scholarly journals Numerical Analysis of the Width Design of a Protective Pillar in High-Stress Roadway: A Case Study

2021 ◽  
Vol 2021 ◽  
pp. 1-18
Author(s):  
FuZhou Qi ◽  
ZhanGuo Ma ◽  
Ning Li ◽  
Bin Li ◽  
Zhiliu Wang ◽  
...  
Keyword(s):  
Numerical Modeling ◽  
Energy Density ◽  
Large Deformation ◽  
High Stress ◽  
Vertical Stress ◽  
Pillar Width ◽  
Modeling Approach ◽  
Roadway Stability ◽  
The Stability

The width design of protective pillars is an important factor affecting the stability of high-stress roadways. In this study, a novel numerical modeling approach was developed to investigate the relationship between protective pillar width and roadway stability. With the 20 m protective pillar width adopted in the field test, large deformation of roadways and serious damage to surrounding rocks occurred. According to the case study at the Wangzhuang coal mine in China, the stress changes and energy density distribution characteristics in protective pillars with various widths were analysed by numerical simulation. The modeling results indicate that, with a 20 m wide protective pillar, the peak vertical stress and energy density in the pillar are 18.5 MPa and 563.7 kJ/m3, respectively. The phenomena of stress concentration and energy accumulation were clearly observed in the simulation results, and the roadway is in a state of high stress. Under the condition of a 10 m wide protective pillar, the peak vertical stress and energy density are shifted from the pillar to roadway virgin coal region, with peak values of 9.5 MPa and 208.3 kJ/m3, respectively. The decrease in vertical stress and energy density improves the stability of the protective pillar, resulting in the roadway being in a state of low stress. Field monitoring suggested that the proposed 10 m protective pillar width can effectively control the large deformation of the surrounding rock and reduce coal bump risk. The novel numerical modeling approach and design principle of protective pillars presented in this paper can provide useful references for application in similar coal mines.

scholarly journals Stability Control Mechanism of High-Stress Roadway Surrounding Rock by Roof Fracturing and Rock Mass Filling

2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Fuzhou Qi ◽  
Zhanguo Ma ◽  
Dangwei Yang ◽  
Ning Li ◽  
Bin Li ◽  
...  
Keyword(s):  
Rock Mass ◽  
Large Deformation ◽  
High Stress ◽  
Coal Pillar ◽  
Surrounding Rock ◽  
Vertical Stress ◽  
Mining District ◽  
Coal Bump ◽  
Novel Approach ◽  
Roadway Stability

Large deformation of roadway and coal bump failures have always been the focus in deep underground engineering. By considering the Lu’an mining district in China, the failure mode and stability improvement process of high-stress roadways were analysed with the field tests and numerical simulations. The field test results showed that a great amount of deformation and serious damage occurred in surrounding rocks during panel retreat due to the suspended roof. A novel approach employing roof fracturing and collapsed rock filling effect was adopted to maintain the roadway stability. A numerical model was established with the Universal Distinct Element Code (UDEC) to research the fracturing characteristics between the roadway and gob roofs and the stress change in the surrounding rock. The modelling results demonstrated that, without fracturing roof, the peak vertical stress of the coal pillar was 18.3 MPa and the peak vertical stress of the virgin coal rib was 15.6 MPa. The roadway was in a state of high stress. With fracturing roof, the peak vertical stress of coal pillar was 9.3 MPa and the peak vertical stress of virgin coal rib was 13.4 MPa. The fractured rock mass in the gob expanded in volume and provided supporting resistance to the overlying strata, which relieved stress concentrations in the coal pillar. Field measurement results indicated that the roadway large deformation was successfully resolved during excavation and panel retreat after implementing the novel approach, providing useful references for the application of this novel approach in similar coal mines.

scholarly journals Case Study on the Stability Control of Broken Surrounding Rock in Roadway Excavation on the Edge of a Collapsed Stope Area

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Yabin Wu ◽  
Jianhua Hu ◽  
Chengyu Xie ◽  
Dongping Shi
Keyword(s):  
Laser Scanning ◽  
Failure Process ◽  
High Stress ◽  
Stability Control ◽  
Surrounding Rock ◽  
Tensile Failure ◽  
Scanning Method ◽  
The Stability ◽  
Underground Chamber

Predicting and controlling the collapse of surrounding rock (especially broken rock masses) in underground chambers is an important topic in mining and geotechnical engineering. Based on an example, this paper introduces a case study of surrounding rock stability control technology in stope mining around abandoned areas. Based on on-site coring, mechanical properties of rock samples, and on-site grouting reinforcement technology, the TRT6000 advanced geological prediction system was used to predict the stability status of the surrounding rock of the underground chamber. AUTODYNA software was used to build a dynamic coupling model for numerical simulation prediction and optimization of blasting parameters and to reveal the dynamic variation in the surrounding rock. The dynamic failure process of the surrounding rock of the chamber before and after optimization of the blasting parameters is simulated, and the deformation characteristics and damage and acoustic emission characteristics of the surrounding rock are clearly shown. The surrounding rock failure first appeared around the surface of the underground chamber because of the high stress concentration around the surface of the chamber after blasting; with the interaction between the explosive gas and the rock mass, the damaged area further propagated into the external rock, eventually leading to a large damage area. At the same time, there is a large tensile failure in the rock, resulting in expansion and rupture around the underground chamber. Finally, the 3D laser scanning method is used to verify the superiority of the optimized blasting initiation sequence. The new edge hole detonation sequence can effectively improve the blasting vibration and successfully control the further damage of the surrounding rock of the underground chamber, thus proving the edge hole drug pack. Moreover, the initiation mode of the delay stage of the side hole charge is determined. This study provides a useful reference for the stability control of surrounding rock in mining in mining areas.

scholarly journals Analysis of support system for a conveyance tunnel in the higher Himalayan zone: A case study on Upper Tamakoshi HEP, Nepal

2021 ◽  
Vol 4 (1) ◽  
pp. 90-97
Author(s):  
Kalyan Paudyal
Keyword(s):  
Numerical Modeling ◽  
Stress Concentration ◽  
Support System ◽  
Empirical Method ◽  
Vital Role ◽  
Site Specific ◽  
Specific Data ◽  
Overburden Thickness ◽  
The Stability

After excavation, insitu stress conditions are changed which lead deformation due to the stress concentration. For the stability in the excavated tunnel profile, appropriate support system is essential. To recommend the support system, site specific data are used from Higher Himalayan Region of Nepal. Study is focused on 3 m and 6 m size inverted D Shaped tunnel with three different overburden thickness. For the analysis of support system: Empirical method, Analytical method and Numerical Modeling are performed. Result obtained from the different approaches for three different overburden heights as well as for both size tunnels are compared and finally required support system is recommended. It was found significant change in deformations while increase in size of tunnel. Overburden thickness is also playing the vital role in this parameter but size effect is more prominent.

A Physical and Numerical Modeling for Launching of Jackets (Case Study on Balal PLQ Platform)

2008 ◽  
Vol 130 (3) ◽  
Author(s):  
M. R. Honarvar ◽  
Moharam D. Pirooz ◽  
Mohammad R. Bahaari
Keyword(s):  
Numerical Modeling ◽  
Physical Modeling ◽  
Oil Field ◽  
Physical Models ◽  
Lower Viscosity ◽  
The Difference ◽  
The Stability ◽  
Stability Of Structures ◽  
Similarity Laws

Platform structures are commonly utilized for various purposes including offshore drilling, processing, and support of offshore operations. A jacket is a supporting structure for deck facilities, stabilized by piles driven through it to the seabed. In a jacket design, operational and environmental loads are very important and must be intensively investigated to secure the stability of structures during their service life, as well as installation phase. The main purpose of this research is to evaluate the results of physical modeling for the launch operation of jackets from barge into the sea, as the most hazardous stage in the installation of a platform, and compare them to those of numerical modeling. Both physical and numerical modeling parameters are described and they are examined on a prototype platform, i.e., Balal oil field production and living quarter platform that is a 1700 tone, eight-legged jacket located in the center of Persian Gulf, some 100km distance from Iranian Lavan Island. It is found that both numerical and physical methods can describe the motion of the barge similarly well, but some differences are traced in the motion of jacket. The inequalities are, then, appeared to be due to the Froude-type parameters applied for modeling purpose. One notable fact investigated in this research is the necessity for choosing Reynolds–Froude type in the physical modeling of the launch, instead of Froude type. This is because, in addition to the importance of gravitational and inertial forces, the viscosity affects the drag hydrodynamic force, as well. It should be noted that viscosity and consequently drag coefficient in Froude type modeling cannot be quite applicable and this causes the difference observed between the results of physical and numerical modeling. Although there have been so many jacket launching designed and probably their physical models have been tested, but to the best of our knowledge from the literature, there was found no study on Reynolds–Froude physical modeling of jacket launch phenomenon. If one is interested in practicing a Reynolds-Froude physical modeling, it could be done either in a centrifuge test or by using a fluid with lower viscosity dependent on the scale of model, or even by finding a fluid (with new viscosity and new density) and a new gravity to have simultaneously the Froude and the Reynolds similarity laws satisfied.

A Physical and Numerical Modeling for Launching of Jackets: Case Study on Balal PLQ Platform

2007 ◽  
Author(s):  
M. R. Honarvar ◽  
Moharram D. Pirooz ◽  
Mohammad R. Bahari
Keyword(s):  
Numerical Modeling ◽  
Physical Modeling ◽  
Oil Field ◽  
Knowledge Based ◽  
Lower Viscosity ◽  
Operational Life ◽  
The Difference ◽  
The Stability ◽  
Stability Of Structures

Platform structures are commonly utilized for various purposes including offshore drilling, processing and support of offshore operations. A jacket is a supporting structure for deck facilities stabilized by leg piles through the seabed. In a jacket design, operational and environmental loads are very important and must be investigated intensively to secure the stability of structures during their operational life, as well as installation phase. The main purpose of this research is to evaluate and compare the results of physical and numerical modeling for the launch operation of jackets from barge into the sea, as the most hazardous stage in the installation of a platform. Both physical & numerical modeling basics are described and they are performed on Balal PLQ (Production and Living Quarter) platform that is one 8-legged, 1700-tone main jacket of Balal oil field, located in the center of Persian Gulf, some 100 kms distance from Iranian Lavan Island. It is found that both methods can describe the motion of the barge similarly well, but some differences are traced in the motion of jacket. Then, the inequalities are evaluated to be due to the Froude-type parameters chosen for modeling purpose. The most important result achieved in this research is the necessity of choosing Reinolds-Froude type for physical modeling of launching, instead of Froude-type. This is due to the effect of viscosity in drag hydrodynamic force in addition to the importance of gravitational and inertial forces. It should be noted that viscosity and consequently drag coefficient in Froude type modeling is not quite correct and causes the difference between the results of physical and numerical modeling. To our knowledge, based on the surveyed done in the literature, although there was no results found on the physical modeling of jacket launch to be addressed, but it seems that Reynolds-Froude modeling could be done either in a centrifuge test or by using a fluid with lower viscosity dependent on the scale of model.

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