The Application Research Of The Ground-Penetrating Radar In Chengdu Metro Line2Shield Disturbance Zone

In recent years, with the continuous socio-economic development, urbanization, continuously push forward the city have been expanding in order to achieve sustainable development strategy, in addition to the development of urban roads, underground space development and utilization of subway, light rail be The history of urban development is inevitable.However, with a lot of construction of the subway, also produced a number of engin-eering problems, such as the subway shield tunnel construction caused surface subsidence. Metro Shield construction is within the rock mass, excavation and construction of the tunnel will inevitably disturbance of underground rock and soil, and destroy the original state of equilibrium, while the conversion to a new equilibrium state. With the conduct of the shield, the dense band and empty ground loss caused by the gradual upward to cause surface subs-idence in the case of lack of synchronization grouting, surface subsidence to a certain extent, will affect the safety of the ground structure and underground pipelines normal to use.Special Chengdu engineering geological conditions, water-rich sand and gravel form-ations, sand and gravel soil, gravel content, particle size, including boulders, high strength stone, sandy filling, poor bond strength between the pebbles, and therefore easier to the for-mation of surface subsidence. Metro Line1, the construction process, the resulting surface subsidence is particularly serious. Therefore, in the process of shield construction of Metro Line2, real-time identification of the disturbed zone caused by the dense band and empty, and the quality of governance evaluation is an important guarantee to ensure that the shield construction security and public safety.Ground-penetrating radar method is mainly based on high frequency electromagnetic wave propagation in the medium and the reflective properties in electrical mutation interface, a nondestructive geophysical method. Chengdu Metro Line2West Extension Line the Xipu station to Tianfu Square station around line a total of approximately24.471kilometers, is located in the downtown area of Chengdu, the flow of people, while the bottom of the mine ground-penetrating radar speed, high efficiency, non-destructive and on surrounding envir-onment affect the advantages of small, so the bottom radar Chengdu Metro Line2Shield construction strata disturbed zone.This paper studies the following aspects:1. Basic principles and data processing method of ground penetrating radar;2. Shield construction disturbance with the pre-test, impact test such as groundwater salinity of ground-penetrating radar, surface probing depth trials and tests of tunnel segments; 3. The development of specific surface and tunnel vaults detection program;4. Inductive analysis of the underground caves and dense band radar response characteristics of typical examples, and retest evaluation to detect the effect of underground caves at the grouting treatment.