After writing this article, I had the opportunity to speak with some certified engineers.<\/p>\n
Talking about stress management, specificallyThe Meaning of Aptitude Tests<\/strong>That's it.<\/p>\n I shared my thoughts, and surprisingly, they seemed to agree with me lol. Building on that discussion, I\u2019d like to share my honest opinion\u2014that \u201cI personally don\u2019t think aptitude tests (multi-cycle) are meaningful\u201d\u2014and explore the question of \u201cwhat really matters, then?\u201d<\/p>\n Let's start by clarifying the criteria.<\/p>\n According to the \u201cDesign and Construction Standards for Ground Anchors\u201d and its explanatory notes (JGS4101-2012, Japan Geotechnical Society),<\/p>\n We have established \"qualification tests\" and \"verification tests\" as tests to evaluate the quality of the anchors we manufacture.<\/p>\n The qualification test covers the volume of construction work5% and 3 or more bottles<\/strong>Targeted at,Multi-cycle loading of 5 cycles or more<\/strong>This method involves conducting tests and using the load-displacement characteristics to determine whether the design and construction are acceptable.<\/p>\n The confirmation test excludes the anchors used in the suitability test.Total<\/strong>Targeted at,1-Cycle Loading<\/strong>It is used to verify the safety margin against the design anchor force.<\/p>\n For details on dwell time and threshold values, see our previous article, \u201cHow to Shorten the Time Required for Ground Anchor Qualification and Verification Tests<\/a>\"I've drawn it in the table, so please take a look at that as well.\"<\/p>\n <\/p>\n To put it simply, here\u2019s what happened back then.<\/p>\n An aptitude test is a test that examines load-displacement characteristics in detail over multiple cycles, butIn actual field work, the conclusion is usually that \u201cas long as the anchor doesn\u2019t pull out under the ultimate anchoring load, it\u2019s acceptable.\u201d<\/strong>That's it.<\/p>\n No matter how detailed the data collected during the cycle is, it all boils down to a simple matter: as long as there are no gaps at the end, it\u2019s fine; if there are gaps, it\u2019s a failure.<\/p>\n After I shared my thoughts, the teachers seemed to agree, with a sort of \u201cWell, I guess that\u2019s how it is, after all\u201d vibe lol. The fact that the aptitude test (multi-cycle) doesn't really mean much in terms of data.<\/p>\n However, this is merelyMy personal opinion, based on my own feelings<\/strong>That said, I am not suggesting that aptitude tests are unnecessary.<\/p>\n Since these standards have been established, the basic premise is that we must adhere to the test methods as they stand at this time. I really hope there\u2019s no misunderstanding about this, lol.<\/p>\n I'll do what I've decided to do. But I guess I have that side to me, too, lol.<\/p>\n So, when it comes to what I think is important, IHolding at Maximum Load During Testing<\/strong>That is my belief.<\/p>\n The maximum test load is specified as 1.25 times the design anchor force (Td) for Rank A and 1.10 times for Rank B, and<\/p>\n The minimum measurement time for the final cycle is generally considered to be about 5 to 15 minutes, depending on the soil conditions.<\/p>\n The criteria are as follows: for sandy soil and bedrock, displacement must be 0.2 mm or less over a period of 2 to 5 minutes; for cohesive soil, displacement must be 0.25 mm or less over a period of 5 to 15 minutes; and the creep coefficient \u03b1 must be 2.0 mm or less.<\/p>\n The creep coefficient is defined by the following equation.<\/p>\n \u03b1 = (Sb \u2013 Sa) \u00f7 log(tb\/ta)<\/p>\n Sa and Sb represent the anchor head displacements (mm) at times ta and tb, respectively.<\/p>\n The way I see it,During this period of maximum load retention, allow sufficient time for the rock mass and the anchor to settle into place and for some plastic deformation to occur.<\/strong>I believe there is meaning in everything.<\/p>\n My view is that as long as we can maintain this properly, it should be sufficient for practical purposes.<\/p>\n To be honest, the data from the middle of the aptitude test cycle... who really cares? lol<\/p>\n Since we need to collect data, we\u2019ll gather it as test data for now, but<\/p>\n Rather than spending time and effort on that,Ensure a secure grip when carrying the maximum load.<\/strong>I feel that this approach is far more practical.<\/p>\n In fact, if you're unable to obtain good data, stretching the material firmly to its maximum load tends to result in better data in subsequent measurements.<\/p>\n This is just a rule of thumb based on my own experience\u2014it\u2019s not something explicitly stated in the manual\u2014so please take it as nothing more than my on-the-job intuition (not that I\u2019m making excuses, lol).<\/p>\n Up to this point, I\u2019ve been honest in saying that I think \u201captitude tests are pointless,\u201d but that doesn\u2019t meanThis doesn't mean we should do away with the exam altogether.<\/strong>\u3002<\/p>\n For now, test methods have been established as standards, so,Conduct in accordance with the standard test methods, based on the judgment of the responsible engineer.<\/strong>It is necessary.<\/p>\n This is a fundamental premise.<\/p>\n What I'm trying to say is about \"the significance of data from mid-cycle measurements,\" not that \"you don't have to take the test\" (this isn't an excuse, lol).<\/p>\n <\/p>\n Ultimately, I believe that \u201censuring the structure holds firmly under maximum load and fully settles into the surrounding rock\u201d is more important than \u201ctaking time to accumulate data over multiple cycles,\u201d<\/p>\n I believe it is highly effective for ensuring safety in practical situations.<\/p>\n This is by no means a call to ignore the standards, but rather a matter of prioritizing what is most important within those standards.<\/p>\n Do you pay close attention to your hold time?<\/p>\n The reason you can't get good data might be that the fixed points aren't secure, or<\/p>\n If you apply the maximum load and then return it to the initial load, and the measured displacement is too short or too long, I think the holding time at the maximum load won't be long enough.<\/p>\n I think opinions on this vary depending on the workplace and experience, so if you\u2019re up for it, I\u2019d love to hear what your experiences have been like on the job lol.<\/p>\n <\/p>\n See you later.<\/p>\n Simple Tension Management | Improving Anchor Installation Efficiency<\/a><\/p><\/blockquote>\n
\nWell, since they\u2019re people in positions of authority, I imagine this isn\u2019t something they can say in public, but I get the feeling that, deep down, that\u2019s probably how they really feel.<\/p>\n![\"Stress](\"https:\/\/norimen.net\/wordpress\/wp-content\/uploads\/2023\/10\/2023-10-10-09.09.18.jpg\")
<\/p>\nWhy are aptitude tests and confirmation tests conducted in the first place?<\/h2>\n
Thoughts from Talking with Certified Engineers | As Long as You Pull It Out, It\u2019s Fine<\/h2>\n
\nI imagine those of you working in construction management probably have a vague idea of this, don't you?<\/p>\nWhy do you think the maximum load holding time during testing is important?<\/h2>\n
![\"Stress](\"https:\/\/norimen.net\/wordpress\/wp-content\/uploads\/2019\/09\/14556747432525e58b8abee389a5b1a7.jpg\")
<\/p>\nWhy We Still Follow the Standards | The Struggle with Fixed Points<\/h2>\n