How was the ancient northwest city of China built?
For example, in Lintao, a section of the Great Wall with a length of 1 1,700 meters is well preserved, and its architectural specifications can be seen. This section of the city wall is about 2.5 meters high, 5 to 8 meters wide at the bottom and 3 meters wide at the top. The rammed layer of banlou is clear, and the thickness of each layer varies from 5 cm to 10 cm. When you meet the cliff edge of the ditch, make full use of the terrain, chisel the outside into a steep wall, and then build a wall on it.
The Great Wall in this area is generally risky, with some walls remaining more than 3 meters and the highest even reaching 7 meters. Ceramic rope tiles can be seen next to the ruins of the city wall, including board tiles, semi-circular pipe tiles and mud pipes. There are round holes and hooks on the edge of ceramic tiles, and drainage with clay pipes is to protect the wall. Tiles vary in size. The largest tile is 70 cm long and 50 cm wide. Ceramic tiles are generally about 45 cm long and 15 cm wide. Most tiles are hard and hot.
In some areas with special terrain and unsuitable for building cities, trenches are used instead of city walls, which is called "graben" in the literature. Historical records? Biography of Montaigne "was blocked by terrain and danger", "Valley of trench" and "The city cut thousands of miles". The combination of "city" and "trench" shows that trench is indeed an important part of the Great Wall defense system. There are still obvious trenches in the Han Great Wall in Shandan County. The general shape is that the outer wall is dug vertically, and the soil is piled on the inner ditch to form a raised ridge. Today, trenches are 0.8-3 meters deep and 5-8 meters wide. The "graben" of Qin Changcheng in the Warring States Period should be the same as this. Against cavalry raids, the moat's defense function is no worse than the city wall.
In many border areas, rivers are the natural dividing line between farming areas and grazing and hunting areas. The defense line in this kind of area basically only builds city piers instead of city walls, taking the bank on the Hanoi side as the city, and ramming the wall when it meets the ditch or river bank. This is what the literature says, "The river is blocked." This is an effective and labor-saving form of defense, so wherever rivers can be "created", the Great Wall always extends as far as possible along the inner side of the river bank. Some scholars roughly estimate that such routes account for about 20% of the entire Great Wall.
The so-called barrier refers to a special defense point that echoes the Great Wall in some dangerous areas or traffic jams. Generally, the peak beams of mountain peaks are cut into straight walls, surrounded by multi-level ridges, forming a highland that can control the surrounding areas and attach various buildings. Obstacles are usually located in the Great Wall. In the later period, some barriers were connected with the Great Wall, forming a so-called "heavy city barrier", which was double-layered to prevent accidents.
A big barricade is actually equivalent to a small castle with a fixed garrison. For the Great Wall of linear defense system, the barrier is a military support base. Therefore, where barriers are set up, cultural remains are quite rich, and the quality and grade of building materials are obviously higher than those in other places.
As for the city pier, it is a routine defense point distributed on the Great Wall Line. "It is divided into density according to different terrain. In flat areas, it is generally 200-230 meters. At the ups and downs, there are also people who are more than 80 meters apart or 100 meters. " Most of the existing remaining heights are between 2.5 meters and 4 meters, which exceeds the remaining height of general city walls.
Some piers are square, and some are lying in the shape of whales. The base line of its horizontal axis is consistent with the wall line of the Great Wall, and both ends are connected with the wall. The width of the foundation is about10m ~12m, and the area on the pier is estimated to be 20 ~ 40m2. A large number of fragments of building materials and daily-use pottery can be found in the existing ruins of the city pier, as well as "thunder stones" used to defend against the enemy, indicating that there are houses and permanent guards on the pier.
The pavilion is a building for the garrison to climb high to observe the dynamic situation of the enemy. They are usually combined with city piers and beacon towers. Beacon is a facility that ignites beanstalk after the enemy appears and transmits information to the adjacent tunnel or the rear with smoke or open flame. Distributed within a few miles of the Great Wall, most of them are built at the highest point of the beam top, forming a beacon line that echoes each other. The distance between beacon tower and the Great Wall, beacon tower and beacon tower is relatively wide, which is the space environment needed by visual signals.
Most beacon towers are conical, and some have square bottoms. They vary in size and spacing, generally ranging from 5 to 7 miles. They are usually compacted, and when conditions permit, they are also cut into headlands, which are usually combined with barriers and city piers. High piers with special positions can be used as lighthouses. Beacon is a way of transmitting military information invented by our ancestors a long time ago. After being included in the Great Wall defense system, its role has been played more effectively.