Deformation and Stability Study of PBA Extension Method Based on Air Defense Tunnel

2012 ◽  
Vol 204-208 ◽  
pp. 1347-1355
Author(s):  
Jian Jia ◽  
Shun Hua Zhou ◽  
Xi Ping Yao ◽  
Chen Shen
Keyword(s):  
Internal Force ◽  
Stability Study ◽  
Surrounding Rock ◽  
Surface Settlement ◽  
Ground Settlement ◽  
Ground Displacement ◽  
Air Defense ◽  
Surrounding Rock Pressure ◽  
Unloading Effect

Jiaohua Square Station of Harbin Metro Line 1 is built by PBA method with the existence of No. 7381 air defense tunnel. In order to control the ground settlement during PBA construction, numerical model is performed to analyse the surrounding rock pressure, plastic zone and structure internal force. The result shows the lower pilot headings have stronger impact on existing tunnel than the upper ones in that the lower ones get the loading effect while the upper ones the unloading effect. The internal force of air defense tunnel and ground displacement can be well controlled by reducing the area of lower pilot headings at the stages of pilot heading excavation, but the final surface settlement is unqualified. The scheme of lower big pilot heading in part with the support of portal frame meets the requirement of surface settlement. The in-situ surface settlement and the vault settlement of defense tunnel are essentially consistent with numerical results.

Study on the Mechanical Behavior of Excavation and Support Construction of Shallow Tunnel

2013 ◽  
Vol 353-356 ◽  
pp. 1693-1698
Author(s):  
Zhen Xing Yang ◽  
Liang Song ◽  
Hao Wang ◽  
Yu Yong Jiao ◽  
Shu Cai Li ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Mechanical Behavior ◽  
Rock Pressure ◽  
Simulation Method ◽  
Internal Force ◽  
Surrounding Rock ◽  
Shallow Tunnel ◽  
Maximum Value ◽  
Surrounding Rock Pressure ◽  
Peak Value

In this paper, the mechanical behavior of excavation and support construction of Weishe tunnel, which is a section of the Yangwu expressway, is studied quantitatively using 3D finite difference numerical simulation method. A sequential excavation method is used and the results show that the vault settlement occurs mainly on the phase of upper bench excavation. The convergences of upper and lower sidewalls occur mainly on the phase of lower bench excavation. During the construction, the surrounding rock pressure in the vault and sidewall of the tunnel decrease. Axial force of anchor reaches the maximum value after the finish of second lining. However, the surrounding rock pressure and internal force of steel arch reach the maximum value after completing the upper bench excavation, and then become as smaller as half of the peak value during the lower bench excavation.

Study on In Situ Monitoring of the Surrounding Rock Pressure of the Shallow Large-Span Tunnel in the Tunnel Construction Process

2011 ◽  
Vol 413 ◽  
pp. 454-458
Author(s):  
Xin Zhi Li ◽  
Shu Cai Li ◽  
Ying Yong Li ◽  
Shu Chen Li
Keyword(s):  
Rock Pressure ◽  
Surrounding Rock ◽  
In Situ Monitoring ◽  
Tunnel Engineering ◽  
Tunnel Face ◽  
Tunnel Excavation ◽  
Large Span ◽  
Parallel Tunnel ◽  
Surrounding Rock Pressure

The surrounding rock pressure which was determined effectively through in-situ monitoring was the important parametric of the tunnel engineering design.According to in-situ monitoring of the surrounding rock pressure in the relied engineering . The adjustment and distribution characteristics of surrounding rock pressure of the shallow large-span tunnel with three-level seven-step parallel tunnel excavation was studied, the results showed that the arch and sides of the tunnel arch foot were the key parts which concentrated the surrounding rock pressure. The adjustment and distribution of surrounding rock pressure had not obvious relationships with tunnel face distance. Finally, the composite factors that impacted monitoring results of the surrounding rock pressure was analysed. The results had great significance on the development and perfection of the surrounding rock pressure theory in shallow large-span tunnel.

Analysis on Ground Settlement Induced by Shallow Buried Cross Channel of CRD Method under Artificial Filling

2013 ◽  
Vol 353-356 ◽  
pp. 1519-1524
Author(s):  
Jin Kui Li ◽  
Jing Jing Li ◽  
Liu Jie Du
Keyword(s):  
Surface Deformation ◽  
Settling Tank ◽  
Ground Surface ◽  
Surrounding Rock ◽  
Surface Settlement ◽  
Ground Settlement ◽  
Tunnel Face ◽  
Underground Tunnel ◽  
The Cross ◽  
The Stability

The shallow underground tunnel is near to the ground; its many construction procedures are complicated, supporting and excavation are intertwined. The ground surface deformation is complex during construction. Through the analysis of the cross passage surface settlement data of Dalian metro Line 1High-tech zone Street station, we found that the ground surface caused by artificial filling integrally sinks during excavation, the shape of its sinking is like a flat funnel, the characteristics of settling tank are obvious. The influence of faces constructing is obvious on surface settlement, and the transverse influence range is about 30m; the longitudinal influence range is about 15m. The results of the paper show that the place of monitoring points should be held at 15m ahead from the tunnel face, effectivemonitoring period is 70d. The monitoring results are enough and safe for the stability requirement of the surrounding rock.

scholarly journals Development and Research on the Vertical Center Diaphragm Method Applied in Shallow Tunnel Construction

Symmetry ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 855
Author(s):  
Zhenliang Zhou ◽  
Zhongsheng Tan ◽  
Jinpeng Zhao ◽  
Han Liang
Keyword(s):  
Three Dimensional ◽  
Earth Pressure ◽  
Internal Force ◽  
Surrounding Rock ◽  
Surface Settlement ◽  
Shallow Tunnel ◽  
Connection Line ◽  
Axisymmetric Structure ◽  
Arch Stress ◽  
Construction Efficiency

As a common method applied in the construction of tunnels with Grade IV and Grade V surrounding rock, the center diaphragm (CD) method has the advantage of resisting the inward horizontal convergence of the tunnel. However, due to the small lateral earth pressure of the shallow tunnel, the curved center diaphragm would have an unstable stress state and cannot provide sufficient support to the surrounding rock. Based on the CD method, this study presents a vertical center diaphragm (VCD) method with an axisymmetric structure. The application condition of the VCD method relies on the comparison of the surface settlement and tunnel deformation with the two methods in different surrounding rock grades and buried depths by using a three-dimensional finite-difference code. Based on the Shenzhen Eastern Transit Expressway Connection Line Tunnel, which has six lanes of double lines, the deformation regularities and mechanical characteristics of the VCD method, including the surface settlement, tunnel deformation, internal force of the center diaphragm, surrounding rock pressure, and steel arch stress, are investigated by numerical calculations and a field comparative test. The results obtained in this study provide several suggestions for constructing shallow tunnels. Furthermore, the construction efficiency and economy of the VCD method are evaluated.

Discussion on the Calculation Method of the Deep Buried Tunnel Surrounding Rock Loose Pressure

2012 ◽  
Vol 193-194 ◽  
pp. 757-761
Author(s):  
Yong Feng Yun ◽  
De Lun Wu
Keyword(s):  
Rock Pressure ◽  
Internal Force ◽  
Structure Design ◽  
Surrounding Rock ◽  
Design Calculation ◽  
Calculation Formula ◽  
Tunnel Structure ◽  
Calculation Results ◽  
Surrounding Rock Pressure ◽  
Surrounding Rock Stress

Adopted the load-structure model to tunnel structure design calculation, our country often use surrounding rock pressure experience calculation formula, This paper analysed the problems existing in the experience calculation formula and calculated the surrounding rock pressure have influence on calculation results of tunnel structure internal force with the formulas, and at last given out more actual modification formula, the surrounding rock stress is continuity with the formula calculated, it is more actual than the traditional experience formula, provided a new way for accurate calculated the surrounding rock pressure.

Study on Deformation and Force Characteristics of Deep-buried Large Section Expansive Red Clay Tunnel

2020 ◽  
Author(s):  
Zhuowu Xie ◽  
Xiyong Wu
Keyword(s):  
Field Measurement ◽  
Pressure Coefficient ◽  
Internal Force ◽  
In Situ Stress ◽  
Surrounding Rock ◽  
Burial Depth ◽  
Red Clay ◽  
Lining Structure ◽  
Force Characteristics

<p>Due to the large burial depth of the Pliocene Red Layer in Qingyang, Gansu and its special historical causes, its engineering mechanical characteristics are quite different from those of the southern red clay. Lack of systematic data on the internal forces of the lining structure through the stratum tunnel. Therefore, this paper takes the Yinchuan-Xian High-speed Railway Qingyang Tunnel as the research object, through field measurement and finite element simulation to obtain the space-time distribution characteristics of the internal force of the lining structure, the surrounding rock pressure, the deep displacement of the surrounding rock from 5 to 10 m, and the convergent deformation of the support. The reasons for the stress state of the lining-surrounding rock composite structure reflected in the results are analyzed, and the ABAQUS software is used to simulate the tunnel excavation process to compare and verify the lining structure stressing law. Internal force characteristics. The results show that: 1) The physical and mechanical indicators of the Pliocene red layer in the Neogene in Qingyang, Gansu belong to the extremely hard soil-very soft rock critical category. Due to the long consolidation pressure and long consolidation history, it can be obvious on the saturated flooding fault surface. Observation of the characteristics of layered joints proves that this layer of red clay has a tendency of sedimentary diagenesis. 2) The quality of the surrounding rock of the stratum lining structure is good. The horizontal in-situ stress is twice that of the vertical in-situ stress. It can be optimized for the design of III-IV surrounding rock while increasing the side pressure coefficient. 3) The unclosed initial support cannot effectively limit the deformation of the surrounding rock, and the temporary stress can be used to improve the state of stress. The numerical simulation results are consistent with the field measurement laws. 4) This stratum with severe deformation is the cave diameter range of the excavation boundary to the surrounding rock. The deformation area is mainly concentrated in the vault. Delayed excavation of the inverted arch can effectively reduce the stress on the internal lining structure of the inverted arch.</p>

scholarly journals Stability of a Rock Tunnel Passing through Talus-Like Formations: A Case Study in Southwestern China

2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Shaoqiang Zhang ◽  
Wenqiang Li ◽  
Jiashan Tan ◽  
Bokuan Li ◽  
Xiaochang Li ◽  
...  
Keyword(s):  
Rock Mass ◽  
Rock Pressure ◽  
Monitoring Program ◽  
Surrounding Rock ◽  
In Situ Monitoring ◽  
Monitoring Data ◽  
Surrounding Rock Pressure ◽  
Set Up ◽  
Highway Project

Tayi tunnel is one of the component tunnels in the Jian-Ge-Yuan Highway Project located in Yunnan Province, southeast of China. It mainly passes through talus-like formations comprised of rock blocks of diverse sizes and weak interlayers with clayey soils with different fractions. Such a special composition leads to the loose and fractured structure of talus-like formations, which is highly sensitive to the excavation perturbation. Therefore, Tayi tunnel has become the controlled pot of the whole highway project as the construction speed has to be slowed down to reduce the deformation of surrounding talus-like rock mass. To better understand the tunnel-induced ground response and the interaction between the surrounding rock mass and tunnel lining, a comprehensive in situ monitoring program was set up. The in situ monitoring contents included the surrounding rock pressure on the primary lining, the primary lining deformation, and the stress of steel arches. Based on the monitoring data, the temporal and the long-term spatial characteristics of mechanical behavior of surrounding rock mass and lining structure due to the excavation process were analyzed and discussed. It is found that the excavation of lower benches released the surrounding rock pressure around upper benches, resulting in the decrease of the surrounding rock pressure on the primary lining and the stress of steel arches. In addition, the monitoring data revealed that the primary lining sustained bias pressure from the surrounding rock mass, which thereby caused unsymmetrical deformation of the primary lining, in accordance with the monitored displacement data. A dynamically adaptive support system was implemented to strengthen the bearing capacity of the lining system especially in the region of an extremely weak rock mass. After such treatment, the deformation of the primary lining has been well controlled and the construction speed has been considerably enhanced.

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.

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