Evaluation of Double-Layer Initial Support Effect of Bench Method in High Stress Soft Rock Tunnel

2022 ◽  
Vol 11 (01) ◽  
pp. 16-24
Author(s):  
易 彭
Keyword(s):  
Double Layer ◽  
High Stress ◽  
Soft Rock ◽  
Support Effect ◽  
Initial Support ◽  
Rock Tunnel

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.

Numerical Analysis for Thermal-Chemical-Stress Coupling in Deep Rock Creep Properties

2013 ◽  
Vol 561 ◽  
pp. 657-662
Author(s):  
Yan Chun Wang ◽  
Yuan Li ◽  
Jian Guang Li
Keyword(s):  
Ph Value ◽  
Coupling Effect ◽  
High Stress ◽  
Soft Rock ◽  
Effect Of Temperature ◽  
Creep Equation ◽  
Creep Properties ◽  
Rock Creep ◽  
Deep Rock ◽  
Rock Tunnel

The control equations for analyzing coupled thermal chemical-mechanical phenomena of deep rocks are established. Using creep equation by experimental data, 3D numerical simulation for creep properties of deep soft tunnel under coupling effect of temperature field, chemical field and stress field are conducted by ANSYS, and different effects of these fields on deep soft rock tunnel creep properties are analyzed, whats more time-creep curves of different temperature, pH value and stress deviation of the mid-point of the top of tunnel are obtained. Effect of these three fields on creep characteristics of deep soft rock cant be ignored. Under deep complex environment, high-stress is main factor of tunnel creep; creep increasing with temperature increasing. From simulation results, we get whether acidic environment or alkaline environment causes significantly stronger corrosive effect on the rock mass than the neutral environment, and increases its creep.

Research on Test of Reducing Deformation of Soft Rock Tunnel with High Stress Level by Pilot Heading

2012 ◽  
Vol 170-173 ◽  
pp. 1565-1568
Author(s):  
Xin Yan ◽  
Yang Sheng Ye
Keyword(s):  
High Stress ◽  
Soft Rock ◽  
Primary Reinforcement ◽  
Geological Exploration ◽  
Ventilation Condition ◽  
Ground Stress ◽  
High Stress Level ◽  
Rock Tunnel ◽  
Primary Support ◽  
Surrounding Rock Deformation

Generally speaking, the pilot heading is aways used for geological exploration，speeding up the construction，improving the draining and Ventilation condition, promoting efficiency of residue transporting. When tunneling on high ground stress soft rock region，the pilot heading will play a more important role. Lan yu line Mu Zhai ling tunnel main passes through the region of carbonaceous slate. Due to the high ground stresses, the primary reinforcement system underwent large deformation, evenmore the lining is cracked. Through excaving the pilot heading, can relief the stress. Then enlarg the pilot heading to main tunnel, the deformation of primary support will be reduced, and the tunnel will be stable. Compare the "pilot and enlarging" excavation method with bench excavation method on surrounding rock deformation. As the result, the "pilot and enlarging" excavation method is effective for control of the deformation of the tunnel.

Analysis of Soft Rock Tunnel Mechanics Effects Based on Strain Softening Model of Surrounding Rock

2012 ◽  
Vol 424-425 ◽  
pp. 520-525
Author(s):  
Jie Hong Zhang
Keyword(s):  
Numerical Analysis ◽  
Strain Softening ◽  
Mechanical Response ◽  
High Stress ◽  
Soft Rock ◽  
Mechanical Effect ◽  
Surrounding Rock ◽  
Plastic Range ◽  
Construction Design ◽  
Rock Tunnel

Aiming at mechanical response of soft surrounding tunnel affected by high stress, the mechanical effect in the process of excavation and supporting of surrounding rockmass was analyzed by softening model. First of all, mechanics properties of soft surrounding rock and strain softening model have been discussed. Then, based on strain softening model, numerical analysis was carried out, and stress and displacement field, plastic range in the in the process of excavation and supporting was obtained. The result was very useful for the optimization of construction design and perfection for supporting program.

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.

The Simulation Analysis of Large Cross-Section Soft Rock Tunnel Excavation under the Bias Terrain

2011 ◽  
Vol 90-93 ◽  
pp. 1853-1858
Author(s):  
Gang Zhang ◽  
Hong Bing Liu
Keyword(s):  
Soft Rock ◽  
Internal Force ◽  
Structure Design ◽  
Surrounding Rock ◽  
Tunnel Excavation ◽  
Advantages And Disadvantages ◽  
Area Distribution ◽  
Tunnel Design ◽  
Initial Support ◽  
Rock Tunnel

Abstract: Taking a High-speed railway tunnel as the background, This paper analyses not only the stress and displacement of surrounding rock , the plastic area distribution and size, but also the size and distribution of initial support internal force in two excavation schemes, based on the criterion of underground engineering structure design theory and rock elastic-plastic succumb Drucker-Prager, Under the guidance of New Austria Tunneling Method, this paper makes numerical simulation of soft rock tunnel excavation in large sections and initial support with the finite software ANSYS11.0. The stress and displacement of surrounding rock and the plastic area distribution and size under two excavation schemes are analyzed, the size and distribution of initial support internal force under two excavation schemes are also investigated .By comprehensive comparing advantages and disadvantages of two schemes, this paper makes some significant conclusions and gives reference for the similar tunnel design and construction.

scholarly journals Research on Supporting Method for High Stressed Soft Rock Roadway in Gentle Dipping Strata of Red Shale

Minerals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 423
Author(s):  
Chunde Ma ◽  
Jiaqing Xu ◽  
Guanshuang Tan ◽  
Weibin Xie ◽  
Zhihai Lv
Keyword(s):  
Failure Process ◽  
High Stress ◽  
Soft Rock ◽  
In Situ Stress ◽  
Mechanical Parameters ◽  
Deformation And Failure ◽  
Deep Mine ◽  
Plastic Energy ◽  
Roadway Stability ◽  
Phosphate Mine

Red shale is widely distributed among the deep mine areas of Kaiyang Phosphate Mine, which is the biggest underground phosphate mine of China. Because of the effect of various factors, such as high stress, ground water and so on, trackless transport roadways in deep mine areas were difficult to effectively support for a long time by using traditional supporting design methods. To deal with this problem, some innovative works were carried out in this paper. First, mineral composition and microstructure, anisotropic, hydraulic mechanical properties and other mechanical parameters of red shale were tested in a laboratory to reveal its deformation and failure characteristics from the aspect of lithology. Then, some numerical simulation about the failure process of the roadways in layered red shale strata was implemented to investigate the change regulation of stress and strain in the surrounding rock, according to the real rock mechanical parameters and in-situ stress data. Therefore, based on the composite failure law and existing support problems of red shale roadways, some effective methods and techniques were adopted, especially a kind of new wave-type bolt that was used to relieve rock expansion and plastic energy to prevent concentration of stress and excess deformation. The field experiment shows the superiorities in new techniques have been verified and successfully applied to safeguard roadway stability.

scholarly journals Construction Monitoring and Numerical Simulation of Water-Rich Tuff Soft Rock Tunnel

2020 ◽  
Vol 455 ◽  
pp. 012163
Author(s):  
Fangliang Chen ◽  
Kaihua Zeng ◽  
Xuejun Li ◽  
Manqing Xu ◽  
Hongtao Dai
Keyword(s):  
Numerical Simulation ◽  
Soft Rock ◽  
Construction Monitoring ◽  
Rock Tunnel

Experimental research on hydrophilic characteristics of natural soft rock at high stress state

2015 ◽  
Vol 25 (3) ◽  
pp. 489-495 ◽  
Author(s):  
Hongyun Guo ◽  
Xiangyang Lei ◽  
Yumei Zhang ◽  
Guoxing Yang ◽  
Zhang Niu
Keyword(s):  
Stress State ◽  
Experimental Research ◽  
High Stress ◽  
Soft Rock

High Strength Combined Support Technology in Deep High Stress Soft Rock Roadway

2012 ◽  
Vol 524-527 ◽  
pp. 598-603
Author(s):  
Nian Jie Ma ◽  
Zhi Qiang Zhao ◽  
Hua Zhao ◽  
Li Shuai Jiang
Keyword(s):  
High Stress ◽  
Soft Rock ◽  
High Strength ◽  
Parameter Determination ◽  
Test Results ◽  
Actual Measurement ◽  
Computer Numerical Simulation ◽  
Soft Rock Roadway ◽  
Rock Roadway

In order to solve the serious damage and repeat revision problem of high stress soft rock roadway in deep -950 level of Tangshan coal mine, based on the theory of the maximum stress level, together with the actual measurement of geostress and the laboratory mechanical parameters of rock-core and computer numerical simulation, the high strength combined support technology and supporting parameters are determined and the engineering test has been done. The engineering test results show that the parameter determination of high strength combined support technology, which based on the actual measurement of geostress, can effective solve the support issue of high stress soft rock roadway and provide useful experience for similar engineering problems.

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