The
bodies of the wall, linking beacon towers, watch towers, and passes
into a defensive line, are the main part of the Great Wall. Their
heights differ depending on the local terrain. In flat areas and
places of military importance, the wall is built quite high. While
in the steep mountains and places of less important military meaning,
the wall is built comparably lower to save financial and human
resources. Generally speaking, the wall measures about 23 to 26
feet tall. The fracture surface of the wall is ladder type with
the base measuring about 7.1 yards wide and the top measuring
6.3 yards wide on average, which makes the wall firm and very
unlikely to collapse.
The constructional materials and methods
The
wall was built using local materials and in a manner according
to the technological level of the periods. Construction was mainly
rammed-earth walls, brick walls, and stone walls. Rammed-earth
wall was the earliest method of wall construction. Before the
Sui Dynasty (581 - 618), workers always adopted this way to build
the wall. They first filled a wooden mold with clay or plaster,
then compressed it by pestle until it was hardened into shape,
and finally laid them piece by piece to the satisfactory height
and length. In desert terrain where suitable earth was not available,
sand mixed with debris and willow branch was used as a replacement.
This kind of wall is much easier to build but also easy to be
destroyed by enemies and susceptible to collapsing after long
periods of time.
Brick
walls became popular during the Tang Dynasty (618 - 907) when
the technique of brick production was fully developed. However,
bricks were expensive at that time which limited its use in the
construction of city gates and nearby walls. The outsides of walls
were built by laying pieces of bricks while the inner walls were
filled with yellow earth. Due to the increase of production levels
of bricks in the Ming Dynasty (1368 - 1644), the cheap but high
quality bricks were largely used in wall construction. The wall
was made strong enough to not only stop the intruders' steps,
but also was able to resist attack from newly-invented firearms
of the period. Of course, bricks must be agglutinated one by one
to make the wall strong. During the Ming Dynasty, workers used
lime mortar mixed with sticky rice juice as cementation materials
which proved to be a very effective method.
Stone walls were made of locally found stones when walls passed
through mountainous areas. Some stones were processed into necessary
stone pieces and others kept their original appearance. Between
stones, mortar mixed with sticky rice juice was used to securely
glue them together. The wall was firm enough to bear more weight,
go through natural erosion and resist any weapon's attack of the
period. Badaling
Great Wall was built in this way.
The attached designs
There are many necessary designs attached to the wall to make
the defense system complete.
Crenel: It refers to the parapets which are
concave-convex shaped and often measures 6.6 feet high. They are
used for watching enemies' activities and shooting at enemies
while at the same time being sheltered.
Parapet
Wall: In Chinese, it is called Nuqiang or Yuqiang, literally
translated as "Women's Wall", to indicate that it is
low enough to allow a woman to climb over. It is built to ensure
the safety of soldiers and horses on the wall, often 1.1 yards
high and built on the inner side of the wall.
The Single Parapet Wall: As the name suggests,
it is only a thin wall built on extremely steep mountain slopes.
In this area, the regular way of building a double parapet wall
is impossible to realize. The lofty peaks serve as natural barriers
on the other side. The height of this kind of wall varies according
to the terrain, often measuring 6.6 to 11.5 feet tall. A famous
and steep single parapet wall is located in Simatai
Great Wall.
The Barrier Wall: It refers to the wall built
vertically to the crenels. Once the enemies' attack approached
the wall, allied soldiers could use barrier walls to provide cover
for themselves.
The Horse Ramps (or Bridle Paths): Beside the
gate tower usually laid a pathway which leads people and horses
to the top of the wall. It measures about 5.5 to 6.6 yards wide.
A parapet wall serving as railing was built on one side of it.
The incline is 30 degrees and bricks were placed with their lateral
surfaces skewed to provide anti-slip.
The
Drainage System: In order to drain precipitation on the
wall in a timely fashion, workers built barrel drains at certain
intervals. Rain water could be drained to the outside of the wall
through the mouth of the barrel drains which extended out from
the wall about one yard. The drainage system has protected the
wall from the erosion of rain water over a long period of time.
Quanmen: On the inner side of the wall, at regular
intervals, there are arched doors. When war was coming, soldiers
could pass through these doors as indicators to the top of the
wall to fight.
Pufang: It is a shelter built on the wall or
watchtower for soldiers on guard.