Study on Construction Time of Secondary Lining for Large Section Shallow Buried Tunnel in Soft Rock

2016 ◽  
Author(s):  
Jianguo Zhang ◽  
Xiaoyun Wang ◽  
Shan Wang ◽  
Shulian Wen
Keyword(s):  
Soft Rock ◽  
Construction Time ◽  
Large Section ◽  
Secondary Lining ◽  
Shallow Buried Tunnel

scholarly journals Study on the Mechanical Behavior of Double Primary Support of Soft Rock Tunnel under High Ground Stresses and Large Deformation

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Zhe Liu
Keyword(s):  
Mechanical Behavior ◽  
Large Deformation ◽  
Design Method ◽  
Characteristic Curve ◽  
Soft Rock ◽  
Support Design ◽  
Deformation Amount ◽  
Secondary Lining ◽  
Rock Tunnels ◽  
Primary Support

Double primary support structures could effectively solve the problem of large deformation of surrounding rock for soft rock tunnels. However, the mechanical behavior of this new support structure is still incomplete, and the design method should be revised. Based on the theory of energy conversion, this paper analyzes the support characteristic curve of double primary support and puts forward the dynamic design method of double primary support. Considering that the secondary lining can be set after monitoring the deformation amount and deformation rate of the first primary support, its support parameters can be dynamically adjusted according to the actual situation. By applying the double primary support design method in the Maoxian tunnel of Chenglan Railway, the field monitoring results show that the double primary support has a significant effect on the energy release of surrounding rocks, greatly reducing the load acting on the secondary lining and ensuring the safety and reliability of the tunnel structure.

scholarly journals Analysis of Surrounding Rock Creep Effect on the Long-Term Stability of Tunnel Secondary Lining

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Xiaoqian Zhang ◽  
Chengmin Wei ◽  
Heng Zhang
Keyword(s):  
Stress Measurement ◽  
Soft Rock ◽  
In Situ Stress ◽  
Calculation Model ◽  
Surrounding Rock ◽  
In Situ Stress Measurement ◽  
Rock Creep ◽  
Secondary Lining ◽  
Rock Tunnel

The secondary lining failure of deep buried soft rock tunnel often occurs, which is obviously related to the time factor. The formation mechanism of this phenomenon is studied in this paper. Therefore, the combination of in situ stress measurement and neural network inversion is used to analyze the distribution characteristics of in situ stress. At the same time, the creep characteristics of surrounding rock are tested in laboratory, and the key parameters are obtained. Combined with the characteristics of surrounding rock, the calculation model is established by using discrete element simulation technology and considering the joints of surrounding rock. According to the above multiple information, the stress characteristics of the secondary lining in different time periods are analyzed creatively. Finally, the method of setting arch and adding anchor bolt in key parts is proposed, and significant effect results are obtained.

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.

Technology of Joint Support on Large Pump House in HS Soft Rock

2012 ◽  
Vol 446-449 ◽  
pp. 2202-2205
Author(s):  
Xing Lin Wen ◽  
Lin Hai Gao ◽  
Xiu Shan Li ◽  
Zhao Ping Liu
Keyword(s):  
Numerical Simulation ◽  
Soft Rock ◽  
Large Section ◽  
Anchor Bolt ◽  
Pump House

Soft rock; Anchor bolt-net-spray support; Twice support; Large section; Numerical simulation

scholarly journals Small Pilot Tunnel Advance and Step Reverse Expansion in Super-Large-Section Tunnel Excavation

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Bole Sun ◽  
Xiaorong Tang ◽  
Yongyi He ◽  
Mingnian Wang
Keyword(s):  
Production Efficiency ◽  
Expansion Method ◽  
Surrounding Rock ◽  
Construction Technology ◽  
Construction Time ◽  
Engineering Project ◽  
Large Section ◽  
Maximum Displacement ◽  
Tunnel Support ◽  
In Situ Conditions

Collapse of the vault and numerous other safety accidents often occur during the construction process of large-section tunnels. The utilization of a small pilot tunnel and a step reverse expansion construction methodology is proposed based on conventional construction methods to explore safe construction technology. First, a theoretical analysis combined with on-site monitoring parameters was conducted. It showed that the maximum displacement of the tunnel surrounding rock was 0.027 m during the elastic stage and increased to 0.031 m during the strength limit stage. The overall surrounding rock deformation does not have a noticeable impact on tunnel safety. A numerical simulation model of the small pilot tunnel advancement and step reverse expansion method was established. Simulation results showed that the first two excavation steps caused 89.6% of the total overlining strata subsidence, and the use of a small pilot tunnel advancement and step reverse expansion method can enhance the tunnel support. The tunnel surrounding rock was adequately stabilized after using this excavation method and provides the in-situ conditions for expanding the pilot tunnel to the large-section tunnel. The proposed method was adopted in an actual engineering project. It protected the subsequent construction of the main tunnel and decreased construction time, saving construction costs while ensuring safety, reducing construction risks, and improving production efficiency. This research can guide similar tunneling projects.

Deformation Failure Analysis and Stability Control Technology of Large Section Soft Rock Chamber in Deep Coal Mine

2013 ◽  
Vol 353-356 ◽  
pp. 1035-1039
Author(s):  
Chang Hui An ◽  
Gui Bin Zhang ◽  
Zhi Da Liu ◽  
Kai Zhao ◽  
Wei Guo ◽  
...  
Keyword(s):  
Coal Mine ◽  
Soft Rock ◽  
Stability Control ◽  
Surrounding Rock ◽  
Mine Safety ◽  
Large Section ◽  
Deformation And Failure ◽  
Deep Coal Mine ◽  
Ground Pressure ◽  
The Impact

The chambers of certain coal mine in Shandong such as central substation situate in soft rock which consists of mudstone and fine sandstone, etc. Obvious ground pressure behaviors, large deformation and failure of surrounding rock have serious effect on mine safety production, with the impact of various complicated deep large ground pressure. This paper presents a rational scheme to control the surrounding rock steadily, based on analysis of deformation and failure on large section soft rock chamber, combined with the concept of the" combined supporting technology of long and short anchors" and "the combined supporting technology of three anchors".

Study on the Construction Time of Secondary Lining in Loess Tunnel

2012 ◽  
Vol 170-173 ◽  
pp. 1427-1431
Author(s):  
Jian Ning Cui ◽  
Yong Tao Gao ◽  
Jin Qiang Wang ◽  
Jian Li ◽  
Fu Gen Deng
Keyword(s):  
Rock Pressure ◽  
Focus Of Attention ◽  
Deformation Characteristics ◽  
Construction Time ◽  
Rate Analysis ◽  
Deformation Rate Analysis ◽  
Discriminant Index ◽  
Distribution State ◽  
Secondary Lining ◽  
The Stability

The construction time of secondary lining in loess tunnel has been the focus of attention in the tunnel field, but no specific quantitative discriminant index of the construction time of the secondary lining has been applied. Relying on the Wofosi tunnel of Zhangjiakou-Zhuolu highway, based on the deformation characteristics and deformation rate analysis of the crown settlement and surrounding convergence, proposed that the stability of basic rate as the indicators of construction time of secondary lining, determined preliminarily the construction time of secondary lining by optimizing the regression model, combined with the characteristics of the rock pressure and pressure distribution state along the hole to determine the best construction time of secondary lining

scholarly journals Study on deformation of surrounding rock in fault tunnel based on field measured data statistics

2021 ◽  
Vol 233 ◽  
pp. 03025
Author(s):  
Chen Hao
Keyword(s):  
Statistical Analysis ◽  
Time Evolution ◽  
Fault Zone ◽  
Surrounding Rock ◽  
Rock Deformation ◽  
Construction Time ◽  
Average Value ◽  
Pass Through ◽  
Secondary Lining ◽  
Surrounding Rock Deformation

Based on the statistical analysis of surrounding rock deformation from 56 fault tunnels in China, the overall distribution characteristics and time evolution laws of surrounding rock deformation and the relationships with buried depth of tunnel and the height-span ratio are studied. The results of the statistical analysis show that the deformation is excessive when the tunnel passes through the fault zone. The average deformation value of surrounding rock in railway fault tunnels is maximum and second in highway fault tunnels and minimum in subway fault tunnels. The average value of peripheral convergence is larger than that of vault settlement. The deformation increases with the increases of buried depth, and the deformation in railway fault tunnels shows obvious concentration with the change of the height-span ratio. There is a significant time evolution law of surrounding rock deformation in fault tunnels, which can be roughly divided into three stages: rapid growth, slow growth and stabilization. The results offer some references for the optimal design of supporting structure and the reasonable construction time of secondary lining when the tunnels pass through the fault zone.

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