Counterweight above using precast concrete blocks specializes for static loading test There aretwo types of load are 5 tons per block and 2.5 tons per block (size 2.0x1.0x1.0m and1.45x0.95x0.75m) Concrete blocks arranged to lock the corners and do not lade the samecircuit Total weight of floor system is larger than 120% largest testing load

5.2.2 Loading part

 Hydraulic jack synchronization system consist of the specialized hydraulic, the total liftingcapacity ensure larger than 150% largest testing load Hydraulic system is put on the head pilethrough the 100mm thick steel pad to ensure loading evenly on the head pile Center ofHydraulic system coincides with pile center

+ Pumping station is manufactured synchronization with Hydraulic system + Pressure meter type 100MPa or equivalent

+ All devices are on the certificate verification period effect

5.2.3 Settlement monitoring

 Use 04 dial gauge with the degree of accuracy is 0.01mm The meters tighten to the standardbeam system The meter is placed in the head pile and symmetric to center pile The meter hasa certificate verification period effect

 Standard steel box beam system is attached to the brackets to independent test pile Thebrackets are arranged so that the distances from the test pile to the bracket not less than 1.5m

5.2.4 Equipments for installation and Accessories

 We will use a self-propelled crane lifting capacity 35 tons, raising the height of 30m, forinstallation of experiments Equipments are in effective control of time

 Depending on actual conditions and requirements progress, we can mobilize more cranesequivalent to ensure the progress of experiments

 The gradienter is used to check the stability of the standard beam system through fixed moldput away area experiments

5.3.2 Process the head of the test piles

 The pile was tested as the pile reached the design strength of the regulations or age of concrete.The processing of the head of the pile is made immediately after the handing over piles andqualified laboratory Part bleach to cut the pile of concrete features makes creating planesurfaces If the head of the test pile is not flat or crack and porous to process flat again

5.3.3 Installing the hydraulically jacks

 Mark center of the test pile. Install steel pad and proceed to check center pile up pad; Install the hydraulically jacks and adjust the jack system to make sure the general load in

central of the pile

5.3.4 Reinforced base, installation floor systems

 Survey site base, calculate intensity to determine size of bearing; Install main beams, check themonitor, invisible, and tension wires;

 Reinforced the ground of bearing if necessary: Installing concreate blocks, check by tensionwire;

 Installing additional beams: Installation from the center outward, the beam sub-assembly isequal, all different ways;

 Counterweight installation: Installation of large concrete blocks before, after the smallerblocks For each class to load flat, square brief, alternate layers to avoid the same rate circuit, akey corner Classes are also classified for downloading from the center out and sequentiallylower grade to grade on

5.3.5 Install monitoring system

 Install dial gauge, pressure meter, supporting main beam;  Test the sensitive of dial gauge, pressure meter before conduct testing; Install geodetic machine: Create geotechnical mark on the main beam and standard marks; Install pump - system, hydraulic clock: Tio and switch, connect pump and jack, test hydraulic

jack before conduct testing

5.3.6 Testing:

 Trial load up to 5% design loading to check equipments;  Load to test (see the testing procedure tables below); Record the site data based on the testing procedure below:

5.4Testing Report

 Project name and location; The owner, designer, pilling contractor and the tester; Tested pile records/ Field testing records;

 Load-settlement relationship graphs; Graphs of load and settlement to time;  Comments and conclusion with suggested load capacity

5.5Table of Testing Procedure

The test shall be conformed to technical requirement of Project: The Bored Pile D500:

Cycle 1

Load up to 5% design loadsLeave for 10 minutes, checking equipments

Load up to 25% design loads Leave until the rate of settlement is leveled to less than0.25mm per hour but no longer 2hrsLoad up to 50% design loadsas above

Load up to 75% design loadsas aboveLoad up to 100% design loads Leave until the rate of settlement is leveled to less than0.25mm per hour or 6 hoursReduce load to 50% Leave for 30 minutes

Reduce load to 0% Leave for 60 minutes

Reduce load to 0% Leave for 60 minutes

 The Bored Pile D500, Design Load is 160 Tons (assumption number):

Cycle 1

Load up to 5% design loads8Leave for 10 minutes, checking equipments

Load up to 25% design loads40 Leave until the rate of settlement is leveled toless than 0.25mm per hour but no longer 2hrs

Load up to 50% design loads80as aboveLoad up to 75% design loads120as aboveLoad up to 100% design loads 160Leave until the rate of settlement is leveledto less than 0.25mm per hour or 6 hours

Cycle 2

Load up to 50% design loads80Leave for 30 minutesLoad up to 100% design loads160as above

Load up to 125% design loads200 Leave until the rate of settlement is leveled toless than 0.25mm per hour but no longer 2hrs

Load up to 150% design loads240as aboveLoad up to 175% design loads280as aboveLoad up to 200% design loads 320Leave until the rate of settlement is leveledto less than 0.25mm per hour or 24 hours

Reduce load to 100% 160as above

 Loading time: Settlement recording at 0, 5, 10, 20, 30, 45, 60, 90, 120, 180, 240, 300, 360, 420,480, 540, 600, 660, 720 minutes and after every 120 minutes

 Notes: The testing will be ceased in case:

1 Completing testing procedure2 Testing equipment is in trouble3 Pile is “damaged” when one of the following phenomena:

+) Pile material is damaged+) The settlement of pile beyond the limit of 10% diameter piles+) Pile suddenly settle, not keep the pressure as in procedure All cases must be reported to the supervising engineer of the investor to carry out methods of

treatment or check before acceptance

6.PILE INTEGRITY TEST

6.1General:

 This test method covers the procedure for determining the integrity of individual vertical orinclined piles by measuring and analyzing the velocity (required) and force (optional) responseof the pile induced by an (hand held hammer or other similar type) impact device usuallyapplied axially and perpendicularly to the pile head surface This test method is applicable tolong structural elements that function in a manner similar to any deep foundation units (such asdriven piles, augeured piles, or drilled shafts), regardless of their method of installationprovided that they are receptive to low strain impact testing

 This test is a quick way to assess the integrity of both precast and cast-in-place concrete piles.Identical results can be obtained using a transient pulse on the top of the pile, using a smallhand hammer that is applied through the top of the pile Advances in microprocessing meanthat time domain signals will be converted to frequencies using the fast Fourier Transform.Analysis of the results will be performed to confirm the length of the foundation and the depthof any defects if they exist

6.2PIT test application standards.

 Standard ASTM D5882: Small strain test method to determine the homogeneity of piles

6.3Contents of PIT small strain experiment.

 The small strain method is based on the theory of unidirectional stress wave propagation in theelastic rod caused by the action of an impulse force, in which the impedance change in the barechoes back to the crest

 When acting on the pile head, the stress wave will propagate along the pile body with velocityC, C is a function of elastic modulus E and density (C2=E/) The time it takes for the reflectedwave to return to the tip of the pile is proportional to the distance the wave is reflected

 Because the pile impedance (Z) directly depends on the area section and the elastic modulus,the resistance value is the quantity that determines the pile cross section and the quality of thepile concrete.

 When the stress wave (Wi) encounters a change in mechanical resistance from Z1 = 1.A1.C toZ2 = 2.A2.C, part of the reflected wave goes up (Wu) and the rest travels down below (Wd) sothat both the following compatibility and equilibrium conditions are satisfied:

Wd = Wi 2 Z2 / (Z2 + Z1)Wu = Wi ( Z2 – Z1) / (Z2 + Z1) At the tip of the free pile (Z2 = 0), the compression wave is fully reflected but opposite in sign,

and for the uniform pile (Z1 = Z2), the compression wave propagates with a constantamplitude

 The stress wave is reflected at every position where there is a change in the mechanicalresistance of the pile and the feedback is received at the top of the pile after a period of timeproportional to the distance of the position of that resistance change

 This feedback wave causes a change in force and velocity measured at the top of the pile. The degree of velocity amplitude change at the top of the pile allows determining the degree of

resistance change, combined with actual geological conditions as the basis for judging theintegrity of the pile

6.4Experimental equipment.

 Specialized equipment “PIT Collector” of Pile Dynamics, USA is used for testing, includingthe following parts:

+ 01 Accelerator;+ 01 Hand held hammer;+ 01 Monitor;

+ 01 Special software

 The main function of the server is to receive and store test data (measurement signals) as wellas test pile details

6.5Pit test procedure.

6.5.1 Preparation of the experiment

 Break down the dirty concrete layer at the top of the pile to good concrete; Clean and smooth with a grinder at least 3 test positions on the pile head. For bored piles or pipe piles filled with concrete, the starting time of the test is taken as the

larger value of+) 7 days from the end of concreting;+) Time for concrete strength to reach 75% of design value. The pile head shall be easily accessible, shall not be flooded, the low quality concrete on the

pile head shall be removed to a good grade of concrete, and the soil and construction wastes onthe pile head surface shall be removed

 The minimum number of test points on the pile head surface is:+) 1 point for piles with cross-sectional diameter of 0.50 m or less+) 3 points for piles with cross-sectional diameter greater than 0.50 m (see Figure 1) On the surface of the pile head, it is necessary to grind flat the expected locations of the

velocity probe and the impulse generating positions (Knock Hammer)

Notes: 1 - Location fo knocking hammer

2 - Velocity measurement position3 - Main Re-Bar

4 - Belt reinforcement

Figure 1: Layout diagram of measuring points

6.5.2 Installation of measuring equipment

 The installation of the velocity transducer on the pile head must ensure that the axis of thetransducer is parallel to the axis of the pile It is recommended to use a buffer material such aswax, vazelin to ensure the contact between the measuring head and the pile head surface Thethickness of the padding material is as thin as possible

 After connecting the probes to the signal recorder, it is necessary to check the operation of theequipment If the device is found to be abnormal, the test must be stopped

6.5.3 Field test

 The experiment was conducted according to the following steps:+) Enter the parameters of the pile (pile name, length, cross section );+) Place the probe in the center of a position so that the probe is perpendicular to the pile face;+) Hammer at other positions, each position at least 3 times