scholarly journals Correlation Research of TBM Tunnel Rock Mechanical Characteristics, Chiseling Specific Energy, and Abrasion Performance: Case Study of Jiaozhou Bay Subsea Tunnel in Qingdao

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Yawei Wang ◽  
You Zhang ◽  
Guang Wu
Keyword(s):  
Compressive Strength ◽  
Uniaxial Compressive Strength ◽  
Specific Energy ◽  
Poisson Ratio ◽  
Jiaozhou Bay ◽  
Reference Value ◽  
Energy Formula ◽  
Subsea Tunnel ◽  
Highly Correlated ◽  
Multifactor Regression

This paper takes Qingdao Jiaozhou Bay subsea tunnel project as the research object to study the relationship among rock mechanical parameters and chiseling specific energy and abrasion performance. SPSS22 was used to analyze the correlation between the parameters. The results show that except for the low correlation with Poisson ratio, all the other parameters in the single factor correlation analysis have high R . By taking the chiseling specific energy and abrasion performance as dependent variables, taking each mechanical parameter as an independent variable, multifactor regression analysis and stepwise multifactor fitting were carried out; it was concluded that the abrasion performance was highly correlated with uniaxial compressive strength and integrity coefficient, and the chiseling specific energy is highly correlated with uniaxial compressive strength and softening coefficient. In the process of verifying the fitting models, it is found that, under the influence of quartz vein and microfissure in the specimens, the chiseling specific energy formula has a higher fitting value, while the fitting formula of abrasion performance has a higher reference value for the specimens in the study area.

scholarly journals Analysis of The Rock Fracture on Uniaxial Compressive Strength Test

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Edward Dinoy ◽  
Yohanes Gilbert Tampaty ◽  
Imelda Srilestari Mabuat ◽  
Joseph Alexon Sutiray Dwene
Keyword(s):  
Compressive Strength ◽  
Uniaxial Compressive Strength ◽  
Poisson Ratio ◽  
Rock Fracture ◽  
Strength Test ◽  
Maximum Pressure ◽  
Test Results ◽  
Average Value ◽  
Compressive Strength Test ◽  
Uniaxial Compressive Strength Test

The compressive strength test is one of the technical properties or compressive strength tests that are commonly used in rock mechanics to determine the collapse point or the elasticity of rock against maximum pressure. The rock collapse point is a measure of the strength of the rock itself when the rock is no longer able to maintain its elastic properties. The purpose of this test is to find out how long the rock maintains its strength or elasticity properties when pressure is applied, and to find out the difference between the strength of compact rock and rock that has fractures when pressure is applied. Rocks that have fractures will break more easily or quickly when pressure is applied compared to compact rocks. This analysis is carried out by comparing the rock strength of each sample, both those that have fractures and compact rocks. To find out these differences, laboratory testing was carried out. The test results show the value (compressive strength test 57.76 MPa), (elastic modulus 5250.000MPa), (Poisson ratio 0.05) and the average value of rock mechanical properties test (axial 0.91), (lateral-0.279), and (volumetric 0.252) . Based on the test results above, it shows that rocks that have fractures will break more easily when pressure is applied, compared to compact rocks that have a long time in the uniaxial compressive strength test.

scholarly journals A new method for roadheader pick arrangement based on meshing pick spatial position and rock cutting verification

PLoS ONE ◽  
2021 ◽  
Vol 16 (11) ◽  
pp. e0260183
Author(s):  
Mengqi Zhang ◽  
Xianguo Yan ◽  
Guoqiang Qin
Keyword(s):  
Compressive Strength ◽  
Prediction Model ◽  
Uniaxial Compressive Strength ◽  
Specific Energy ◽  
Cutting Speed ◽  
Rock Cutting ◽  
Spatial Position ◽  
Height Loss ◽  
Cutting Head ◽  
Longitudinal Cutting

This paper proposes a cutting head optimization method based on meshing the spatial position of the picks. According to the expanded shape of the spatial mesh composed of four adjacent picks on the plane, a standard mesh shape analysis method can be established with mesh skewness, mesh symmetry, and mesh area ratio as the indicators. The traversal algorithm is used to calculate the theoretical meshing rate, pick rotation coefficient, and the variation of cutting load for the longitudinal cutting head with 2, 3, and 4 helices. The results show that the 3-helix longitudinal cutting head has better performance. By using the traversal result with maximum theoretical meshing rate as the design parameter, the longitudinal cutting head CH51 with 51 picks was designed and analyzed. The prediction model of pick consumption is established based on cutting speed, direct rock cutting volume of each pick, pick rotation coefficient, uniaxial compressive strength, and CERCHAR abrasivity index. And the rock with normal distribution characteristics of Uniaxial Compressive Strength is used for the specific energy calculating. The artificial rock wall cutting test results show that the reduction in height loss suppresses the increase in pick equivalent loss caused by the increase in mass loss, and the pick consumption in this test is only 0.037–0.054 picks/m3. In addition, the correlation between the actual pick consumption and the prediction model, and the correlation between the actual cutting specific energy and the theoretical calculation value are also analyzed. The research results show that the pick arrangement design method based on meshing pick tip spatial position can effectively reduce pick consumption and improve the rock cutting performance.

scholarly journals Determination Method of Reasonable Reinforcement Parameters for Subsea Tunnels Considering Ground Reinforcement and Seepage Effect

2019 ◽  
Vol 9 (17) ◽  
pp. 3607 ◽  
Author(s):  
Zhenyu Sun ◽  
Dingli Zhang ◽  
Qian Fang
Keyword(s):  
Jiaozhou Bay ◽  
Reference Value ◽  
Surrounding Rock ◽  
Reinforcement Scheme ◽  
Sequencing Method ◽  
Geological Conditions ◽  
Curtain Grouting ◽  
Subsea Tunnel ◽  
Full Face ◽  
Reinforcement Design

The key issue for construction of subsea tunnels through unfavorable geological conditions is to determine a reasonable reinforcement scheme, while the core problem for the reinforcement design is to accurately evaluate the mechanical behavior of surrounding rock with ground reinforcement. Considering that advanced curtain grouting and full-face grouting are widely used in subsea tunnels, a mechanical model for the subsea tunnel surrounding rock accounting for both ground reinforcement and seepage effect was established. According to the distribution and extent of the plastic zone(s), six potential configurations were appropriately analyzed, which were validated by numerical simulations and analytical solutions for simplified settings from the literature. The sensitivities of the reinforcement parameters were examined, and by taking into account the tunnel radial displacement and the seepage quantity as the main objectives, the multi-objective optimization of the reinforcement parameters was put forward via the stratified sequencing method. Finally, application of the proposed method to the Qingdao Jiaozhou bay subsea tunnel project in China was explained. Research results could provide insightful ideas for the quantitative design of the ground reinforcement of subsea tunnels and may have reference value for their construction safety through unfavorable geological conditions.

Impact on the Cement Mortar’s Uniaxial Compressive Strength under Erosion of SO42-

2014 ◽  
Vol 584-586 ◽  
pp. 1001-1004
Author(s):  
Nan Zheng ◽  
Yue Wang
Keyword(s):  
Compressive Strength ◽  
Uniaxial Compressive Strength ◽  
Building Material ◽  
Cement Mortar ◽  
Reference Value ◽  
Solution Concentration ◽  
Complex Environment ◽  
Simulated Experiment ◽  
Strain Relationship ◽  
Ion Erosion

Cement mortar is one of the commonly used building material . The effect of erosion is widely seen after a certain time. Based on the method of simulated experiment, Erosive ions at different concentrations, different age under uniaxial compressive strength of cement mortar and the influence of stress strain relationship are discussed. The results show that ion erosion was evident on cement mortar. Especially, certain solution concentration of SO42- can enhance the strength of cement mortar. This research has important reference value for the application of cement mortar in complex environment.

Property Analysis for Correlation of Specific Energy with Penetration Rate and Bit Wear Rate

2011 ◽  
Vol 367 ◽  
pp. 547-553
Author(s):  
B. Adebayo ◽  
W. A. Bello
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Wear Rate ◽  
Uniaxial Compressive Strength ◽  
Specific Energy ◽  
Penetration Rate ◽  
Point Load ◽  
Coefficient Of Correlation ◽  
Rock Samples ◽  
Bit Wear

This study evaluates rock properties for correlation of specific energy with penetration rate and bit wear rate. In order to achieve these objectives five rock samples were obtained from the study area. These samples were tested in the laboratory for uniaxial compressive strength and tensile strength using 1100kN compression machine and point load tester respectively. Also, the mineral composition of the samples was determined by thin section examination. Bit deterioration was measured with digital vernier calliper at regular intervals. The specific energy was determined from field data using empirical equations. The results of the uniaxial compressive strength of the five rock samples varied from 165-320 MPa and were classified as having very high compressive strength characteristics. The point load strength index of the samples had values ranging from 5.50 – 10.67 MPa representing the tensile strength. The result of the statistical correlation matrix revealed that penetration rate and bit wear rate are dominant factors affecting the prediction of specific energy having high coefficient of correlation. The regression model had multiple coefficient of correlation of R2 = 0.893 which means that 89.3% of variation in specific energy could be attributed to variation in penetration rate and bit wear rate. Ultimately, computer programme DRILLING PROFESSIONAL 2009 was developed to compute penetration rate, wear rate and specific energy when necessary inputs are supplied. This gives quarry operators advance information on time of drilling and bit consumption.

scholarly journals Experimental Analysis of the Mechanical Properties and Resistivity of Tectonic Coal Samples with Different Particle Sizes

Energies ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2303
Author(s):  
Congyu Zhong ◽  
Liwen Cao ◽  
Jishi Geng ◽  
Zhihao Jiang ◽  
Shuai Zhang
Keyword(s):  
Mechanical Properties ◽  
Particle Size ◽  
Compressive Strength ◽  
Elastic Modulus ◽  
Uniaxial Compressive Strength ◽  
Coalbed Methane ◽  
Coal Sample ◽  
Fine Particles ◽  
Particle Sizes ◽  
Tectonic Coal

Because of its weak cementation and abundant pores and cracks, it is difficult to obtain suitable samples of tectonic coal to test its mechanical properties. Therefore, the research and development of coalbed methane drilling and mining technology are restricted. In this study, tectonic coal samples are remodeled with different particle sizes to test the mechanical parameters and loading resistivity. The research results show that the particle size and gradation of tectonic coal significantly impact its uniaxial compressive strength and elastic modulus and affect changes in resistivity. As the converted particle size increases, the uniaxial compressive strength and elastic modulus decrease first and then tend to remain unchanged. The strength of the single-particle gradation coal sample decreases from 0.867 to 0.433 MPa and the elastic modulus decreases from 59.28 to 41.63 MPa with increasing particle size. The change in resistivity of the coal sample increases with increasing particle size, and the degree of resistivity variation decreases during the coal sample failure stage. In composite-particle gradation, the proportion of fine particles in the tectonic coal sample increases from 33% to 80%. Its strength and elastic modulus increase from 0.996 to 1.31 MPa and 83.96 to 125.4 MPa, respectively, and the resistivity change degree decreases. The proportion of medium particles or coarse particles increases, and the sample strength, elastic modulus, and resistivity changes all decrease.

scholarly journals Determination of Mechanical Properties of Altered Dacite by Laboratory Methods

Minerals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 813
Author(s):  
Veljko Rupar ◽  
Vladimir Čebašek ◽  
Vladimir Milisavljević ◽  
Dejan Stevanović ◽  
Nikola Živanović
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Rock Mass ◽  
Uniaxial Compressive Strength ◽  
Rock Material ◽  
Strength Parameter ◽  
Gradual Transition ◽  
Strength Parameters ◽  
Triaxial Compressive Strength ◽  
Heterogeneous Rock

This paper presents a methodology for determining the uniaxial and triaxial compressive strength of heterogeneous material composed of dacite (D) and altered dacite (AD). A zone of gradual transition from altered dacite to dacite was observed in the rock mass. The mechanical properties of the rock material in that zone were determined by laboratory tests of composite samples that consisted of rock material discs. However, the functional dependence on the strength parameter alteration of the rock material (UCS, intact UCS of the rock material, and mi) with an increase in the participation of “weaker” rock material was determined based on the test results of uniaxial and triaxial compressive strength. The participation of altered dacite directly affects the mode and mechanism of failure during testing. Uniaxial compressive strength (σciUCS) and intact uniaxial compressive strength (σciTX) decrease exponentially with increased AD volumetric participation. The critical ratio at which the uniaxial compressive strength of the composite sample equals the strength of the uniform AD sample was at a percentage of 30% AD. Comparison of the obtained exponential equation with practical suggestions shows a good correspondence. The suggested methodology for determining heterogeneous rock mass strength parameters allows us to determine the influence of rock material heterogeneity on the values σciUCS, σciTX, and constant mi. Obtained σciTX and constant mi dependences define more reliable rock material strength parameter values, which can be used, along with rock mass classification systems, as a basis for assessing rock mass parameters. Therefore, it is possible to predict the strength parameters of the heterogeneous rock mass at the transition of hard (D) and weak rock (AD) based on all calculated strength parameters for different participation of AD.

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