2/16/2017 11:33:02 AM
10/6/2015 9:54:00 AM
WESTERN DAM ENGINEERING NEWSLETTER, VOLUME 2, ISSUE 1, APRIL 2014
DRILLING AND SAMPLING FOR EMBANKMENT DAMS, RAINFALL RUNOFF, ESTIMATING FLOODINFLOWS, TEAM EFFORT SPECIFICATIONS
Document Type - Reference Library
Research, Thesis, Technical Publications
There are no annotations on this page.
Document management portal powered by Laserfiche WebLink 9 © 1998-2015
All rights reserved.
Pages to print
Enter page numbers and/or page ranges separated by commas. For example, 1,3,5-12.
After downloading, print the document using a PDF reader (e.g. Adobe Reader).
View plain text
Western Dam Engineering <br />Technical Note <br />6 <br />Odex Drilling <br />Odex drilling (also known as TUBEX) is a percussive <br />drilling method that uses an air powered down-the-hole <br />hammer to advance a casing string. Odex casing can be <br />driven through almost all soil and rockfill materials and <br />weak rock in the foundation. SPT and core samples can <br />be obtained through the inside of the casing by changing <br />the drill string and other methods of drilling can be used <br />to deepen the test hole, if required. Drill fluid consists of <br />air and a large air compressor is required. During drilling <br />cuttings from inside the casing are carried to the surface <br />using air. Odex drilling is generally not advisable within <br />the embankment portion of the dam due to the potential <br />damage that can be induced by the percussive action of <br />the hammer and the high pressure air used for cuttings <br />removal. <br />Odex Drilling Considerations <br />Pros Cons <br />Can drill through loose/soft to very <br />dense/hard material, and rock fill <br />Not suitable for strong rock <br />Casing provides embankment <br />protection <br />Generally more expensive and less <br />widely available <br />Samples can be obtained after the <br />hammer is pulled from the casing <br />Performing SPTs are more <br />difficult/costly than with HSA <br />Air required as a drilling fluid <br />Photo 5.Odex Drill Rig <br />Sonic Drilling <br />Sonic drilling (ASTM D6914) uses an oscillating hammer in <br />the drill head to vibrate and advance the drill casing. This <br />drilling method provides almost continuous sample <br />recovery of drilled material in the form of a continuous, <br />albeit disturbed, core. Sonic drilling can be used to <br />efficiently advance through almost all soil and weak rock; <br />however, slow drilling and refusal may be encountered in <br />strong rock or large boulders. Flowing sands and gravels <br />may be problematic and fall out when pulling the core <br />barrel. Drill fluid is not required for sonic drilling; <br />however, some water may be poured into the casing to <br />reduce friction and to keep the sample cool. Samples <br />other than the sonic core (i.e. SPT, Shelby tube, etc.) can <br />be obtained through the casing after the wireline core <br />barrel has been retrieved; however, sampling is time <br />consuming. <br />The test hole can be deepened into rock upon refusal <br />using mud rotary or core drilling methods. Sonic drilling is <br />generally preferred for drilling through coarse or dense <br />embankment materials over Odex due to the limited <br />potential disturbance. However, it is generally one of the <br />most expensive drilling methods. <br />Photo 6.Sonic Drill Rig <br />Sonic Drilling Considerations <br />Pros Cons <br />Can quickly drill through loose/soft <br />to very dense/hard material <br />Slow and inefficient for strong rock <br />with a potential for refusal <br />Casing provides embankment <br />protection <br />Generally more expensive and less <br />widely available <br />Yields a continuous core Core sample is disturbed <br />Drilling fluid not required Performing SPT tests is more <br />difficult/costly <br />Limits embankment disturbance <br />compared to percussive methods or <br />mud rotary methods <br />May result in disturbance of loose <br />in-place material, and therefore <br />care should be taken when <br />performing SPTs
The URL can be used to link to this page
Your browser does not support the video tag.