Accurately recognizing the influence of excavation disturbance on the traversing cross-type deep foundation pit of the subway, determining the active range of the disturbance, and reasonably arranging the structure within its range can effectively ensure the safety of the project and save resources to achieve the goal of sustainable development. A three-dimensional model was established using the soil small strain hardening model to examine the subway deep foundation pit project in the CBD (central business district) core area of Fuzhou Coastal New City, where the soil is mainly soft soil with high natural water content, high compressibility, and weak permeability. The model was verified against the theoretical solution of Melan, and the deformation characteristics of the cross-asymmetric foundation pit excavation were analyzed. The results show that, due to repeated disturbance from excavation and unloading between the foundation pits, the soil arching effect, and changes in the boundary conditions, the structure at the intersection and the surrounding soil interact. The horizontal displacement of the retaining structure and the surrounding surface settlement are quite different from those observed from a single foundation pit excavation. For instance, the maximum horizontal displacement of profile 1-3 in Zone I decreases by 26.1%, while the maximum horizontal displacement of profile 1-1 in Zone II increases by 20.4%, and the maximum surface settlement around the profiles also has similar characteristics. The disturbance on the retaining structure and soil in different areas at the intersection can be divided into positive and negative effects. The active range of the “disturbance influence zone” is determined: the foundation pit of Metro Line 6 is 3.5 He and the foundation pit of Metro Line F1 is 3.0 He. Finally, the influence of changes in the groundwater level on the active range of the “disturbance influence zone” is discussed.
Abstract-When designing barrier tolls, the shape, size and merging pattern need to be taken into consideration. Besides, the safety codes and standard of accident prevention and throughout capacity must be met while the development and operating costs should be kept as low as possible. Six major factors impacting the toll plaza performance were discussed, including the corresponding relationship between the amount of main lanes in single direction and tollbooth, the critical length of toll plaza meeting safety codes and standards, the critical width of toll plaza, the critical size of transition region, the development cost of toll plaza and its throughput capacity. We set up a multiple index analysis system after calculating those six factors to analyze the pros and cons of the existing toll plaza, which could provide scientific basis for the new design. Moreover, difference motivated principle was applied to determine the weight vector, to comprehensively evaluate the impact of each parameter. To determine the optimal design, we designed and compared three control schemes. The evaluation system was applied to compare the pros and cons of each scheme based on the actual situations, and the optimal scheme was designed through combining the strengths of all three. By investigating the adjustment strategy and corresponding performance of the toll plaza of the different scheme in the case of light and heavy traffic flow, the case when the proportion of automatic driving vehicles increases, and the case under different charging modes, the feasibility and rationality of the optimal scheme was tested. In the process of inspection, we used the queuing theory model to determine the maximum capacity of the toll plaza under the manual toll mode, and used the integer programming model to solve the optimal proportional relation of the three tolling models.
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