scholarly journals Support Measures to Prevent the Deformation and Failure of a Carbonaceous Mudstone Tunnel

2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Yongdong Wang ◽  
Haitao Jiang ◽  
Xin Yan ◽  
Huiru Liang ◽  
Guoan Li ◽  
...  
Keyword(s):  
Soft Rock ◽  
Control Measures ◽  
Rock Stratum ◽  
Deformation And Failure ◽  
Pipe System ◽  
Deformation Control ◽  
Support Measure ◽  
Connection System ◽  
Prevention And Control Measures ◽  
Rock Tunnel

A carbonaceous mudstone tunnel is a type of soft rock tunnel. There is little research on the prevention and control measures for the deformation and failure of carbonaceous mudstone tunnels. In this article, we investigated the construction of the Qiguding carbonaceous mudstone tunnel in Meizhou City, Guangdong Province, China. We monitored and analyzed the deformation and stress characteristics of a section under the original support scheme. The monitoring data showed that this section had large peripheral convergence, vault subsidence, steel arch strain, and concrete strain. The deformations exhibited significant differences in the horizontal and vertical directions, eventually resulting in concrete cracking, steel arch bulging, and distortion in the section. The analysis showed that the primary mechanisms for the failure were the softening characteristics of the carbonaceous mudstone, the plastic rheology, and the shear slip of the rock stratum. Based on a comparative analysis and numerical simulation, we proposed a new support measure called the longitudinal rigid enlarged foundation that consists of a steel arch longitudinal connection system and a locking foot anchor pipe system. Several comparative tests were performed at the tunnel site. The results demonstrated the excellent performance and reliability of the proposed support scheme for the deformation control of the carbonaceous mudstone, providing a reference for similar projects.

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

Discussion for Displacement Control Criteria of Soft Rock Tunnel in the Seismic Area

2013 ◽  
Vol 353-356 ◽  
pp. 1440-1445
Author(s):  
Jin Hua Xu ◽  
Chuan He ◽  
Yi Zhou ◽  
Hai Bin Wu
Keyword(s):  
Cross Section ◽  
Soft Rock ◽  
Surrounding Rock ◽  
Great Earthquake ◽  
Displacement Control ◽  
Deformation Control ◽  
The One ◽  
Rock Tunnel ◽  
Control Criteria ◽  
Seismic Area

This paper studies on a certain highway project which passes through Longmen Shan fault zone, the one triggers 5.12 Wenchuan earthquakes directly. The region where the project resides is characterized by high percentage of soft rock mass, in particular the phyllite. Series of landslide have hitherto happened due to the instability of mountains along the highway which was caused by the great earthquake. Besides, since the phyllite-dominated rock was low-strength and easily soften by water, engineering disasters such as cave-in and large deformation of surrounding rock occurred frequently during the construction of tunnels located along the highway. The existing deformation control criteria fail gradually to fill the requirements of safe tunnelling. The author analyzed monitoring data from different tunnels with different cross-section types and different surrounding rock conditions, referred to relevant norms and eventually proposes new deformation control criteria based on allowable deformation and deformation rate.

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.

Squeezing deformation control during bench excavation for the Jinping deep soft-rock tunnel

2020 ◽  
Vol 116 ◽  
pp. 104761
Author(s):  
Chuanqing Zhang ◽  
Guojian Cui ◽  
Yang Zhang ◽  
Hui Zhou ◽  
Ning Liu ◽  
...  
Keyword(s):  
Soft Rock ◽  
Deformation Control ◽  
Rock Tunnel

scholarly journals Application of Modified Hoek–Brown Strength Criterion in Water-Rich Soft Rock Tunnel

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Xianghui Deng ◽  
Yuncai Wang ◽  
Rui Wang ◽  
Daohong Xia ◽  
Zhiqing Zhao
Keyword(s):  
Soft Rock ◽  
Strength Criterion ◽  
Surrounding Rock ◽  
Calculation Formula ◽  
Rock Stratum ◽  
Rock Stability ◽  
Deformation Limit ◽  
Disturbance Factor ◽  
The Stability ◽  
Rock Tunnel

When a tunnel is excavated in the water-rich soft rock stratum, the strength of the soft rock is greatly reduced due to the seepage of groundwater. The condition may result in engineering accidents, such as large deformation, limit invasion, and even local collapse of the tunnel. Therefore, it is very important to research the stability of the surrounding rock in the water-rich soft rock tunnel. The water-rich disturbance factor considering the seepage influence of groundwater and blasting disturbance is proposed, and the generalized Hoek–Brown strength criterion is modified on the basis of the immersion softening test of soft rock. In accordance with the classical elastic–plastic mechanics theory, the stress, strain, and displacement calculation formulas of the tunnel surrounding rock are derived. The displacement of tunnel surrounding rock is analyzed using the derived formula and the modified Hoek–Brown strength criterion and then compared with the measured value. Results show that the displacement of surrounding rock, which is calculated by modified Hoek–Brown strength criterion considering water-rich disturbance factor and the displacement calculation formula, is close to the measured deformation of surrounding rock in water-rich soft rock tunnel, and the error is small. Therefore, the modified Hoek–Brown strength criterion can be applied to the water-rich soft rock tunnel, and the derived displacement calculation formula can accurately calculate the deformation of tunnel surrounding rock. It is of great significance to the study of surrounding rock stability of water-rich soft rock tunnel.

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 Research on the Law of Large-Scale Deformation and Failure of Soft Rock Based on Microseismic Monitoring

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Feng Chen ◽  
Tianhui Ma ◽  
Chun’an Tang ◽  
Yanhong Du ◽  
Zhichao Li ◽  
...  
Keyword(s):  
Monitoring System ◽  
Large Scale ◽  
Failure Process ◽  
Soft Rock ◽  
Microseismic Monitoring ◽  
Surrounding Rock ◽  
Deformation And Failure ◽  
Microseismic Events ◽  
Rock Tunnel ◽  
Microseismic Event

Based on the existing Canadian ESG microseismic monitoring system, a mobile microseismic monitoring system for a soft rock tunnel has been successfully constructed through continuous exploration and improvement to study the large-scale nucleation and development of microfractures in the soft rock of the Yangshan Tunnel. All-weather, continuous real-time monitoring is conducted while the tunnel is excavated through drilling and blasting, and the waveform characteristics of microseismic events are analysed. Through the recorded microseismic monitoring data, the variation characteristics of various parameters (e.g., the temporal, spatial, and magnitude distributions of the microseismic events, the frequency of microseismic events, and the microseismic event density and energy) are separately studied during the process of large-scale deformation instability and failure of the soft rock tunnel. The relationship between the deterioration of the rock mass and the microseismic activity during this failure process is consequently discussed. The research results show that a microseismic monitoring system can be used to detect precursors; namely, the microseismic event frequency and energy both will appear “lull” and “active” periods during the whole failure process of soft rock tunnel. Two peaks are observed during the evolution of failure. When the second peak occurs, it is accompanied by the destruction of the surrounding rock. The extent and strength of the damage within the surrounding rock can be delineated by the spatial, temporal, and magnitude distributions of the microseismic events and a microseismic event density nephogram. The results of microseismic analysis confirm that a microseismic monitoring system can be used to monitor the large-scale deformation and failure processes of a soft rock tunnel and provide early warning for on-site construction workers to ensure the smooth development of the project.

Discussion of Tunnel Displacement Control Reference Group the Relevance of Factors for Earthquake Zone

2013 ◽  
Vol 353-356 ◽  
pp. 1446-1450
Author(s):  
Yi Zhou ◽  
Chuan He ◽  
Hai Bin Wu ◽  
Jin Hua Xu
Keyword(s):  
Reference Group ◽  
Soft Rock ◽  
Burial Depth ◽  
Displacement Control ◽  
Factors Affecting ◽  
Deformation Control ◽  
Construction Methods ◽  
Earthquake Zone ◽  
Rock Tunnel ◽  
Control Criterion

In order to explore the factors affecting the establishment of displacement control criterion for the soft rock tunnel in the earthquake region and then to provide basis for the following establishment of base values, this paper in the context of a highway soft-rock-tunnel passing through the Long-men-shan Fault, summarized the main influencing factors on the basis of the existing deformation control criterion and then proposed the main factors of deformation control criterion suited for the project after combining its own characteristics. The result revealed that: the burial depth of tunnels and the characteristic of the rock masses are critical factors affecting the deformation control criterion of the soft-rock tunnel in earthquake area; the construction methods and the cross-section dimensions are both the important factors for the deformation control criterion.

Research on construction method and deformation control technology of high ground stress interbedded soft rock tunnel

2020 ◽  
pp. 1-9
Author(s):  
Zhichun Fang ◽  
Zhengguo Zhu ◽  
Xinyu Chen
Keyword(s):  
Numerical Models ◽  
Soft Rock ◽  
Construction Method ◽  
Gansu Province ◽  
Control Measures ◽  
Deformation Characteristics ◽  
Deformation Control ◽  
Geological Conditions ◽  
Ground Stress ◽  
Rock Tunnels

The construction of tunnels is often long and deep buried tunnels, and the geological conditions are more complex. Based on Jianshan tunnel in Gansu Province, the special geological conditions such as high ground stress and weak interbedded surrounding rock make the excavation of tunnel easy to produce large deformation. In this article, the software finite difference software FLAC3D was used to establish numerical models and select the best construction method by comparing the deformation of the tunnel under different construction methods. Aiming at the deformation characteristics of soft rock tunnels in highland interbedded layers, the control measures of tunnel deformation are discussed. Mainly consider the two aspects of the bolt support plan and the second lining construction time, comprehensively compare the deformation characteristics of the tunnel, and select the best working condition. The research results show that the combination of three-step temporary invert method and three-step ultra short bench method is recommended for the tunnel construction; when the bench length is 4 m, the deformation control effect of the tunnel is the best; by improving the length and angle of the anchor rod, the deformation of the tunnel can also be well controlled.

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