I really get asked this a lot!<\/p>\n
Is it injected one at a time?<\/p>\n
Is it okay to inject them all at once?<\/p>\n
Is there any literature on this somewhere?<\/p>\n
And so on.<\/p>\n
![\"Grout](\"https:\/\/norimen.net\/wordpress\/wp-content\/uploads\/2018\/03\/IMG_1868.jpg\")
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I'm going to write this out in detail this time, so keep it in mind lol<\/p>\n
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1. Why use double-pipe drilling?<\/span><\/strong><\/p>\n Because rebar cannot be inserted after drilling in single-hole drilling (Site Conditions I). (Design Philosophy)<\/p>\n <\/p>\n 2. Is it necessary to inject one at a time?<\/span><\/strong><\/p>\n If the mountain stands on its own, then there's no need for that, but...<\/p>\n <\/p>\n Regarding 1<\/strong><\/span><\/p>\n As the name \"rebar insertion method\" suggests, this is a construction method in which rebar is inserted and secured with cement slurry. (Full-surface securing)<\/p>\n Since the whole point is that it\u2019s pointless if the rebar isn\u2019t inserted, if the rebar cannot be inserted using a single-hole drilling method, a double-pipe drilling method is used.<\/p>\n However, when drilling a double-pipe borehole, it is often the case that the surrounding rock is consolidated by the rotation, impact, and friction of the casing, causing the borehole wall to become self-supporting.<\/p>\n In this case, you can wrap the injection hose around the rebar, insert it into the hole, and then inject the material all at once.<\/p>\n <\/p>\n Regarding 2<\/strong><\/span><\/p>\n The idea that we need to inject one dose just came out of nowhere, but,<\/p>\n It\u2019s probably because the construction method for ground anchors is the same\u2014using double pipes\u2014that someone made that comment.<\/p>\n However, as mentioned above, when using double pipes in rebar insertion work,<\/p>\n Since they stand on their own quite often, it\u2019s perfectly possible to inject them in batches. (This is strictly based on observations made during construction.)<\/p>\n <\/p>\n In single-hole drilling, batch injection is generally used. (It\u2019s the only option.)<\/p>\n But you might be wondering, \u201cWait, what do you mean \u2018inject into one tube\u2019 right after it becomes a double tube?\u201d<\/p>\n I end up feeling the same way, lol.<\/p>\n Whether it's a single or a double, why is the only difference the bore diameter?<\/p>\n The construction method should have been selected based on whether or not it is possible to insert rebar.<\/p>\n <\/p>\n In other words, this means it can also be interpreted to mean that even with bulk injection, as long as the injection hose is in place, there\u2019s no problem at all.<\/p>\n However,<\/span><\/strong><\/span>If you bring in the ground anchor construction method, it\u2019ll end up being just one injection, lol.<\/p>\n <\/p>\n Personally, I don't mind either way, but that will reduce construction efficiency and increase the estimate.<\/p>\n It also increases the cost burden on those purchasing the materials.<\/p>\n To perform a single injection, the mixing agent must be changed from Leobild to FT700. (This will result in a slight increase in the unit price.)<\/p>\n While the final strength may not vary much, there could be significant differences in weekly strength (depending on temperature and other conditions).<\/p>\n Since the strength verification is delayed, the final tightening (of the nuts) will be slightly delayed. (Well, that\u2019s putting it a bit dramatically.)<\/p>\n As for subcontractors, the grout mixer gets dirty (the grout hardens), so cleanup work is required after installation.<\/p>\n If you outsource the surface preparation work to a maintenance contractor, the surface preparation alone will cost about 100,000 yen.<\/p>\n <\/p>\n Ultimately, either option is fine, but using a single syringe does increase the cost.<\/p>\n I'm pretty sure the standard practice in Fukui Prefecture was to use a single injection in all cases!<\/p>\n I heard the supervisor stays right on top of them the whole time while they're working? lol (That's what I heard, but is it true? lol)<\/p>\n No matter what the circumstances are when administering the injection,<\/p>\n Please take photos of the test pieces at AM and PM, and be sure to take clear photos during the injection process as well (you know what I mean, right?).<\/p>\n <\/p>\n And one more important thing: be sure to tap the rebar after grouting!<\/p>\n \"Shaku\" means to shake something back and forth or side to side, and<\/p>\n Vibrating the mixture improves the bond between the cement slurry and the rebar.<\/p>\n That way, you can be sure to inject the cement slurry properly and prevent construction defects.<\/p>\n <\/p>\n It depends on the general contractor\u2019s supervisor\u2019s approach as to which method will be used, so I can\u2019t say for sure, but,<\/p>\n In reality, single-hole drilling and double-pipe drilling are the same.<\/p>\n This means that just because the diameter changes, it doesn\u2019t necessarily follow that the same approach used for ground anchor construction applies here.<\/p>\n Obviously, they\u2019re different trades, so their approaches are different.<\/p>\n Make sure to hold the injection hose firmly and inject from the bottom! (This is absolutely essential!!)<\/p>\n And I don't think there are any books about this particular incident.<\/p>\n Is that mentioned on the NEXCO website??<\/p>\n If anyone knows, please let me know.<\/p>\n <\/p>\n See you later.<\/p>\n Various Drilling Methods for Slope Drilling (Part 3)<\/a><\/p><\/blockquote>\n![\"Reinforcing](\"https:\/\/norimen.net\/wordpress\/wp-content\/uploads\/2021\/11\/2021-09-21-09.26.44-1.jpg\")
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