Size Effect on the Stability of Tunnel Excavation

2013 ◽  
Vol 838-841 ◽  
pp. 1409-1413
Author(s):  
Xiao Dong Ju ◽  
Chao Shuai Yang ◽  
Yu Jun Zhang
Keyword(s):  
Rock Mass ◽  
Size Effect ◽  
Fractured Rock ◽  
Vertical Displacement ◽  
Tunnel Excavation ◽  
Result Show ◽  
Key Factor ◽  
Dip Angle ◽  
The Stability ◽  
Tunnel Size

Size effect of tunnel excavation in fractured rock mass was analyzed with UDEC in this paper. For simplicity, two series of orthogonal equidistant joints were conceived in the calculation area. Change the excavation size and keep the constitutive model and its parameters of the rock mass around the tunnel to be constant during the solution. The result show, with the increasing of excavation size, vertical displacement of tunnel roof become larger, and the excavation stability turn weaker. So excavation size has great effect on the stability of fractured tunnel. In addition, another key factor, the joint set dip angle, whose effect to the tunnel stability was unearthed by comparing the results of horizontal and 45°joints. The larger the dip angle the weaker the stability at the same tunnel size.

Application of ABAQUS in Surrounding Rock Stability Analysis of Shallow Large Cross-Section Tunnel

2015 ◽  
Vol 777 ◽  
pp. 8-12 ◽  
Author(s):  
Lin Zhen Cai ◽  
Cheng Liang Zhang
Keyword(s):  
Numerical Simulation ◽  
Rock Mass ◽  
Strong Support ◽  
Surrounding Rock ◽  
Tunnel Engineering ◽  
Tunnel Excavation ◽  
Rock Stability ◽  
Rock Bolting ◽  
Excavation Support ◽  
The Stability

HuJiaDi tunnel construction of Dai Gong highway is troublesome, the surrounding-rock mass give priority to full to strong weathering basalt, surrounding rock integrity is poor, weak self-stability of surrounding rock, and tunnel is prone to collapse. In order to reduce disturbance, taking advantage of the ability of rock mass, excavation adopt the method of "more steps, short footage and strong support". The excavation method using three steps excavation, The excavation footage is about 1.2 ~ 1.5 m; The surrounding rock bolting system still produce a large deformation after completion of the first support construction, it shows that the adopted support intensity cannot guarantee the stability of the tunnel engineering. Using ABAQUS to simulate tunnel excavation support, optimizing the support parameters of the tunnel, conducting comparative analysis with Monitoring and Measuring and numerical simulation results, it shows that the displacement - time curves have a certain consistency in numerical simulation of ABAQUS and Monitoring and Measuring.

Study of the geometrical size effect of a fractured rock mass based on the modified blockiness evaluation method

2018 ◽  
Vol 11 (11) ◽  
Author(s):  
Qingfa Chen ◽  
Tingchang Yin ◽  
Wenjing Niu ◽  
Wenshi Zheng ◽  
Junguang Liu
Keyword(s):  
Rock Mass ◽  
Size Effect ◽  
Evaluation Method ◽  
Fractured Rock ◽  
Fractured Rock Mass ◽  
Geometrical Size

scholarly journals Transient Analysis of Grout Penetration With Time-Dependent Viscosity Inside 3D Fractured Rock Mass by Unified Pipe-Network Method

Water ◽  
2018 ◽  
Vol 10 (9) ◽  
pp. 1122 ◽  
Author(s):  
Zizheng Sun ◽  
Xiao Yan ◽  
Rentai Liu ◽  
Zhenhao Xu ◽  
Shucai Li ◽  
...  
Keyword(s):  
Rock Mass ◽  
Large Scale ◽  
High Efficiency ◽  
Fractured Rock ◽  
Time Dependent ◽  
Pipe Network ◽  
Fractured Rock Mass ◽  
Network Method ◽  
The Stability ◽  
Dependent Viscosity

Grouting is widely used for mitigating the seepage of underground water and enhancing the stability of fractured rock mass. After injection, the viscosity of the grout gradually increases until solidification. Conventional multifield analysis models ignoring such effects greatly overestimate the penetration region of the grout and the stability of the grouted rock structures. Based on the 3D unified pipe-network method (UPM), we propose a novel numerical model considering the time-dependent viscosity of the grout, therein being a quasi-implicit approach of high efficiency. The proposed model is verified by comparing with analytical results and a time-wise method. Several large-scale 3D examples of fractured rock mass are considered in the numerical studies, demonstrating the effectiveness and robustness of the proposed method. The influence of the time-dependent viscosity, fracture properties, and grouting operation methods are discussed for the grout penetration process.

Study on Support of Roadways in Fractured Rock Mass under Mining-Induced Stresses

2013 ◽  
Vol 807-809 ◽  
pp. 2332-2339
Author(s):  
Qiang Wang ◽  
Jin Yu Chen
Keyword(s):  
Rock Mass ◽  
Abutment Pressure ◽  
Underground Mining ◽  
Fractured Rock ◽  
The State ◽  
In Situ Monitoring ◽  
Initial Stresses ◽  
Induced Stresses ◽  
The Stability

One of the difficult issues in underground mining is the ground control of roadway subject to mining induced stresses. As a longwall face advances, the state of initial stresses dramatically changes. Accordingly, lateral abutment pressure forms on the pillar and frontal abutment pressure on the roof and lateral sides of the roadway. These pressures will lead to severe deformation and deterioration of the rock mass surrounding the entries. In this paper, a systemic study on this issue is proposed using the combination of numerical modeling and in-situ monitoring which was carried out at a coal mine in the Lu.An Group, China. The condition of stress redistribution caused by mining-induced stresses and the state of the surrounding rock mass of the roadway situated in front the work face are systematically investigated. Different patterns of support and reinforcement as well as their effects on the stability of the roadway are also presented.

Fractured Rock Mass Compressive Strength Size Effect Based on Similar Materials

2013 ◽  
Vol 19 (7) ◽  
pp. 1964-1968
Author(s):  
Dongping L ◽  
Jun Li ◽  
Yangjian Xu ◽  
Wei Wei
Keyword(s):  
Compressive Strength ◽  
Rock Mass ◽  
Size Effect ◽  
Fractured Rock ◽  
Fractured Rock Mass ◽  
Similar Materials

scholarly journals Parameter optimization of double side wall method for soft surrounding rock tunnel

2019 ◽  
Vol 136 ◽  
pp. 04021
Author(s):  
Zhihua Yang ◽  
Rumiao He ◽  
Ke Li ◽  
Hongyan Guo
Keyword(s):  
Side Wall ◽  
Horizontal Displacement ◽  
Vertical Displacement ◽  
Surrounding Rock ◽  
Radius Of Curvature ◽  
Tunnel Excavation ◽  
The Stability ◽  
Rock Tunnel ◽  
Double Wall ◽  
Wall Method

When the Xiaojiazhai tunnel is constructed by the double-wall method, different curvature radii have different effects on controlling the stability of the surrounding rock and speeding up the construction progress. By numerically simulating the tunnel excavation under different radius of curvature, it is concluded that R is adopted respectively. The deformation displacement of surrounding rock is =11.6m∠520 and R=5.76m∠1060. The maximum horizontal displacement and vertical displacement are smaller when R=5.76m∠1060 is selected. According to the analysis results, when R=5.76m∠1060 is selected, the deformation of surrounding rock can be controlled to ensure the safety of construction and provide reference for future construction.

Simulation on Freeze-Thaw Action in Multi-Cracks in Rock Mass

2014 ◽  
Vol 1049-1050 ◽  
pp. 426-429
Author(s):  
Wen Dong Ji ◽  
Yong Shui Kang ◽  
Xiao Yu An ◽  
Yue Zhao
Keyword(s):  
Rock Mass ◽  
Freezing Point ◽  
Fractured Rock ◽  
Key Factors ◽  
Fractured Rock Mass ◽  
Freeze Thaw ◽  
Factors Influencing ◽  
Field Temperature ◽  
Temperature Filed ◽  
The Stability

Freeze-thaw action in fractured rock mass is discussed. Moist rock exposed to subfreezing temperature would suffer from freeze-thaw deterioration, which would pose serious threat to the stability of geotechnical engineering. Some key factors influencing freeze-thaw action in rock mass is analyzed, such as temperature, freezing rate, freeze-thaw cycles and porosity of the rock. Further more, using the theory of physical chemistry, the freezing point and frozen ratio were derived. Finally, the model of frost crack was built by ANSYS and then imported into FLAC3D by converting procedure. The stress field, temperature filed as well as the normal and shear stress on surface of the cracks were demonstrated. The effect of freezing pressure is reflected in the results.

Stability Analysis of Dangerous Rocks on the Slope of a Hydropower Station

2013 ◽  
Vol 405-408 ◽  
pp. 621-629 ◽  
Author(s):  
Hai Feng Li ◽  
Guo Xing Zhang ◽  
Tao Huang ◽  
Qiu Jing Zhou
Keyword(s):  
Rock Mass ◽  
Fractured Rock ◽  
Discontinuous Deformation Analysis ◽  
Hydropower Station ◽  
Deformation Analysis ◽  
Time Interval ◽  
Block Method ◽  
Fractured Rock Mass ◽  
Unstable Failure ◽  
The Stability

Dangerous rocks are among the most significant factors in analyzing the stability of high slopes, and are the main geological hazards on such slopes. These rocks are typical spatial blocks. The unstable failure of dangerous rocks poses evident spatial features. Consequently, their stability should be calculated by considering it as a three-dimensional (3-D) problem. In this research, the general block method of fractured rock mass and 3-D discontinuous deformation analysis (DDA) are used to study the stability of dangerous rocks on the slope of a hydropower station. The general block method of fractured rock mass is used to generate dangerous rocks and to assess the geometric mobility of blocks. The progressive unstable failure of dangerous rocks is also analyzed. Moreover, 3-D DDA is implemented to examine the stability of dangerous rocks, including the regularity of their unstable failure. The failure sequence of each batch of blocks estimated by general block theory is the same as that in the results of 3-D DDA. The decrease in the shear parameters of the structural plane shortens the time interval of failures, but increases the number and capacity of blocks.

scholarly journals Influence of Weak Interlayer on the Mechanical Performance of the Bolted Rock Mass with a Single Free Surface in Deep Mining

Minerals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 496
Author(s):  
Shuxue Ding ◽  
Yuan Gao ◽  
Hongwen Jing ◽  
Xinshuai Shi ◽  
Yanjun Qi ◽  
...  
Keyword(s):  
Free Surface ◽  
Rock Mass ◽  
Mechanical Performance ◽  
Test System ◽  
Surrounding Rock ◽  
Mining Engineering ◽  
Weak Interlayer ◽  
Dip Angle ◽  
The Stability ◽  
The Impact

The existence of the weak interlayer in the roadway surrounding rock mass presents a huge threat to the stability of the underground structure and the safety of mining engineering. By the characteristics of strong adaptability, superior anchoring effect and high efficiency of construction, rock bolt has been widely applied in mine reinforcement. However, the influence of the weak interlayer on the compressive performance of the bolted rock mass is still poorly understood due to the challenges in constructing an efficient experimental platform and complex testing processes. Here, we used the self-developed test system to investigate the influence of the thickness, uniaxial compressive strength, and dip angle of the weak interlayer on the compressive behavior of the bolted rock mass with a single free surface. The results show that the weak interlayer has a great weakening effect on the peak strength and elastic modulus of the specimens due to its low mechanical properties, as well as influencing the crack distribution and failure mode of the samples. As the strength of the weak interlayer is lower than 1.27 MPa, the thickness exceeds 20 mm, and the dip angle exceeds 15°, the synergistic bearing effect will be significantly reduced and affect the mechanical performance of the specimens. The evolution of the bolt force and bending moment are greatly impacted by the deformation process which could be divided into distinct stages of destruction, thereby providing an excellent detection method for judging the stability of the surrounding rock of the mine. The discovery of this research promote a better understanding of the impact of the weak interlayer on mining engineering and guide the mine reinforcement in the future.

Analyze of the Affection of Excavation Unloading of the Rock Mass of the Spillway Tunnel of a Hydropower Station on the Slope’s Stability

2012 ◽  
Vol 594-597 ◽  
pp. 621-626 ◽  
Author(s):  
Le Hua Wang ◽  
Jun Lei Bai
Keyword(s):  
Rock Mass ◽  
Hydropower Station ◽  
Engineering Practice ◽  
Tunnel Face ◽  
Tunnel Excavation ◽  
Slope Rock ◽  
Spillway Tunnel ◽  
The Stability ◽  
Unloading Effect

After the excavation of the rock , the rock mass stress state changes and the quality of rock mass damage deterioration. Rock excavation of spillway tunnel of the hydropower station may have some influence on the stability of the tunnel-face side slope. In this paper, combined with the engineering practice, based on the unloading rock mass theory and through two dimensional finite-difference method. Selected seven feature points near the excavation surface as monitoring points for calculation ,then calculated the effect on the stress and strain of the slope caused by the excavation of the spillway tunnel and analysed the changes in the distribution of the slope rock mass plastic zone and the point factor of safety. The results show that spillway tunnel excavation in excavated slope have some impact on the excavated slope stability, and it is more obvious for the effect on stability of excavated slope in considering rock mass unloading effect than do not consider the rock mass unloading effect.

Sign in / Sign up

Export Citation Format

Share Document