mine

-- 14 coal
-- 15 torch
-- 16 ender chest
D=16  --how far to go
T=3  --tunnel
C=16  --how far left and right chanel go
function CINV()
 if turtle.getItemCount(13) > 0 then
  turtle.digUp()
  turtle.select(16)
  turtle.placeUp()
   for invs=1,13 do
    turtle.select(invs)
    turtle.dropUp()
   end
  turtle.select(16)
  turtle.digUp()
  turtle.select(15)
 end
end
function CRF()
  if turtle.getFuelLevel() <= 100 then
   turtle.select(14)
   turtle.refuel(1)
   turtle.select(15)
  end
end

function FWRD()
  if turtle.forward() == false then
   repeat
    turtle.dig()
    CINV()
    sleep(0.25)
   until turtle.forward() == true
  end
end

function TUNL()
 turtle.digUp()
 CINV()
 turtle.dig()
 CINV()
 CRF()
 FWRD()
end

function CHAN()
 turtle.dig()
 CINV()
 CRF()
 FWRD()
 turtle.digUp()
 CINV()
end

--start

for i=1,D do --
  for i=1,T do
   TUNL()
  end
 turtle.digUp()
 CINV()
 turtle.turnLeft()
  for i=1,C do
   CHAN()
  end
 turtle.select(15)
 turtle.placeUp()
 turtle.suckUp()
 turtle.turnLeft()
 turtle.turnLeft()
 P=0
  for i=1,C do
      P=P+1
       if P == 8 then
     turtle.select(15)
        turtle.placeUp()
     turtle.suckUp()
       end
      CRF()
      FWRD()
  end
  for i=1,C do
   CHAN()
  end
  turtle.select(15)
 turtle.placeUp()
 turtle.suckUp()
 turtle.turnLeft()
 turtle.turnLeft()
 P=0
  for i=1,C do
      P=P+1
       if P == 8 then
     turtle.select(15)
       turtle.placeUp()
     turtle.suckUp()
       end
      CRF()
   FWRD()
  end
  CRF()
  turtle.turnRight()
end
turtle.turnLeft()
turtle.turnLeft()
for i=1,D*T do
 FWRD()
end