scholarly journals Strength Assessment of Broken Rock Postgrouting Reinforcement Based on Initial Broken Rock Quality and Grouting Quality

2017 ◽  
Vol 2017 ◽  
pp. 1-14 ◽  
Author(s):  
Hongfa Xu ◽  
Hansheng Geng ◽  
Feng Chen ◽  
Xiao Chen ◽  
Liangliang Qi
Keyword(s):  
Rock Mass ◽  
Internal Friction ◽  
Growth Rates ◽  
Strength Criterion ◽  
Friction Angle ◽  
Uniaxial Tensile ◽  
Strength Assessment ◽  
Uniaxial Tensile Strength ◽  
Quantitative Calculation ◽  
Grouting Reinforcement

To estimate postgrouting rock mass strength growth is important for engineering design. In this paper, using self-developed indoor pressure-grouting devices, 19 groups of test cubic blocks were made of the different water cement ratio grouting into the broken rock of three kinds of particle sizes. The shear strength parameters of each group under different conditions were tested. Then this paper presents a quantitative calculation method for predicting the strength growth of grouted broken rock. Relational equations were developed to investigate the relationship between the growth rates of uniaxial compressive strength (UCS), absolute value of uniaxial tensile strength (AUTS), internal friction angle, and cohesion for post- to pregrouting broken rock based on Mohr-Coulomb strength criterion. From previous test data, the empirical equation between the growth rate of UCS and the ratio of the initial rock mass UCS to the grout concretion UCS has been determined. The equations of the growth rates of the internal friction coefficient and UCS for grouting broken rock with rock mass rating (RMR) and its increment have been established. The calculated results are consistent with the experimental results. These observations are important for engineered design of grouting reinforcement for broken rock mass.

Estimation of rockburst wall-rock velocity invoked by slab flexure sources in deep tunnels

2014 ◽  
Vol 51 (5) ◽  
pp. 520-539 ◽  
Author(s):  
Shili Qiu ◽  
Xiating Feng ◽  
Chuanqing Zhang ◽  
Tianbing Xiang
Keyword(s):  
Rock Mass ◽  
Seismic Source ◽  
Friction Angle ◽  
Wall Rock ◽  
Assessment Method ◽  
Source Mechanism ◽  
Uniaxial Tensile ◽  
Roughness Coefficient ◽  
Support Design ◽  
True Triaxial

For rock support in burst-prone ground, the wall-rock velocity adjacent to the surface of underground openings is a vital support design parameter, and depends on the seismic source mechanism inducing rockburst damage. In this study, to estimate the wall-rock velocity evoked only by rock slab buckling (an important rockburst source mechanism), a comprehensive velocity assessment method is proposed, using an excellent slab column buckling model with a small eccentricity, which relies on a novel compressive or tensile buckling failure criterion of rock slab. The true-triaxial loading–unloading tests and rockburst case analyses reveal that rock mass slabbing induced by high rock stress has major impacts on the evolution and formation of buckling rockburst in deep tunnels. Using a method based on the energy balance principle, the slabbing thickness of intact rock mass is also calculated by an analytical method, which indicates that the slabbing thickness parameter has a nonlinear relation to the following six parameters: uniaxial tensile strength (UTS), uniaxial compressive strength (UCS), normal stress (σn), length of joint (L), friction angle ([Formula: see text]), and joint roughness coefficient (JRC). These proposed models and methods have been quite successfully applied to rockburst and slabbing cases occurring in deep tunnels. These applications show that slab flexure is an important source mechanism invoking high wall-rock velocities and leading to severe rockburst damages in the area surrounding deep tunnels.

Analysis on Anchorage Length of Compression Anchor

2011 ◽  
Vol 255-260 ◽  
pp. 345-349 ◽  
Author(s):  
Bing Xiong Tu ◽  
Jin Qing Jia ◽  
Hong Sheng Yuan ◽  
Hai Tao Wang
Keyword(s):  
Rock Mass ◽  
Elastic Modulus ◽  
Internal Friction ◽  
Critical Length ◽  
Friction Angle ◽  
Analytic Solutions ◽  
Internal Friction Angle ◽  
Effective Length ◽  
Anchorage Length ◽  
New Model

This paper proposes a new model to calculate anchorage length for the compression anchor. Then the analytic solutions for the effective length and the critical length are derived according to the model. The analysis to the solutions show that the larger the rock mass’s elastic modulus, cohesion and internal friction angle, the smaller the anchorage length. Besides, the larger the load, the greater the anchorage length. However, the poisson’s ratio of rock mass nearly has no influence on the anchorage length. It is most important that the two calculation length show great agreement with present codes or specification.

Research of Fractured Surrounding Rock Physical and Mechanical Characteristics in Shuguang Mine No.2 Mining Area

2014 ◽  
Vol 580-583 ◽  
pp. 1364-1368 ◽  
Author(s):  
Hua Jun Xue ◽  
Jun Long Xue ◽  
Ming Lun Yin ◽  
Jie Kong ◽  
Zong Ming Gao
Keyword(s):  
Mechanical Characteristics ◽  
Friction Angle ◽  
Mining Area ◽  
Surrounding Rock ◽  
Rock Deformation ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Strength ◽  
Important Basis ◽  
Surrounding Rock Deformation ◽  
Physical And Mechanical Characteristics

Since the excavation of roadway in Shuguang mine No.2 mining area, shotcrete layer has fallen off and the surrounding rock deformation was serious. For studying big deformation of roadway in Shuguang mine No.2 mining area, the paper analyzed fractured surrounding rock physical and mechanical characteristics of No.2 mining area. The results show that the uniaxial compressive strength, uniaxial tensile strength, cohesion, internal friction angle of fractured surrounding rock were very low. And the whole physical and mechanical characteristics were poor. It is the basic reason of big deformation of roadway surrounding rock physical and the important basis of late supporting of roadway.

Approximate Theoretical Analysis on Excavation Disturbed Zone of a Soft Rock Slope in Suining-Ziyang Expressway Engineering in Southwestern China

2013 ◽  
Vol 790 ◽  
pp. 347-352
Author(s):  
Xing Song Cao ◽  
Ya Yun Hu ◽  
Shi Xiong Liu
Keyword(s):  
Stress State ◽  
Soft Rock ◽  
Strength Criterion ◽  
Uniaxial Tensile ◽  
Elastic Wedge ◽  
Uniaxial Tensile Strength ◽  
Cutting Slope ◽  
Disturbed Zone ◽  
Excavation Disturbed Zone ◽  
Body Theory

A cutting slope model can be simplified as plane strain one, the stress field of cutting slope can be analyzed with elastic wedge body theory. By using strength criterion of slope material (Mohr-Coulomb strength criterion with safety reserve and uniaxial tensile strength criterion), the disturbed zone caused by excavation can be calculated in 3D stress state, so all the disturbed zone after each step of excavation from the top down can be searched out. The main analysis steps for judging disturbed zone are described in the paper, including the methods to calculate the stress state of cutting slope, the unloading value and the scope of disturbed zone after last step of excavation. Finally, an example in Suining-Ziyang expressway engineering is chosen to explain detailedly the analytical process with elastic wedge body theory to determine the disturbed zone.

scholarly journals Influence of Water Content on the Mechanical Parameters of the Intact Rock and Rock Mass

2018 ◽  
Author(s):  
Balázs Vásárhelyi ◽  
Morteza Davarpanah
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Rock Mass ◽  
Internal Friction ◽  
Water Content ◽  
Uniaxial Compressive Strength ◽  
Water Saturation ◽  
Friction Angle ◽  
Intact Rock ◽  
Mechanical Parameters

The goal of this paper is to present the influence of the water saturation of the intact rock on different mechanical parameters, such as internal friction angle, cohesion, Hoek-Brown constant (mi ). Analyzing the previously published results, it was found that due to water saturation both the uniaxial compressive strength and tensile strength decrease similarly, i.e. the ratio of these two values is constant, thus the internal friction angle does not change but only the cohesion. Likewise, Hoek-Brown constant (mi ) remains constant; it is independent on the moisture content.The ratio of the elastic modulus and the uniaxial compressive strength of the intact rock is also calculated. According to the laboratory results, this ratio (namely modulus ratio) is also independent on the water content.It is shown that the mechanical parameters of the rock mass (such as compressive strength, tensile strength, deformation modulus) similarly depend on the water content than the intact rock.

Characterization of Shear Strength and Interface Friction of Organic Soil

2020 ◽  
Vol 857 ◽  
pp. 203-211
Author(s):  
Majid Hamed ◽  
Waleed S. Sidik ◽  
Hanifi Canakci ◽  
Fatih Celik ◽  
Romel N. Georgees
Keyword(s):  
Shear Stress ◽  
Shear Strength ◽  
Internal Friction ◽  
Moisture Content ◽  
Water Content ◽  
Friction Angle ◽  
Structural Materials ◽  
Organic Soil ◽  
Internal Friction Angle ◽  
Interface Friction

This study was undertaken to investigate some specific problems that limit a safe design and construction of structures on problematic soils. An experimental study was carried out to examine the influence of loading rate and moisture content on shear strength of organic soil. Influece of moisture content on interface friction between organic soil and structural materials was also attempted. A commonly used soil in Iraq was prepared at varying moisture contents of 39%, 57% and 75%. The experimental results showed that the increase in water content will decrease the shear stress and the internal friction angle. An increase of the shearing rate was found to decrease the shear stress and internal friction angle for all percetanges of water contents. Further, direct shear tests were carried out to detect the interface shear stress behavior between organic soil and structural materials. The results revealed that the increase in water content was shown to have significant negetavie effects on the interface internal friction and angle shear strength.

Rock Mass Strength Assessment for Bedrock Landsliding

1996 ◽  
Vol II (3) ◽  
pp. 325-338 ◽  
Author(s):  
K. M. SCHMIDT ◽  
D. R. MONTGOMERY
Keyword(s):  
Rock Mass ◽  
Strength Assessment ◽  
Rock Mass Strength
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