Spatialtemporal Characteristics of Tunnel Traffic Accidents in China from 2001 to Present

Sun, Haiyan; Wang, Qiuping; Zhang, Peng; Zhong, Yujian; Yue, Xiabing

doi:10.1155/2019/4536414

Cited by 46 publications

(39 citation statements)

References 28 publications

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“…Well-point dewatering is a method of lowering groundwater level by setting dewatering wells first and then by pumping equipment, and it is suitable for dewatering in shallow and medium strata within the range of 6∼15 m [30,31]. Well-point dewatering on surface is arranged as in Figure 4, and target dewatering layer is clay and silty soil [32][33][34].…”

Section: Well-point Dewateringmentioning

confidence: 99%

Displacement Characteristics of an Urban Tunnel in Silty Soil by the Shallow Tunnelling Method

Zhang

Qiu

et al. 2020

Advances in Civil Engineering

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The urban shallow tunnelling process in silty soil is easy to cause large displacement of surface and tunnel. Obviously, if the strata and the tunnel face are not treated by reasonable reinforcement method, instability and collapse phenomenon will be encountered during the tunnel excavation. There are a series of studies on construction methods of shallow tunnels, but these methods have limitations in silty soil. In this study, a comprehensive construction plan of the urban shallow tunnel in silty soil was proposed and applied to a case study in Fuzhou, Fujian Province in South China. The in situ monitoring tests and numerical simulation were employed to address displacement characteristics of surface and tunnel. Results indicated that the urban shallow tunnelling process could achieve good effect by dewatering of silty soil, reinforcing surface by vertical jet grouting piles, and advanced small pipes and circumferential grouting in the tunnel face; surface settlement during dewatering process accounted for about 30% of total surface settlement in silty soil; the excavation of the top heading, the middle, and lower benches had great effect on displacement of surface and tunnel for three-bench seven-step excavation method in silty soil; surface settlement troughs in silty soil were deeper and wider; lock-feet bolts had good effect on restricting horizontal convergence; and ratio of total crown settlement and total horizontal convergence was in range of 1.43∼1.59 when b/h was 0.88 in silty soil. The construction plan proposed in this paper is helpful for further study of shallow tunnel tunnelling process in silty soil.

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Section: Well-point Dewateringmentioning

confidence: 99%

Displacement Characteristics of an Urban Tunnel in Silty Soil by the Shallow Tunnelling Method

Zhang

Qiu

et al. 2020

Advances in Civil Engineering

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“…Underground pile foundations are dense in cities with crowded buildings. If the distance between pile foundation and shield is too close, tunneling may cause uneven settlement, structural deformation, and cracks in buildings [32][33][34][35][36][37]. To ensure the smooth advance of shield and the safety of adjacent pile foundations, it is necessary to take some protective measures [38][39][40][41][42][43][44][45][46][47][48][49][50].…”

Section: Introductionmentioning

confidence: 99%

A Comparative Study of Protective Schemes for Shield Tunneling Adjacent to Pile Groups

Lai

et al. 2020

Advances in Civil Engineering

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Shield tunneling adjacent to pile groups is always an unavoidable problem in urban metro construction. A case was found in the project of Tianjin Metro Line 7, where a shield tunnel would be constructed near the existing pile groups of Shiyou Bridge. The whole shield tunnel is close to pile groups, and the minimum distance is only 0.8 m. Therefore, four kinds of protective schemes are proposed in this paper. It is vital to select an appropriate protective scheme to guarantee the safety during the tunnel construction. In this study, the main mechanical characteristic and physical parameters of site soil were obtained through laboratory tests. Besides, the three-dimensional finite element method was carried out to compare and analyze the effectiveness of the protective schemes in mitigating the effects of tunneling on adjacent pile groups. The results show that the deep-hole grouting scheme has better control effect on the lateral deformation and bending moment of piles, while the pile foundation underpinning scheme has better effectiveness on reducing the settlement of bridge structure and ground deformation. Finally, the deep-hole grouting reinforcement scheme will be adopted to ensure the shield passing through the pile groups smoothly.

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“…ough multiple forms of grout diffusion occur simultaneously in injected soil, one of them often plays a leading role under certain conditions. For example, materials with large porosity in the sandy layer produce the larger internal pore passages that engender less inhibitory effect during grout flow, which is favorable for effective implementation of the permeation grouting technique [13,14]. In terms of the utilization of the grout materials, the cement slurry now is most commonly used for grouting practices as a result of low cost compared with other grout materials.…”

Section: Introductionmentioning

confidence: 99%

Modelling of Permeation Grouting considering Grout Self-Gravity Effect: Theoretical and Experimental Study

Wang

Zhang

et al. 2019

Advances in Materials Science and Engineering

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Self-gravity is one key parameter for behavior characterization of grout permeation and diffusion.is study proposes mathematical models for permeation grouting with consideration of grout self-gravity effect. e models concerning power law, Bingham, and Newtonian grouts are based on the generalized Darcy's law and spherical diffusion theory. In addition, a prediction model of grout concretion dimension used for Bingham grout was developed. An analysis of the injection pressure distribution law and a comparative evaluation of diffusion radius considering self-gravity effect using established models were conducted subsequently. Moreover, grouting experiments were performed to check and verify the prediction model. e experimental results showed that injection pressure decreases linearly with increase of diffusion radius for the power-law grout, while nonlinear decrease of injection pressure was confirmed in Bingham and Newtonian grouts in this case. ree grouts approximately diffuse in an "ellipsoidal" shape, and it is confirmed that the diffusion radius is closely related to grout self-gravity. e Newtonian grout produces the maximum diffusion radius compared with the other two grouts whether the gravity effects were considered or not. e grout quantity under a smaller water-to-cement (w/c) ratio exhibits a significant difference and undergoes two increasing stages, whereas the quantity simply tends to be stable after it reaches its maximum in terms of the larger (w/c) ratios. e constructed dimension prediction model agrees well with the experimental results, which can be helpful for design and assessment of the grouting scheme.

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Spatialtemporal Characteristics of Tunnel Traffic Accidents in China from 2001 to Present

Cited by 46 publications

References 28 publications

Displacement Characteristics of an Urban Tunnel in Silty Soil by the Shallow Tunnelling Method

Displacement Characteristics of an Urban Tunnel in Silty Soil by the Shallow Tunnelling Method

A Comparative Study of Protective Schemes for Shield Tunneling Adjacent to Pile Groups

Modelling of Permeation Grouting considering Grout Self-Gravity Effect: Theoretical and Experimental Study

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