use strict;
use Data::Dumper;

my @mainarr;
my @arr1=qw(a b c d e);
my @arr2=qw(f g h i j);
my @arr3=qw(k l m n o);
push(@mainarr,@arr1);
push(@mainarr,@arr2);
push(@mainarr,@arr3);

print Dumper \@arr1;
print Dumper \@arr2;
print Dumper \@arr3;
print "-- mainarr\n";
print Dumper \@mainarr;


##</code><code>##

...

push(@mainarr,\@arr1);
push(@mainarr,\@arr2);
push(@mainarr,\@arr3);

print Dumper \@mainarr;