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The dynamic load pile test, which is a simple quality control test offering a considerable savings of time and cost and requires less space, can be used for predicting pile capacity and pile integrity under proper care and it should be calibrated by at least one static test. The pile design for projects should be optimized by determining the actual ultimate pile capacity, which may need to conduct pile test to failure or near to failure.
The static pile load test is conducted at low strain and takes longer time than the dynamic pile load test, which is conducted at considerably higher strain . This will be achieved by taking four case studies, conducted in Red Sea State in eastern Sudan. It consists of estimating soil resistance and its distribution from force and velocity measurements obtained near the top of a foundation impacted by a hammer or drop weight. The impact produces a compressive wave that travels down the shaft of the foundation.
A pair of strain transducers receives the signals necessary to compute force, while measurements from a pair of accelerometers are integrated to yield velocity. These sensors are connected to an instrument such as a pile driving analyzer , that records, processes and displays data and results , , . The capacity of the hammer should be large enough to achieve sufficient pile settlement so that the resistance of the tested pile can be fully mobilized. The load should be applied axially on the pile.
The pairs of accelerometers and strain transducers are fixed to opposite sides of the tested pile, about at least one shaft diameter below the head, either by drilling and bolting directly to the pile or by welding mounting blocks to ensure a reasonably uniform stress field at the measuring elevation , .
The modern change, which is considered as one of the significant beneficial changes that have been made to the system since the last Irish survey in is the introduction of theodolite to measure the pile displacement during the impact , . There are two known methods, based on wave propagation theory, for the analysis and interpretation of the dynamic pile load test.
Essential preparations should be made before the test is carried out in the field. A pile cap, as an extension to the shaft head with the same diameter as the shaft , should be constructed.
The length of the cap should be at least 1. The cap must be cylindrical, smooth, well-reinforced and of good quality concrete. The side of the cap is instrumented with two strain gauges, two accelerometers and electronic theodolite target. The electronic theodolite is placed 3 to 5m from the pile head.
A schematic sketch of SIMBAT equipment and instrumentation is presented in Figure 2 , whereas a photograph of a complete set of the equipment is shown in Figure 3. A series of hammer blows are made with the hammer drop height progressively increased and decreased . Q The main difference between this system and other dynamic load test systems is the using of an electronic scanning theodolite that records penetration for each blow and records real time elastic displacement .
The measured force at the pile top is separated into components upward and downward. The dynamic or total reaction, Rdy is calculated for each hammer blow and plotted versus cumulative penetration for the whole set of blows.
The dynamic load is converted to static load and the predicted static load-settlement curve can be plotted. The static plot is verified by modeling. Svinkin analyzed a distinctive case history presented by Briaud et al. All tests were carried out on bored concrete piles. Three projects are residential tower buildings representing a part of the residential tower buildings complex of Red Sea state.
This is Portsudan city, which is located in western coast of the Red Sea in eastern Sudan . The formation at this area is predominantly coralline deposits consisting of completely to slightly weathered coral reef limestone that contains marine shells and fossils. This formation is characterized with great variability in horizontal and vertical directions.
Q Tower 7 Load kN D. L Load KN 0 0 0. Q D. In our opinion, it is wise that to determine the actual pile ultimate capacity for a project by testing at least one pile to failure. This will enable an economical pile design and offer a considerable saving of cost for the project. The comparisons of load-settlement behaviors for dynamic and static load tests, shown in Figure 5 , Figure 6 and Figure 7 , indicate that the predicted settlement from dynamic and the measured settlement from static are generally consistent to a reasonable extent as reflected by the results of towers 7 and 8.
But generally the settlements predicted by dynamic load test are slightly higher than the settlement measured by the static load test. This is very clear especially in the results of the pile of tower 1 project. This paper has been focused on this type of pile loading test. Four case studies of dynamic and static pile loading tests conducted in the eastern of Sudan have been presented.
The load-settlement behaviors for dynamic and static load tests were compared for the three case studies of the residential tower buildings complex project. This shows a reasonable agreement between the two test results. Q settlement. It can be concluded that the dynamic load pile test can be used for predicting pile capacity and pile integrity under proper care and it should be calibrated by at least one static test. Therefore, it is strongly recommended to optimize the pile design for projects by determining the actual ultimate pile capacity, which may need to conduct pile test to failure or near to failure.
Svinkin, Ph. ASCE Rajagopal, Post Graduate Student, C. Solanki, Associte Professor, and Y. Tandel, Research Scholar. Q Mhaiskar, S. Related Papers. By Mohamed Osman and elfatih ahmed. Evaluation of design capacity of bored pile based on high strain dynamic test.
By Nurly Gofar. By Dharmik Navadiya. Analysis of piles in a residual soil—The ISC'2 prediction. By Jaime Santos. By Rodrigo Salgado. Download pdf. Remember me on this computer. Enter the email address you signed up with and we'll email you a reset link.
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