استكمالا لموضوع الفحوصات التي تتم على الاوتاد فقد قدمت
Pile Dynamic Test
واليوم اقد م لكم فحص Pile Integrity Test
وهو من الفحوص المهمه حيث يتم في التأكد من سلامة الاوتاد piles من حيث انه لا يوجد فجوات او فراغات Voides وكذلك تجانس مقطع الوتد لكامل الطول .
ويتم هذا الفحص من خلال الموجات الصوتية ومن خلال معرفة سرعة الموجات المرتدة يمكن تحديد مدى سلامة الوتد واليكم الشرح بالتفصيل .
Pile Integrity Test
Pile integrity test is used to assess the continuity of piles. With this test, necking or bulging and uniformity of quality of concrete is checked.Piles that are doubtful for integrity are taken up for Dynamic load testing along with some piles which are ok. Typical defects identified by this test are shown below.
Method of Testing : There are Indian Standards for the pile integrity test & the most commonly used worldwide is Pile Integrity Test as per ASTM – D 5882 – 00, “Standard Test Method for Low Strain Integrity Testing of Piles”. Relevant clause from the said ASTM standard is reproduced below: Clause no. 5.2.3 : Placement of Transducers – The motion sensor should be placed at or near the pile head using a suitable, or temporary, bonding material (that is wax, vaseline etc.) so that it is assured that it correctly measures the axial pile motion. The motion sensor is placed generally near the center of pile. Additional locations should be considered for piles with diameters greater than 500 mm. The low strain impact should be applied to the pile head within a distance of 300 mm from the motion sensor.
Objective: To check the pile for continuity for the continuity of the shaft of the pile
In the sonic test, the top of the pile is hit with a plastic hammer and the reflected waves are recorded by a suitable computerized equipment. From the resulting signal, or reflectogram, one can determine both length and continuity of the pile. Although a powerful tool, the sonic method also has limitations, such as: the test produces no information regarding the pile capacity, and gives only limited information about the concrete quality. The sonic system, can only discover material impedance changes. It cannot tell anything whether these impedance changes are due to poor concrete or due to reduced cross section. Even then this test is a fast & economical tool for determining discontinuities in the pile shaft. If pile records are available, then the results can be fine tuned for greater & more reliable information.
Limitations of the test:
The accuracy of the length determination depends on the assumed wave velocity. This factor, which depends on the grade and age of the concrete, varies from pile to pile and may cause an error of the order of 10 percent.
Site preparation Guide:
For the test to be effective, the top of the pile should consist of clean concrete and free of debris, laitance and bentonite. Testing a pile with a head which was not properly prepared may yield misleading results.
Table 2: Sample Report Sheet (Pile Integrity Test)
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