scholarly journals Research on Supporting Measure at Intersection of Inclined Shaft and Major Tunnel in Highway

2020 ◽  
Vol 2020 ◽  
pp. 1-15 ◽  
Author(s):  
Xiaoming Sun ◽  
Bo Zhang ◽  
Zhigang Tao ◽  
Chengwei Zhao ◽  
Jian Wang
Keyword(s):  
Large Deformation ◽  
Three Dimensional ◽  
Surrounding Rock ◽  
Local Pressure ◽  
Tunnel Support ◽  
Maximum Deformation ◽  
Anchor Cable ◽  
Constant Resistance ◽  
Before And After ◽  
High Geostress

The deformation characteristics of the rock mass in the intersection between the Muzhailing highway tunnel and the inclined shaft is a complicated three-dimensional problem. Under the influence of high geostress, large deformation hazards may occur in the surrounding rock. Taking this as the research background, this paper analyzes the deformation mechanism of surrounding rock before and after prestressed anchor cable support through numerical simulation. Then, through theoretical analysis, a new tunnel support method using high prestressed constant resistance and large deformation anchor cable was proposed. The field monitoring results show that the constant resistance and large deformation anchor cable support can well control the deformation of surrounding rock, and the maximum deformation is within 300 mm. At the same time, the constant resistance anchor cable can always maintain a high prestress, which makes the stress of the surrounding rock uniform, and reduces the risk of damage to the steel arch due to local pressure. Moreover, the support method limits the expansion of the plastic zone and improves the overall stability of the surrounding rock.

scholarly journals Application of Constant Resistance and Large Deformation Anchor Cable in Soft Rock Highway Tunnel

2019 ◽  
Vol 2019 ◽  
pp. 1-19 ◽  
Author(s):  
Xiaoming Sun ◽  
Bo Zhang ◽  
Li Gan ◽  
Zhigang Tao ◽  
Chengwei Zhao
Keyword(s):  
Large Deformation ◽  
Support System ◽  
Field Tests ◽  
Soft Rock ◽  
Internal Force ◽  
Surrounding Rock ◽  
Gansu Province ◽  
Tunnel Engineering ◽  
Anchor Cable ◽  
Constant Resistance

Muzhailing Highway Extra-long Tunnel in Lanzhou, Gansu Province, China, belongs to the soft rock tunnel in the extremely high geostress area. During the construction process, large deformation of the soft rock occurred frequently. Taking the no. 2 inclined shaft of Muzhailing tunnel as the research object, an NPR (negative Poisson’s ratio) constant resistance and large deformation anchor cable support system based on high prestress force, constant resistance, and releasing surrounding rock pressure was proposed. The characteristics of the surrounding rock under the steel arch support and NPR anchor cable support were compared and analyzed by using 3DEC software. A series of field tests were conducted in the no. 2 inclined shaft, and the rock strength, displacement of the surrounding rock, deep displacement of the surrounding rock, internal force of steel arch, and axial force of anchor cable were measured to study the application effect of the NPR anchor cable support system in tunnel engineering. Moreover, the 3DEC numerical simulation results were compared with the field test results. The research results show that the application of NPR constant resistance and large deformation anchor cable support system in tunnel engineering has achieved good results, and it plays a significant role in controlling the large deformation of the tunnel surrounding rock.

scholarly journals Constant Resistance and Yielding Support Technology for Large Deformations of Surrounding Rocks in the Minxian Tunnel

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Jinyan Fan ◽  
Zhibiao Guo ◽  
Xiaobing Qiao ◽  
Zhigang Tao ◽  
Fengnian Wang ◽  
...  
Keyword(s):  
Large Deformation ◽  
Large Deformations ◽  
Field Tests ◽  
Field Application ◽  
Deformation Monitoring ◽  
Surrounding Rock ◽  
Maximum Deformation ◽  
Constant Resistance ◽  
Structural Deformations ◽  
Yielding Support

During the excavation of the Minxian tunnel, problems of large deformations of surrounding rocks and failure of support structures appeared frequently, which caused serious influences on construction safety and costs of the tunnel. Based on laboratory analysis of mineral composition and field investigations on deformation characteristics of the surrounding rocks, the large deformation mechanism of surrounding rocks of the tunnel was considered as water-absorbing swelling molecules of carbonaceous slate and stress-induced asymmetric structural deformations of the surrounding rocks. The structural deformations of surrounding rocks mainly include bending deformation, interlayer sliding, and crushing failure of local rock blocks. Then, a new constant resistance and yielding support technology based on the constant resistance and large deformation (CRLD) anchor cable was proposed to control large deformations of surrounding rocks. The field tests and deformation monitoring were carried out. The monitoring results showed that compared with original support measure, the surrounding rock deformations, stresses of primary supports, and permanent lining using new support technology decreased greatly. Among them, the maximum deformation of surrounding rock was only 73 mm. The effects of field application and results of deformation monitoring showed that the new support technology can effectively control large deformations of the surrounding rocks in the Minxian tunnel.

scholarly journals Numerical Simulation on Large Deformation of Weak Rock Mass Tunnel Under High Geostress

2018 ◽  
Vol 175 ◽  
pp. 03025
Author(s):  
Feng Zhou ◽  
Hongjian Jiang ◽  
Xiaorui Wang
Keyword(s):  
Rock Mass ◽  
Large Deformation ◽  
Lateral Pressure ◽  
Simulation Analysis ◽  
Pressure Coefficient ◽  
Surrounding Rock ◽  
Analog Simulation ◽  
Lateral Pressure Coefficient ◽  
High Geostress ◽  
The Stability

The problem about the stability of tunnel surrounding rock is always an important research object of geotechnical engineering, and the right or wrong of the result from stability analysis on surrounding rock is related to success or failure of an underground project. In order to study the deformation rules of weak surrounding rock along with lateral pressure coefficient and burying depth varying under high geostress and discuss the dynamic variation trend of surrounding rock, the paper based on the application of finite difference software of FLAC3D, which can describe large deformation character of rock mass, analog simulation analysis of surrounding rock typical section of the class II was proceeded. Some conclusions were drawn as follows: (1) when burying depth is invariable, the displacements of tunnel surrounding rock have a trend of increasing first and then decreasing along with increasing of lateral pressure coefficient. The floor heave is the most sensitive to change of lateral pressure coefficient. The horizontal convergence takes second place. The vault subsidence is feeblish to change of lateral pressure coefficient. (2) The displacements of tunnel surrounding rock have some extend increase along with increasing of burying depth. The research conclusions are very effective in analyzing the stability of surrounding rock of Yunling tunnel. These are going to be a reference to tunnel supporting design and construction.

Numerical Analysis on Tunnel Support Nearly Mined Area and Stability Evaluation

2011 ◽  
Vol 255-260 ◽  
pp. 3749-3753 ◽  
Author(s):  
Wei Jian Yu
Keyword(s):  
Numerical Analysis ◽  
Plastic Region ◽  
Surrounding Rock ◽  
Stability Evaluation ◽  
Tunnel Support ◽  
Anchor Cable ◽  
Working Face ◽  
Flac 2D

Since deformations of tunnel nearly mined area are larger, the reasonable support is very important. According to a side working face tunnel nearly mined area in one Mine, FLAC 2D was applied to numerical analyze on two type bolt net supported tunnel of “short bolt and long anchor cable” and “full anchor cable”. The results showed as follows: (1) plastic region of surrounding rock relatively large, which supported by short bolt and long anchor cable. Displacement reaches 27cm, the effect of this type supporting not significant; (2) The supporting of full anchor cable can effectively control deformation of tunnel, displacement less than 5cm, plastic region of surrounding rock also less than 2.3m. So, the supporting of full anchor cable can meet operating requirements.

The Three Dimensional Numerical Analysis of Consolidation of Rock Mass with Pre-Stressed Anchor Cables

2011 ◽  
Vol 179-180 ◽  
pp. 9-12
Author(s):  
Zhong Chang Wang
Keyword(s):  
Axial Stress ◽  
Three Dimensional ◽  
White Paper ◽  
Equivalent Strain ◽  
Surrounding Rock ◽  
Concentration Zone ◽  
Compression Zone ◽  
Anchor Cable ◽  
Area Use ◽  
Working Mechanisms

A new method of equivalent pre-stress is suggested by used of methods of equivalent strain and temperature according to different working mechanisms between free segment and consolidated segment of anchor cable. The mechanism on reinforcement of pre stress anchor cable is simulated by finite element. It is concluded that the axial stress and displacement of consolidated segment tends to be initiated gets to decrease with the increase of depth. The shear stress of the out end of free segment increases rapidly and arrives at the biggest value, then decreases slowly with the increase of depth. The stress and displacement of rock is distributed in axi-symmetric mode with anchor cables. The concentration zone in shape of a funnel is formed at the out anchor head. The concentration zone in tension is formed at the inner consolidated segment. The surrounding rock at consolidated segment is the interface in shape of paraboloid between the compression zone and tension zone.This document explains and demonstrates how to prepare your camera-ready manuscript for Trans Tech Publications. The best is to read these instructions and follow the outline of this text. The text area for your manuscript must be 17 cm wide and 25 cm high (6.7 and 9.8 inches, resp.). Do not place any text outside this area. Use good quality, white paper of approximately 21 x 29 cm or 8 x 11 inches (please do not change the document setting from A4 to letter). Your manuscript will be reduced by approximately 20% by the publisher. Please keep this in mind when designing your figures and tables etc.

Study on Stability of Layered Roof Surrounding Rock Reinforced by Anchor in Rectangular Roadway

2014 ◽  
Vol 638-640 ◽  
pp. 864-869
Author(s):  
Zhong Ming Zhao ◽  
Zhi Yuan Xi
Keyword(s):  
Shear Stress ◽  
Stress Distribution ◽  
Maximum Shear Stress ◽  
Maximum Tensile Stress ◽  
Surrounding Rock ◽  
Point Location ◽  
Anchor Cable ◽  
Mechanics Of Materials ◽  
Before And After ◽  
Dangerous Point

Under the assumptions of plane strain, vertical normal stress and shear stress distribution in surrounding rock of rectangular tunnels before and after installing anchor cable are studied. And according to the mechanics of materials, the formula of stress distribution in the roof is corrected. According to the corrected formula of the stress distribution, the dangerous points are found. And the dangerous point location does not change before and after installing anchor cable. It still locates in the middle and ends of roadway roof. Just the dangerous stress value decreases after installing anchor cable. There are the maximum tensile stress in the midpoint roof and the maximum shear stress on both ends of the roof.

scholarly journals Static tension test and the finite element analysis of constant resistance and large deformation anchor cable

2018 ◽  
Vol 10 (12) ◽  
pp. 168781401881063 ◽  
Author(s):  
Zhigang Tao ◽  
Zhen Zhu ◽  
Wenshuai Han ◽  
Chun Zhu ◽  
Wenfang Liu ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Finite Element ◽  
Large Deformation ◽  
Elongation Rate ◽  
Tension Test ◽  
Experimental Results ◽  
Engineering Practice ◽  
Static Tension ◽  
Anchor Cable ◽  
Constant Resistance

Compared to the traditional anchor cable, the constant resistance and large deformation anchor cable (constant resistance and large deformation anchor cable) has good applications in many fields of geotechnical engineering. Through the indoor static tension test, this study reveals the variation law of constant resistance, axial strain, the outer diameter of the sleeve, and the thermal effect of constant resistance and large deformation anchor cables during static tension. The ANSYS software was used for the first time to establish the nonlinear thermomechanical coupling analysis model of the finite element structure of constant resistance and large deformation anchor cables for the numerical calculation and analysis of static tension mechanical properties of constant resistance anchor cables. The experimental results that the average elongation of this batch of constant resistance anchor cables is 905 mm with an average elongation rate of 45.2% and an average constant resistance of 650 kN prove that constant resistance anchor cables are characterized by good constant resistance and large deformation, which can meet the requirements of deep soft rock roadway support and advanced landslide monitoring. The numerical simulation results show that the elongation of this type of anchor cables is 902 mm with an elongation rate of 45.1% and a constant resistance of 660 kN, which are basically consistent with the experimental results, indicating that numerical simulation is relatively accurate for testing the mechanical property of constant resistance and large deformation anchor cables, and the combination of the indoor test and numerical simulation provides the reference for engineering practice and design optimization of constant resistance and large deformation anchor cables.

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.

scholarly journals Constant-Resistance, Rigid, and Flexible Coupling Support Technology for Soft Rock Entrances in Deep Coal Mines:A Case Study in China

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Yong Zhang ◽  
Chengwei Zhao ◽  
Ming Jiang ◽  
Jiaxuan Zhang ◽  
Chen Chen ◽  
...  
Keyword(s):  
Large Deformation ◽  
Support System ◽  
Soft Rock ◽  
High Strength ◽  
Surrounding Rock ◽  
Constant Resistance ◽  
The Stability ◽  
Control Principle ◽  
Soft Rock Roadway ◽  
Rock Roadway

The stability control of a soft rock roadway is a crucial problem for sustainable utilization of limited coal resources in deep mining practices. To solve it, the soft rock types and failure mechanism of −890 entrance surrounding rock have been analyzed, taking Daqiang Coal Mine of China as an engineering example. The analysis shows that the damage to the surrounding rock was characterized by asymmetry, large deformation, severe damage, and extended durations. The surrounding rock can be divided into high-stress-jointed-strong expansion soft rock based on S-M scanning and mineral analysis. Numerical simulation is used to reproduce the failure process of the original supporting system and analyze the deformation of the surrounding rock, range of plastic zone, and distribution of the stress field. The failure mechanism is thus defined for a deep soft rock roadway. Combined with the above studies, the deformation mechanics of the surrounding rock is summarized as type IABIIABIIIABC. The stability transformation mechanism of the surrounding rock is proposed, based on which the control principle of deformation stability of a surrounding rock is formed. According to the control principle, “high strength support controls the surrounding rock deformation. The large deformation of the flexible support system releases the accumulated energy to the surrounding rock, and long-term deformation of the surrounding rock is controlled by high strength truss support.” Meanwhile, the constant-resistance, rigid, and flexible coupling (CRRFC) support system is proposed. The numerical analysis demonstrated that the CRRFC support system can effectively reinforce the shallow surrounding rock and improve the bearing capacity. Simultaneously, the development of the surrounding rock malignant plastic zone is effectively controlled. The application results show that the large deformation of the roadway can be effectively controlled by the CRRFC support system, which provides applications for similar engineering.

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