scholarly journals Quantitative Study on Empirical Strength Parameters of Extremely Fractured Phyllite Based on Fractal Theory

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Yongbin Xie ◽  
Xiaoyu Yang ◽  
Jianhua Dong ◽  
Guosheng Liu
Keyword(s):  
Fractal Dimension ◽  
Fracture Zone ◽  
Shear Test ◽  
Fractal Theory ◽  
Surrounding Rock ◽  
Strength Parameter ◽  
Strength Parameters ◽  
Significant Difference ◽  
Fault Fracture Zone ◽  
Fractal Description

Extremely broken phyllite is widely distributed and is easily seen in engineering construction. Aiming at the problem that the empirical strength parameters of extremely broken surrounding rock have intense subjectivity and significant difference, based on the characteristics of the existence of particle group state in the highly broken surrounding rock, the fractal theory and large-scale direct shear test are used, the fractal description of polar broken phyllite samples with different pile numbers in fault fracture zone of Qinyu Tunnel is carried out, and the fractal dimensions and empirical strength parameters of each sample are determined. Based on a fractal description and large shear test, the functional relationship between fractal dimension and empirical strength parameter of extremely broken phyllite in fault fracture zone is established, and the quantitative value method of empirical strength parameter determined by fractal dimension of extremely broken phyllite is given, which provides ideas for the quantitative value of empirical strength parameter of the similar extremely broken surrounding rock.

Study on the Geological Forecast and Treatment for Water-Bearing Fault of the Qingdao Kiaochow Bay Subsea Tunnel

2013 ◽  
Vol 671-674 ◽  
pp. 1114-1121
Author(s):  
Zhi Peng Li ◽  
Shu Cai Li ◽  
Qing Song Zhang ◽  
De Ming Wang ◽  
Bing Hui ◽  
...  
Keyword(s):  
Fracture Zone ◽  
Surrounding Rock ◽  
Tunnel Excavation ◽  
Bearing Fault ◽  
Grouting Material ◽  
Fault Fracture Zone ◽  
Analysis Of Results ◽  
Subsea Tunnel ◽  
The Stability ◽  
Fissure Water

Water-bearing fault of subsea tunnel has fissure water developed, fractured surrounding rock with low strength, which gets a risk of sudden water inflow and affects the tunnel security. This paper takes the geological forecast and treatment for water-bearing fault of the Qingdao kiaochow bay subsea tunnel for example, according to the water assignment characteristics, using the detect method of TEM and advance borehole to make accurate decision for the position of water-bearing body、the scale of fracture zone and the inflow of water. Through the analysis of results, the grouting form, materials and parameters are chosen and adjusted. The grouting material seals the water flowing fracture, forming water-stopping curtain outside tunnel excavation contour line and strengthening the fault fracture zone to improve the stability of rock.

scholarly journals Numerical Simulation of Ultra-Shallow Buried Large-Span Double-Arch Tunnel Excavated under an Expressway

2021 ◽  
Vol 12 (1) ◽  
pp. 39
Author(s):  
Jianxiu Wang ◽  
Ansheng Cao ◽  
Zhao Wu ◽  
Zhipeng Sun ◽  
Xiao Lin ◽  
...  
Keyword(s):  
Fracture Zone ◽  
Horizontal Displacement ◽  
Surrounding Rock ◽  
Spatial Effects ◽  
Partition Wall ◽  
Tunnel Support ◽  
Large Span ◽  
Construction Design ◽  
Excavation Process ◽  
Fault Fracture Zone

The temporal and spatial effects of a complicated excavation process are vital for an ultra-shallow buried large-span double-arch tunnel excavated under an expressway in service. Numerical simulations are urgent and necessary to understand the effect of the total construction process. Taking Xiamen Haicang tunnel as a research object, the total excavation process of three pilot tunnels and the three-bench reserved core soil method of an ultra-shallow buried large-span double-arch tunnel with a fault fracture zone under an expressway was simulated using software FLAC3D. The deformation of the surface, surrounding rock, underground pipelines, tunnel support structure and partition wall of the three pilot tunnels and the main tunnel was analyzed, and the dangerous areas and time nodes were obtained. When the tunnel was excavated to the fault fracture zone, the deformation of the surface and surrounding rock increased significantly. The rock and soil within 20 m behind the excavation surface of the pilot tunnel were greatly disturbed by the excavation. During the excavation of the main tunnel, the horizontal displacement of the middle partition wall moved slightly towards the main tunnel excavated first. The research results can provide a reference for the construction design of double-arch tunnels.

Effect of a Fault Fracture Zone on the Stability of Tunnel-Surrounding Rock

2017 ◽  
Vol 17 (6) ◽  
pp. 04016135 ◽  
Author(s):  
Yingchao Wang ◽  
Hongwen Jing ◽  
Haijian Su ◽  
Jiangyue Xie
Keyword(s):  
Fracture Zone ◽  
Surrounding Rock ◽  
Fault Fracture Zone ◽  
The Stability

Research on the Mechnical Characteristics of Primary Supports in Guanjiao Tunnel Fault Fracture Zone and its Influence Zone by Field Tests

2011 ◽  
Vol 105-107 ◽  
pp. 1203-1210 ◽  
Author(s):  
Da Li ◽  
Zhan Fu Luo ◽  
Yong Sheng Li
Keyword(s):  
Fracture Zone ◽  
Field Tests ◽  
Surrounding Rock ◽  
Tunnel Construction ◽  
Railway Tunnel ◽  
Influence Zone ◽  
Geological Conditions ◽  
Fault Fracture Zone ◽  
Under Construction ◽  
Primary Support

The tunnel which excavated through the fault fracture zone is still one of the difficulties in the current tunnel construction. Guanjiao tunnel is the longest high-altitude tunnel in the world, and also the longest railway tunnel which is under construction in China. The 9# shaft which located in Erlang fault fracture zone with several faults, complicated geological conditions is difficult to excavate. In the representative section of F3 fault and its influence zone, F22 fault fracture zone, the monitoring tests on contact pressure between surrounding rock and primary support and stress of steel arch is conducted. According to the above monitoring results，the project recommendations are proposed to ensure the smooth construction of tunnel.

The Reasearch of the Level of Tunnel Surrounding Rock and the Stability Based on Fractal Theory

2014 ◽  
Vol 1020 ◽  
pp. 411-414
Author(s):  
Jian Tao He ◽  
Jun Dong
Keyword(s):  
Fractal Dimension ◽  
Fractal Theory ◽  
Longitudinal Section ◽  
Surrounding Rock ◽  
Contour Line ◽  
Box Counting ◽  
Stability Of Surrounding Rock ◽  
Box Counting Method ◽  
The Stability ◽  
Complex Phenomena

A new nonlinear discipline named Fractal theory which is a scientific theory and method studied the irregular of nature and complex phenomena has been used in civil engineering direction successfully in recent years. Take the Kuo changshan tunnel as an example, this paper will use the Range finder to measure the shape of surrounding rock along different longitudinal section contour line, then using the fractal theory to analyze it as follows: using section assumption, box counting method and higher dimensional method to calculate the fractal dimension, and to explore the relative relations between fractal dimension and stability of surrounding rock of the tunnel. The research results show that the more rough the tunnel longitudinal section contour line, the bigger the fractal dimension, the worse the corresponding stability of surrounding rock and the worse the lower the level of surrounding rock . Above all the tunnel longitudinal irregular section contour line has obvious fractal characteristics.

scholarly journals Study on Mechanical Properties and Control Technology of Surrounding Rock in the Fracture Zone of a Roadway

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Yushun Yang ◽  
Zhiming Fang ◽  
Guangying Ji ◽  
Baigao Zhao ◽  
Sijiang Wei
Keyword(s):  
Rock Mass ◽  
Fracture Zone ◽  
Rock Fracture ◽  
Industrial Test ◽  
Surrounding Rock ◽  
Mine Pressure ◽  
Three Dimensional Model ◽  
Silty Mudstone ◽  
Fracture Development ◽  
Fault Fracture Zone

We aim at the problem of the large deformation and difficult control of surrounding rock when passing through a fault fracture zone in the centralized rail transportation lane along the south wing of Xinyi Coal Mine; the stress environment and failure mechanism of surrounding rock are analyzed through field investigation, numerical simulation, and field industrial test. The instability of the surrounding rock in the fault fracture zone was considered to be the result of the joint effect of the surrounding rock fracture development, lithology differences, water gushing occurrences, low strength of the original support, high in situ stress, and fault-related tectonic stress. Rock blocks are collected on site at the fracture zone, and the remoulded samples are prepared for mechanical experiments in the laboratory. The basic mechanical parameters of the roadway passing through silty mudstone, sand-mudstone interlayer, and fine sandstone were analyzed. A three-dimensional model is established to analyze the distributions of the stress, deformation, and plastic area in the surrounding rock mass after the tunnel passes through, considering both a single-rock mass and a multilayer-rock mass. Based on the above analysis, the “closed support + shotcrete + grouting + anchor mesh cable coupling support” is proposed. Three stations were arranged on site to observe the mine pressure, and the field industrial test shows that, within the 100 days of observation, the maximum roof-to-floor convergence is 38 mm, while the maximum horizontal convergence is 56 mm. The overall reinforcement effect of the roadway is good, the surface is smooth, and there is no phenomenon of concrete cracking and bolt fracture.

scholarly journals Influence of vetiver root on strength of expansive soil-experimental study

PLoS ONE ◽  
2020 ◽  
Vol 15 (12) ◽  
pp. e0244818
Author(s):  
Gui-yao Wang ◽  
Yong-gang Huang ◽  
Run-fa Li ◽  
Jing-mei Chang ◽  
Jin-liang Fu
Keyword(s):  
Shear Strength ◽  
Internal Friction ◽  
Root System ◽  
Shear Test ◽  
Expansive Soil ◽  
Friction Angle ◽  
Internal Friction Angle ◽  
Strength Parameter ◽  
Shear Strength Parameters ◽  
Strength Parameters

Grassroots have received more attention than the traditional method as soil reinforcement materials, especially the use of vetiver and other vegetation protection methods to treat expansive soil slope, have been tried and applied. To study the influence of grassroots on the strength properties of expansive soil, the laws of vetiver root growth over time and its vertical distribution of root content(δ) were firstly investigated by the experiment of planting vetiver. Then different δ and depth of planted soil were obtained. Simultaneously different δ and water content(ω) of grafted soil were made. With the direct shear test, the shear strength parameters of root-soil with different δ were analyzed. The shear test on root-soil composites with different δ was carried out to compare the strength characteristics of planted and grafted soil. The results showed that the δ of vetiver decreased with the increase of depth, and the δ of each layer increased with the growth period. The δ of 180d was 70.5% higher than that of 90d. The cohesion(c) of root-soil can be increased by more than 97%, and internal friction angle(φ) can be increased by more than 15.4% after 180 days. The c of 90 d vetiver root system can be increased by more than 18%, and the φ can be increased by more than 1.5%. At each depth, the c and φ of composite soil increases with the increase of δ, and the increment of cohesion (Δc) and the increment of internal friction angle (Δφ) increase with the increment of δ. But the increase in the ω will weaken the shear strength parameters of root-soil. Under the condition of the planted root system and grafted root system, the influence degree of δ on strength parameter of root-soil is different, and the law of strength parameters versus δ of grafted soil of 365d is similar to that of planted soil of 90d. And the root reinforcement of grafted soil is weaker than planted soil. Hence the grafted soil can´t accurately reflect the root-soil interaction of the existing root system.

scholarly journals Effect of the Location of Fault Fracture Zones on the Stability of Symmetrical Submarine Tunnels

Symmetry ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1111
Author(s):  
Wei Fang ◽  
Gang Wang ◽  
Chang Wang
Keyword(s):  
Safety Factor ◽  
Working Conditions ◽  
Axial Force ◽  
Fracture Zone ◽  
Bending Moment ◽  
Surrounding Rock ◽  
Fracture Zones ◽  
Fault Fracture Zone ◽  
Lining Structure ◽  
The Stability

In this paper, we aim to reveal the influence of fault fracture zones on the stability of submarine tunnels and the surrounding rock under different water and drainage measures. Firstly, four typical working conditions of submarine tunnels intersecting with fault fracture zones were selected. On the basis of the typical cross section of the intersections of submarine tunnels and faults, they were divided into four working conditions. Then, the displacement and plastic zones of the surrounding rock of the tunnel were studied, and the stability of the rock surrounding the submarine tunnel was discussed. This research structure indicates that the bending moment and axial force of the lining structure of the submarine tunnel increase with increasing sealing degree, but the safety factor exhibits a downward trend. When the fault fracture zone goes through the section above the tunnel axis, the bending moment and axial force at the lining vault are greater than the other working conditions, and the displacement of the surrounding rock at the vault and spandrel is prominent. When the fault fracture zone completely passes through the tunnel, the safety factor of the lining structure is at its lowest, and the displacement of the surrounding rock at the arch waist develops laterally. When the fault fracture zone passes through the part below the tunnel axis, the arch foot displacement converges significantly, and the surrounding rock displacement exhibits a downward inclination. In addition, the plastic zone is mainly developed in the arch and the shoulder. These research results provide a reliable reference for tunnel design and excavation support.

Evolution of delayed water inrush in fault fracture zone considering time effect

2021 ◽  
Vol 14 (11) ◽  
Author(s):  
Jiwen Bai ◽  
Shaolong Duan ◽  
Rentai Liu ◽  
Lin Xin ◽  
Jiawei Tian ◽  
...  
Keyword(s):  
Fracture Zone ◽  
Water Inrush ◽  
Time Effect ◽  
Fault Fracture Zone

scholarly journals Dynamic characteristics and fractal representations of crack propagation of rock with different fissures under multiple impact loadings

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Bing Sun ◽  
Shun Liu ◽  
Sheng Zeng ◽  
Shanyong Wang ◽  
Shaoping Wang
Keyword(s):  
Fractal Dimension ◽  
Crack Propagation ◽  
Crack Growth ◽  
Impact Test ◽  
Fractal Theory ◽  
Dynamic Change ◽  
Fractal Dimensions ◽  
Peak Stress ◽  
Dynamic Mechanical Properties ◽  
Gravitational Potential Energy

AbstractTo investigate the influence of the fissure morphology on the dynamic mechanical properties of the rock and the crack propagation, a drop hammer impact test device was used to conduct impact failure tests on sandstones with different fissure numbers and fissure dips, simultaneously recorded the crack growth after each impact. The box fractal dimension is used to quantitatively analyze the dynamic change in the sandstone cracks and a fractal model of crack growth over time is established based on fractal theory. The results demonstrate that under impact test conditions of the same mass and different heights, the energy absorbed by sandstone accounts for about 26.7% of the gravitational potential energy. But at the same height and different mass, the energy absorbed by the sandstone accounts for about 68.6% of the total energy. As the fissure dip increases and the number of fissures increases, the dynamic peak stress and dynamic elastic modulus of the fractured sandstone gradually decrease. The fractal dimensions of crack evolution tend to increase with time as a whole and assume as a parabolic. Except for one fissure, 60° and 90° specimens, with the extension of time, the increase rate of fractal dimension is decreasing correspondingly.

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