scholarly journals Countermeasures against large deformation of deep-buried soft rock tunnels in areas with high geostress: A case study

2022 ◽  
Vol 119 ◽  
pp. 104238
Author(s):  
Huang-Shi Deng ◽  
He-Lin Fu ◽  
Yue Shi ◽  
Yun-Ya Zhao ◽  
Wei-Zhi Hou
Keyword(s):  
Large Deformation ◽  
Soft Rock ◽  
High Geostress ◽  
Rock Tunnels

Mechanisms of large deformation in soft rock tunnels: a case study of Huangjiazhai Tunnel

2017 ◽  
Vol 78 (1) ◽  
pp. 431-444 ◽  
Author(s):  
Kang Bian ◽  
Jian Liu ◽  
Zhenping Liu ◽  
Shangge Liu ◽  
Fei Ai ◽  
...  
Keyword(s):  
Large Deformation ◽  
Soft Rock ◽  
Rock Tunnels

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 Research on Deformation Mechanisms of a High Geostress Soft Rock Roadway and Double-Shell Grouting Technology

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Fengnian Wang ◽  
Shizhuang Chen ◽  
Pan Gao ◽  
Zhibiao Guo ◽  
Zhigang Tao
Keyword(s):  
Mechanical Properties ◽  
Rock Mass ◽  
Large Deformation ◽  
Coal Mine ◽  
Soft Rock ◽  
In Situ Stress ◽  
Deformation Monitoring ◽  
Deformation And Failure ◽  
Working Face ◽  
High Geostress

In this study, the deformation characteristics and mechanical properties of coal and rock mass in the S2N5 working face of the Xiaokang coal mine are analyzed to address the problem of large deformation of soft rocks with high in situ stress surrounding roadways. Through a newly developed grouting pipe, a double-shell grouting technology, consisting of low-pressure grouting and high-pressure split grouting, is proposed for the Xiaokang coal mine. In addition, the effect of grouting is evaluated by borehole peeping and deformation monitoring. The results show that the double-shell grouting technology can effectively improve the overall mechanical properties of the surrounding coal and rock mass, preventing the large deformation and failure of the roadway. This technology can be useful when analyzing and preventing large deformation of soft rock roadways.

scholarly journals Field Tests and research of Large Deformation Control Measures for Soft Rock Tunnel with High Geostress

2020 ◽  
Vol 570 ◽  
pp. 042006
Author(s):  
Xiaoming Sun ◽  
Bo Zhang ◽  
Yong Zhang ◽  
Xiaobing Qiao ◽  
Zhijiao Wang ◽  
...  
Keyword(s):  
Large Deformation ◽  
Field Tests ◽  
Soft Rock ◽  
Control Measures ◽  
Deformation Control ◽  
High Geostress ◽  
Rock Tunnel

Analysis of Deformation Mechanism and Control Technology of Soft Rock Tunnel with High Geostress

2014 ◽  
Vol 638-640 ◽  
pp. 794-797
Author(s):  
Fei Pan ◽  
Sheng Guo Cheng
Keyword(s):  
Deformation Mechanism ◽  
Traffic Engineering ◽  
Soft Rock ◽  
Control Technology ◽  
Engineering Construction ◽  
Deformation Control ◽  
High Geostress ◽  
Rock Tunnels ◽  
Rock Tunnel ◽  
And Control

With the development of transportation construction, soft rock tunnel with high geostress construction has become a key problem to overcome of traffic engineering construction. In order to explore the deformation mechanism and control technology of soft rock tunnel with high geostress, Xiakou tunnel engineering as an example, the geological characteristics and deformation characteristics of the tunnel were analyzed, to obtain the deformation mechanism of soft rock tunnels with high geostress, and to develop deformation control technology, the results provide a basis and reference for the domestic and foreign the similar engineering construction.

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.

A case study on large deformation failure mechanism of deep soft rock roadway in Xin'An coal mine, China

2017 ◽  
Vol 217 ◽  
pp. 89-101 ◽  
Author(s):  
Sheng-Qi Yang ◽  
Miao Chen ◽  
Hong-Wen Jing ◽  
Kun-Fu Chen ◽  
Bo Meng
Keyword(s):  
Large Deformation ◽  
Failure Mechanism ◽  
Coal Mine ◽  
Soft Rock ◽  
Soft Rock Roadway ◽  
Rock Roadway

scholarly journals A Case Study on Large Deformation Failure Mechanism and Control Techniques for Soft Rock Roadways in Tectonic Stress Areas

2019 ◽  
Vol 11 (13) ◽  
pp. 3510 ◽  
Author(s):  
Xue ◽  
Gu ◽  
Fang ◽  
Wei
Keyword(s):  
Numerical Simulation ◽  
Large Deformation ◽  
Failure Mechanism ◽  
Support System ◽  
Soft Rock ◽  
Tectonic Stress ◽  
Geological Conditions ◽  
Soft Rock Roadway ◽  
Rock Roadway

Large deformation and failure of soft rock are pressing problems in the mining practice. This paper provides a case study on failure mechanisms and support approaches for a water-rich soft rock roadway in tectonic stress areas of the Wangzhuang coal mine, China. Mechanic properties of rock mass related to the roadway are calibrated via a geological strength index method (GSI), based on which a corresponding numerical simulation model is established in the Universal Discrete Element Code (UDEC) software. The failure mechanism of the roadway under water-saturating and weathering conditions is revealed by field tests and numerical simulation. It is found that the stress evolution and crack development are affected by weathering and horizontal tectonic stresses. The roadway roof and floor suffer from high stress concentration and continuous cracking, and are consequently seen with rock failure, strength weakening, and pressure relief. Unfortunately, the current support system fails to restrain rock weathering and strength weakening, and the roadway is found with serious floor heave, roof subsidence, and large asymmetric deformation. Accordingly, a new combined support system of “bolt–cable–mesh–shotcrete + grouting” is proposed. Moreover, numerical simulation and field testing are conducted to validate the feasibility and effectiveness of the proposed approach, the results of which demonstrate the capacity of the proposed new support method to perfectly control the surrounding rock. Findings of this research can provide valuable references for support engineering in the soft rock roadway under analogous geological conditions.

scholarly journals Frame Structure and Engineering Applications of the Multisource System Cloud Service Platform of Monitoring of the Soft Rock Tunnel

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Fengnian Wang ◽  
Songyang Yin ◽  
Aipeng Guo ◽  
Zhicai Wang ◽  
Meng Mi ◽  
...  
Keyword(s):  
Real Time ◽  
Large Deformation ◽  
Monitoring System ◽  
Early Warning ◽  
Soft Rock ◽  
Cloud Service ◽  
Surrounding Rock ◽  
Anchor Cable ◽  
Time Operation ◽  
Rock Tunnels

Throughout engineering construction, large deformation disasters in soft rock tunnels are encountered increasingly frequently. Therefore, structural health monitoring not only ensures accurate construction management but also provides a basis for dynamic adjustment of the support structure. The existing monitoring technology has certain shortcomings, such as poor anti-interference ability, non-real-time operation, and great security risks. Consequently, high-precision real-time monitoring has become a key scientific issue in tunnel engineering. For this work, multisource information fusion technology was adopted, while data security reserve systems, such as cloud server (ECS) based on the fiber Bragg grating multisource sensing system, cloud database (RDS), and cloud website, were embedded into the No. 2 inclined shaft of the Muzhailing tunnel. Based on the negative Poisson’s ratio (NPR) anchor cable control technology for large deformation of the soft rock in the No. 2 inclined shaft of the Muzhailing tunnel, reasonable and effective intelligent monitoring was carried out for tunnel construction. Monitoring and early warning cloud service platforms, based on the Internet of Things and cloud technology, could quickly produce query and statistic tunnel monitoring information. The monitoring system provided the collection, transmission, storage, processing, and early warning information sending of data, such as NPR anchor cable axial force, steel arch stress, deep surrounding rock displacement, surrounding rock deformation, and contact pressure between primary support with secondary lining. This monitoring system ensured construction safety and provided monitoring application case support for the related problems of similar projects.

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