PLEASE EXPLAIN LINES 157 TO 175 OF THE TRIUMPH OF LIFE BY P.B. SHELLEY.PLEASE GIVE SIMILES USED BY THE POET IN THESE LINES.SOME OF THE WORDS SEEM...

This is the section of the poem to which you are
referring:

readability="34">

..the fiery band which held
Their
natures, snaps--while the shock still may tingle
One falls and then another in
the path
Senseless--nor is the desolation single, _160

Yet
ere I can say WHERE--the chariot hath
Passed over them--nor other trace I
find
But as of foam after the ocean's wrath

Is spent upon
the desert shore;--behind,
Old men and women foully disarrayed,
_165
Shake their gray hairs in the insulting wind,

And
follow in the dance, with limbs decayed,
Seeking to reach the light which
leaves them still
Farther behind and deeper in the
shade.

But not the less with impotence of will _170
They
wheel, though ghastly shadows interpose
Round them and round each other, and
fulfil

Their work, and in the dust from whence they
rose
Sink, and corruption veils them as they lie,
And past in these
performs what,...

Generally,
lines of poetry can be discussed as a separate entity and as a part of the greater
whole.  It is generally best to do both.

These lines
discuss the decay and degeneration of the people whom the Chariot of Life has both run
over and enslaved.  These people are described as being broken and demoralized but have
no choice but to slavishly continue to follow the
Chariot. 

These lines may be confusing by themselves, but
in the greater context of the poem, the reader can see that these people are those that
have given in to the worldy temptations of Life, which is personified as the Shape and
its Chariot.  Metaphorically, Life has "run over" them, leaving them in God's anger and
without salvation, which is most apparent in lines
168-169.

The words you mention are, indeed, misspelled. 
They  are "natures," "deserts," and "foully,"  from lines 2,7, and 8
respectively. 

You specifically ask about similes.  In the
lines directly preceeding this selection, lines 152-155, similes are
used.

...and
as they glow,
Like moths by light attracted and repelled,
Oft to
their bright destruction come and go,

Till like two clouds into one
vale impelled, _155
That shake the mountains when their lightnings mingle And
die in rain..

This passage
refers to young people who, during their youth, are attracted like insects to light, or
to bright but senseless things such as wealth.  Then they seem to dart back and forth. 
He uses another simile for the destruction they turn into by comparing them to two
clouds which cause a violent and fatal storm.