scholarly journals Optimization and Application of Support Scheme for Tunnel with High In-situ Stress in Ningchan

2021 ◽  
Vol 248 ◽  
pp. 03004
Author(s):  
Zhang Xueqiang
Keyword(s):  
Large Deformation ◽  
Double Layer ◽  
Optimization Design ◽  
High Stress ◽  
Tunnel Support ◽  
Stability Period ◽  
Deformation Stability ◽  
Initial Support ◽  
Ground Stress ◽  
Cumulative Deformation

Based on the national highway 569 Mandala Datong highway Ningchan tunnel, the study on the optimization design of high ground stress tunnel support parameters is carried out. The results show that the single-layer primary support with I20b as the main support framework cannot control the large deformation of high ground stress tunnel, mainly manifested as arch frame failure and concrete spalling; adopting “double-layer initial support” can control large deformation to a certain extent; increasing the stiffness of inner layer support can reduce the “double-layer” to a certain extent The results show that the cumulative deformation of “support”, but cannot significantly shorten the deformation stability period; appropriately increasing the reserved deformation between the inner and outer layers of the initial support has the best supporting effect, the cumulative deformation is small, and the deformation stability period is shortened. The research results provide a basis for similar high stress tunnel support measures.

scholarly journals Discussion on the Large Deformation Law of Muzhailing Tunnel in Lanhai Expressway

2017 ◽  
Vol 6 (2) ◽  
Author(s):  
Xi Cheng
Keyword(s):  
Tibetan Plateau ◽  
Large Deformation ◽  
The Tibetan Plateau ◽  
Deformation Law ◽  
Initial Support ◽  
Ground Stress ◽  
The Law

Muzhailing tunnel is a key project of Weiwu section Lanhai Expressway. It is located in the northeastern margin of the Tibetan Plateau. The complex geological enviorments, such as high ground stress, large buried-depth, fault and fold development, soft and fragmented rock, leads to poor self-stabilizing ability. 2# inclined shaft of Muzhailing tunnel is the main object we studied in this paper. During the construction of the tunnel, large deformation, spalling and fall-block occured on the initial support. The accumulated dome sinking vale and peripheral convergence value are large, mainly presented by the vault sinking, wall squeezing, shotcrete spalling, fall-block, and steel arch twisting and so on. In this paper, the law of large deformation of the tunnel is discussed.

scholarly journals Analysis of Stress and Deformation Characteristics of Deep-Buried Phyllite Tunnel Structure under Different Cross-Section Forms and Initial Support Parameters

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Hao Wu ◽  
Xiaohua Yang ◽  
Shichun Cai ◽  
Binjing Zhao ◽  
Kunlong Zheng
Keyword(s):  
Large Deformation ◽  
Double Layer ◽  
Soft Rock ◽  
Surrounding Rock ◽  
Original Design ◽  
Supporting Structure ◽  
Initial Support ◽  
Stress And Deformation ◽  
Rock Tunnels ◽  
Layer Steel

Deep-buried soft rock tunnels exhibit low strength and easy deformation under the influence of high ground stress. The surrounding rock of the soft rock tunnel may undergo large deformation during the construction process, thereby causing engineering problems such as the collapse of the vault, bottom heave, and damage to the supporting structure. The Chengwu Expressway Tunnel II, considered in this study, is a phyllite tunnel, with weak surrounding rock and poor water stability. Under the original design conditions, the supporting structure exhibits stress concentration and large deformation. To address these issues, three schemes involving the use of the double-layer steel arch to support, weakening of the steel arch close to the excavation surface, and weakening of the steel arch away from the excavation surface to support were proposed. Using these schemes, the inverted radius was varied to explore its influence on different support schemes. For simulation, the values of the inverted radius selected were as follows: 1300 cm, 1000 cm, and 700 cm. The proposed support plan was simulated using FLAC3D, and the changes in the pressure between the initial support and surrounding rock, the settling of the vault, and the surrounding convergence were investigated. The numerical simulation results of monitoring the surrounding rock deformation show that the double-layer steel arch can effectively reduce the large deformation of the soft rock well. When the stiffness of one of the steel arches was weakened, the support’s ability to control the deformation was weakened; however, it still showed reliable performance in controlling deformation. However, changing the radius of the invert had an insignificant effect on the deformation and force of the supporting structure.

scholarly journals Stability Control of Deep Coal Roadway under the Pressure Relief Effect of Adjacent Roadway with Large Deformation: A Case Study

2021 ◽  
Vol 13 (8) ◽  
pp. 4412
Author(s):  
Houqiang Yang ◽  
Nong Zhang ◽  
Changliang Han ◽  
Changlun Sun ◽  
Guanghui Song ◽  
...  
Keyword(s):  
Large Deformation ◽  
Coal Mine ◽  
High Stress ◽  
Surrounding Rock ◽  
Western China ◽  
Engineering Practice ◽  
Pressure Relief ◽  
Coal Roadway ◽  
And Control ◽  
Relief Effect

High-efficiency maintenance and control of the deep coal roadway surrounding rock stability is a reliable guarantee for sustainable development of a coal mine. However, it is difficult to control the stability of a roadway that locates near a roadway with large deformation. With return air roadway 21201 (RAR 21201) in Hulusu coal mine as the research background, in situ investigation, theoretical analysis, numerical simulation, and engineering practice were carried out to study pressure relief effect on the surrounding rock after the severe deformation of the roadway. Besides, the feasibility of excavating a new roadway near this damaged one by means of pressure relief effect is also discussed. Results showed that after the strong mining roadway suffered huge loose deformation, the space inside shrank so violently that surrounding rock released high stress to a large extent, which formed certain pressure relief effect on the rock. Through excavating a new roadway near this deformed one, the new roadway could obtain a relative low stress environment with the help of the pressure relief effect, which is beneficial for maintenance and control of itself. Equal row spacing double-bearing ring support technology is proposed and carried out. Engineering practice indicates that the new excavated roadway escaped from possible separation fracture in the roof anchoring range, and the surrounding rock deformation of the new roadway is well controlled, which verifies the pressure relief effect mentioned. This paper provides a reference for scientific mining under the condition of deep buried and high stress mining in western China.

Structure Topology Optimization Design and Shock Resistance Study on Nuclear Power Safety DCS Cast Aluminum Cabinet

2020 ◽  
Author(s):  
Wang Dongwei ◽  
Liu Mingxing ◽  
Wu Xiao ◽  
Yan Hao ◽  
Wu Zhiqiang
Keyword(s):  
Topology Optimization ◽  
Power Plant ◽  
Nuclear Power Plant ◽  
Nuclear Power ◽  
Optimization Design ◽  
High Stress ◽  
Shock Load ◽  
Normal Operation ◽  
Cast Aluminum ◽  
Structure Topology

Abstract Offshore floating nuclear power plant (FNPP) is characterized by its small and mobility, which is not only able to provide safe and efficient electric energy to remote islands, but to the oil and gas platforms. The safety digital control system (DCS) cabinet, as a carrier for the electronic devices, plays a significant role in ensuring the normal operation of the nuclear power plant. To satisfy the requirements of cabinet used in the sea environment, such as well rigidity, shock load resistance, good seal and corrosion resistance, etc, more and more attention is focused on the cast aluminum cabinet. However, the cast aluminum structure may cause larger weight of cabinet, which inevitability affects the mobility of cabinet, and increases the carried load of ship as well. Therefore, seeking for an effective approach to design a light weight cast aluminum cabinet for the offshore FNPP is definitely necessary. In this work, a frame of cast aluminum cabinet with lightweight is obtained successfully via structure topology optimization design, it is found that the weight of the frame can be reduced to 50% after optimization iterations. Subsequently, the natural frequency of the optimized cast aluminum cabinet is calculated by using ABAQUS, it is seen that the first mode frequency of the frame is beyond 30 Hz, which can meet the basic stiffness requirement. Accordingly, dynamic design analysis method (DDAM) is performed to verify the ability of the optimized cast aluminum cabinet in resisting sudden shock load, and the shock response characteristics of the cabinet are determined. Numerical results support that the optimized frame of cabinet possesses good resistance to high level shock. However, for the assembled cast aluminum cabinet, the vertical shock circumstance turns out to be the most critical condition, high stress and deformation regions occurs at the bracket and column. Reinforcements are proposed to make the bracket stiffer in this shock loading condition.

scholarly journals Study on the Treatment Timing of Large Deformation of the Tunnel in Swelling Rock

2018 ◽  
Vol 206 ◽  
pp. 01005
Author(s):  
Zhongmin Yang ◽  
Yongtao Gao ◽  
Ziqiao Cheng ◽  
Zijie Cong
Keyword(s):  
Large Deformation ◽  
Surrounding Rock ◽  
Stress Release ◽  
Construction Time ◽  
Treatment Timing ◽  
Final Stress ◽  
Initial Support ◽  
Swelling Rock ◽  
Rock Tunnel ◽  
Deformation Treatment

When large deformation of the tunnel occurred in the swelling rock, the large deformation treatment will not only greatly delay the construction time, but also lead to instability or even collapse of the tunnel. Selecting the reasonable timing for large deformation initial support replacement can solve this problem effectively. Based on the LiRang tunnel, the deformation and stress of the tunnel in anhydrite were analysed by FLAC software after excavation. Then replace the deformed first liner at different vault settlement value. The displacement and stress of surrounding rock were analysed when the model reaches equilibrium state again. The results showed that stress concentration at the arch wall and arch foot of the tunnel, and the stress release at the vault and invert is very large after excavation. If the large deformation was treatment when the crown settlement of the tunnel reaches 90% ~95% of the final predicted settlement value, the tunnel deformation and the final stress state could be in a small value. This study can provide a reference for the treatment of large deformation in the swelling rock tunnel.

Study on the Supporting Technology of Complex Deep Coal Roadways

2012 ◽  
Vol 524-527 ◽  
pp. 743-746
Author(s):  
Zhi Yang Liu
Keyword(s):  
Large Deformation ◽  
Experimental Test ◽  
High Stress ◽  
Surrounding Rock ◽  
Abscission Layer ◽  
Ground Pressure ◽  
Pressure Water ◽  
Observation Results

Suffering from the effect of the high ground pressure, water spraying from roof surrounding rock or geological tactics such as faults or collapse columns, roadways used to have large deformation, even lead to caving accidents. Based on the supporting research of the above complex conditions, the supporting background of a typical roadway No.202 affected by high stress, water spraying and large faults is analyzed and the corresponding technology is put forward. In addition, the support experimental test is conducted on the roadway, and the observation results show that the convergence of both sides is controlled well, and abscission layer is little.

Numerical Simulation Research of Optimization Design of Supporting Half-Coal Roadway in Deep Stope Working Face

2014 ◽  
Vol 945-949 ◽  
pp. 1169-1174
Author(s):  
Xian Tao Zeng ◽  
Ning Wang ◽  
Cong Jiang ◽  
Yun Yi Zhang ◽  
Chang Hai He
Keyword(s):  
Numerical Simulation ◽  
Optimization Design ◽  
Mining Area ◽  
Support Design ◽  
Simulation Research ◽  
Actual Measurement ◽  
Design Scheme ◽  
Coal Roadway ◽  
Working Face ◽  
Ground Stress

In this paper, design of roadway with stope working face Yeqing 8459 had been optimized combined with geological characteristics of the working face based on the actual measurement of ground stress and mechanical properties of coal rock of Yangquhe mine in Feng Feng mining area. Analyzing eight kinds of roadway support design scheme through numerical simulation and evaluating the supporting effect of each supporting design scheme, designating the construction guidelines ultimately.

scholarly journals Research on Control Mechanism of Surrounding Rock of Deep Gob-Side Entry Retaining

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Jianxiong Liu ◽  
Jingke Wu ◽  
Yun Dong ◽  
Yanyan Gao ◽  
Jihua Zhang ◽  
...  
Keyword(s):  
Large Deformation ◽  
High Stress ◽  
Original System ◽  
Field Investigation ◽  
Surrounding Rock ◽  
Eccentric Load ◽  
Deformation And Failure ◽  
Body Fracture ◽  
Stress States ◽  
Term Creep

To address the large deformation of the surrounding rock of deep gob-side entry retaining under high stress, lithological characteristics of the surrounding rock and failure model of support body and their evolutionary processes are analyzed through field investigation and theoretical analysis. Failure mechanisms of surrounding rock and the technology to control it are studied systematically. The results show that the causes of the large deformation of the surrounding rock are weak thick mudstones with softening property and water absorption behavior, as well as its fragmentation, dilatancy, and long-term creep during strong disturbance and highly centralized stress states. The cross-section shape of the roadway after deformation and failure of the surrounding rock is obviously asymmetric in both the horizontal and vertical directions. Since the original system supporting the surrounding rock is unable to completely bear the load, each part of the supporting system is destroyed one after the other. The failure sequences of the surrounding rock are as follows: (1) roadway roof fracture in the filling area, (2) filling body fracture under eccentric load, (3) rapid subsidence of the roadway roof, and (4) external crack drum and rib spalling at the solid coal side. Due to this failure sequence, the entire surrounding rock becomes unstable. A partitioned coupling support and a quaternity control technology to support the surrounding rock are proposed, in which the roof of the filling area plays a key role. The technology can improve the overall stability of gob-side entry retaining, prevent support structure instability caused by local failure of the surrounding rock, and ensure the safety and smoothness of roadways.

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