Design and Testing of Bored Piles Essay

Undertaking 1

Preambles

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The contractor shall read all the specification clauses before citing his rates for the

stacking plants. The rates of work shall include the cost of the stuffs and labours

required in the executing of stacking plants as described in this specification except

otherwise stated in the Bills of Quantities or agenda of plants. All the stuffs used

shall be antecedently approved by the Engineer.

Pricing:

Ratess for stacking shall include: –

  1. Preparation of works and equipment on site
  2. Managing and traveling of the works and equipment on site.
  3. Cuting off tops of hemorrhoids to required degrees
  4. Re-driving of heaved heap
  5. Replacement for unsatisfactory hemorrhoids ( Falsely driven, Damaged or Failure in trials )
  6. Punishment hemorrhoids
  7. Excavating, make fulling and taking spoil off site
  8. Preparation and entry of stacking records and drawings
  9. Boring through any type of dirt strata including stone
  10. Disposing belowground obstructors
  11. Keeping the digging free of surface H2O
  12. Operating clip of all equipment
  13. Platforms for installing of world-weary hemorrhoids
  14. Leveling and readying plants
  15. Site clearance before, during and after the installing of hemorrhoids
  16. Sundry work

Specification FOR BORED PILING

  1. GENERAL

Work in conformity with Specifications

Stacking shall be corresponded with the rules in BS8004.

Concrete, support and formwork shall follow the demands in specification of concrete in construction unless otherwise stated.

Puting out

The contractor is required to use a accredited Surveyor to put up the place of hemorrhoids.

The nog are set up by the Surveyor and the Contractor should continue it. The Contractor shall come out with the drawings to demo the location of hemorrhoids installed upon the completion of stacking plants. Licensed Surveyor will verify the place of hemorrhoids.

Tolerances

It can be categorized into 3 facets, which are place, verticalness and rectification.

The place of pile caputs shall in conformity to the Drawings with a maximal divergence of 75mm on the either sides from the planned place. For the verticalness, the upper limit permitted divergence of the finished bored hemorrhoids from the perpendicular to any degree is 1 in 150. For the rectification, the Contractor shall come out with the remedial proposal and transport out the remedial ways one time they found that the hemorrhoids installed are beyond the tolerances which will impact the structural design.

Person in Charge

The individuals in charge in the pile plants should be full clip operators and supervisory staff who have experiences in put ining the proposed type of hemorrhoids.

Stacking Equipment and Accessories

At the undertaking site, the equipment and accoutrements used to prosecute the pile works must be capable to put in the hemorrhoids in term of safety, velocity and efficiency.

The equipment and accoutrements provided must be sufficient.

Forcible Correction Not Permitted

No methods of rectification will be permitted if the hemorrhoids are non been positioned within the scope of stated bounds.

Rejected Hemorrhoids

The pile work which is rejected by the Engineers due to the building and installing is non in conformity with the specification shall be made good by the Contractor to the blessing of Engineers.

The procedures may include design and building of a modified foundation, reinstallation of hemorrhoids, and besides building of extra hemorrhoids.

Records

The signifier of record shall be foremost approved by the Engineer before any beginning of work. All unforseen conditions during drilling or installing shall be recorded. The Contractor shall submitted 2 bound sets of stacking records to the Engineer when the pile plants are done.

  1. BORED CAST IN-PLACE PILES

General

The Contractor shall carry on the plants harmonizing to a set of methods to the blessing of the Engineer where the method statements include, size of impermanent shell, inter alia, inside informations of stuffs of boring fluid used in stabilising the world-weary holes, the review method, inside informations of concrete design mix, concreting method and the minimal on the job clip between two hemorrhoids.

The Contractor shall guarantee that there is no any harm occurred upon completion by utilizing his methods of installation.. The world-weary hemorrhoids digging must non be commenced within 8m from the concreted hemorrhoids which has non been cured for 24 hours.

Concrete

  1. Trial Mix

Before get downing the field work, the Contractor shall transport out the test mix with Engineer’s presence. The test mix shall be commenced harmonizing to the design mix to the blessing of the Engineer.

  1. Concrete for Piles

Unless otherwise stated, the class of concrete shall be 35, with a minimal cement content of 400kg per three-dimensional metre of concrete. The contractor shall besides guarantee that the Engineer have the entree to the supplier’s commixture works all the clip for review and look intoing on the quality of blending concrete.

  1. Concrete Testing

A set of at least three 6” regular hexahedrons shall be taken for every 10 three-dimensional meters or every group of 10 batches of concrete shall be used as concrete proving unless the Engineer otherwise directs. For the latter method, the samples shall be indiscriminately chosen from one individual batch which is selected from one group of batches. One regular hexahedron of each set should be tested at 7 yearss and the remainder of two shall be tested at 28 yearss after the procedure of projecting. The trial cubes shall be labelled to be determined with inside informations related to specimen to the borehole.

The trial can merely be conducted by sanctioned lab. The Contractor shall subject the trial consequence to the Engineer within 48 hours.

  1. Workability

Slump test shall be carried out to prove the workability of concrete. Slump measured at the clip of discharge into pile shaft or concrete pump hopper shall follow the criterions which are shown below unless otherwise stated.

Class of Workability

Slump ( millimeter )

Typical Conditionss of Use

A

100 ± 25

Where concrete is to be placed in water-free

shaft.

Bacillus

175 ± 25

Where concrete is to be placed by tremie method under boring fluid.

  1. Failure of Concrete Cube Trials

If the failure of concrete regular hexahedron trial show that the concrete is non suited to be used, the Contractor shall take remedial step to the blessing of the Engineer.

Pile Excavation

  1. Pile size and length

The Contractor shall transport ain trials along the proposed wall alliance to find the bedrock degree. Probing of bedrock shall be carried out along the proposed wall line at intervals to be agreed by the Engineer.

  1. Boring near late Cast Piles

Hemorrhoids shall non be installed following to the hemorrhoids which has been late casted less than 24 hours.

  1. Stability of Boreholes

The stableness of boreholes depends on the proviso of all stuffs, labor and works. The sides of borehole shall be tight and loose stuff are non permitted to fall into the underside of the boreholes. Steel shell is used to back up the sides of boreholes if the sides of drilling are found to be non stable. If the groundwater is found to be sufficient to impact the procedure of drilling, the steel shell will be used in conjuction with the boring fluid.

The impermanent shell should be mild steel cylindrical shell and spirally welded.

  1. Rock Coring

Rock coring is conducted utilizing a coring pail. The usage of chisel is prohibited. Rock coring other than the two points specified below shall be considered as the coring of dirt.

  1. Rock socket length
  2. Cavity roof
  1. Spillage and Disposal

The cast-off boring fluid shall be disposed from site without any hold.

  1. Inspection of pile digging

All pile digging shall be inspected for their full length before concreting. Inspection shall be carried out either from land degree or below land degree. In the instance of review from land degree, the base of drilling is inspected by sanctioned method for wet hole whereas for dry hole, utilizing agencies of a visible radiation. The review below the land degree shall be conducted for hemorrhoids with shaft of 760mm and supra.

  1. Pumping from Bored Holes

Pumping from bored holes can be carried out from clip to clip to verify the suitableness of dry hole building or to rectify the cold articulation in a heap shaft.

  1. Surface H2O

All boreholes shall be protected from surface H2O come ining.

Placement of Reinforcement

The support shall be stiff plenty to stand in the right place during the procedure of concreting and pull outing the impermanent shell. The minimal concrete screen to the support shall non be less than 75mm unless otherwise stated. At the interval of every 3m, concrete spacer shall be provided. The chief longitudinal support saloon that is less than 12 meters in length shall be arranged in one uninterrupted length.

Concreting in Wet Hole

Concrete to be placed into the world-weary holes with boring fluid shall be placed utilizing a tremie pipe harmonizing to B.S. 8004. The tremie concrete pipe shall be consisted of metal pipes of internal diameter non less than 250mm. The tremie pipe mercantile establishment shall be kept at least at a degree of 1.5m below the surface of concreting.

All bored holes shall be concreted in the same twenty-four hours. When raining, equal shelter shall be provided. Impermanent casing shall be removed non more than

2 hours after the completion of concreting. The pile caput shall non be below land H2O degree unless certain safeguards have been taken.

Upon the completion of concreting, the empty world-weary holes shall be backfilled with sand or thin concrete.

Depriving Pile Heads and Bonding

Upon the completion of pile, the Contractor should unearth and cut back the hemorrhoids to cut-off degrees. Defective concrete heap caputs should be cut off and made good with a new concrete which is good bonded to stack caput.

Boring fluid and Soil Trials

Minimal frequence of testings are as follow:

  1. Fresh Drilling Fluid
  2. Boring fluid taken from the underside of the heap before concreting
  3. Recycle boring fluid taken from desanding machine
  4. Boring fluid left in the world-weary hole for more than 12 hours

Control tests shall be used to mensurate the denseness of the boring unstable day-to-day by utilizing suited setup. If the sand content is more than 0.5 % , procedure of desanding in boring fluid must be taken topographic point to test out the sand.

Pile Acceptance Criteria

The needed socket length, mark expiration deepness, the needed working heap capacities and the concrete strength and are as shown in the drawings.

Projecting Degree

Concrete shall be finished non less than 300mm above the cut-off degree.

  1. INTEGRITY TESTING OF PILES

General

Integrity testing of hemorrhoids shall be conducted by independent proving organisation.

Working hemorrhoids shall be undergone daze method and sonic logging trials.

Shock Method

  1. Preparation of pile caput

The pile caput shall be non more than 1.0 below or above land degree. The surface of pile caput shall be smooth over its cross subdivision, free from abnormalities and perpendicular to the perpendicular axis of the heap.

  1. Shock Test Equipment

The daze which is to be transmitted onto the pile caput and the procedure shall be carried utilizing a suited cock. The electronic pick-ups such as speed transducers or accelerometers which is located on the pile caput connected through a frequence analyzer to a X-Y schemer. The Y axis will be plotted as mechanical entree and the X axis will be frequence.

  1. Shock Test

Experienced proving squad shall be prepared by the Contractor.

Before get downing the trial, the proving squad shall prove for the soundness and regularity of the heap caputs, and if there is any unsatisfactory heap caput shall be reported to the Engineer. If necessary, epoxy howitzer will be used to do good the unsatisfactory pile caput to the satisfaction of the Engineer.

Sonic Logging Method

To transport out the sonic logging method, the Contractor should fix tubing for trials at all pile point.

The tubings can be mild steel pipe with the internal diameter non less than 50mm. For the heap which has the diameter more than or equal to 700 millimeter, the figure of tubing required is 4 and for the diameter smaller than 700mm, merely 2 tubings are needed.

The tubes shall be watertight which the underside of the tubing is sealed. The tubes shall be steadfastly secured to the internal face of reinforcement longitudinal bars with an equal distance to each other on the perimeter.

During the trial, the if there is any abnormality found, the trial shall be repeated with a smaller graduated table.

After the trials have been carried out, the tubings shall be grouted with heavy non-shrink cement grout.

Undertaking 2

Clause A.2 Bills of measures shall to the full depict and accurately stand for the

measure and quality of the plants to be carried out. Work which can non be measured shall be given as aprovisional amount. Work the extent of which is non known shall be described as probationary or given in a measure of approximative measures.

In Bills of Quantities for all plants, measure rates all the procedures and stuffs to be used in the executing of plants shall be to the full described. The measure and the quality of the plants to be carried out shall be included accurately in the BQ in order to forestall any unexpected loss or misidentify occurred. However, there are some plants which can non be measured such as pumping of belowground H2O. These plants are described utilizing probationary amount. Provisional amount is the measures of plants which can non be defined. The plants can non be clearly foreseen and so that the probationary amount is best to be used to depict the plants. The plants which can non be clearly measured shall be given allowance for the possible addition of monetary value and provided as probationary amount. For the extent work which can non be predicted, the probationary amount shall be used to depict or a measure is produced to enter the approximative measures of these plants.

Stacking plants are measured as probationary amounts. It is because there are so many uncertainnesss and unanticipated conditions. Therefore, we can non accurately predict the measure and cost to be used in the pile works. For illustration, pumping of H2O and disposal of belowground H2O are the plants that can non be measured in exact measure. Testing of hemorrhoids to find the burden capacities is besides given in probationary measure. Due to the unpredictable conditions, stacking plants are measured as probationary amount.