1      Introduction

 

This document described the possibilities for participation in the demonstration day of the Stress wave conference. We did an extensive field survey and installed many piles.

For more information goto chapter 2  Instructions for Test Events

 

Behavior during pile installation and performance of piles (part A, B and C)

We install several types of piles and apply several installation techniques. For more information, goto chapter 3 Installation_and_testing_program

You can participate by making a prognosis of the behavior during driving and performance of the piles based on the available field survey.

Some piles are tested after installation. You can participate by making a prognosis of the performance, based on pile driving data and /or on Rapid and Dynamic test results. This relates to concrete and steel piles with several newly developed installation techniques.

For more information, goto chapter 4 Prediction_events_pile_behavior

 

Sonic integrity testing of piles (part D)

We also install CFA piles and prefabricated concrete piles. On these piles sonic pile integrity test can be done and coMPared with other results.

For more information, goto chapter 5  Pile_integrity_testing

 

2      Short overview Information

 

A map with the overview of the test field.

Almost all piles will be installed at a position where a CPT is available. Download CPTs for prediction event.

CPT’s are made by Fugro (S01-S12), Ingenieursbureau Rotterdam (S13-S22) and Van der Straaten Geotechniek B.V. (S23-S32). Some additional results from borings are presented.

Some piles (meant for sonic testing) are at a position without a CPT. These points are indicated with a T, the number of the nearest CPT and a letter related with the direction (seen from the CPT).

A spreadsheet with additional information of all piles that will be installed.

It shows the equipment and the monitoring parameters during installation and after installation. The time-schedule for installation and testing and prognoses are summarized in this memo.

3      Installation and testing program

We will install 2 open ended steel tube piles diameter 1220 mm, length 20 m (part A). Two installation methods are applied: iMPact driving and vibratory driving. These piles are not tested afterwards.

We will install 12 open ended steel tube piles (part B), diameter 610 mm, length 17 m (part B). The following four installation methods are applied

  • start with a light vibratory hammer, driving with iMPact hammer to depth
  • driving to depth with a heavy vibratory hammer
  • application of a resonator
  • Application of GDP-shaker (Gentle Driving of Piles)

Moreover, we install four concrete piles

  • two prefabricate piles thickness 0.35 m length 17.5 m (part C-1)
  • two cast in-situ (CFA) piles (part C-2)

The piles will be tested by Static Load testing (SLT), Rapid Loat Testing (RLT) and Dynamic Load testing (DLT). The pile that will be tested by a SLT is instrumented with strain gauges at pile head, at 4 m ­‑NAP and 4 D above the pile toe. Some of the piles that will be tested by RLT are identically instrumented with strain gauges.

4       Prediction events pile behavior

 

We organize two prediction events:

  1. The prognosis of the behavior during driving and the performance of the piles based on soil survey data
  2. The performance of the piles based on additional information (installation data, DLT and RLT)

It is stressed that participants don’t to have answer all questions for all piles. Please choose the aspects you think that are important or interesting for yourself and are doable with sufficient attention.

 

4.1       Pile behavior prognosis before installation

We ask you to make a prognosis for the following variables.

 

Table 1 Behavior during installation, steel piles (part A and B)

installation and position Requested Variable To be presented
iMPact driving peak stress vs. depth [MPa]

FNLS05

FNLS34

amplitude stress during driving vs. depth [MPa]
  transfered energy/enthru during driving vs. depth [MPa]
  blow count vs. depth [blows per 0.25 m]
  SRD (soil resistance to driving) vs. depth [MN]
vibratory driving refusal depth one number (depth [m])
FNLS05 peak stress during driving vs. depth [MPa]

FNLS06

FNLS33

amplitude stress during driving vs. depth [MPa]
  SRV (soil resistance to vibration)  

 

Table 2 Requested results for behavior during driving concrete driven piles (part C-1)

installation and position Requested Variable To be presented
iMPact driving peak stress vs. depth [MPa]
S13 amplitude stress during driving vs. depth [MPa]
S14 transfered energy/enthru during driving vs. depth [MPa]
  blow count versus [blows per 0.25 m]
  SRD (soil resistance to driving) vs. depth [MN]

 

Table 3 Requested results for performance of piles
Note: ultimate static capacity at continuously increasing deformation at constant load (Part B and C)

Position Requested Unit
FNLS05 ultimate static capacity at continuously increasing deformation at constant load [MN]
FNLS06 contribution shaft and toe (to total capacity) [MN]
FNLS3 (optional) load-settlement curve pile head  
FNLS4 (optional)    
S13    
S14 (optional)    
S31    
S32 (optional)    

 

 

4.2      Timetable

The prognoses for this event must be available in week 34 at 1 September 2022.

 

4.3      Prognosis performance based on SLT and DLT results

Some piles will be tested by a RLT and SLT. The results of these tests together with regular installation records will be available.

 

4.4      Timetable

The test data will be available at 11 September (start of week 37). The prognoses should be available 19 September (start of week 38).  Although this period is very short, we encourage you participate even with a limited number of answers.

5      (Sonic) Pile integrity testing (part D)

5.1      Introduction

We offer you the opportunity to participate in a field test on sonic pile testing.

The first test focus on getting the echo response as a function of pile length and the dependency of a correct picking of the reflection wave on pile length. This will be done on hammer driven prefabricated piles without defects (before driving).

The second test focus on the determination of defects in cast in situ piles.  The defects are created by realistic errors during installation. The piles have no additional provisions, apart from a few that has a central casing (see spreadsheet).

At the demonstration day the results are published in a presentation with tables anonymously. If possible, some statistics will be shown. We plan to make a publication afterwards on these results.

 

5.2      Available information

5.2.1    General

Three types of piles will be installed

  1. The prefabricated piles with variable length are at the position S15, S16, S17, S18, T19N, S19, S20, T20S (Part D-1).
  2. The cast-in situ piles (CFA piles) are placed on the points S25 … S30 (Part D-2).
  3. The prefabricated piles with defects are located at the positions T21N, S21, S22, T22S (part D-3).

At the positions starting with an “S”, CPT data is available, at the positions starting with “T” no CPT-data is available. The number coincides with the number of the nearest CPT.

 

5.2.2    Information delivered before testing

All information delivered before the test is described in this document, the pile plan and the spreadsheet Testing piles. The results of all field tests are in the field description.

 

5.2.3    Information delivered after testing

These data are described per pile type. These will freely available for further analysis

 

5.3      Prefabricated piles (part D-1)

The prefabricated pile s has a length varying between 6 m and 20 m. The slenderness (length / diameter) is between 20 and 50. The piles are hammer driven with Junttan HHK-7A equipment.

 

If we succeed to measure the wave speed before pile driving by an independent method, we give you an indication of the measured wave speed.

 

The question to be answered in the prescribed spreadsheet:

  • What is the travel time of the pulse [ms] (or if your equipment presents a pile length after input of the wave velocity, we ask to give the pile length [m] and wave velocity [m/s])?
  • What is your opinion about the reliability of the number (certain, hesitating, uncertain, not detectable)?

5.4      Cast in situ piles (part D-2)

The CFA piles are installed with ?? equipment. The nominal diameter is 500 mm and length is approximately 17 m

We intend to create some piles with one defect per pile.

 

The question to be answered in the prescribed spreadsheet:

  • Has the pile a defect? yes/no
  • What is the type of the defect?
  • What is the position of the defect (starts at, ends at) both in meter from pile head.?

After the tests the installation length and standard production data will be published. After regaining of the piles, a visual inspection will be done and published.

 

5.5      Prefabricated piles with defects (part D-3)

This part refers to relatively short piles with complicated defects, especially meant to show the application of more advanced inspection methods that can be lowered in the central casing. We invite you to test your equipment and inventiveness in this unrealistic and extreme situation. Participation is done by giving a short description of your observations and analysis.

 

5.6      Timetable

The test site will be open for sonic testing from Sunday 18 September – Tuesday 20 September. The results in the spreadsheets must be send by e-mail Before Wednesday 12:00. The summary of the results is presented at the demonstration day and available at the website afterwards.

 

The measured time signals must be uploaded to the data system before 1 October.

 

The results of the inspection of the regained piles will be available at the beginning of November.