scholarly journals Field Experimental Study on the Broken Rock Zone of Surrounding Rock and the Rock Borehole Shear Tests of the Large Deformation Tunnel

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Guansheng Han ◽  
Bo Meng ◽  
Hongwen Jing ◽  
Jiangyu Wu
Keyword(s):  
Large Deformation ◽  
Field Experiments ◽  
Friction Angle ◽  
Surrounding Rock ◽  
Test Results ◽  
In Situ Tests ◽  
Tunnel Support ◽  
The Status ◽  
The Stability

A large deformation tunnel in LIXIANG railway, named Zhongyi tunnel is located in Southwest of China, was taken for the engineering background. The field experiments of the broken rock zone and the borehole shear test were conducted. The results show that the range of the broken rock zone of the test sections is 4.20∼4.45 meters. The cohesive force and the internal friction angle of the test sections are 221.4∼224 kPa and 14.25∼15.14°, respectively. The test results are in good agreement with the status of the surrounding rock. The surrounding rock is mainly composed of shale, which is badly broken, and the integrity and the stability are poor. In this study, the reasons for the deformation and instability of the tunnel are analyzed combined with the in situ tests and the site condition, and the suggestions for the tunnel support are put forward. This study is of great significance to ensure the safety of the constructors and can improve the service years of the tunnel. In addition, it can provide reference for the same type of the tunnel construction.

Tunnel Support Parameters Optimization Based on Micro-Seismic Monitoring

2012 ◽  
Vol 226-228 ◽  
pp. 1495-1499
Author(s):  
Dan Guang Pan ◽  
Ying Xiao Xiong ◽  
Jian Li
Keyword(s):  
Elastic Wave ◽  
Seismic Monitoring ◽  
Surrounding Rock ◽  
Parameters Optimization ◽  
Shanxi Province ◽  
Tunnel Engineering ◽  
Tunnel Support ◽  
Engineering Construction ◽  
The Stability

The monitoring is important to keep tunnel engineering construction stability. But, regular monitoring means cannot detect the position of the rock which has much stress accurately, accordingly, cannot monitor the influence of the construction process. In order to detect the local surrounding rock cracking due to excavation, a new method named micro-seismic monitoring is proposed to identify the elastic wave of rock bursting. Micro-seismic monitoring technology can find the bursting position by use the elastic wave of the rock, then, it can make an evaluation about the stability of the rock. In the method, using several sensors monitoring data of elastic wave identifies the bursting location. Then, the stability of the rock is analyzed and tunnel support parameters are optimized. At last, the method is used to monitor the Yuanyanghui tunnel located in Shanxi Province, China. The monitoring results identified the relatively stable and relatively unstable area. In-situ measurements on the surrounding rock have been used in the two areas, and therefore we use the analysis results to improve the initial tunnel support parameters.

Assessment of the range of variation of Nγ from 60 estimation methods for footings on sand

2013 ◽  
Vol 50 (7) ◽  
pp. 793-800 ◽  
Author(s):  
Edgar Giovanny Diaz-Segura
Keyword(s):  
Friction Angle ◽  
Standard Penetration Test ◽  
Estimation Methods ◽  
Penetration Test ◽  
In Situ Tests ◽  
Vertical Loading ◽  
Simplified Method ◽  
Bearing Capacity Factor ◽  
Range Of Variation

The range of variation of the bearing capacity factor, Nγ, was assessed using 60 estimation methods for rough footings on sand subjected to static vertical loading. The influence on the Nγ values of the use of correlations for the estimation of the friction angle, [Formula: see text], derived from in situ tests was also assessed. The analysis shows a marked dependency on the methods used to determine Nγ, showing differences for the same [Formula: see text] values of up to 267% between estimated values. Uncertainty in the estimation of [Formula: see text], due to the use of correlations with in situ tests, leads to a range of variation for Nγ higher than that seen using the 60 estimation methods. Finally, given the regular use of the in situ standard penetration test (SPT) on sands, and based on a series of analyses using finite elements, a simplified method in terms of the SPT N-values is proposed for estimation of Nγ in footings on sands.

Judgement Method for Surrounding Rock Stability of Guanjiao Tunnel Based on Catastrophe Theory

2011 ◽  
Vol 90-93 ◽  
pp. 2307-2312 ◽  
Author(s):  
Wen Jiang Li ◽  
Su Min Zhang ◽  
Xian Min Han
Keyword(s):  
Plastic Strain ◽  
Catastrophe Theory ◽  
Soft Rock ◽  
Surrounding Rock ◽  
In Situ Monitoring ◽  
Engineering Practice ◽  
Stability Of Surrounding Rock ◽  
The Stability ◽  
Rock Tunnel

The stability judgement of surrounding rock is one of the key jobs in tunnel engineering. Taking the Erlongdong fault bundle section of Guanjiao Tunnel as the background, the stability of surrounding rock during construction of soft rock tunnel was discussed preliminarily. Based on plastic strain catastrophe theory, and combining numerical results and in-situ data, the limit displacements for stability of surrounding rock were analyzed and obtained corresponding to the in-situ monitoring technology. It shows that the limit displacements obtained corresponds to engineering practice primarily. The plastic strain catastrophe theory under unloading condition provides new thought for ground stability of deep soft rock tunnel and can be good guidance and valuable reference to construction decision making and deformation managing of similar tunnels.

scholarly journals Numerical Simulation on Large Deformation of Weak Rock Mass Tunnel Under High Geostress

2018 ◽  
Vol 175 ◽  
pp. 03025
Author(s):  
Feng Zhou ◽  
Hongjian Jiang ◽  
Xiaorui Wang
Keyword(s):  
Rock Mass ◽  
Large Deformation ◽  
Lateral Pressure ◽  
Simulation Analysis ◽  
Pressure Coefficient ◽  
Surrounding Rock ◽  
Analog Simulation ◽  
Lateral Pressure Coefficient ◽  
High Geostress ◽  
The Stability

The problem about the stability of tunnel surrounding rock is always an important research object of geotechnical engineering, and the right or wrong of the result from stability analysis on surrounding rock is related to success or failure of an underground project. In order to study the deformation rules of weak surrounding rock along with lateral pressure coefficient and burying depth varying under high geostress and discuss the dynamic variation trend of surrounding rock, the paper based on the application of finite difference software of FLAC3D, which can describe large deformation character of rock mass, analog simulation analysis of surrounding rock typical section of the class II was proceeded. Some conclusions were drawn as follows: (1) when burying depth is invariable, the displacements of tunnel surrounding rock have a trend of increasing first and then decreasing along with increasing of lateral pressure coefficient. The floor heave is the most sensitive to change of lateral pressure coefficient. The horizontal convergence takes second place. The vault subsidence is feeblish to change of lateral pressure coefficient. (2) The displacements of tunnel surrounding rock have some extend increase along with increasing of burying depth. The research conclusions are very effective in analyzing the stability of surrounding rock of Yunling tunnel. These are going to be a reference to tunnel supporting design and construction.

scholarly journals Analytical Solution of Tunnel Surrounding Rock for Stress and Displacement Based on Lade–Duncan Criterion

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
MingZheng Zhu ◽  
Yugui Yang ◽  
Feng Gao ◽  
Juan Liu
Keyword(s):  
Internal Friction ◽  
Plastic Zone ◽  
Yield Criterion ◽  
Surrounding Rock ◽  
Rock Stress ◽  
Deformation And Failure ◽  
Displacement Based ◽  
The Stability ◽  
Coulomb Criterion

The deformation and failure of tunnel surrounding rock is the result of tunnel excavation disturbance and rock stress release. When the local stress of surrounding rock exceeds the elastic limit of rock mass, the plastic analysis of surrounding rock must be carried out to judge the stability of tunnel. In this study, the Lade–Duncan yield criterion is used to calculate the analytic solutions for the surrounding rock in a tunnel, and the radius and displacement of the plastic zone are deduced using an equilibrium equation. The plastic zone radius and displacement based on Lade–Duncan criterion and Mohr–Coulomb criterion were compared by using single-factor analysis method under the different internal friction angles, in situ stresses, and support resistances. The results show that the solutions of the radius and displacement of plastic zone calculated by the Lade–Duncan criterion are close to those of Mohr–Coulomb criterion under the high internal friction angle and support resistance or low in situ rock stress; however, the radius and displacement of the plastic zone calculated by the Lade–Duncan criterion are larger under normal circumstances, and the Lade–Duncan criterion is more applicable to the stability analysis of the surrounding rock in a tunnel.

scholarly journals Evaluating shear mobilization in rockfill columns used for riverbank stabilization

2009 ◽  
Vol 46 (8) ◽  
pp. 976-986 ◽  
Author(s):  
Marolo C. Alfaro ◽  
James A. Blatz ◽  
Wisam F. Abdulrazaq ◽  
Chang-Seok Kim
Keyword(s):  
Large Scale ◽  
Experimental Testing ◽  
Test Results ◽  
Lake Agassiz ◽  
Shearing Resistance ◽  
Glacial Lake Agassiz ◽  
The Stability ◽  
Rockfill Columns ◽  
The City

The major rivers within the City of Winnipeg are founded in glacial Lake Agassiz clay and silt sediments that have low shear strength. As such, riverbank instabilities are a common issue along many stretches of the rivers. The use of rockfill columns has become an increasingly utilized approach for stabilizing failing banks. Recent cases in Winnipeg have shown that movements can occur following installation of rockfill columns. Uncertainty regarding the magnitude of these movements that is required to mobilize shearing resistance in the rockfill columns has resulted in situations where the stability of riverbanks following remediation has been questioned. This has provided a need to improve our understanding about how much movement a stabilized slope must undergo before sufficient shear resistance of the rockfill column will be mobilized. The results of experimental testing conducted to assess the shear mobilization of rockfill column materials using a large-scale direct shear test apparatus are presented in this paper. The testing methodology is described along with the test results. The results show that the development of material specifications, construction, and placement methods and appropriate methods of analysis requires understanding of the stress–strain properties of the in situ soil and the rockfill material.

Stability of Submarine Foundation Pits Under Wave Loads

2012 ◽  
Author(s):  
Julian Bubel ◽  
Jürgen Grabe
Keyword(s):  
Ground Surface ◽  
Friction Angle ◽  
Shallow Foundation ◽  
Cohesionless Soil ◽  
Wave Loads ◽  
In Situ Tests ◽  
Sea Floor ◽  
The North ◽  
The Stability ◽  
Wave Induced

Shallow foundation structures offer ecological benefits compared to pile foundations as less noise is emitted at sea floor level during construction process. On the other hand, shallow offshore foundations can rarely be placed on top of the sea floor. Weak soils usually need to be excavated to place the foundation structure on more stable ground and thus, anthropogenic submarine pits result. Steep but stable slopes of the pit meet both economic and ecologic aims as they minimise material movement and sediment disturbance. According to Terzaghi [1] the angle β between slope and the horizontal of the ground surface of cohesionless soil is at most equal to the critical state friction angle φc. However, it can be observed that natural submarine slopes of sandy soils are always much more shallow. Artificial (temporary) slopes do not appear and behave as natural submarine slopes, since the latter are already shaped by perpetual loads of waves, tide and mass movements. Physical simulations of different scales were presented at the OMAE 2011 [2] to analyse the stability of artificial submarine slopes of sandy soil in the North Sea. The laboratory tests focused on gravitational forces and impacts from the excavation processes. This paper presents additional numerical simulations of wave-induced bottom pressure on the suggested submarine foundation pits. Furthermore, in-situ tests will be performed in 2012 and 2013. Both dredging process and resulted foundation pits will be considerably surveyed.

scholarly journals EFFECT OF BLASTING ON THE STABILITY OF LINING DURING EXCAVATION OF NEW TUNNEL NEAR THE EXISTING TUNNEL

2021 ◽  
Vol 30 (1) ◽  
Author(s):  
Tuan Minh Tran ◽  
Quang Huy Nguyen
Keyword(s):  
Field Data ◽  
Damage Zone ◽  
Field Tests ◽  
Surrounding Rock ◽  
In Situ Test ◽  
The Stability ◽  
Relationship Of ◽  
The Impact ◽  
The Relationship

In recent years, experimental and numerical researches on the effect of blasting pressure on the stability of existing tunnels was widely obtained. However, the effect of the blasting pressure during excavation a new tunnel or expansion old tunnels on an existing tunnel has disadvantages and still unclear. Some researches were carried out to study the relationship of the observed Peak Particle Velocity (PPV) on the lining areas along the existing tunnel direction, due to either the lack of in situ test data or the difficulty in conducting field tests, particularly for tunnels that are usually old and vulnerable after several decades of service. This paper introduces using numerical methods with the field data investigations on the effect of the blasting in a new tunnel on the surrounding rock mass and on the existing tunnel. The research results show that not only predicting the tunnel lining damage zone under the impact of blast loads but also determination peak maximum of explosion at the same time at the surface of tunnel working.

Benchmarking of VIV Suppression Systems

2008 ◽  
Author(s):  
Kenneth J. Schaudt ◽  
Christopher Wajnikonis ◽  
Don Spencer ◽  
Jie Xu ◽  
Steve Leverette ◽  
...  
Keyword(s):  
Reynolds Number ◽  
The Body ◽  
Test Results ◽  
In Situ Tests ◽  
Image Velocimetry ◽  
High Reynolds ◽  
Viv Suppression ◽  
Almost All ◽  
Flow Splitter

A new form of Vortex-Induced Vibration (VIV) suppression device, the AIMS Dual-fin Flow Splitter (ADFS), has been developed, tested and benchmarked against bare-pipe, 5d and 15d pitch strakes and conventional teardrop fairings. Testing included high-mode number in-situ tests as well as low Reynolds number (<300,000) and high Reynolds number (<1.9 million) forced and free tank tests. Finally, wind tunnel tests and in-water Particle Image Velocimetry (PIV) were used to test the hypothesis that the dual-fin flow splitter replaces the oscillating wake of a blunt body with a stable, attached circulation behind the body and between the fins. Such a replacement was hypothesized to result in reduced drag, and the elimination of almost all VIV. The paper will describe the testing program and results, and present the incorporation of the test results into riser models.

Initial DPSH Soil Test Results with Accelerometer Installed in the Probe Cone

2016 ◽  
Author(s):  
Kęstutis Kelevišius ◽  
Gintaras Žaržojus
Keyword(s):  
Soil Analysis ◽  
Cohesive Soil ◽  
Test Results ◽  
Cone Penetration ◽  
In Situ Tests ◽  
Soil Response ◽  
Dynamic Penetration ◽  
Dynamic Cone Penetration ◽  
Cpt Test

Dynamic penetration test (DPSH) is one of the large amount of soil in-situ tests are known. In world practice, this method usually used for granular soil investigations although it could be applied in cohesive soils. Correlation of received DPSH test results with soil properties is complex and often not reliable. Especially it becomes obvious after application in cohesive soil analysis. In most cases, correlation depends on soil response to dynamic cone penetration and deformation of dynamic sounding equipment. Measurement of cone accelerations allows precisely evaluate loss of hammer energy, displacement of the cone during strike and other parameters. Correlation of DPSH (measured acceleration of the cone) and CPT test results are presented in this article. In this article also presented studies of possibilities to determine dynamic soil characteristics.

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