In constructing super-large section shield tunnels, it is difficult to guarantee the filling efficiency and uniformity of grouting behind the segments. Studies on grout diffusion models often simplify the grout filling process, leading to inaccurate results, especially for shield tail void with special noncircular profiles. This paper presents a theoretical study on the grout filling diffusion mechanism and its mechanical behaviour, with a particular focus on the grout actual motion process at the synchronous grouting filling stage when the shield is advancing. A semi-elliptical surface compound diffusion model without the predetermined flowing passage was developed, and this model was used to derive the grout filling pressure and diffusion distance formulas. To address the time-varying diffusion surface and irregular integral region issues in derived equations, a stepwise solution algorithm based on the spatiotemporal discretisation operation was proposed. Finally, the grout pressure distribution patterns and some critical influence factors were analysed using a case study in the soft silty clay area to compare the presence and absence of circumferential-longitudinal correlations in the grout filling diffusion process. The results show that the diffusion mechanical behaviour and force transmission significantly affected the total and per-unitarea grout pressures, and the proposed theoretical model is more consistent with the field-measured data. The local trend and fluctuation characteristics of grout filling pressure are clearly different from those of a circular tunnel. The grout filling diffusion mechanism was determined to be the main cause of pressure distribution changes under the premise of a certain initial grouting pressure.

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This paper proposed a new solution to the situation that the moving objects detection in natural environment might be disturbed by some natural conditions, such as wind, light, etc. Firstly, the background image was modeled with Gaussian mixture models, to eliminate the interference of some slight and cyclical movements caused by wind, like branches swinging. Secondly, the foreground was segmented through background subtraction, and the background model was updated to adapt to the gradual change of illumination. Finally, the shadows of moving objects were detected and removed in HSV color model, meaning that the detection was completed. The experiment verified that the solution above can effectively realize the preliminary detection of moving objects in natural environment.

In this paper, we analyze the working mechanism of the wedge-type anchorage in the hydraulic synchronizing lifting device and tradition one, discuss the engagement effect between the wedge and the steel strand, establish a mathematical model to analyze the wedge tooth strength and evaluate carrying contaminant capacity qualitatively. The results of the study indicate that: the hardness difference between the wedge and the steel strand, the tooth shape and relevant parameters, the inside tooth surface geometric structure, are key factors to improve the performance of the wedge-type anchorage, which provides the basis to the wedge tooth optimization design and its working life prediction.