scholarly journals A case study on severe damage at a tunnel in serpentinite rock mass

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Y. Fujii ◽  
N. Ikeda ◽  
Y. Onoe ◽  
Y. Kanai ◽  
T. Hayakawa ◽  
...  
Keyword(s):  
Rock Mass ◽  
Creep Test ◽  
Triaxial Compression ◽  
Friction Angle ◽  
Primary Creep ◽  
Time Dependent ◽  
Severe Damage ◽  
Floor Heave ◽  
Triaxial Creep ◽  
Triaxial Creep Test

Abstract Face squeezing, floor heave, and buckling of invert were found after a 10-day holiday in 2014 around the serpentinite face of a tunnel in Hokkaido, Japan. The damage continued for over 2 months, extending 400 m toward the entrance causing a massive roof fall. The tunnel was excavated again with a circular section and extra-thick shotcrete, and the face had crossed the damaged part 6 years after the damage occurred. Uniaxial and triaxial compression tests were carried out to obtain the mechanical properties of the serpentinite to clarify the severe damage mechanism at the tunnel. The main experimental findings are as follows. The uniaxial compressive strength of the serpentinite samples was very low, and the ratio of the strength to the estimated overburden pressure was extremely low. The parameter n indicated that the time-dependent deformation of the serpentinite was not large but the same as ordinary rocks. All specimens showed strain-hardening in the triaxial compression test, and the friction angle was very low by the brucite content. Only primary creep was observed in the multistage triaxial creep test. The pressure on the shotcrete from rock mass for the damaged tunnel was enough to cause creep deformation and failure of shotcrete. From the above findings, designing the concrete lining that can support the earth and water pressure is recommended for tunnel excavation in such a weak serpentinite rock mass, particularly with a very low friction angle by brucite. Highlights Face squeezing, floor heave, and buckling of invert were found after a 10-day holiday around the serpentinite face in Hokkaido, Japan. The time-dependent deformation of the serpentinite was not large but the same as ordinary rocks. All specimens showed strain-hardening in the triaxial compression test, and the friction angle was very low by the brucite content. Only primary creep was observed in the multistage triaxial creep test. The severe damage to the tunnel was not a brittle creep failure of the serpentinite rock mass itself but the shotcrete lining.

In situ triaxial creep test for investigating deformational properties of gravelly sliding zone soil: example of the Huangtupo 1# landslide, China

Landslides ◽  
2018 ◽  
Vol 15 (12) ◽  
pp. 2499-2508 ◽  
Author(s):  
Qinwen Tan ◽  
Huiming Tang ◽  
Lei Fan ◽  
Chengren Xiong ◽  
Zhiqiang Fan ◽  
...  
Keyword(s):  
Creep Test ◽  
Triaxial Creep ◽  
Triaxial Creep Test ◽  
Sliding Zone

scholarly journals Experimental Investigation on Failure Modes and Mechanical Properties of Rock-Like Specimens with a Grout-Infilled Flaw under Triaxial Compression

2019 ◽  
Vol 2019 ◽  
pp. 1-14
Author(s):  
Huilin Le ◽  
Shaorui Sun ◽  
Feng Zhu ◽  
Haotian Fan
Keyword(s):  
Mechanical Properties ◽  
Rock Mass ◽  
Epoxy Resin ◽  
Failure Modes ◽  
Shear Failure ◽  
Fractured Rock ◽  
Triaxial Compression ◽  
Friction Angle ◽  
Confining Pressure ◽  
Compression Tests

Flaws existing in rock mass are one of the main factors resulting in the instability of rock mass. Epoxy resin is often used to reinforce fractured rock mass. However, few researches focused on mechanical properties of the specimens with a resin-infilled flaw under triaxial compression. Therefore, in this research, epoxy resin was selected as the grouting material, and triaxial compression tests were conducted on the rock-like specimens with a grout-infilled flaw having different geometries. This study draws some new conclusions. The high confining pressure suppresses the generation of tensile cracks, and the failure mode changes from tensile-shear failure to shear failure as the confining pressure increases. Grouting with epoxy resin leads to the improvement of peak strengths of the specimens under triaxial compression. The reinforcement effect of epoxy resin is better for the specimens having a large flaw length and those under a relatively low confining pressure. Grouting with epoxy resin reduces the internal friction angle of the samples but improves their cohesion. This research may provide some useful insights for understanding the mechanical behaviors of grouted rock masses.

scholarly journals Analysis of Mechanical Parameters and Creep Characteristics of Surrounding Rock in Fully Weathered Sandstone Tunnel

2019 ◽  
Vol 136 ◽  
pp. 04022
Author(s):  
Kaicheng Hua ◽  
hongyan Guo ◽  
Ke Li ◽  
Xiang Yang Cui
Keyword(s):  
Structural Parameters ◽  
Friction Angle ◽  
Surrounding Rock ◽  
Mountainous Area ◽  
Mechanical Parameters ◽  
Creep Characteristics ◽  
Geological Conditions ◽  
Triaxial Creep ◽  
Deformation Test ◽  
Triaxial Creep Test

Based on the geological conditions of the fully weathered sandstone stratum in the expressway of the mountainous area, the Huizhou-Qingyuan section of the Yuzhan Expressway is used to analyze the mechanical parameters and creep characteristics of the surrounding rock of the tunnel through the indoor model test. It is concluded that: 1) The uniaxial compression deformation test measured the structural parameters of the fully weathered sandstone stratum structure, and obtained that the elastic modulus and internal friction angle φ of the fully weathered sandstone was 14.20°, and the cohesion c was 0.343Mpa. 2) The failure mode of fully weathered sandstone specimens was obtained by triaxial creep test. The creep curves of different weathered loads were analyzed and the Xiyuan rheological model was established. 3) The creep data was analyzed by MATLAB software, and the surrounding rock parameters under different surrounding rock were obtained.

Elastic viscoplastic modelling of the time-dependent stress-strain behaviour of soils

1999 ◽  
Vol 36 (4) ◽  
pp. 736-745 ◽  
Author(s):  
Jian-Hua Yin ◽  
James Graham
Keyword(s):  
Strain Rate ◽  
Creep Test ◽  
Triaxial Compression ◽  
Constant Strain Rate ◽  
Time Dependent ◽  
Model Parameters ◽  
Stress Strain ◽  
Equivalent Time ◽  
Strain Behaviour ◽  
Modified Cam Clay

This paper presents a new framework for elastic viscoplastic (EVP) constitutive modelling. In developing the model, a general one-dimensional elastic viscoplastic (1D EVP) relationship is first derived for isotropic stressing conditions using an "equivalent-time" concept. This 1D EVP model is then generalized into a three-dimensional EVP model based on Modified Cam-Clay and viscoplasticity. Fitting functions are proposed for fitting data when model parameters are being determined. Using these functions, a specific EVP model is developed which describes the time-dependent stress-strain behaviour of soils under triaxial stress states. This model has been calibrated using data from a densely compacted sand-bentonite mixture. The calibrated model is used to compute time-dependent (or strain rate dependent) stress-strain curves from a multistage shear creep test and a step-changed, constant strain rate undrained triaxial compression test. Predictions from the EVP model are in general agreement with measured values. It is demonstrated that the model can simulate accelerating creep when deviator stresses are close to the shear strength envelope in a q creep test. It can also model the behaviour in unloading-reloading and relaxation. Limitations and possible improvements are also indicated.Key words: equivalent time, stress-strain, time dependent, elastic, viscoplastic, triaxial.

A Creep-Damage Constitutive Model for Sandstone

2012 ◽  
Vol 170-173 ◽  
pp. 289-294 ◽  
Author(s):  
Wei Wang ◽  
Jun Lv ◽  
Hai Cheng Wang
Keyword(s):  
Constitutive Model ◽  
Creep Test ◽  
Creep Damage ◽  
Creep Model ◽  
Whole Process ◽  
Proposed Model ◽  
Accelerated Creep ◽  
Damage Constitutive Model ◽  
Triaxial Creep ◽  
Triaxial Creep Test

Based on the results obtained by the triaxial creep test, a creep-damage constitutive model for sandstone is presented by using the damage theory and by introducing the concept of “the whole process of damage” into Burgers creep model. The parameters of the model are determined by fitting the creep test data. The result shows that the proposed model can not only describe efficiently the variation of decay and steady creep under relatively low stress condition, but also give a satisfied representation of damage behavior in accelerated creep stage.

scholarly journals Particle Size Distribution of Cemented Rockfill Effects on Strata Stability in Filling Mining

Minerals ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 407 ◽  
Author(s):  
Jiangyu Wu ◽  
Meimei Feng ◽  
Jingmin Xu ◽  
Peitao Qiu ◽  
Yiming Wang ◽  
...  
Keyword(s):  
Particle Size ◽  
Rock Mass ◽  
Particle Size Distribution ◽  
Coal Seam ◽  
Size Distribution ◽  
Longwall Mining ◽  
Poisson Ratio ◽  
Triaxial Compression ◽  
Friction Angle ◽  
Economic Benefits

It is of great significance for engineering safety, economic benefits, environmental protection, and sustainable development to investigate the strata stability in filling mining with cemented rockfill. Consequently, this paper is based on a specific coal mine where we applied the fully-mechanized longwall mining and filling and designed a cemented rockfill material for which the particles satisfied the Talbot gradation. Uniaxial and triaxial compression experiments were carried out on the cemented rockfill specimen, which obtained the relations between the mechanical parameters (Poisson ratio, elastic modulus, compressive strength, cohesive force, internal friction angle, and tensile strength) and the particle size distribution of the aggregate. The excavation and filling processes in the coal seam were simulated based on the numerical software FLAC3D. The characteristics of the displacement and stress fields of the strata when the goaf was filled by cemented rockfill with different granule gradations were discussed. The influences of the particle size distribution and mining distance on the maximum subsidence displacement of the coal seam roof, internal stress of the backfill, and the stress of the rock mass in the coalface were analyzed. The feasibility and effectiveness of the filling mining with cemented rockfill to protect the integrity of the overlying strata were discussed. The results showed that optimizing the particle size distribution of the aggregate in cemented rockfill could increase the loading capacity of the backfill to improve the filling effect, effectively control the strata movement, and decrease the stress of rock mass in the coalface to reduce the potential danger.

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