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

Abstract

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.

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

“…e diagram for the dimension measurement of grout concretion from grouting test at three directions (i.e., transverse, vertical, 6 Advances in Materials Science and Engineering and longitudinal) is shown in Figure 8. Also, the theoretical values obtained based on the dimension prediction model are also used for the comparative analysis and verification.…”

“…Grouting technique has been extensively used in soil reinforcement, water plugging, and deviation rectification of buildings as well as other engineering practices [1][2][3][4][5][6]. Based on grout diffusion behaviors and mechanism, three methods are commonly used for grouting activities, compaction grouting [7], fracture grouting [8][9][10][11], and permeation grouting [12].…”

Thermal Conductivity Characteristics of Thermal Insulation Materials Immersed in Water for Cold‐Region Tunnels

“…e rapid development of transportation systems has led to progressive growth of tunnel construction in cold regions; however, damage caused by freezing of tunnels constructed in cold regions also commonly occurs [1][2][3][4][5]. Problems associated with frost damage, including lining leakage, spalling of lining, frost heave of the surrounding rock, and watering and freezing of the road surface, often render the tunnel unusable from August to September annually, significantly affecting the efficiency of the tunnel [6][7][8][9][10]. e typical engineering solution to tunnel frost damage in cold regions is laying a thermal insulation layer [11][12][13][14].…”

Simulation Research on the Effectiveness of a Multiagent Mine Safety Supervision System and Its Verification

“…Maslach and Jackson used a three-dimensional model to define job burnout. ey considered that job burnout is a psychological syndrome, which includes three aspects: emotional exhaustion, personality disintegration, and sense of the loss of personal accomplishment [12,13]. In 2003, Li used a questionnaire to dynamically define and measure job burnout [14].…”