Numerical investigation of the geomechanical response of adjacent backfilled stopes

2015 ◽  
Vol 52 (10) ◽  
pp. 1507-1525 ◽  
Author(s):  
Nooshin Falaknaz ◽  
Michel Aubertin ◽  
Li Li
Keyword(s):  
Rock Mass ◽  
Stress State ◽  
Friction Angle ◽  
Critical Issue ◽  
Surrounding Rock ◽  
Filling Sequence ◽  
Natural Stress ◽  
Simulation Results ◽  
Backfill Strength ◽  
Backfilled Stopes

Backfilling of mine stopes helps provide a safe workplace underground. The interaction between the backfill and surrounding rock mass has to be evaluated to ensure the secure application of backfill. This critical issue has led to much research on the stress state in single (isolated) backfilled stopes. However, the stress distribution in multiple openings that interact with each other has not yet been investigated as thoroughly. In this paper, the authors are using numerical simulations to evaluate the response of two adjacent backfilled stopes created in sequence, with a new assumption that is based on an explicit relationship between Poisson’s ratio and the internal friction angle of the backfill; as shown here, the use of this relationship can significantly modify the stress state in backfilled stopes. The simulation results, presented in terms of stresses, displacements, and strains, illustrate the influence of different parameters including backfill strength, pillar width, stope depth, rock mass stiffness, natural stress state, and excavation and filling sequence. Complementary aspects are also considered. A discussion follows on some of the characteristics and limitations of this investigation.

scholarly journals Primary Investigation on Equivalent Anchoring Method of Jointed Rock Mass Tunnel and Its Engineering Application

2020 ◽  
Vol 2020 ◽  
pp. 1-16
Author(s):  
Min Gao ◽  
Shanpo Jia
Keyword(s):  
Rock Mass ◽  
Three Dimensional ◽  
Engineering Application ◽  
Friction Angle ◽  
Jointed Rock ◽  
Jointed Rock Mass ◽  
Surrounding Rock ◽  
Rock Masses ◽  
Reinforcement Effect ◽  
Rock Bolts

Rock bolts, one of the main support structures of the tunnel, can improve the stress state and mechanical properties of the surrounding rocks. The rock bolts are simulated by bar or beam elements in present numerical calculations for most 2D tunnel models. However, the methods of simulating rock bolt in three-dimensional models are rarely studied. Moreover, there are too many rock bolts in the long-span tunnel, which are hardly applied in the 3D numerical model. Therefore, an equivalent anchoring method for bolted rock masses needs to be further investigated. First, the jointed material model is modified to simulate the anisotropic properties of surrounding rock masses. Then, based on the theoretical analysis of rock bolts in reinforcing mechanical properties of the surrounding rock masses, the equivalent anchoring method of the jointed rock mass tunnel is numerically studied. The equivalent anchoring method is applied to the stability analysis of a diversion tunnel in Western China. From the calculation results, it could be found that the reinforcement effect of rock bolts could be equivalently simulated by increasing the mechanical parameter value of surrounding rocks. For the jointed rock mass tunnel, the cohesion and internal friction angle of the surrounding rocks are improved as 1.7 times and 1.2 times of the initial value, which can simulate the reinforcement effect of rock bolts. Comparing with analytical results, the improved internal friction angle is nearly consistent with analytical result. The reinforcement effect of rock bolts is simulated obviously when the mechanical parameters of surrounding rocks are increased simultaneously. The engineering application shows that the equivalent anchoring method can reasonably simulate the effect of rock bolts, which can provide reference for stability analysis of three-dimensional tunnel simulations.

scholarly journals Effect of Wetting-Drying Cycle on the Deformation and Seepage Behaviors of Rock Masses around a Tunnel

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Qingzhen Guo ◽  
Haijian Su ◽  
Hongwen Jing ◽  
Wenxin Zhu
Keyword(s):  
Rock Mass ◽  
Principal Stress ◽  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Water Inrush ◽  
Surrounding Rock ◽  
Tunnel Excavation ◽  
Cycle Number ◽  
Simulation Results

Water inrush caused by the wetting-drying cycle is a difficult problem in tunnel excavation. To investigate the effect of the wetting-drying cycle on the stability of the tunnel surrounding rock, physical experiments and numerical simulations regarding the process of tunnel excavation with different wetting-drying cycle numbers were performed in this study. The evolutions of stress, displacement, and pore water pressure were analyzed. With the increase in cycle number, the pore water pressure, vertical stress, and top-bottom approach of the tunnel surrounding rock increase gradually. And the increasing process could be divided into three stages: slightly increasing stage, slowly increasing stage, and sharply increasing stage, respectively. The failure process of the surrounding rock under the wetting-drying cycle gradually occurs from the roof to side wall, while the baseplate changes slightly. The simulation results showed that the maximum principal stress in the surrounding rock mass of the tunnel increases, while the minimum principal stress decreases. Furthermore, the displacement of the rock mass decreases gradually with the increasing distance from the tunnel surface. By comparing the simulation results with the experimental results, well consistency is shown. The results in this study can provide helpful references for the safe excavation and scientific design of a tunnel under the wetting-drying cycle.

scholarly journals TESTING THE EFFECT OF UNDERMINING ON POSITIONAL ACCURACY OF THE DIGITAL TECHNICAL MAP OF OSTRAVA IN THE PŘÍVOZ CADASTRAL DISTRICT / PŘÍVOZ KADASTRINIO RAJONO ĮTAKOS OSTRAVOS SKAITMENINIO TECHNINIO ŽEMĖLAPIO POZICINIAM TIKSLUMUI PADARINIŲ TYRIMAS / АНАЛИЗ ВЛИЯНИЯ РАЗРУШАЮЩИХ СИЛ НА ПОЗИЦИОННУЮ ТОЧНОСТЬ ЦИФРОВОЙ ТЕХНИЧЕСКОЙ КАРТЫ Г. ОСТРАВА В КАДАСТРОВОМ РАЙОНЕ ПРИВОЗ

2011 ◽  
Vol 37 (3) ◽  
pp. 111-118
Author(s):  
Milan Mikoláš ◽  
Jiří Žváček ◽  
Michal Vaněk ◽  
Roman Donocik ◽  
Petra Zápalková ◽  
...  
Keyword(s):  
Rock Mass ◽  
Stress State ◽  
Coal Mining ◽  
Tectonic Stress ◽  
Surrounding Rock ◽  
Recent Past ◽  
Positional Accuracy ◽  
Landscape Morphology ◽  
The Town ◽  
Town Area

Intensive underground exploitation took place in the area of the Ostrava corporate town in recent past. After the coal mining was shut down in 1994 gradual subsidence in the town area has slowed down, however, establishing of the Digital Technical Map of Ostrava (DTMMO) dates back to 1992. When working a seam the original geostatic and tectonic stress state in the surrounding rock mass changes, which is accompanied by rock transformation and displacement from the roof towards the stope. Undermining is manifested in landscape morphology in many different ways that we can divide to continuous and discontinuous deformations. Residual mining effects could therefore have impacted positional accuracy of DTMMO in the last 18 years. The Bohumín 8-9/43 topographic sheet was selected for testing purposes in the Přívoz cadastral district. Santrauka Netolimoje praeityje Ostravos, miesto Čekijos rytuose, savivaldybėje buvo intensyviai eksploatuojama žemė. Nustojus užsiiminėti angliakasyba, nuo 1994-ųjų, palaipsnis žemės smukimas miesto vietovėse sulėtėjo. Skaitmeninis techninis Ostravos žemėlapis (DTMMO) sukurtas dar 1992 metais. Vykstant darbams žemės tarpsluoksnyje pirminis geostatinis ir tektoninis slėgis aplinkinėje uolienų masėje keitėsi, ir tai lėmė uolienų transformaciją ir slinktį. Kraštovaizdžio morfologijoje žala pasireiškia įvairiais būdais. Skiriama nenutrūkstamoji ir nutrūkstamoji deformacijos. Liekamasis kasybos poveikis per pstaruosius 18 metų galėjo paveikti pozicinį DTMMO tikslumą. Tiriant Přívoz kadastrinį rajoną, pasirinkta Bohumín 8-9/43 topografinio žemėlapio lapas. Резюме В недавнем прошлом в районе корпоративного г. Острава интенсивно эксплуатировались нижние слои грунта. После прекращения добычи угля в 1994 г. постепенное оседание поверхности города замедлилось. Созданная цифровая техническая карта г. Остравы (DTMMO) восходит к 1992 г. При работе с пластом возникающее исходное геостатическое и тектоническое возбуждение приводит к изменениям в окружающих пласт горных массивах, которые сопровождаются преобразованием пород и перемещениями в направлении забоя. Разрушение проявляется в морфологии ландшафта в самых разных формах, которые можно подразделить на непрерывные и разрывные деформации. Поэтому остаточные явления горных разработок могут оказывать влияние на позиционную точность DTMMO за последние 18 лет. Для анализа была выбрана топографическая плита Богумин 8-9/43 в кадастровом районе Привоз.

scholarly journals Management of geomechanical processes - the basis for selecting the optimal technologies for the development of mineral deposits

2018 ◽  
Vol 56 ◽  
pp. 02005
Author(s):  
Anatolii Kozyrev ◽  
Iuliia Fedotova ◽  
Eduard Kasparyan
Keyword(s):  
Rock Mass ◽  
Stress State ◽  
Rock Massif ◽  
Mineral Deposits ◽  
Mining Operations ◽  
Mining Technology ◽  
Geomechanical Monitoring ◽  
Gas Dynamic ◽  
Natural Stress ◽  
Mining Methods

When carrying out mining operations, a rock massif responds to technological impacts in the form of developing strains and fractures. Under certain conditions, this response occurs as dynamic and gas dynamic destructions of rocks with intensive release of energy, which creates threats to security and disrupts a working technology. To substantiate the optimal mining technology, which would be maximum adequate to the specific geological and geomechanical conditions of a deposit development, it is necessary to organize a comprehensive monitoring of geomechanical processes in rock massifs. The paper considers general principles to organize the geomechanical monitoring under conditions of the hierarchically-blocked rock massifs in the gravitational-tectonic field of the natural stress state. The authors give main recommendations for managing geomechanical processes in the rock mass for various mining methods.

In situ seepage testing method for fractured zones of rock mass

2020 ◽  
Vol 54 (1) ◽  
pp. qjegh2020-050
Author(s):  
Sihong Liu ◽  
Siyuan Xu ◽  
Bin Zhou
Keyword(s):  
Rock Mass ◽  
Large Scale ◽  
Surrounding Rock ◽  
Hydropower Station ◽  
Permeability Characteristics ◽  
Critical Hydraulic Gradient ◽  
Testing Method ◽  
Natural Stress ◽  
Stress States

The permeability characteristics of rock mass discontinuities are important in the stability of hydropower station projects. We propose a large-scale in situ seepage testing method and use this method to test gently dipping bedding faults (C3 zone) and steep faults (F14) in a hydropower station construction field in China. The in situ test results are compared with those of both undisturbed and reconstituted specimens. The comparison indicates that the largest critical hydraulic gradient and the smallest seepage permeability coefficient are obtained via in situ tests because they are performed under stress states that simulate the natural stress of the surrounding rock mass. The natural stress of the surrounding rock mass cannot be reflected in tests of undisturbed and reconstituted specimens.

An improved analytical solution to estimate the stress state in subvertical backfilled stopes

2008 ◽  
Vol 45 (10) ◽  
pp. 1487-1496 ◽  
Author(s):  
Li Li ◽  
Michel Aubertin
Keyword(s):  
Stress State ◽  
Analytical Solution ◽  
Surrounding Rock ◽  
Underground Mines ◽  
Good Representation ◽  
Normal Stresses ◽  
Numerical Investigations ◽  
Backfilled Stopes ◽  
Buried Conduits ◽  
Opening Width

The increasing use of backfill in underground mines requires a better understanding of the interaction between the relatively soft fill material and the surrounding rock mass. In recent years, it has been shown that stresses in backfilled stopes can be estimated using an approach based on Marston’s arching formulation developed initially for buried conduits in trenches. However, despite its advantages, this approach has some shortcomings. For instance, it postulates that both the vertical and horizontal normal stresses are uniformly distributed across the opening width. Numerical investigations conducted by the authors have shown that this assumption is not always valid. This paper presents a modification to the Marston-based solution, which leads to a nonuniform vertical stress distribution across the opening. This modification of the analytical solution involves parameters that have been calibrated against some numerical modelling results. The same equations and parameters are then shown to provide a good representation of additional modelling cases for which the stress state is correctly predicted.

Influence of Pipe Ramming on Stress State of Surrounding Soil and Nearby Tunnel Lining

2016 ◽  
Vol 843 ◽  
pp. 81-86 ◽  
Author(s):  
Alexandr A. Pankratenko ◽  
Nguyen Quang Huy ◽  
Nguyen Duyen Phong ◽  
Andrey S. Samal ◽  
Abdrahman B. Begalinov ◽  
...  
Keyword(s):  
Rock Mass ◽  
Stress State ◽  
Analytical Solution ◽  
Surrounding Rock ◽  
Tunnel Lining ◽  
Circular Tunnel ◽  
Under Construction ◽  
Pipe Ramming ◽  
Plane Problem Of Elasticity ◽  
Surrounding Soil

ANNOTATIONThis article proposes an approach to the prediction of stress state and assessing the strength of a circular tunnel lining and the surrounding rock mass under construction near the production used by the micro-tunneling technology of pipe ramming. The basis of this method is an analytical solution of the corresponding plane problem of elasticity theory.

Determination of the natural stress state in a Brazilian rock mass by back analysing excavation measurements: a case study

2002 ◽  
Vol 39 (8) ◽  
pp. 1005-1032 ◽  
Author(s):  
J.A. de Mello Franco ◽  
J.L. Armelin ◽  
J.A.F. Santiago ◽  
J.C.F. Telles ◽  
W.J. Mansur
Keyword(s):  
Rock Mass ◽  
Stress State ◽  
Natural Stress

scholarly journals Calculation Model and Influencing Factors of Surrounding Rock Loosening Pressure for Tunnel in Fold Zone

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Jianhao Liu ◽  
Caijin Xie ◽  
Junying Rao
Keyword(s):  
Rock Mass ◽  
Lateral Pressure ◽  
Pressure Coefficient ◽  
Friction Angle ◽  
Research Process ◽  
Tectonic Stress ◽  
Calculation Model ◽  
Surrounding Rock ◽  
Initial Stage ◽  
Surrounding Rock Pressure

This research aims to study the surrounding rock loosening pressure variation law of tunnel in the fold area. Based on the calculation method of surrounding rock loosening pressure for shallow tunnel, a new calculation model of the surrounding rock pressure was proposed for tunnel in the fold area; through this calculation model, the effects of tectonic stress (F), the angle ( φ 1 ) between tectonic stress and horizontal plane, tunnel buried depth (h), friction angle ( θ ), the multiple (k) between tectonic stress and rock mass gravity in the upper part of the tunnel, lateral pressure coefficient ( λ ), and tunnel midline offset (t) on tunnel surrounding rock loosening pressure in fold area are studied, respectively. Results show that in the anticline area, when φ 1 increases, the vertical loosening pressure (q) decreases; when q > 0, the surrounding rock is in the elastic deformation stage, and q decreases monotonously as F increases; when q < 0, the rock mass is in the initial stage of failure, and as F continues to increase, the number of internal cracks increases, the rock mass reaches its ultimate bearing capacity and then fails completely, and q increases linearly in this process; q decreases with the increase of θ and k; the greater k is, the easier it is to reach its bearing limit; the horizontal loosening pressure (e) increased monotonously with the increase of h and λ . The research process of surrounding rock loosening pressure of tunnel in the syncline area is similar to that of tunnel in the anticline area; q decreases with the increase of θ and λ ; q monotonically increases with F increasing.

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