scholarly journals Study on Stability of Tunnel Surrounding Rock and Precipitation Disaster Mitigation in Flowing Sand Body

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Yongyi He ◽  
Bole Sun ◽  
Mingnian Wang
Keyword(s):  
Numerical Simulation ◽  
Negative Pressure ◽  
Surrounding Rock ◽  
Precipitation Method ◽  
Tunnel Face ◽  
Water Seepage ◽  
Sand Body ◽  
The Stability ◽  
Vacuum Dewatering ◽  
Sand Bodies

Flowing sand is a special surrounding rock encountered by tunnel construction. Due to the looseness and low viscosity of the flowing sand, after excavation, the sand body is easy to flow along the open surface. In addition, the water seepage also causes tunnel instability. Considering the characteristics of water seepage, how to improve the stability of flowing sand bodies and prevent the instability of surrounding rocks has become a difficult problem. In this paper, a parametric experiment on the surrounding rock taken from the project site was carried out, and then, a numerical simulation of the flowing sand body was conducted to study the precipitation construction method and stability of the flowing sand body. Other than that, the tunnel face vacuum dewatering, vertical vacuum dewatering at the top of the tunnel, and the vacuum dewatering technology of the gravity well in poor geological section were systematically analyzed in our research. A radial vacuum enclosed precipitation process for the face of the tunnel was proposed, which effectively solved the problem concerning continuous seepage of water in the front. Through numerical simulation and field experiments, the basis for determining the precipitation parameters of the tunnel face was obtained, while aiming at the top position of the tunnel, a vertical vacuum negative pressure precipitation method of intercepting the top seepage water and the water supply behind the top of the tunnel was proposed. For the bottom of the tunnel, setting gravity wells on the side walls for the purpose of preventing seepage at the bottom was put forward. The application of these methods in the project ensured the safety of construction and improved the construction schedule. After the completion of the dewatering construction, the method of inserting plywood into the small pipe was adopted to avoid the collapse of the dry sand. Then, to solve the problem of borehole collapse in flowing sand bodies, pipe feeding was introduced, thus further enhancing the precipitation effect. Furthermore, in view of the problem that the dewatering hole in the flowing sand body is easy to collapse, resulting in the failure of 60% of the dewatering hole and the sand body is extracted from the dewatering pipe, causing the risk of the cavity at the top of the tunnel, a method of pipe following is presented to avoid the damage of geotextile caused by directly inserting the dewatering pipe and further improve the dewatering effect. All the above processes together form an omnidirectional three-dimensional negative pressure precipitation method that considers the special sand body flow and water seepage of unfavorable geology and that has been proved to enhance the stability of surrounding rock in practice.

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.

scholarly journals Surrounding Rock Movement of Steeply Dipping Coal Seam Using Backfill Mining

2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Wenyu Lv ◽  
Kai Guo ◽  
Jianhao Yu ◽  
Xufeng Du ◽  
Kun Feng
Keyword(s):  
Numerical Simulation ◽  
Coal Seam ◽  
Surrounding Rock ◽  
Maximum Deflection ◽  
Coal Seams ◽  
Physical Similarity ◽  
Working Face ◽  
Rock Structure ◽  
Backfill Mining ◽  
The Stability

The movement of the overlying strata in steeply dipping coal seams is complex, and the deformation of roof rock beam is obvious. In general, the backfill mining method can improve the stability of the surrounding rock effectively. In this study, the 645 working face of the tested mine is used as a prototype to establish the mechanical model of the inclined roof beam using the sloping flexible shield support backfilling method in a steeply dipping coal seam, and the deflection equation is derived to obtain the roof damage structure and the maximum deflection position of the roof beam. Finally, numerical simulation and physical similarity simulation experiments are carried out to study the stability of the surrounding rock structure under backfilling mining in steeply dipping coal seams. The results show the following: (1) With the support of the gangue filling body, the inclined roof beam has smaller roof subsidence, and the maximum deflection position moves to the upper part of working face. (2) With the increase of the stope height, the stress and displacement field of the surrounding rock using the backfilling method show an asymmetrical distribution, the movement, deformation, and failure increase slowly, and the increase of the strain is relatively stable. Compared with the caving method, the range and degree of the surrounding rock disturbed by the mining stress are lower. The results of numerical simulation and physical similarity simulation experiment are generally consistent with the theoretically derived results. Overall, this study can provide theoretical basis for the safe and efficient production of steeply dipping coal seams.

Numerical Simulation on Supporting of Deep Surrounding Rock with Zonal Disintegration Tendency

2013 ◽  
Vol 671-674 ◽  
pp. 230-234
Author(s):  
Yu Jun Zuo ◽  
De Kang Zhu ◽  
Wan Cheng Zhu
Keyword(s):  
Numerical Simulation ◽  
Finite Element ◽  
Surrounding Rock ◽  
Zonal Disintegration ◽  
Finite Element Software ◽  
Stability Of Surrounding Rock ◽  
Ground Stress ◽  
Zonal Disintegration Phenomenon ◽  
The Stability ◽  
The Zonal Disintegration Phenomenon

In order to study the supporting of deep surrounding rock with zonal disintegration tendency, the zonal disintegration phenomenon of deep surrounding rock under three supporting forms is analyzed by the ABAQUS finite element software in this paper, and three supporting forms are un-supporting, bolting and grouting, and combined “Bolting and grouting plus Anchor rope” supporting. The results show that the different effects to zonal disintegration under different supporting forms will occur. Supporting can help to restrain the zonal disintegration of the reinforcement part advantageously, and also lower rupture degree of zonal disintegration and reduce the size of rupture zone. Meanwhile, the stability of surrounding rock is improved. But zonal disintegration may occur outside reinforcement part under greater ground stress. The results are great importance to a better understanding of the deep roadway supporting.

scholarly journals Stability Analysis of Shallow and Bias Loess Tunnel Based on Finite Difference Method

2019 ◽  
Vol 131 ◽  
pp. 01027
Author(s):  
Li Yongbing ◽  
Binglei Li ◽  
Guanyu Hua ◽  
Xinran Jia ◽  
Yanqiao Chen ◽  
...  
Keyword(s):  
Finite Difference ◽  
Shear Failure ◽  
Surrounding Rock ◽  
Tunnel Construction ◽  
Failure Zone ◽  
Tunnel Face ◽  
Whole Process ◽  
The Earth ◽  
Practical Engineering ◽  
The Stability

Based on the Mohr-Coulomb elastic-plastic model and the practical engineering background of Mopanshan tunnel, this paper applies the finite-difference software FLAC3D to simulate and analyse the whole process of loess tunnel construction. Then, it analyses the stability of the surrounding rock and sup-port structure after partial excavation of the loess tunnel under the shallow burying and unsymmetrical load-ing condition. The study showed that in the absence of support, the shear failure occurred to the top/upper pilot tunnel of the tunnel face, the failure zone under tensile stress happened to the shallow soil of the earth surface, and the soil of tunnel face appeared to be damaged. Finally, according to the analysis results, a rea-sonable construction method suitable for the shallow and bias loess tunnel is determined.

Stability Analysis of Tunnel during the Excavation Based on ANSYS

2014 ◽  
Vol 577 ◽  
pp. 1135-1138
Author(s):  
Bing He ◽  
Guang Zhi Yin
Keyword(s):  
Numerical Simulation ◽  
Stability Analysis ◽  
Stress Condition ◽  
Stability Control ◽  
Simulation Software ◽  
Surrounding Rock ◽  
Geological Condition ◽  
Rock Stability ◽  
Before And After ◽  
The Stability

This paper combines the geological condition of Miaoziwan tunnel and numerical simulation software ANSYS to analyze the displacement and stress condition of surrounding rock before and after the excavation. Furthermore, the stability of overlying rock in the tunnel was studied based on the displacement and stress condition of surrounding rock. The breaking law of overlying rock was studied considering the influencing factors to the stability of surrounding. The study and analysis to the breaking law of overlying rock can be helpful to the improvement of surrounding rock stability control and supporting system. Moreover, the result can be the guidance to the excavation.

Analysis on Ground Settlement Induced by Shallow Buried Cross Channel of CRD Method under Artificial Filling

2013 ◽  
Vol 353-356 ◽  
pp. 1519-1524
Author(s):  
Jin Kui Li ◽  
Jing Jing Li ◽  
Liu Jie Du
Keyword(s):  
Surface Deformation ◽  
Settling Tank ◽  
Ground Surface ◽  
Surrounding Rock ◽  
Surface Settlement ◽  
Ground Settlement ◽  
Tunnel Face ◽  
Underground Tunnel ◽  
The Cross ◽  
The Stability

The shallow underground tunnel is near to the ground; its many construction procedures are complicated, supporting and excavation are intertwined. The ground surface deformation is complex during construction. Through the analysis of the cross passage surface settlement data of Dalian metro Line 1High-tech zone Street station, we found that the ground surface caused by artificial filling integrally sinks during excavation, the shape of its sinking is like a flat funnel, the characteristics of settling tank are obvious. The influence of faces constructing is obvious on surface settlement, and the transverse influence range is about 30m; the longitudinal influence range is about 15m. The results of the paper show that the place of monitoring points should be held at 15m ahead from the tunnel face, effectivemonitoring period is 70d. The monitoring results are enough and safe for the stability requirement of the surrounding rock.

scholarly journals Comprehensive Experimental Study of Affecting Factors on Rectangular Roadway Stability

2020 ◽  
Vol 2020 ◽  
pp. 1-10 ◽  
Author(s):  
Zhongcheng Qin ◽  
Bin Cao ◽  
Tan Li ◽  
Xin Yu ◽  
Guangbo Chen
Keyword(s):  
Numerical Simulation ◽  
Pressure Coefficient ◽  
Surrounding Rock ◽  
Affecting Factors ◽  
Similar Material ◽  
Simulation Test ◽  
Five Factors ◽  
Roadway Stability ◽  
The Stability ◽  
Similar Material Simulation

In this paper, two methods of orthogonal numerical simulation test and similar material simulation test are used to study the influence of five factors on the stability of rectangular roadway: roadway width, roadway height, roadway buried depth, lateral pressure coefficient of surrounding rock, and comprehensive strength of surrounding rock. The results show that five factors have influence on the stability of roadway, but the degree of influence is different. The depth of the tunnel and the coefficient of the side pressure of the surrounding rock are positively correlated with the stability of the tunnel; the comprehensive strength of the surrounding rock is negatively correlated with the stability of the tunnel, but the correlation between the width and height of the tunnel and the stability of the tunnel is not obvious. The results of orthogonal numerical simulation test and similar material simulation test verify each other. The results of the field practice of the Fucun coal mine are basically consistent with the results of the two test methods, which shows that the research results have a certain guiding effect on the field roadway support.

scholarly journals Study on the influence of surrounding rock parameters on the stability of tunnel face

2021 ◽  
Vol 643 ◽  
pp. 012038
Author(s):  
Xiaohang Wei ◽  
Ze Sun ◽  
Zheng Wang ◽  
Dequan Zhuang ◽  
Wenwen Ba
Keyword(s):  
Surrounding Rock ◽  
Tunnel Face ◽  
The Stability ◽  
Rock Parameters

scholarly journals Study of the stability of tunnel construction based on double-heading advance construction method

2020 ◽  
Vol 12 (1) ◽  
pp. 168781401989696 ◽  
Author(s):  
Zhanping Song ◽  
Guilin Shi ◽  
Baoyun Zhao ◽  
Keming Zhao ◽  
Junbao Wang
Keyword(s):  
Numerical Simulation ◽  
Construction Method ◽  
Field Monitoring ◽  
Surrounding Rock ◽  
Tunnel Construction ◽  
Successful Implementation ◽  
Simulation Results ◽  
The Stability ◽  
Sand Stratum ◽  
The Right

The deformation and significant settlement of surrounding rock often occur during tunnel construction with the condition of abundant water and weak cementing sand. In order to study the construction method and stability under such soft stratum, this article takes Taoshuping tunnel as the engineering background and puts forward a new tunnel construction method—double-heading advance construction method by comparing the advantages and disadvantages of various traditional construction schemes. The numerical simulation of tunnel construction process using this method is carried out to illustrate the rationality and feasibility of the method. The conclusions are drawn by comparing the numerical simulation results with the field monitoring data analysis. The numerical simulation results show that the maximum settlement value caused by excavation construction is in the parts 5 and 6 of the upper half-section and the part 7 of the central section. The settlement values of parts 5, 6, and 7 accounted for 32.4%, 24.3%, and 18.9% of the total settlement values, respectively. So, the supporting measures for double-heading advance excavation construction of these three parts should be strengthened properly. The stress of the right hance changes greatly before and after the demolition of temporary support. The maximum positive value of stress is 23 kPa and the maximum negative value of stress is −32 kPa. Therefore, the length of temporary bracing should be strictly controlled during construction and the monitoring of the right hance area should be strengthened. Furthermore, it is necessary to strengthen the supporting measures and monitoring in the right spandrel area as the surrounding rock pressure in the right spandrel area is higher than the left spandrel area. The optimum excavation height of the upper half-section in Taoshuping tunnel is determined to be 5.4 m and the reasonable excavation distance between parts 1 and 5 is determined to be 25–30 m by parameter optimization. Finally, the variation law of numerical simulation and field monitoring results is consistent, which shows that the double-heading advance construction method has a better effect on the stability control of surrounding rock, and the rationality and feasibility of this method are validated effectively. Therefore, the double-heading advance method is suitable for tunnel construction in the sand stratum with rich water and weak cementation, and the successful implementation of this method in Taoshuping tunnel also provides a reference for subsequent tunnel construction in the sand stratum with rich water and weak cementation.

scholarly journals Numerical Simulation and Analysis of Tunnel Failure Mode by Stochastic Fracture Model

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Fukun Xiao ◽  
Lei Xu ◽  
Gang Liu ◽  
Zhiyuan Hou ◽  
Le Xing
Keyword(s):  
Numerical Simulation ◽  
Rock Burst ◽  
Monte Carlo Model ◽  
High Stress ◽  
Tectonic Stress ◽  
Simulation Software ◽  
Surrounding Rock ◽  
Structural Plane ◽  
Dip Angle ◽  
The Stability

The dip angle, length, spacing, and fracture distance of rock fissure affect the morphology of roadway after collapse. The numerical simulation software CDEM is used to simulate the morphology of roadway collapse. The Monte Carlo model is used to simulate different types of crack models in two-dimensional plane and generate different crack models. The effects of crack angle, crack length, fracture distance, and spacing on the deformation of surrounding rock are analyzed. The influence of different rock burst on the failure strap-fall modes of fissure roadway and roadway in different sections is analyzed, and the stability law of roadway is studied. Under the condition of high stress, the roadway shape has little influence on the distribution of the principal stress difference of surrounding rock, but the equivalent excavation radius determines the distribution of the plastic zone of surrounding rock. The larger the ineffective reinforcement zone is, the larger the deformation around the roadway will be. The decrease of the angle between the structural plane and the vertical stress increases the failure range of the roadway under the gravity burst pressure. Under the horizontal tectonic stress type rock burst, when the structural plane inclination angle is 0°, the two-sided caving body fills the roadway and the roof caving range becomes smaller.

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