Abstract
Constructing deeply-buried stormwater sewage and storage tunnels is an effective method to mitigate the waterlogging and sewer overflow problems in modern cities. Prior to construction of such tunnels, a structural loading test is essential for acquiring the mechanical responses under complex loading conditions, such as cyclic inner hydraulic head, during which capturing the full-ring deformation of the tunnel lining is significant for a comprehensive understanding of the tunnel’s mechanical behaviors. This paper introduces the application of terrestrial laser scanning (TLS) technology in the full-scale structural loading tests of a large stormwater sewage and storage tunnel, which gives the full-ring deformation throughout the tests. A data processing methodology was developed to extract the key data points of the lining segments from the original data cloud by removing noise points and mitigating data jump, based on which the deformation of testing the lining segments at arbitrary locations can be calculated. Furthermore, a post-processing software was developed to visualize the full-ring deformation. The full-ring deformation at different loading conditions and its evolution under cyclic loading were captured. It is shown that the lining’s convergence deformation is more sensitive to the inner hydraulic head than to the external soil-water pressure, and the deformation cannot fully recover in a water-inflow-and-drainage cycle due to the presence of joints.
Highlights
Modern cities nowadays encounter serious issues related to waterlogging and sewer overflow due to population expansion and aging of drainage systems, especially in the rainy seasons
The structure of the paper is as follows: firstly, the fundamental principles and workflow of applying terrestrial laser scanning (TLS) to measure the full-ring deformation of lining structure are introduced; the methodology of extracting the contour of tunnel cross-section from the three-dimensional point cloud data is elucidated; a post-processing software called ‘Cloud Viewer’ is developed to visualize the tunnel deformation; the validity and effectiveness of the proposed method are demonstrated through an application example investigating the mechanical response of a stormwater sewage and storage tunnel
It is the first time in Shanghai to construct such a large stormwater sewage and storage tunnel with a maximal burial depth up to 50 m and an internal hydraulic head
Summary
Modern cities nowadays encounter serious issues related to waterlogging and sewer overflow due to population expansion and aging of drainage systems, especially in the rainy seasons. Though the methods mentioned above have shown satisfactory performance in practice, the application of TLS technology in measuring tunnel deformation is still challenging due to the existence of joints and hand holes, which create discontinuities in the curvature and brings about many points of noise in the data cloud These issues have not been resolved satisfactorily in both scientific and commercial works. The structure of the paper is as follows: firstly, the fundamental principles and workflow of applying TLS to measure the full-ring deformation of lining structure are introduced; the methodology of extracting the contour of tunnel cross-section from the three-dimensional point cloud data is elucidated; a post-processing software called ‘Cloud Viewer’ is developed to visualize the tunnel deformation; the validity and effectiveness of the proposed method are demonstrated through an application example investigating the mechanical response of a stormwater sewage and storage tunnel
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