scholarly journals Evaluation and Deformation Control Study on the Bias Pressure of Layered Rock Tunnels

2021 ◽  
Vol 2021 ◽  
pp. 1-20
Author(s):  
Qi Yanli ◽  
Wen Shaoquan ◽  
Bai Mingzhou ◽  
Shi Hai ◽  
Li Pengxiang ◽  
...  
Keyword(s):  
Rock Mass ◽  
Surrounding Rock ◽  
Tunnel Construction ◽  
Deformation Characteristics ◽  
Deformation Control ◽  
Layered Rock ◽  
Deformation Law ◽  
Layered Rock Mass ◽  
Rock Tunnels ◽  
Surrounding Rock Deformation

In the process of tunnel construction, the bias of layered rock mass tunnels has always been a prominent problem that troubles the construction and safe operation of tunnels. In this paper, a comprehensive method that combines monitoring technology and discrete element (3DEC) numerical simulation is proposed to analyze the deformation characteristics of the surrounding rock in the layered rock tunnel and the deformation law of the bias tunnel. The results indicate that the tunnel surrounding rock deformation in the study area showed the characteristics of bias. Based on the bias mechanism, the surrounding rock deformation law, the construction deformation control, and the optimization measures of layered rock mass in the bias tunnel were studied by means of combining monitoring technology with discrete element (3DEC) numerical simulation. Based on the research results, appropriate methods for controlling the deformation of the surrounding rock of the tunnel with comprehensive consideration of the anchor rod length, anchor rod angle, and anchor rod layout spacing were proposed. The method proposed in this paper could visually reveal the deformation characteristics of the surrounding rock of layered rock tunnels and the deformation law of bias tunnels. It could also better solve the problem of deformation control in the tunnel construction process. This approach provides a novel idea for special layered rock mass tunnel bias evaluation and deformation control parameter optimization and serves as a valuable reference for analogous engineering cases through engineering case analysis.

scholarly journals Space-Time Distribution Laws of Tunnel Excavation Damaged Zones (EDZs) in Deep Mines and EDZ Prediction Modeling by Random Forest Regression

2019 ◽  
Vol 2019 ◽  
pp. 1-13 ◽  
Author(s):  
Qiang Xie ◽  
Kang Peng
Keyword(s):  
Rock Mass ◽  
Random Forest ◽  
Time Distribution ◽  
Space Time ◽  
Surrounding Rock ◽  
Layered Rock ◽  
Blasting Excavation ◽  
Layered Rock Mass ◽  
Distribution Laws ◽  
The Stability

The formation process of EDZs (excavation damaged zones) in the roadways of deep underground mines is complex, and this process is affected by blasting disturbances, engineering excavation unloading, and adjustment of field stress. The range of an excavation damaged zone (EDZ) changes as the time and space change. These changes bring more difficulties in analyzing the stability of the surrounding rock in deep engineering and determining a reasonable support scheme. In a layered rock mass, the distribution of EDZs is more difficult to identify. In this study, an ultrasonic velocity detector in the surrounding rock was used to monitor the range of EDZs in a deep roadway which was buried in a layered rock mass with a dip angle of 20–30°. The space-time distribution laws of the range of EDZs during the excavation process of the roadway were analyzed. The monitoring results showed that the formation of an EDZ can be divided into the following stages: (1) the EDZ forms immediately after the roadway excavation, which accounts for approximately 82%–95% of all EDZs. The main factors that affect the EDZ are the blasting load, the excavation unloading, and the stress adjustment; (2) as the roadway excavation continues, the range of the EDZs increases because of the blasting excavation and stress adjustment; (3) the later excavation zone has a comparatively larger EDZ value; and (4) an asymmetric supporting technology is necessary to ensure the stability of roadways buried in layered rocks. Additionally, the predictive capability of random forest modeling is evaluated for estimating the EDZ. The root-mean-square error (RMSE) and mean absolute error (MAE) are used as reliable indicators to validate the model. The results indicate that the random forest model has good prediction capability (RMSE = 0.1613 and MAE = 0.1402).

scholarly journals Experimental Study of Blasting Excavation for Large Cross-Section Tunnel in Horizontal Layered Rock Mass

2021 ◽  
Author(s):  
Jie Mei ◽  
Wanzhi Zhang ◽  
Bangshu Xu ◽  
Yongxue Zhu ◽  
Bingkun Wang
Keyword(s):  
Rock Mass ◽  
Cross Section ◽  
Surrounding Rock ◽  
Large Cross Section ◽  
Large Area ◽  
Layered Rock ◽  
Blasting Excavation ◽  
Tunnel Blasting ◽  
Layered Rock Mass ◽  
Upper Face

Abstract The drilling and blasting method is still the main method in mountain tunnel excavation. For large cross-section tunnel in horizontal layered rock mass, tunnel blasting often causes serious overbreak and underbreak. In this study, blasting excavation tests of tunnel upper face were conducted and failure mechanisms of surrounding rocks with weak beddings and joints were analyzed based on the Panlongshan tunnel. Then, the blasthole pattern, the cut mode, a variety of peripheral holes, the charge structure and the maximum single-hole charge were optimized. Compared with the failure characteristics, overbreak and underbreak, and deformations of surrounding rocks before and after optimization, the latter was better in tunnel contour forming and surrounding rock stability. The results show that after optimization, the large-area separation of vault rock mass is solved, the step-like overbreak of spandrel rock mass is reduced and the large-size rock blocks and underbreak are avoided. The maximum linear overbreak of vault, spandrel, and haunch surrounding rocks is decreased by 42.3%, 53.7% and 45.1%, respectively. The underbreak at the bottom of the upper face is reduced from -111.5 to - 16.5 cm. The average overbreak area is decreased by 61.1%. In addition, the displacements after optimization finally converge to the smaller values. The arch crown settlement and the horizontal convergence of haunch are reduced by about 21.6% and 18.3%, respectively. Furthermore, from the completion of blasting excavation to the stabilization of surrounding rock, it takes less time by using the optimized blasting scheme.

Model Test Study on Influences of Layered Rock Mass Dip Angle on Stability of Deep-Buried Tunnel

2011 ◽  
Vol 90-93 ◽  
pp. 2363-2371
Author(s):  
Bin Wei Xia ◽  
Ke Hu ◽  
Yi Yu Lu ◽  
Dan Li ◽  
Zu Yong Zhou
Keyword(s):  
Rock Mass ◽  
Physical Model ◽  
Model Test ◽  
Physical Models ◽  
Physical Model Test ◽  
Stress Distributions ◽  
Failure Characteristics ◽  
Layered Rock ◽  
Layered Rock Mass ◽  
Dip Angle

Physical models of layered rock mass with different dip angles are built by physical model test in accordance with the bias failure characteristics of surrounding rocks of layered rock mass in Gonghe Tunnel. Bias failure characteristics of surrounding rocks in thin-layered rock mass and influences of layered rock mass dip angle on stability of tunnel are studied. The research results show that failure characteristics of physical models generally coincide with those of surrounding rocks monitored from the tunnel site. The failure regions of surrounding rock perpendicular to the stratification planes are obviously larger than those parallel to. The stress distributions and failure characteristics in the surrounding rocks are similar to each physical model of different dip angles. The stress distributions and failure regions are all elliptic in shape, in which the major axis is in the direction perpendicular to the stratification planes while the minor axis is parallel to them. As a result, obvious bias failure of surrounding rocks has gradually formed. The physical model tests provide reliable basis for theoretical analysis on the failure mechanism of deep-buried layered rock mass.

Constitutive model and elastic parameters for layered rock mass based on combined Hooke spring

2018 ◽  
Vol 10 (3-4) ◽  
pp. 145-156
Author(s):  
Zhang Ligang ◽  
Qu Guangqiu ◽  
Qu Sining ◽  
Liu Zhaoyi
Keyword(s):  
Rock Mass ◽  
Constitutive Model ◽  
Elastic Parameters ◽  
Layered Rock ◽  
Layered Rock Mass

scholarly journals Research on the Layered Rock Mass Excavation Relaxation Stability of Underground Caverns

2020 ◽  
Vol 165 ◽  
pp. 03024
Author(s):  
Ying Zhang ◽  
Heng Zhou ◽  
Shengjie Di ◽  
Xi Lu
Keyword(s):  
Rock Mass ◽  
Mechanical Characteristics ◽  
Generation System ◽  
Yield Zone ◽  
Layered Rock ◽  
Underground Caverns ◽  
Structure Surface ◽  
Layered Rock Mass ◽  
Power Generation System ◽  
The Stability

In order to compare the influence of rock mass parameters weakening on the deformation and stability of excavation caverns in layered rock mass, based on power generation system caverns of a hydropower station, the stability and deformation of the caverns is analyzed. The results show that the mechanical characteristics of the structure surface play a major role in controlling the stability of caverns. And the displacement and yield zone value of plan 3, which adopt elastic-plastic softening model, are significantly larger than other two. The method which consider the residual strength of structure surface is more suitable for the excavation calculation of layered rock mass cavern.

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