The Application Research Of The Ground-penetrating Radar In Lag Subsidence Monitoring Of Shield Tunnelling In Chengdu Metro Line2

In recent years, China’s national economy steady forward has made significant progress, especially in infrastructure construction. With the requirements of scientific and technological development and the work efficiency, the city subway has become an integral part of our daily lives.Shield method of construction used in the underground tunnel, there are over a hundred years of history. It can also be used in the past decade, with the improvement of the shield machine construction technology, especially the improvement of the cutting cutter and other ancillary equipment, the shield device and the combination of the rock tunnel boring machine in the broken and weak rock tunnel boring shield method of construction. Compared with other projects, the city subway has a prominent characteristic of the hidden nature, complexity and uncertainty, and construction process requires smaller impact on surface facilities as much as possible, coupled with survey means lack of restrictions, we can not grasp the detailed engineering geological problems in the project area. In this case, even if the shield construction techniques on how to improve the characteristics of the construction technology process quality and geotechnical media and the surrounding environment, the shield method of construction caused by the formation disturbance is impossible to completely eliminate. Especially in water-rich sand and gravel formations of the Chengdu Metro Shield construction, the first of its kind in the domestic and international engineering examples. Because of this, domestic and international engineering community is the lack of construction experience in a similar formation. Therefore, the construction of the Chengdu Metro Shield lag settlement problem is particularly difficult. Due to the particularity of the water-rich sand and gravel formations in Chengdu, in the formation of shield tunneling formation caused by settlement lag is extremely significant surface subsidence subsidence caused by the lag frequently occur, resulting in large economic losses and negative social impact. Therefore, how to solve the Chengdu unique water-rich sand and gravel stratum shield tunneling lag settlement must face new problems and challenges.Found in the actual construction, the application of ground penetrating radar to more accurately and efficiently solve this problem. Use of ground penetrating radar technology, proven geological conditions within the tunnel, grasp the surrounding rock changes and not dense with empty, and timely adjustment of the various support parameters at any time to change the surrounding rock in the tunnel construction avoid the lag settlement and the various security risks, to achieve the purpose of safe and rapid construction to protect citizens and property.