scholarly journals Temporal and Spatial Effect of Surrounding Rock and Supporting Construction of a Large Soil Tunnel

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Wanjun Ye ◽  
Yuntao Wu ◽  
Ming Chen ◽  
Chong Gao
Keyword(s):  
Contact Pressure ◽  
Rock Pressure ◽  
Release Rate ◽  
Rapid Growth ◽  
High Speed ◽  
Surrounding Rock ◽  
Measuring Point ◽  
Finite Element Software ◽  
Surrounding Rock Pressure ◽  
Secondary Lining

Based on the Zaosheng No. 3 tunnel of the Yinchuan-Xi’an high-speed railway, the surrounding rock pressure, contact pressure of the primary support, and secondary lining and internal force of the secondary lining concrete are systematically tested using a vibrating wire sensor, and the correlation between the advance construction distance and the surrounding rock release rate is studied with finite element software. The results show that the pressure on the surrounding rock is low when the deeply buried soil tunnel is excavated and can be divided into three stages: rapid growth, slow growth, and flattening with time. It is more reasonable to calculate the surrounding rock pressure by using tunnel planning calculations. For the contact pressure, although the value of each measuring point in the inverted arch changes a little, the arch pressure obviously has the characteristics of rapid growth and a sharp rebound. Most of the test points of the second lining concrete show a compression state, which is far less than the ultimate compressive strength. At the same time, the initial support of the tunnel bears a large load, while the secondary lining bears a relatively small force, and the load sharing ratio of the two ranges between 0.1 and 0.7; with the progress of the excavation section, the surrounding rock deformation (deformation release rate) increases gradually. When the excavation face is close to the monitoring section, the deformation (deformation release rate) is the most severe. With the increase in the distance between the excavation section and the monitoring section, the deformation (deformation release rate) tends to be flat.

scholarly journals Monitoring and support optimization analysis of surrounding rock pressure and initial supporting stress in deep-buried soft rock tunnel

2020 ◽  
Vol 36 (4) ◽  
Author(s):  
Q. Liu ◽  
R. Li ◽  
W. Tian ◽  
Y. Wang ◽  
X. Li
Keyword(s):  
Rock Pressure ◽  
Soft Rock ◽  
Northwest China ◽  
Surrounding Rock ◽  
Steel Frame ◽  
Control Effect ◽  
Measuring Point ◽  
Deformation Control ◽  
Surrounding Rock Pressure ◽  
Rock Tunnel

Attempting at the problems of surrounding rock pressure and initial supporting stress of deep-buried soft rock tunnel, a soft rock highway tunnel project in Northwest China was monitored on-site for surrounding rock deformation, surrounding rock pressure, initial stress and other items.Discuss the deformation laws and stress characteristics of surrounding rock and steel arch at different construction stages, and compare and analyze the deformation control effect of surrounding rock with different initial lining thickness, different initial elastic modulus and different anchor length through numerical simulation.The results show that the excavation stage of the upper step is a stage where the pressure and deformation of the surrounding rock increase rapidly. The steel arch support is mainly compressed, and the average stress can reach more than 50% of the peak value within 5 days. The stress is mostly higher than the measuring point of the lower step. The initial steel frame support of the upper step and the middle step bears a greater load. The excavation of the upper middle step should be "passed quickly and supported in time", and the construction should adopt The “letting first,then resisting” method appropriately increases the reserved deformation of the surrounding rock to relieve the support stress of the primary steel frame. When the deformation of the surrounding rock and the growth rate of the surrounding rock pressure slow down, the secondary lining can be applied in advance. The research results can provide reference and reference for the design and construction of similar tunnel projects.

scholarly journals Theoretical Study on Relaxed Surrounding Rock Pressure on Shallow Bias Neighborhood Tunnels under Seismic Load

2021 ◽  
Author(s):  
Xinrong Liu ◽  
Fei Xiong ◽  
Dongshuang Liu ◽  
Xiaohan Zhou ◽  
Dongliang Li ◽  
...  
Keyword(s):  
Rock Pressure ◽  
Seismic Intensity ◽  
Surrounding Rock ◽  
Mode Analysis ◽  
Seismic Load ◽  
Surface Slope ◽  
Finite Element Software ◽  
Seismic Force ◽  
Combined Action ◽  
Surrounding Rock Pressure

To study the distribution of relaxed surrounding rock pressure on the shallow bias neighborhood tunnels under the combined action of horizontal and vertical earthquake force, finite element software was used for failure mode analysis. Moreover, with the pseudo-static method, the calculation formula for the relaxed pressure on the shallow bias neighborhood tunnels was derived and used to analyze the variation of the rupture angle of these tunnels under the action of the seismic force. The study shows that: shallow bias neighborhood tunnels basically follow a “W” failure pattern under the combined action of horizontal and vertical seismic force, and the failure scope of the surrounding rock is controlled by four rupture angles. Rupture angles β2 and β3 between the deep and shallow tunnels of the shallow bias neighborhood tunnels are not affected by the surface slope. For tunnels with the same grade of the surrounding rock, the greater the seismic intensity, the smaller the value of β2, and the greater the value of β3. While at the same seismic intensity, the higher the grade of the surrounding rock, the smaller the β2 and β3. Ruptures angles β1 and β4 are influenced by the surface slope, seismic intensity and surrounding rock grades. A steeper surface slope leads to a smaller β1 and a greater β4; β1 increase and β4 decrease with increasing seismic intensity; while, β1 and β4 both show a decreasing trend with an increasing rock grade.

Study on the Prediction Method of Tunnel Surrounding Rock Pressure Based on the Theory of Progressive Destruction

2012 ◽  
Vol 446-449 ◽  
pp. 1432-1436
Author(s):  
Suo Wang
Keyword(s):  
Rock Pressure ◽  
Characteristic Curve ◽  
Prediction Method ◽  
Surrounding Rock ◽  
Progressive Damage ◽  
Tunnel Excavation ◽  
Practical Engineering ◽  
Surrounding Rock Pressure ◽  
The Relationship ◽  
Rock Parameters

In order to predict tunnel surrounding rock pressure, this paper puts forward a series of dynamic numerical simulative model on the tunnel excavation. According to the change of rock damage in the construction program, it adjusts dynamically the mechanical material parameters of surrounding rock. So the model achieves the purpose which is controlling and simulating the process of tunnel progressive damage. In accordance with the numerical simulative results, it analyzes the relationship between the rock parameters with the plastic strain, radial displacement. Then this paper proposes a prediction method of tunnel surrounding rock pressure based on the theory of the progressive damage and method of characteristic curve. Finally, it compares the pressure on the numerical simulative models with on the site date, and it proves that the prediction method has practical engineering value.

FBG Earth Pressure Sensors Applied in Surrounding Rock Pressure of Tunnel

2013 ◽  
Vol 351-352 ◽  
pp. 1173-1178
Author(s):  
Zhou Chun Cai ◽  
Chuan Li ◽  
Yuan Yu Guan ◽  
Wu Fen Chen ◽  
Li Jun Guo ◽  
...  
Keyword(s):  
Fiber Bragg Grating ◽  
Rock Pressure ◽  
Pressure Sensors ◽  
Earth Pressure ◽  
Surrounding Rock ◽  
Bragg Grating ◽  
Wavelength Shift ◽  
Stress Changes ◽  
Surrounding Rock Pressure

During the period of tunnel excavation, shoring, forming and long-term operation, stress changes of tunnel surrounding rock are complex, the real-time monitoring of surrounding rock pressure is the key factor in ensuring long-term stability in tunnel. Fiber Bragg grating earth pressure sensors apply in surrounding rock pressure of tunnel which can change the pressure of the surrounding rock into fiber Bragg grating wavelength shift. According to the feature of pressure and temperature in Tian Xin Tunnel, 40 earth pressure sensors are embedded in 20 representative sections and one earth pressure sensor is embedded in each arch shoulder. In addition, one temperature compensation sensor is embedded in each arch crown. During the 235 monitoring days, the biggest daily change of surrounding rock pressure reaches 800 KPa. In 3 months of the sensor installation, the average monthly variation is within 50 KPa. The long-term measurement results indicate that the changes of surrounding rock pressure are different in different locations. When the surrounding rock is close to the excavated and blasted surface the surrounding rock pressure changes largely.

Study on Optimized Mix-Proportion and Crack Resistance of Modern Secondary Lining Concrete for High-Speed Railway Tunnel

2010 ◽  
Vol 168-170 ◽  
pp. 106-110 ◽  
Author(s):  
Li Ping Guo ◽  
Wei Sun ◽  
Qing Yu Cao ◽  
Jin Yu Zong
Keyword(s):  
Crack Resistance ◽  
High Speed ◽  
Test Results ◽  
Railway Tunnel ◽  
Curing Conditions ◽  
Air Voids ◽  
Mix Proportion ◽  
Surrounding Rock Pressure ◽  
Secondary Lining ◽  
Fine Organic

Cracking is the most common damage in the secondary lining concrete because of its continuous thin-walled structure, potential surrounding rock pressure and poor curing conditions. In order to improve the crack resistance of concrete and to reduce the responding costs, seven series modern concretes including ultra-fine pozzolanic powder and different organic fibers are prepared and investigated. The optimized modern secondary lining concrete is determined as the concrete including 0.08% or 0.1% volume fractions of ultra-fine organic fiber (UF), based on the test results of segregation, air voids parameters, primary strengths and multi-factorial crack resistance. The spacing factor and average chord length of concretes including UF are less than 0.1mm, which is positive for mixing UF to enhance the crack resistance of concrete at micro- and meso-scale.

Surrounding rock pressure of shallow-buried bilateral bias tunnels under earthquake

2015 ◽  
Vol 9 (4) ◽  
pp. 427-445 ◽  
Author(s):  
Xin-Rong Liu ◽  
Dong-Liang Li ◽  
Jun-Bao Wang ◽  
Zhen Wang
Keyword(s):  
Rock Pressure ◽  
Surrounding Rock ◽  
Surrounding Rock Pressure

scholarly journals Calculation of Surrounding Rock Pressure of Undercut Subway Station Based on Multi-Factor Affecting Pressure Arch Theory

Engineering ◽  
2020 ◽  
Vol 12 (02) ◽  
pp. 59-70
Author(s):  
Bin Shang ◽  
Xiaoguang Jin ◽  
Guiyong Ao ◽  
Qiao Chen ◽  
Qiong Qiu
Keyword(s):  
Rock Pressure ◽  
Surrounding Rock ◽  
Subway Station ◽  
Surrounding Rock Pressure
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