1. Starting from the square shield in brunell, the shield technology has been improved for 23 years, and the second tunnel across the Thames was built on 1869. This project was undertaken by Great, and it took 80 years from Torevix's repeated defeats to Brunel's shield construction method and then to Great's shield construction method.

2. From19th century to the middle of 20th century, shield method was introduced to America, France, Germany, Japan, the Soviet Union and other countries, and developed to a certain extent. During this period, although the shield method has made some progress, it is mainly the promotion and popularization of shield method in all countries of the world.

3. From 1960s to 1980s, the shield method has been continuously developed and improved, with remarkable achievements. During this period, a variety of shield construction methods appeared, mainly mud and earth pressure shield construction methods.

4. 1990 to 2003, the progress of shield construction technology is very remarkable: shield tunnel has long distance and large diameter; The shield shape is diversified, and there are different circular sections such as rectangle, ellipse and multi-circle overlapping shield shape; Construction automation, automatic control system of neutral direction and posture in shield tunneling.

Extended data

Shield construction principle

Using shield machine, while controlling the collapse and instability of excavation face and surrounding soil, tunnel excavation and slagging are carried out, segments are assembled in the machine to form lining, and grouting is carried out behind the wall to make the surrounding soil undisturbed and build the tunnel.

The so-called "shield" of the shield machine refers to the cutter head and pressure chamber that maintain the stability of the excavation surface, as well as the shield steel shell that supports the surrounding soil. The so-called "structure" refers to the segments and grouting body behind the wall that constitute the tunnel lining.

Shield construction is a very complicated engineering process, and its influence on the surrounding environment is closely related to the construction technology. As early as 1969, Peck pointed out that the stratum loss caused by shield construction and its influence on adjacent structures are inseparable from the specific details of construction. Therefore, only by accurately grasping the main factors of shield construction can we get the results in line with the actual situation in theoretical analysis.