テンソルデータのスライス操作を実現します。

import tensorflow as tf
a=tf.constant([[[1,2,3,4],[4,5,6,7],[7,8,9,10]],
      [[11,12,13,14],[20,21,22,23],[15,16,17,18]]])
print(a.shape)
b,c=tf.split(a,2,0) #  1、   2、       3、                  b,c
print(b.shape)
print(c.shape
with tf.Session() as sess: #      
  print(sess.run(b))
  print(sess.run(c))

(2, 3, 4)
(1, 3, 4)
(1, 3, 4)
[[[ 1 2 3 4]
 [ 4 5 6 7]
 [ 7 8 9 10]]]
[[[11 12 13 14]
 [20 21 22 23]
 [15 16 17 18]]]

d=tf.reshape(b,[3,4])
print(d.shape)   

#output
(3, 4)