^^^ The article on digging the Pokharan shaft reveals what I knew years ago and codified in an article in the old BR Monitor 2002. I had said then the shaft was around 210 m-225m deep. This was based on work by Nordyke and the scaling laws he had found in his work at Nevada test sites which he tabulated for IAEA. This depth translates to around 680 feet. The author ^^^ says the shaft
was over 600 feet. As an additional check in my article from 2002 I used the fact that Chengappa in his book had stated the amount of steel needed to line the shaft. This provided a second check on the depth that was trivially computed via Nordyke's scaling laws. SS who was a forum admin at that time, even sent my article to some external people at BARC for review. So as far as I am concerned there is nothing new in what the author says except the mechanics of how to dig a deep shaft without adequate institutional support, and related high jinks in the desert with water diviners.
My article explained in great depth how scaling laws are found and the difference in cratering between chemical and nuclear explosions. It is actually all curve fitting with very little serious mathematics if at all. For example in very hard granite a certain event at Nevada allowed Nordyke to show that a Retarc is formed(reversed crater) if the emplacement depth is 60Y^{1/3}, why 60 and why the cube root, there is no mathematics involved here, just taking 70 events and plotting. Naively the cube root is possibly related to the volume, this sort of analysis is what engineers like and called dimension analysis. If it is a an equation like Navier-Stokes then one scales all the variables and arrives at say the Reynolds number in such a reasoning. It is the reason why wind tunnels sort of work. In such crater analysis there is not even a Navier-Stokes equation, just a guess that explosive forces will move soil a certain way. For example one could also use Y^{1/3.3} if you please and adjust the 60 to 75. There were graphs in that article and also a partial list of events from Nevada test site which formed a basis for Nordyke's papers. Most of the research was done in the heady days when people thought they could use such explosions for
peaceful purposes and the IAEA was even on board for such studies. This was the so-called Plowshares Program. The test
Sulky which was conducted in dry granite with a basalt overlayer surprised people as a retarc was formed instead of a subsidence crater. It determines the scaling law above. S-1 at Pokaran had a retarc, but one has to be careful as there was water in the shaft as Chengappa states in his book and this latest report corroborates and so I made adjustments in the scaling law in my article for BR Monitor. Test
Baneberry which was conducted in a shaft 1010 feet deep and so far deeper than S-1, but about 60kt, had a stemming failure and vented with serious spread of radioactive Iodine.
As far as tunneling goes I grew up around engineers who did amazing things in a newly independent India and taught me the concept of excellence. Dad helped them indirectly as he was always one for an engineering challenge. Project diagrams would sometimes be unfolded over the dining table in the mid 1960s when these projects were being done. Dad's slide rule bought in 1951 lies on my desk and is always a reminder to what excellence is all about. Projects done chief engineer A. R. Raichur, project advisor Mayashanker Pattani, Consulting engineer P. V. Keskar, some of the finest, funniest and intelligent people I knew. Some projects above gentlemen did, not that anybody here or in Eendia will ever care, but some do.
1. DBK Railway, 58 tunnels the highest broad gauge railway in the world then, now Kashmir railway is higher. Project came in under budget and before time. Never happened in IR since. Started in 1962. Beautiful Araku valley
https://en.wikipedia.org/wiki/Kothavala ... andul_lineMost of the tunnels were over 500m and in very difficult terrain, in what is now Naxal infested parts. Dantewada is on the Kirandul line.
2. Kalagarh twin diversion tunnels Ramganga hydel project started in 1964. (Corbett National Park, those days nobody knew what the heck was this park) Two tunnels were constructed. The Ramganga was diverted through those two tunnels and the dam built. Later one tunnel was used for the hydroelectric equipment, Penstocks etc and the other one is used for drawing irrigation water. Each tunnel was 9.45 m in diameter.
https://en.wikipedia.org/wiki/Ramganga_DamThis was in the Siwaliks and lower Himalayas with peculiar unstable geology. In 1964 I am amazed how they managed to do it. Same with #3 below, it was difficult with massive cave ins.
3. Giri-Bata project Nahan, HP
Hahahaha I remember this
https://www.researchgate.net/publicatio ... ATA_TUNNEL4. Doubling of Itarsi--Nagpur line 1966, Maramjhiri-Ghoradongiri on Chennai-Delhi line. The newer double line displays the legend 1966 on the tunnel portals.
https://www.irfca.org/gallery/Trips/cen ... A.jpg.html?
The original line was from 1929 when the Angrez built it to finally connect Chennai and Delhi. These guys did not blame the Illuminati, The Knights Templars, Nehru, illiteracy of 20% for the woes and wait for foreign advisors etc to come in the 1960s and 1970s, they built it with their brains and with what equipment they had and with what they could do best and dam it it has stood 60 odd years and will last for a long, long time. Now some guy digs a shaft and run to a magazine to say Hey look what a good boy am I and this in the late 1980s. The list is partial, I can go on. Even with Navier-Stokes I can go on ....

Keskar and Pattani had a chess game going where they would write a postcard everyday with their move when both were in Mumbai. The rule was never to talk about the game when they met at work etc.