CONE PENETRATION TEST
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CONE PENETRATION TEST

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CONE PENETRATION TEST  

OBJECTIVES.

The purpose of this procedure is to define the method for the Land electric cone penetration test. The cone penetration test is an in-situ testing method used to determine the geotechnical engineering properties of soil.  This method covers the determination of the resistance of soil in situ to the continuous penetration at a slow uniform rate of a series of pushrods having a cone at the base and measuring continuously the penetration resistance of the cone including local friction, tip resistance, friction ratio, pore pressure and speed.  

RESPONSIBILITIES.

Only members of staff who have been approved to perform the tasks detailed in this document at the appropriate level as documented on their training record are permitted to carry out the tasks specified in this procedure.  

REFERENCE STANDARDS AND DOCUMENTS. 

BS 1377 Part 9 :1990 Section 3.14.


DEFINITIONS. 

CONE RESISTANCE.

The total force acting on the cone is called cone resistance and quantifies the strength of the soil. 


TOTAL FRICTION.

Force acting on the sounding rods is called total friction. Measurement with an electric cone  
Equipped with sleeve friction, provides the local sleeve friction.  

APPARATUS.


CPT Apparatus includes various parts as described below:  

Thrust Machine: apparatus providing thrust to the pushrods so that the required constant rate penetration is controlled.  

Reaction Equipment: reaction for the thrusting machine.  

Pushrod: thick-walled cylindrical tube used for advancing the penetrometer to the required depth.  

Peizo-cone penetrometer: cylindrical terminal body mounted on the lower end of the pushrods, including a cone, a friction sleeve, a filter, and internal sensing devices for the measurement of cone resistance, sleeve friction, hydrostatic pressure, and inclination.




PROCEDURE FOR LAND OPERATION.

The principle to be followed will be that of continuous penetration of electric cone in which the soil resistance will be measured while all elements of the penetrometer tip are moving downwards simultaneously and at the standard rate. 

In order to obviate the disturbance, locate the position at least 1m from the previously performed cone penetration test.

The verticality of the push rods will be checked regularly.  

The rate of penetration will be between 15 to 25mm/sec.

Piezocone Penetration Tests (PCPTs) will be performed using MLD’s electric cone, with a cone area of 10 cm2 and 15 cm2, an apex angle of 60 degrees, and a friction sleeve area of 200 cm2. Penetration is achieved.

By hydraulic jacking system, the cone advances at a constant rate of 20mm per second.  The cone contains electrical load transducers measuring the cone tip resistance, sleeve friction, and pore pressure. Readings of the cone tip resistance, sleeve friction resistance, and pore pressure are obtained continuously via an electric cable in the cone rods, to a computer. 

During the test, the data is displayed on the computer screen and continuously recorded to the hard drive for later processing at the office.   

The results of the PCPTs are presented in the form of plots of cone resistance, sleeve friction, friction ratio, and pore pressure versus depth of penetration. During the testing, hydraulic pressure and electric circuits can be controlled automatically from the control panel. Electric Cone Penetration tests are performed up to the target depth required or refused.    




Reporting.


The engineering analyses and design will be carried out by appropriately experienced, laboratory engineers by using the software. 

 

The analytical and reporting works will be performed under the supervision of the laboratory manager, with in excess of twenty years of related experience.


The experience and local knowledge will ensure a high quality of our engineering analyses, and reporting,  which accounts for typical foundation requirements with respect to regional soil conditions and environmental conditions. 

POST CHEKS AND RECORDS 

All the checks and records will be in accordance with BS 1377-part 9 Section 3.1.4.9.  


TEST REPORT.

The engineering analyses and design will be carried out by appropriately experienced, engineers by using the software. The analytical and reporting works will be performed under the supervision of the laboratory manager, with an excess of twenty years of related experience.
The experience and local knowledge will ensure a high quality of our engineering analyses, and reporting,  which accounts for typical foundation requirements with respect to regional soil conditions and environmental  conditions  


Following details will be added in the test report.  

 -Test location, test number, and structure reference where appropriate.  

- Date of test, and person performing the test.  

-Graphic representation with respect to the depth/ elevation, coordinates/ chainage of the following measurements.  

Tip Resistance (Qc)  

Local friction (fs)  

Pore pressure 

Friction Ratio (Rf)  

Speed  


-All the reporting requirements of BS 1377 Part 9 Section 3.1.3  

- All applicable information listed in MLD Quality Manual Section 5.10 “Test                Reports”  

CALCULATION.  

All the calculations of Tip Resistance, Pore Pressure, Local Sleeve Friction will be done by software.  

UNCERTAINTY.  

Due to the nature of the materials tested by this procedure, it is not feasible to produce multiple specimens that have uniform physical properties.  







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