scholarly journals Experimental Study on Structural Form and Excavation Model of Urban Metro Cross Transfer Station with Super Large Cross Section and Shallow Excavation

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Zhi Lin ◽  
Xiang Chen ◽  
Hongyun Yang ◽  
Chongguo Cheng ◽  
Huasong Wang ◽  
...  
Keyword(s):  
Large Scale ◽  
Ground Surface ◽  
Construction Method ◽  
Surrounding Rock ◽  
Structure Form ◽  
Large Section ◽  
Response Characteristics ◽  
Ground Surface Settlement ◽  
Transfer Structure ◽  
The Stability

The construction of urban underground cross-interchange transfer subway stations often encounters the difficulties of shallow-buried, different surrounding rock, large spans and heights, congested road traffic, and surrounding buildings sensitive to the construction sequence. Therefore, there is a need for an underground project that controls the stability of underground space and ground subsidence. Based on the construction difficulties of a certain station (the maximum excavation area over 760 m2), this paper conducts a comprehensive selection design of the structure, construction mechanics response, and control technology of this type of interchange station structure and construction excavation. First of all, based on the design experience of large-scale underground transfer transportation engineering and taking full consideration of the stratum conditions, an “arch-wall” cross transfer structure method is proposed. The refined numerical analysis shows that the structure can fully utilize the stratum conditions to reduce the ground surface settlement. Then, in view of the stability of surrounding rock during the construction of a large section, based on the traditional large section excavation method, a construction method of “cross rock beam + heading method” was proposed. In order to verify the effect of the construction method, the three-dimensional detailed numerical model was used to simulate the construction conditions, and the mechanical response characteristics and displacement changes of surrounding rock under each excavation step are explored. Simultaneous interpreting with the traditional large section excavation method, the results show that the new method has advantages in controlling the stability of the surrounding rock. Meanwhile, in order to ensure the safe construction of the project, the self-developed multifunctional engineering test system for traffic tunnels is used to carry out a large-scale physical model experiment to simulate the entire process of the “arch-wall” cross transfer structure construction response characteristics. By analyzing the data of measuring points, the results show that the structure form and the excavation method cause the ground surface settlement, stress, and structural forces meet the requirements for safe construction. Finally, the station can be safely constructed under the new structure form and construction method. Therefore, the structure form and method proposed in this paper can be adapted to the large-scale underground structure under construction in complex environments.

Numerical Analysis of Construction Method in Shallow-Buried Large-Section Loess Tunnel

2014 ◽  
Vol 580-583 ◽  
pp. 997-1000 ◽  
Author(s):  
Zhi Jie Sun
Keyword(s):  
Numerical Simulation ◽  
Numerical Analysis ◽  
Ground Surface ◽  
Construction Method ◽  
Surrounding Rock ◽  
3D Numerical Simulation ◽  
Large Section ◽  
Research Results ◽  
Construction Methods ◽  
Ground Surface Settlement

To research the deformation regularity of large section loess tunnel in construction procession with different construction methods, 3D Numerical Simulation is applied and the large-section loess tunnel of highway is taken as an example. Comparing deformation regularity of surrounding rock in three types of construction method conditions, the research results show that:The CRD method takes precedence in the condition of the convergence of surrounding rock is large. The both sides heading method takes precedence in the condition of ground surface settlement is large.

Study on the Stochastic Law of Gob Stowing Effect

2012 ◽  
Vol 170-173 ◽  
pp. 502-505
Author(s):  
Li Guo ◽  
Bing Xie
Keyword(s):  
Finite Element Method ◽  
Ground Surface ◽  
Surrounding Rock ◽  
Stochastic Finite Element Method ◽  
Confined Aquifer ◽  
Stability Of Surrounding Rock ◽  
Ground Surface Settlement ◽  
The Stability ◽  
Statistical Rule ◽  
Cut And Fill

The cut-and-fill mining is the main content of the technical system of green coal mining. And it is an effective way for solving the environmental problems and mining the coal under buildings, under railway, under water and over confined aquifer. No matter what kind of filling way, the gob stowing cannot achieve ideal filling effect, the filling effect is random in certain scope. Taking a coal mine as an example, with the aid of stochastic finite element method, the three situations of gob stowing were calculated and analyzed to explore the statistical rule of the ground surface settlement and the stability of surrounding rock because of random variation of gob stowing effect.

scholarly journals Study on instability failure mode and monitoring early warning standard of surrounding rock in fully weathered argillaceous sandstone section of large section tunnel

2019 ◽  
Vol 136 ◽  
pp. 04023
Author(s):  
Ming Zhao ◽  
Ke Li ◽  
Hong Yan Guo ◽  
KaiCheng Hua
Keyword(s):  
Limit State ◽  
Stable State ◽  
Simulation Software ◽  
Surrounding Rock ◽  
Large Section ◽  
Rock Stability ◽  
Geological Conditions ◽  
Construction Step ◽  
The Face ◽  
The Stability

Based on the special geological conditions of a tunnel in Qingyuan section of Huizhou-Zhanzhou Expressway, FLAC3d numerical simulation software is used to simulate the rheological properties and instability of surrounding rock in large-section fully weathered sandstone section, and the stability and loss of surrounding rock are analyzed. The deformation of the dome and the face at steady state is analyzed. It is found that: 1) when the surrounding rock is in a stable state, the deformation curve of the dome is smooth. When the surrounding rock of the face is unstable, the front of the face appears ahead. Deformation should be first strengthened on the surrounding rock in front of the face. 2) The arched foot is an important part of the instability of the surrounding rock. In order to prevent the expansion of the collapsed part, the arched part should be reinforced. 3) In order to obtain the limit state of surrounding rock stability, the strength of surrounding rock is reduced, and the strength reduction coefficient corresponding to the displacement sudden point is taken as the safety factor of rock stability around the hole, and the stability safety coefficients of surrounding rock of each construction step are greater than 1.2. 4) The dynamic standard values of deformation control in the whole construction stage are obtained by analyzing the deformation curves of each data monitoring point with time in the corresponding time period of each construction step.

scholarly journals Stability Analysis of Surrounding Rock of Large Section Ultradeep Shaft Wall

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Cheng Li ◽  
Wang Chunlong ◽  
Wang Xi ◽  
Chen Kexu
Keyword(s):  
Control Method ◽  
Stress Test ◽  
Stability Control ◽  
Surrounding Rock ◽  
Main Shaft ◽  
Large Section ◽  
Masonry Construction ◽  
Temporary Support ◽  
The Stability ◽  
Shaft Wall

In order to study the stability of deep surrounding rock during the excavation of new main shaft in Xincheng gold mine, a construction method suitable for large section ultradeep shaft is proposed. A series of analyses were carried out in this study, including the in situ stress test, stress response of surrounding rock disturbance, deformation and failure characteristics, and numerical simulation. Based on the above analysis, the stability control method of surrounding rock in the process of deep excavation of the new main shaft is proposed. The results show that (1) the maximum principal stress of deep surrounding rock of new main shaft is horizontal stress, and the surrounding rock of the shaft has strong rock burst tendency after excavation; (2) the influence range of the deep shaft excavation disturbance is 6.4 times the shaft radius, in which the temporary support should be strengthened to avoid the influence of excavation disturbance on the stability of shaft wall rock; (3) the failure shape of surrounding rock of the deep shaft excavation was “ear” failure, and the failure depth was not more than 2.5 m; (4) after replacing the original “one-excavation and one-masonry” construction with “three-excavation and one-masonry” construction, the temporary support span of the main shaft was adjusted to 12 m, which can make the subsequent concrete shaft wall in the state of “no pressure bearing or slow low pressure bearing,” and the lining compressive safety coefficient was increased to 1.98, which meets the safety requirements.

scholarly journals Stability Analysis and Protection Measures of Large Section Tunnel in Coal Rich Weak Rock Stratum

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Guannan Zhou ◽  
Zijiang Zhao ◽  
Zhanping Song ◽  
Hongjian Wang
Keyword(s):  
Coal Seam ◽  
Large Scale ◽  
Economic Benefits ◽  
Surrounding Rock ◽  
Tunnel Construction ◽  
Weak Rock ◽  
Large Section ◽  
Tunnel Face ◽  
Finite Element Software ◽  
Geological Conditions

Due to poor engineering geological conditions of Liujiazhuang tunnel on Shanghai-Kunming Passenger Dedicated Line, the large deformation of weak rock occurs repeatedly during tunnel construction. In this paper, the large-scale finite element software ABAQUS is used to simulate the construction process of a large-section tunnel in weak surrounding rock. It is found that when tunnel face passes through the coal seam, the displacement and stress simulated by the bench method increase abruptly. The maximum stress reaches up to 18 MPa, and displacement reaches 45 mm, which is about twice when without crossing coal seam. It is technically feasible to use the bench method for tunnel construction, under the condition when large settlements is allowed; additionally, the bench method has better technical and economic benefits than that of the CD method. Through the comparative analysis of onsite monitoring data and numerical simulation results, it can be seen that the tunnel is in a dangerous state when passing through the coal seam and measures such as strengthening support or auxiliary advance support should be taken immediately to control the surrounding rock and to ensure tunnel construction safety.

scholarly journals Study on Identification of Construction Method for Ultra-Large-Span Tunnel

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Xu Chongbang ◽  
Qin Youlin
Keyword(s):  
Rock Strength ◽  
Construction Method ◽  
Surrounding Rock ◽  
Orthogonal Test ◽  
Tunnel Construction ◽  
Test Model ◽  
Large Span ◽  
Construction Methods ◽  
The Stability

Although the determination of tunnel construction methods is extremely critical for the construction of ultra-large-span tunnels, the determination of construction methods is still at a qualitative level, which relies on the engineering experience of on-site technicians and lacks rigorous and systematic theoretical basis and technical standards. By means of orthogonal test method, the proper construction method was established for the deep-buried ultra-large-span tunnel where the tunnel excavation span, tunnel surrounding rock strength, and rock integrity coefficient were set as the main control factors. The stability of tunnel surrounding rock under various test conditions was quantified according to the plastic zone properties calculated by the three-factor and five-level orthogonal test model. Meanwhile, the macro form and quantitative method of test combinations under different levels of various factors were proposed to obtain the influence of each factor on the stability of tunnel surrounding rock, and thus the functional relations between various factors and tunnel stability were obtained. On this basis, the identification and the criterion of the ultra-large-span tunnel construction method were established, which can quantitatively reflect the contribution of excavation span of the tunnel, the number of lateral drifts in cross section, surrounding rock strength, and rock integrity coefficient to surrounding rock stability of the tunnel. The construction method calculation results of the Malin tunnel, a practical underground project, are obtained according to the orthogonal test model calculation. Based on the method, Malin tunnel can be constructed safely and efficiently. The research results could provide the theoretical basis for the identification and selection of construction method for ultra-large-span tunnel.

scholarly journals Study on Safety Benchmark Value of Monitoring and Early Warning for Large Section Highway Tunnels

2019 ◽  
Vol 136 ◽  
pp. 04024
Author(s):  
Yuwen Wang ◽  
Xiang Yang Cui ◽  
Hongyan Guo ◽  
Ke Li
Keyword(s):  
Side Wall ◽  
Construction Method ◽  
Surrounding Rock ◽  
Large Section ◽  
Deformation Law ◽  
Initial Support ◽  
Under Construction ◽  
Monitoring And Measurement ◽  
Ultimate Displacement ◽  
Wall Method

Taking several tunnels under construction of a highway as the research object, the ultimate displacement of four buried depth sections of 0-50, 50-100, 100-300, 300-500 m in the surrounding rock of grade III, IV and V is numerically simulated by three-step and seven-step excavation method, middle-wall method, cross-middle-wall method and double-side-wall guide pit method for initial support of large-section highway tunnels. Through analysis, the deformation law of tunnel surrounding rock is obtained: under the same buried depth, the displacement ultimate displacement of the two-sided guide pit method and the cross-middle-wall method is the largest, the middle-wall method is the second, and the three-step seven-step excavation method is the smallest. Through the analysis and collation of the measured data obtained by monitoring and measurement of each construction method in the construction site, the surrounding rock deformation datum values of large-span and large-section tunnel under each construction method are obtained.

Optimization of Construction Method for Shijiazhuang Xinbai Subway Station

2014 ◽  
Vol 580-583 ◽  
pp. 1203-1206
Author(s):  
Chun Yan Gao ◽  
Jian Guang Niu ◽  
Dong Yang Geng
Keyword(s):  
Environmental Influence ◽  
Fuzzy Optimization ◽  
Ground Surface ◽  
Optimization Theory ◽  
Construction Method ◽  
Surface Settlement ◽  
Subway Station ◽  
Construction Methods ◽  
Ground Surface Settlement ◽  
The Impact

To choose an appropriate construction scheme for subway, it,s feasible to use fuzzy optimization theory and comprehensively consider the security of four construction methods as well as such factors as environmental influence, construction period, construction difficulty and construction cost, etc. to set up a mathematical model for the construction method of subway station. An analysis is made on the impact of group-effect in the excavation construction of pilot tunnel presented in PBA construction method on arch crown settlement and ground surface settlement, and a study is made on the arch crown settlement and ground surface settlement caused by the four construction methods in construction process. In addition, a contrastive analysis is made to draw a conclusion that PBA construction method is the most suitable construction method for Xinbai Square Subway Station in Shijiazhuang.

scholarly journals Research on Construction Optimization of Three-Connected-Arch Hydraulic Underground Cavities Considering Creep Property

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Bao-yun Zhao ◽  
Nian-chun Xu ◽  
Zi-yun Li ◽  
Tong-qing Wu
Keyword(s):  
Large Scale ◽  
Creep Property ◽  
Construction Method ◽  
Surrounding Rock ◽  
Creep Model ◽  
Secondary Development ◽  
Underground Cavity ◽  
Construction Methods ◽  
Nonlinear Viscoelastic ◽  
Construction Optimization

In order to prevent the creep of surrounding rock in long-term construction, with consideration of different construction methods and other factors during the construction of large-scale underground cavity, three different construction schemes are designed for specific projects and a nonlinear viscoelastic-plastic creep model which can describe rock accelerated creeping is introduced and applied to construction optimization calculation of the large-scale three-connected-arch hydraulic underground cavity through secondary development of FLAC3D. The results show that the adoption of middle cavity construction method, the second construction method, enables the maximum vault displacement of 16.04 mm. This method results in less stress redistribution and plastic zone expansion to the cavity’s surrounding rock than the other two schemes, which is the safest construction scheme. The conclusion can provide essential reference and guidance to similar engineering for construction optimization.

Monitoring and Analysis for Air Defense Shelters in Freeze Soil Region

2011 ◽  
Vol 99-100 ◽  
pp. 332-337
Author(s):  
Bao Fu Duan ◽  
Hong Chun Li ◽  
Yu Kun Zhang ◽  
Meng Zhang ◽  
Lei Li
Keyword(s):  
Freeze Soil ◽  
Ground Surface ◽  
Surrounding Rock ◽  
Underground Excavation ◽  
Frozen Ground ◽  
Air Defense ◽  
Stability Of Slopes ◽  
Steel Bracing ◽  
The Stability ◽  
Major Factors

Abstract. Based on the monitored surrounding rock displacement and the settlement of ground surface and structures of No.7381 tunnel in Harbin, major factors which influence the safety of construction are analyzed and discussed. Results of the analyses indicated, enlargement excavation of tunnel has significant effect on the settlement of ground surface but has less effect on surrounding rock displacement and settlement of structures. Enlargement excavation during rainy season relay influences the structures and ground surface, by contrast, it influences the open-cut part a lot especially for the stability of slopes. It is pointed that the scope which seasonally frozen ground influences in open-cut part is larger than that in underground excavation part but have less effect on the displacement of surrounding rock underground. Seasonally frozen ground also leads to a remarkable displacement of ground surface. The application of temporary steel bracing is needed and effective for controlling surrounding rock displacement and the settlement of ground surface.

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