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

2020 ◽  
Vol 2020 ◽  
pp. 1-16 ◽  
Author(s):  
Shaobing Zhang ◽  
Siyue He ◽  
Junling Qiu ◽  
Wei Xu ◽  
Rodney Sheldon Garnes ◽  
...  
Keyword(s):  
Soil Surface ◽  
Surface Settlement ◽  
In Situ Monitoring ◽  
Good Effect ◽  
Shallow Tunnel ◽  
Tunnel Face ◽  
Face Surface ◽  
Silty Soil ◽  
Construction Methods ◽  
Jet Grouting

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.

scholarly journals Seepage in Water-Rich Loess Tunnel Excavating Process and Grouting Control Effect

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Zhengde Wei ◽  
Yanpeng Zhu
Keyword(s):  
Moisture Content ◽  
Surrounding Rock ◽  
Gansu Province ◽  
Surface Settlement ◽  
High Moisture Content ◽  
Control Effect ◽  
High Moisture ◽  
Tunnel Face ◽  
Construction Methods ◽  
Curtain Grouting

The tunnel passing through the loess stratum with high moisture content can easily lead to the seepage and mud burst accident and the instability and collapse of the tunnel face. Under the condition of high groundwater level, the seepage situation is more complicated, it is difficult to control the groundwater seepage, and the excavation progress is very slow. In order to solve the various disasters when the tunnel passes through the water-rich loess stratum, taking a water-rich loess tunnel in Gansu Province as an example, the method of comprehensive prevention and control of seepage and mud inrushing disaster by basement grouting and curtain grouting was introduced. Firstly, the basic situation of the Yulinzi tunnel is introduced, including site conditions, seepage collapse accident, and its cause analysis. On this basis, the design and construction methods of basement grouting and curtain grouting are introduced, and the effect of grouting reinforcement is evaluated in detail through on-site monitoring. The results show that the basement grouting and curtain grouting can effectively control the deformation of surrounding rock and the surface settlement, the decrease of the deformation of surrounding rock can reach 36%-71%, and the decrease of the surface settlement can reach 55%. After grouting, the deformation of the surface and surrounding rock can be controlled within the allowable value in the code. Grouting plus solid can effectively block the seepage of groundwater and prevent the surface cracks, water gushing, mud gushing, collapse, and other disasters in the process of tunnel excavation. It can be seen that the basement grouting combined with curtain grouting technology has a good reinforcement effect, which has significant engineering value for quickly and efficiently passing through high moisture content loess strata.

Effects of tunnel face distance on surface settlement

2016 ◽  
pp. 323-326
Author(s):  
A Marto ◽  
H Sohaei ◽  
M Hajihassani ◽  
A Makhtar
Keyword(s):  
Surface Settlement ◽  
Tunnel Face

scholarly journals Deformation Characteristics of Raising, Widening of Old Roadway on Soft Soil Foundation

Symmetry ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 2117
Author(s):  
Keke Li ◽  
Wenyuan Xu ◽  
Liang Yang
Keyword(s):  
Lateral Displacement ◽  
Soft Soil ◽  
Ground Surface ◽  
Surface Settlement ◽  
Deformation Characteristics ◽  
Construction Methods ◽  
Ground Surface Settlement ◽  
Total Settlement ◽  
Soil Foundation ◽  
Soft Soil Foundation

The deformation characteristics of a raised and widened old Chinese roadway on a soft soil foundation are investigated in this study via finite element numerical simulation. The rules of ground surface settlement, slope foot lateral displacement, and ground surface settlement evolution of the roadbed under three modes (one-time construction of an eight-lane expressway, widened four-lane expressway, and raised/widened four-lane expressway) are compared. The ground surface settlement process of the eight-lane road foundation, which is formed by first widening and then raising the road, is highly complex. The ground surface settlement curve under the old road foundation increases and then decreases. The lateral displacement of the slope foot also interacts with the widening and raising of the eight-lane roadbed foundation. The range of lateral displacement is 70.05, 42.58, 124.81, 104.54 mm. Fifteen years after construction, the total settlement of the raised and widened roadbed is much larger than that of the one built directly. The total settlement values at the center of the two roadbeds are 297.05 and 234.85 mm, respectively. This manuscript provides data support for the reconstruction and expansion of roads on soft soil foundations, for choosing appropriate construction methods to build roads, and for avoiding major road damage, which is of great significance to the construction of road infrastructure in the future.

scholarly journals Numerical analysis and application of the construction method for the small interval tunnel in the turn line of metro

2020 ◽  
Vol 103 (3) ◽  
pp. 003685042093206 ◽  
Author(s):  
Zhanping Song ◽  
Xiaoxu Tian ◽  
Qi Liu ◽  
Yuwei Zhang ◽  
Heng Li ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Numerical Analysis ◽  
Construction Method ◽  
Surface Settlement ◽  
Underground Excavation ◽  
Small Interval ◽  
Resource Configuration ◽  
Construction Methods ◽  
Initial Support ◽  
Left And Right

The surrounding rock may become unstable or even fall down and the initial support may crack and be destroyed when the construction method of the underground excavation tunnel is not properly selected in the turn line of metro. . A section of the Santunbei turn line of Urumqi Metro Line 1# was taken as the engineering background. The proposed construction method was analyzed by numerical simulation. Numerical analysis shows that the final surface settlement caused by the proposed construction method is 3.0 mm and the horizontal convergence is 3.2 mm. It also turns out that the proposed construction method causes less deformation, and the method can be applied to the construction of the small interval tunnel in the Santunbei turn line of metro. The rationality of the method and numerical model was further verified by comparison between the monitored data of surface settlement, horizontal convergence and vault sinking, and numerical simulation results. Finally, the deformation and stress of the six construction methods were compared. The deformation and stress caused by the six construction methods are almost the same. It indicates that the construction spacing between the left and right tunnels does not affect the safety of tunnel construction. Therefore, the appropriate construction spacing could be selected according to the resource configuration, instead of deformation and stress.

High Performance Ferrocement Laminate Strengthening Technology

2013 ◽  
Vol 779-780 ◽  
pp. 88-95
Author(s):  
Shou Ping Shang ◽  
Long Li
Keyword(s):  
High Performance ◽  
Low Cost ◽  
Structural Member ◽  
Good Effect ◽  
Simple Construction ◽  
Construction Methods ◽  
Work Effect ◽  
The Way

High Performance Ferrocement Laminate (HPFL) is a new strengthening structure method which needs to imbed the shear dowel on the strengthened material in order to ensure the associated work effect of high performance ferrocement laminate and the original structural member. This paper introduces the measures and examples of high performance ferrocement laminate. The way has the characteristic of good effect, low cost and simple construction methods, and it is suitable for the vast areas which need resisting earthquake.

scholarly journals A Theoretical Calculation Method of the Unsupported Span for the Shallow Tunnel in the Soft Stratum

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Xiaoxu Tian ◽  
Zhanping Song ◽  
Guannan Zhou ◽  
Xiaowei Zhang
Keyword(s):  
Soft Rock ◽  
Friction Angle ◽  
Soil Mass ◽  
Calculation Model ◽  
Support Pressure ◽  
Shallow Tunnel ◽  
Tunnel Face ◽  
Rock Stratum ◽  
The Stability ◽  
Shallow Buried Tunnel

During the construction of the tunnel in soft stratum, it is often found that the unsupported span is too large, resulting in instability of the tunnel face and collapse of the vault. However, the unsupported span was often selected according to the experience of engineers in the actual construction process, which was lack of the theoretical basis. Therefore, based on the calculation model of the surrounding rock pressure of shallow buried tunnel, this paper analyzed the stability of the tunnel face and the vault and then obtained the calculation formula of the unsupported span of the shallow buried tunnel in soft rock stratum. It was pointed out that the unsupported span is not determined by the arch crown stability or the tunnel face stability alone, but by both. The rationality of the formula was verified by a centrifugal test and an engineering case. The analysis and discussion showed that the unsupported span is sensitive to the cohesion and internal friction angle of the rock-soil mass, especially the cohesion. The unsupported span of the shallow buried tunnel in the soft rock stratum is a linear function of the support pressure. The support pressure has a more significant contribution to the increase of the unsupported span by the centre cross diaphragm (CRD) method, and the unsupported span increases linearly with the increase of the support pressure. The research results provide a theoretical reference for the determination of the unsupported span for the shallow tunnel in the soft stratum.

Real-Time Detection of Tunnel Face Surface Displacement by 3D Scanner

2017 ◽  
Vol 2017 (0) ◽  
pp. 2A2-N12
Author(s):  
Takahiro SANPEI ◽  
Tomohiro MIZOGUCHI ◽  
Makoto YAMAMOTO ◽  
Tadashi YAMAMOTO ◽  
Hidenobu KAGE ◽  
...  
Keyword(s):  
Real Time ◽  
Surface Displacement ◽  
3D Scanner ◽  
Tunnel Face ◽  
Face Surface ◽  
Real Time Detection
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