ORCID Profile
0000-0002-0017-1745
Current Organisation
University of Newcastle Australia
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Civil Engineering | Civil Geotechnical Engineering | Civil engineering | Civil geotechnical engineering |
Road Infrastructure and Networks | Civil Construction Planning | Civil Construction Design | Construction Materials Performance and Processes not elsewhere classified
Publisher: Springer Science and Business Media LLC
Date: 07-07-2020
Publisher: Springer Science and Business Media LLC
Date: 08-04-2023
Publisher: Springer Science and Business Media LLC
Date: 21-08-2017
Publisher: EDP Sciences
Date: 2019
DOI: 10.1051/E3SCONF/20199217010
Abstract: The use of pressure grouting techniques in the soil reinforcement system is frequent as it has many advantages over gravity grouting. Pressure grouting can be injected by pressure and volume (flow) controlled techniques. A preliminary study was conducted for a newly developed pressure grouted soil-nail system, where a latex membrane was used as a liner around the grouting outlet to form a Tube a Manchette (TAM) for direct injection of grout into sand. In addition, a grout bag was formed with the membrane to prevent the grout injection into the sand for simulating a compaction grouting. In the investigation, a newly developed volume controlled injection system was used to inject the cement grout into the sand or grout bag for a specified flow rate and the interaction of injected grouted with the soil mass (i.e., soil stress state) was monitored by the installed total earth pressure cell around the grout outlets. From the investigation, it was found that the injected grout volume was much less for the soil-nail (TAM) than that with a grout bag around for a certain flow rate. In addition, the preliminary results indicated that the pullout capacity of the pressure grouted soil-nail controlled by the injected grout volume (grout bulb).
Publisher: Elsevier BV
Date: 06-2009
Publisher: Elsevier BV
Date: 08-2017
Publisher: Canadian Science Publishing
Date: 08-2021
Abstract: This paper describes an experimental investigation of a newly developed driven and grouted soil nail (x-Nail), which combines the capabilities of a purely frictional driven nail and a compaction-grouted nail. The innovative design allows the x-Nail to be driven into the ground with a latex balloon attached that is subsequently used for compaction grouting. A grout bulb is thus formed at the driven end of the nail to improve its pull-out resistance. For compaction grouting, a special type of additive−mixed cement grout was used in this investigation because of its zero bleeding and high bond strength. A series of pullout model tests was conducted to examine the performance of the x-Nail compared to a purely frictional soil nail. It was found that more than 90% of the pullout force of the x-Nail was resisted by the expanded grout bulb and the end bearing resistance of the grout bulb increased with the increment of the injected grout volumes. The experimental results revealed that the pullout force of the x-Nail increased approximately 1800%, 1550%, 1200%, and 900% compared to the purely frictional soil nail for the injected grout volumes of about 350, 270, 220, and 170 mL, respectively.
Publisher: MDPI AG
Date: 26-03-2020
DOI: 10.3390/APP10072246
Abstract: One of the growing concerns in the construction industry is energy consumption and energy efficiency in residential buildings. Moreover, management of non-degradable solid glass wastes is becoming a critical issue worldwide. Accordingly, incorporation of recycled expanded glass aggregates (EGA) as a substitution for natural fine aggregate in cement composites would be a sustainable solution in terms of energy consumption in the buildings and waste management. This experimental research aims to investigate the effects of EGA on fresh and hardened properties and thermal insulating performance of cement mortar. To enhance the mechanical properties and water resistance of the EGA-mortar, nano titanium dioxide (nTiO2) was used as nanofillers. The results showed an increase in workability and water absorption of the EGA-mortar. In addition, a significant decrease in bulk density and compressive strength observed by incorporating EGA into the cement mortar. The EGA-mortar exhibited a low heat transfer rate and excellent thermal insulation property. Furthermore, inclusion of nTiO2 increased compressive strength and water resistance of EGA-mortar, however, their heat transfer rate was increased. The results demonstrated that EGA-mortar can be integrated into the building envelop or non-load bearing elements such as wall partition as a thermal resistance to reduce the energy consumption in residential buildings.
Publisher: Springer Science and Business Media LLC
Date: 14-01-2015
Publisher: Springer Science and Business Media LLC
Date: 14-03-2018
Publisher: Elsevier BV
Date: 06-2019
Publisher: Elsevier BV
Date: 04-2022
Publisher: Springer Science and Business Media LLC
Date: 08-12-2017
Publisher: Elsevier BV
Date: 07-2018
Publisher: Springer Science and Business Media LLC
Date: 18-11-2016
Publisher: Elsevier BV
Date: 09-2016
Publisher: Elsevier BV
Date: 06-2018
Publisher: Springer Science and Business Media LLC
Date: 13-09-2022
Publisher: Elsevier BV
Date: 11-2019
Publisher: Elsevier BV
Date: 05-2017
Publisher: Emerald
Date: 06-04-2020
Abstract: This paper aims at the problem of surrounding rock excavation damage zone of tunneling in the rich water region, this paper aims to propose a new seepage-stress-damage coupling model and studied the numerical algorithm. This reflects the characteristics of rock damage evolution, accompanied by plastic flow deformation and multi-field interaction. First of all, rock elastoplastic damage constitutive model based on the Drucker–Prager criterion is established, the fully implicit return mapping algorithm is adopted to realize the numerical solution. Second, based on the relation between damage variation and permeability coefficient, the rock stress-seepage-damage model and multi-field coupling solving iterative method are presented. Finally, using the C++ language compiled the corresponding programs and simulated tunnel engineering in the rich water region. Results show that difference evolution-based back analysis inversed damage parameters well, at the same time the established coupling model and calculating program have more advantages than general conventional methods. Multiple field coupling effects should be more considered for the design of tunnel support. The proposed method provides an effective numerical simulation method for the construction of the tunnel and other geotechnical engineering involved underground water problems.
Publisher: Elsevier BV
Date: 07-2019
Publisher: Springer Science and Business Media LLC
Date: 09-04-2018
Publisher: Springer Science and Business Media LLC
Date: 21-06-2014
Publisher: Elsevier BV
Date: 08-2013
Publisher: Elsevier BV
Date: 02-2021
Publisher: Springer Science and Business Media LLC
Date: 02-09-2017
Publisher: American Society of Civil Engineers (ASCE)
Date: 02-2013
Publisher: Elsevier BV
Date: 10-2020
Publisher: Elsevier BV
Date: 07-2018
Publisher: Elsevier BV
Date: 09-2012
Publisher: Wiley
Date: 12-09-2017
DOI: 10.1002/BSE.1983
Publisher: JVE International Ltd.
Date: 30-06-2019
Abstract: To obtain the optimal probability distribution models of geotechnical parameters, the goodness of fit of the normal information diffusion (NID) distribution and Weibull distribution were investigated and compared for actual engineering s les and Monte Carlo (MC) simulated s les. Two datasets from actual engineering parameters (the strength of a rock mass and the average wind speed) were used to test the fitting abilities of these two distributions. The results show that the parameters of the NID distribution are easily estimated, the Kolmogorov-Smirnov (K-S) test results of the NID distribution are smaller than those of the Weibull distribution, and the NID distribution curves can perfectly reflect the stochastic volatility of geotechnical parameters with small s le sizes. The s le size effects on the fitting accuracy of the NID distribution and Weibull distribution were also investigated in this paper. Eight simulated s les with different s le sizes, namely, 15, 20, 30, 50, 100, 200, 500, and 1000, were produced by using the MC method based on two known Weibull distributions. The results show that with an increase in the s le size, the K-S test results of the NID distribution gradually decrease and tend to converge, while the chi-square test results of the NID distribution remain low and are always lower than those of the Weibull distribution. The cumulative probability values of the NID distribution are larger than those of the Weibull distribution and are always equal to 1.0000. Finally, the comparison of the fitting accuracy between the NID distribution and normalized Weibull distribution was also analyzed.
Publisher: Elsevier BV
Date: 2017
Publisher: Springer Science and Business Media LLC
Date: 21-10-2021
Publisher: Springer Science and Business Media LLC
Date: 29-06-2019
Publisher: Springer Science and Business Media LLC
Date: 06-2022
Publisher: Elsevier BV
Date: 04-2023
Publisher: Springer Science and Business Media LLC
Date: 23-12-2018
Publisher: Springer Science and Business Media LLC
Date: 06-12-2014
Publisher: Springer Science and Business Media LLC
Date: 20-02-2019
Publisher: Elsevier BV
Date: 08-2019
Publisher: Springer Science and Business Media LLC
Date: 14-02-2017
Publisher: Elsevier BV
Date: 12-2018
Publisher: Elsevier BV
Date: 08-2019
Publisher: Research Publishing Services
Date: 2010
Publisher: MDPI AG
Date: 31-10-2022
DOI: 10.3390/APP122111023
Abstract: The support theory of the excavation disturbance zone (EDZ) cannot provide an accurate physical explanation or theoretical description of the time-dependent properties required for the development of an EDZ. Therefore, the primary factors that cause the formation of an EDZ should be determined to further improve the support theory of the EDZ and grasp the principle underlying the control of the long-term stability of rock masses. Considering the headrace tunnel and nuclear waste repository as the research background, this study aimed to understand the deformation damage evolution process of the surrounding rock after tunnel excavation under different working conditions using the self-developed realistic failure process analysis (RFPA2D) code. The simulation revealed the following. First, an EDZ is formed, although the deformation damage to the surrounding rock is relatively small under the action of environmental factors. Second, under the action of stress in the abovementioned case, the deformation speed, damage degree, and scope of the surrounding rock significantly increase, accelerating the formation and development of the EDZ. Therefore, the boundary of the EDZ expands significantly. Third, when environmental factors are blocked, the range of the EDZ is small due to the small deformation damage to the surrounding rock. Thus, the main factors responsible for the formation of the EDZ are environmental factors, whereas stress is only an auxiliary factor. A numerical simulation method that considers environmental factors can more accurately reproduce the formation of an EDZ. Therefore, a study of the internal mechanism of the EDZ phenomenon can provide a more in-depth understanding of the essential characteristics of an EDZ at the macro level. Furthermore, it can provide a scientific basis and method for the construction and support designs of underground excavation projects and widen the possibilities for further improving the support theory of the EDZ.
Publisher: Elsevier BV
Date: 11-2010
Publisher: Springer Science and Business Media LLC
Date: 28-11-2022
Publisher: InTech
Date: 17-05-2013
DOI: 10.5772/56012
Publisher: Springer Science and Business Media LLC
Date: 24-04-2012
Publisher: Elsevier BV
Date: 04-2021
Publisher: Elsevier BV
Date: 04-2018
Publisher: Springer Science and Business Media LLC
Date: 2023
Publisher: Springer Science and Business Media LLC
Date: 10-07-2023
DOI: 10.1007/S40948-023-00628-X
Abstract: Rock cuttability has great influence on the rock excavation efficiency of TBM (tunnel boring machine). In order to evaluate rock cuttability in real time, quickly, accurately and efficiently during TBM excavating, the relevant excavation parameters of Zagros, Kerman and Bazideraz tunnels were first collected. Then, the regression analyses between excavation parameters and rock cuttability were carried out. The two-dimensional regression analyses studied the relationship between operating parameters (thrust F and rotation speed RPM ) and the characterization parameters (torque T and penetration rate PR ). The three-dimensional regression analyses were utilized to create the PR and specific energy SE models based on operating parameters. The result shows that the established three-dimensional regression models have good prediction performance, and its performance is superior to two-dimensional models. Moreover, the prediction model of uniaxial compressive strength UCS and the classification model of rock cuttability were founded based on SE . The rock cuttability is ided into three levels, namely, easy (level 1), medium (level 2), and poor (level 3), in which the corresponding SE ranges are 0 to 6, 6 to 10 and exceeds 10 kWh·m −3 , respectively. Finally, the intelligent algorithms, combined with excavation parameters, were introduced to establish UCS prediction model and rock cuttability classification model, and the good prediction performance was achieved. The above studies can provide necessary references and ideas for real-time, rapid, accurate and effective evaluation of rock cuttability based on TBM excavation parameters, and has certain guiding significance for engineering application.
Publisher: Elsevier BV
Date: 10-2022
Publisher: Springer Science and Business Media LLC
Date: 09-2021
Publisher: Hindawi Limited
Date: 08-01-2021
DOI: 10.1155/2021/6615016
Abstract: The main challenge for metro station construction is to ensure the construction schedule while minimizing the impact on the surrounding environment. Based on the characteristics of the upper-soft and lower-hard stratum in the Dalian city of China, a special structure with six pilot tunnels and three spans of the pile-beam-arch (PBA) method is proposed and applied to the construction of the Labor Park metro station. In this study, laboratory experiments, numerical simulation analysis, and field monitoring data are used to investigate the applicability of six pilot tunnels and three spans of the PBA method in the process of construction. In the process of numerical simulation, the ground surface settlement, arch vertical displacement, the horizontal displacement of rock mass on both sides of the station, and vertical stress of support structure are analyzed. The numerical simulation results are found to be in good agreement with field measurement. Furthermore, the results indicate that, in the construction of six pilot tunnels and three spans of the PBA method, pilot tunnel construction and arch construction have a great influence on the surface settlement. The part of the initial vertical support of the pilot tunnels is removed, which caused the change of the position of maximum vertical stress and the redistribution of vertical stress. Because of reinforcement by side piles on both sides of the station, the horizontal displacement of the rock mass was reduced by 44.76% compared with that without reinforcement. The six pilot tunnels and three spans of the PBA method can effectively control the surface settlement, arch vertical displacement, and horizontal displacement of the rock mass.
Publisher: Elsevier BV
Date: 2023
Publisher: Elsevier BV
Date: 11-2021
Publisher: Elsevier BV
Date: 10-2019
Publisher: Springer Science and Business Media LLC
Date: 29-03-2021
Publisher: Springer Science and Business Media LLC
Date: 22-06-2021
DOI: 10.1038/S41598-021-92277-X
Abstract: To 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.
Publisher: Elsevier BV
Date: 11-2019
Publisher: Springer Science and Business Media LLC
Date: 21-01-2023
Publisher: Springer Science and Business Media LLC
Date: 28-03-2023
Publisher: Springer Science and Business Media LLC
Date: 17-10-2022
Publisher: Springer Science and Business Media LLC
Date: 13-01-2021
Publisher: Elsevier BV
Date: 06-2013
Publisher: Elsevier BV
Date: 10-2020
Publisher: Springer Science and Business Media LLC
Date: 30-03-2023
Publisher: Springer Science and Business Media LLC
Date: 19-03-2022
Publisher: Elsevier BV
Date: 06-2023
Publisher: Springer Science and Business Media LLC
Date: 21-11-2005
Publisher: Elsevier BV
Date: 08-2019
Publisher: Informa UK Limited
Date: 23-05-2018
Publisher: Elsevier BV
Date: 10-2018
Publisher: Informa UK Limited
Date: 17-02-2011
Publisher: MDPI AG
Date: 24-01-2017
DOI: 10.3390/MA10020096
Publisher: Elsevier BV
Date: 02-2017
Publisher: Springer Science and Business Media LLC
Date: 09-2021
Publisher: Elsevier BV
Date: 09-2019
Publisher: Springer Science and Business Media LLC
Date: 09-12-2017
Publisher: American Society of Civil Engineers
Date: 15-05-2006
DOI: 10.1061/40867(199)35
Publisher: Springer Science and Business Media LLC
Date: 2023
Publisher: MDPI AG
Date: 08-02-2021
DOI: 10.3390/APP11041521
Abstract: Prestressed anchor support is one of the most important support methods for coal mine roadways. As the coal mining depth increases, the adaptability of existing prestressed anchor has become weaker and weaker, which is mainly reflected in the current anchor prestress is much smaller than the support resistance required for the stability of the roadways and makes it difficult to effectively control the roadways. In order to solve the problem, a group anchor structure was proposed to realize higher prestressed anchor support technology and improve the support status of deep roadways. For coal mine roadways, group anchor structure is a new technology and new topic, and the design method and theoretical basis of the group anchor support are lacking. Therefore, the paper studied the bearing capacity of the group anchors through physical tests and numerical simulations. Among them, a special set of group anchor drawing tooling was designed and processed to match the physical test. The test results show that the group anchor structure can double the bearing capacity and bearing rigidity compared with traditional anchors, and the group anchor support can further optimize the support parameters to improve the bearing capacity of the surrounding rock. Therefore, the group anchor support is helpful to the stability control of the surrounding rock of the deep roadway.
Publisher: Informa UK Limited
Date: 22-05-2018
Publisher: Elsevier BV
Date: 10-2016
Publisher: American Association for Cancer Research (AACR)
Date: 15-11-2015
DOI: 10.1158/0008-5472.CAN-15-0378
Abstract: The urokinase-type plasminogen activator receptor (uPAR) has a well-established role in cancer progression, but it has been little studied at earlier stages of cancer initiation. Here, we show that uPAR deficiency in the mouse dramatically reduces susceptibility to the classical two-stage protocol of inflammatory skin carcinogenesis. uPAR genetic deficiency decreased papilloma formation and accelerated keratinocyte differentiation, effects mediated by Notch1 hyperactivation. Notably, Notch1 inhibition in uPAR-deficient mice rescued their susceptibility to skin carcinogenesis. Clinically, we found that human differentiated keratoacanthomas expressed low levels of uPAR and high levels of activated Notch1, with opposite effects in proliferating tumors, confirming the relevance of the observations in mice. Furthermore, we found that TACE-dependent activation of Notch1 in basal kerantinocytes was modulated by uPAR. Mechanistically, uPAR sequestered TACE within lipid rafts to prevent Notch1 activation, thereby promoting cell proliferation and tumor formation. Given that uPAR signaling is nonessential for normal epidermal homeostasis, our results argue that uPAR may present a promising disease-specific target for preventing skin cancer development. Cancer Res 75(22) 4895–909. ©2015 AACR.
Publisher: Springer Science and Business Media LLC
Date: 17-07-2015
Publisher: Elsevier BV
Date: 11-2022
Publisher: Springer Science and Business Media LLC
Date: 04-11-2011
Publisher: Elsevier BV
Date: 05-2021
Publisher: GeoScienceWorld
Date: 27-03-2022
DOI: 10.2113/2022/9320619
Abstract: In this study, numerical simulations of uniaxial compression, biaxial compression, and biaxial unloading were performed on granite specimens that contained different prefabricated defects. The microscopic parameters in numerical models were verified by the uniaxial compression experiments on the intact standard cylindrical granite specimen and the square granite specimens with prefabricated defects. The influences from different stress paths, different shapes of prefabricated defects, different numbers of defects, and different distribution of defects on the strength, deformation, and crack initiation stress characteristics of the rock specimens were investigated. Furthermore, the initial cracking and cracking stage distributions, cumulative crack amounts, ultimate failure modes, and crack propagation fractal dimensions of specimens with different prefabricated defects under biaxial unloading conditions were analyzed and compared. The experiment was ided into three stages to analyze crack evolution mechanisms. The results show that most cracks appeared after peak strength, and different shapes, the number of defects, and the relative defect positions significantly affected crack initiation, crack propagation, and crack coalescence.
Publisher: Elsevier BV
Date: 02-2017
Publisher: Hindawi Limited
Date: 10-03-2019
DOI: 10.1155/2019/6260351
Abstract: A series of experimental tests were conducted to investigate the effects of loading rate on the tensile strength of sandstone by using four test methods, including a direct tensile method and three typical Brazilian disc methods (plate loading, circular arc loading, and strip loading). The loading rates used in these tests varied from 10 −2 MPa/s to 10 0 MPa/s. The results show that the rate effects are clear for these test methods, and the tensile strength of sandstone will increase linearly with the logarithm of the loading rate. At the same loading rate, it is found that the tensile strengths of the sandstone specimens under plate loading and arc loading are relatively similar and are much greater than the direct tensile strength, while the tensile strength under strip loading is less than the direct strength. A comprehensive comparison suggested that the strip loading method can be adopted for the Brazilian disc test, while the obtained strength should be modified with a coefficient of 1.37 to obtain the direct tensile strength.
Publisher: Elsevier BV
Date: 09-2019
Publisher: Elsevier BV
Date: 12-2020
Publisher: Elsevier BV
Date: 09-2015
Publisher: Springer Science and Business Media LLC
Date: 2015
Publisher: American Society of Civil Engineers
Date: 12-05-2006
DOI: 10.1061/40862(194)36
Publisher: Springer Science and Business Media LLC
Date: 20-12-2011
Publisher: Springer Science and Business Media LLC
Date: 20-07-2018
Publisher: Elsevier BV
Date: 2019
Publisher: MDPI AG
Date: 04-2022
DOI: 10.3390/APP12073605
Abstract: Engineered cementitious composite (ECC) is a unique material, which can significantly contribute to self-healing based on ongoing hydration. However, it is difficult to model and predict the self-healing performance of ECC. Although different machine learning (ML) algorithms have been utilized to predict several properties of concrete, the application of ML on self-healing prediction is considerably rare. This paper aims to provide a comparative analysis on the performance of various machine learning models in predicting the self-healing capability of ECC. These models include four in idual methods, linear regression (LR), back-propagation neural network (BPNN), classification and regression tree (CART), and support vector regression (SVR). To improve prediction accuracy, three ensemble methods, namely bagging, AdaBoost, and stacking, were also studied. A series of experimental works on the self-healing performance of ECC s les was conducted, and the results were used to develop and compare the accuracy among the ML models. The comparison results showed that the Stack_LR model had the best predictive performance, showing the highest coefficient of determination (R2), the lowest root-mean-squared error (RMSE), and the smallest prediction error (MAE). Among all in idual models studies, the BPNN model performed the best in terms of the RMSE and R2, while SVR performed the best in terms of the MAE. Furthermore, SVR had the smallest prediction error (MAE) for crack widths less than 60 μm or greater than 100 μm, while CART had the smallest prediction error (MAE) for crack widths between 60 μm and 100 μm. The study concluded that the in idual and ensemble methods can be used to predict the self-healing of ECC. Ensemble models were able to improve the accuracy of prediction compared to the in idual model used as their base learner, i.e., a 2.3% to 4.9% reduction in MAE. However, selecting an appropriate in idual and ensemble method is critical. To improve the performance accuracy, researchers should employ different ensemble methods to compare their effectiveness with different ML models.
Publisher: Springer Science and Business Media LLC
Date: 12-0005
Publisher: Springer Science and Business Media LLC
Date: 27-09-2020
Publisher: American Society of Civil Engineers
Date: 12-05-2006
DOI: 10.1061/40862(194)33
Publisher: Elsevier BV
Date: 08-2023
Publisher: Elsevier BV
Date: 05-1970
Publisher: Springer Science and Business Media LLC
Date: 16-09-2021
Publisher: Elsevier BV
Date: 03-2018
Publisher: Springer Science and Business Media LLC
Date: 15-06-2023
DOI: 10.1007/S40948-023-00603-6
Abstract: Field penetration index (FPI) is a representative key indicator for tunnel boring machine (TBM) performance estimation, however its application in real tunneling projects is still limited because of the lack of some theoretical knowledge on the relationships between FPI, rock mass properties, and TBM specifications. This study aims to establish a theoretical FPI model by analyzing the tool–rock interaction of disc cutters from a theoretical perspective. This was first done by comparison of the tool–rock interaction of the disc cutter with that of the polycrystalline diamond compact (PDC) bit, which indicated that they share similar rock breakage mechanisms and force equilibrium. A series of cutting tests were then conducted on granite, marble, and limestone to determine the relationship between rotary torque and applied thrust during the rock cutting. Referring to the test results and tool–rock interaction features of the PDC bit and disc cutter, a theoretical FPI model of the disc cutter was derived and verified using the field TBM performance dataset. It was found that the rotary torque was linearly correlated with the thrust but independent of the rotation speed during the rock cutting. In addition to the machine specifications’ contribution, rock mass parameters and abrasiveness purely control this linear relationship. The theoretical FPI model proved that FPI shows a strong positive linear relationship with rock mass properties (uniaxial compressive strength and rock integrity), even under different drilling conditions, providing a theoretical basis for empirical FPI model establishment. Therefore, in practical engineering, it is recommended to use multi-parameter rock mass classification system values—such as rock structure rating (RSR), rock mass rating (RMR), and tunneling quality index(Q)—instead of in idual rock mass properties —such as uniaxial compressive strength, to establish or update semiempirical FPI models.
Publisher: Hindawi Limited
Date: 12-10-2020
DOI: 10.1155/2020/8876099
Abstract: A series of dynamic fracture experiments on semicircular bend (SCB) marble specimens were conducted to characterize the loading rate effect using the INSTRON testing machine and the modified SHPB testing system. The fracture toughness of the marble specimens was measured from a low loading rate to a high loading rate (10-3~106 MPa·m1/2s-1). The results show that the fracture toughness will increase with the loading rate. Since the fracture toughness at a magnitude of 10-3 MPa·m1/2s-1 is regarded as the static fracture toughness, the specific value of DI F f (the dynamic increase factor of fracture toughness) can be obtained at the other loading magnitudes from dynamic fracture tests. To describe the variation in DI F f from low to high loading rates, a new continuous model of DI F f was put forward to express the quantitative relation between the loading rate and rock dynamic fracture toughness. It is shown that the new DI F f model can accurately describe the loading rate effect on the dynamic fracture testing data for rock materials.
Publisher: Springer Science and Business Media LLC
Date: 23-06-2018
Publisher: Elsevier BV
Date: 04-2023
Publisher: American Society of Civil Engineers (ASCE)
Date: 02-2021
Publisher: Elsevier BV
Date: 09-2019
Publisher: Elsevier BV
Date: 07-2011
Publisher: Springer Science and Business Media LLC
Date: 22-01-2022
Publisher: Elsevier BV
Date: 10-2021
Publisher: Elsevier BV
Date: 03-2009
Publisher: American Society of Civil Engineers (ASCE)
Date: 04-2018
Publisher: Elsevier BV
Date: 08-2021
Publisher: Research Publishing Services
Date: 2010
Publisher: Springer Science and Business Media LLC
Date: 04-11-2014
Publisher: Elsevier BV
Date: 10-2021
Publisher: Elsevier BV
Date: 12-2019
Publisher: Springer Science and Business Media LLC
Date: 21-11-2018
Publisher: Springer Science and Business Media LLC
Date: 12-02-2013
Publisher: American Thoracic Society
Date: 2016
Publisher: Springer Science and Business Media LLC
Date: 17-01-2012
Publisher: Springer Science and Business Media LLC
Date: 19-11-2013
Publisher: Springer Science and Business Media LLC
Date: 26-07-2018
Publisher: Hindawi Limited
Date: 11-07-2018
DOI: 10.1155/2018/3616942
Abstract: Shale reservoirs are characterized by extremely low permeability and high clay content. To further study the stress sensitivity of a shale reservoir, the Lower Cambrian shale in north Guizhou was utilized. Through laboratory testing, the relationships between the shale porosity and permeability and the effective stress were established, and the stress sensitivity of shale was analysed. The mechanical properties and mineral composition of this shale were studied by rock mechanics testing and X-ray diffraction. The main factors affecting the stress sensitivity were analysed. The results show that the porosity and permeability of this shale decrease with increasing effective stress the shale reservoir permeability damage rate is 61.44 ~ 73.93%, with an average of 69.92% the permeability stress sensitivity coefficient is 0.04867 ~ 0.05485 MPa −1 , with an average of 0.05312 MPa −1 and the shale reservoir stress sensitivity is strong. Shale stress sensitivity is related to the rock mineral composition and rock mechanical properties. The higher the clay content in the mineral composition, the lower the elastic modulus of shale, the higher the compressibility, and the greater the stress sensitivity coefficient.
Publisher: Informa UK Limited
Date: 31-07-2017
Publisher: Elsevier BV
Date: 03-2019
Publisher: Elsevier BV
Date: 02-2013
Publisher: American Society of Civil Engineers (ASCE)
Date: 2023
Publisher: Elsevier BV
Date: 06-2010
DOI: 10.3208/SANDF.50.441
Publisher: MDPI AG
Date: 14-03-2022
DOI: 10.3390/MATH10060922
Abstract: To understand the fracture features of zonal disintegration and reveal the failure mechanisms of circle tunnels excavated in deep jointed rock masses, a series of three-dimensional heterogeneous models considering varying joint dip angles are established. The strength reduction method is embedded in the RFPA method to achieve the gradual fracture process, macro failure mode and safety factor, and to reproduce the characteristic fracture phenomenon of deep rock masses, i.e., zonal disintegration. The mechanical mechanisms and acoustic emission energy of surrounding rocks during the different stages of the whole formation process of zonal disintegration affected by different-dip-angle joints and randomly distributed joints are further discussed. The results demonstrate that the zonal disintegration process is induced by the stress redistribution, which is significantly different from the formation mechanism of traditional surrounding rock loose zone the dip angle of joint set has a great influence on the stress buildup, stress shadow and stress transfer as well as the failure mode of surrounding rock mass the existence of parallel and random joints lead the newly formed cracks near the tunnel surface to developing along their strikes the random joints make the zonal disintegration pattern much more complex and affected by the regional joint composition. These will greatly improve our understanding of the zonal disintegration in deep engineering.
Publisher: Elsevier BV
Date: 09-2023
Publisher: Springer Science and Business Media LLC
Date: 29-06-2019
DOI: 10.1007/S11356-019-05777-9
Abstract: In the past 20 years, the green economy has increasingly attracted the attention of governments and policy makers. However, most studies have only focused on the relationship between the green economy and innovation, and little attention has been given to the relationship between the different innovation stages and the green economy. This study draws on eco-innovation and institutional theories and proposes a model to empirically investigate the effects between the different innovation stages and green economy. Furthermore, it explores how these effects are mediated by knowledge spillover and moderated by absorptive capacity and environment regulations. We use data from the last 5 years (2012-2016) obtained from different China regions to empirically test the model. Results show that knowledge innovation, research and development (R&D) innovation, and product innovation have the same significant positive impact on knowledge spillovers. R&D and product innovation have a significant positive impact on green economy, whereas knowledge innovation has no significant effect on the development of the green economy. Knowledge spillover partially mediates the relationship between the innovation stage and the green economy. Meanwhile, absorptive capacity positively moderates the relationship between knowledge spillover and the green economy. However, environmental regulation negatively moderates the relationship between knowledge spillover and the green economy. In addition, corresponding measures are proposed based on the conclusions.
Publisher: American Society of Civil Engineers (ASCE)
Date: 08-2020
Publisher: Elsevier BV
Date: 12-2017
Publisher: Hindawi Limited
Date: 06-2020
DOI: 10.1155/2020/9030484
Abstract: To investigate the permeability changes and the mechanisms of fractured rock under dynamic and static stresses produced by earthquakes, permeability experiments on fractured rock with rough surfaces under axial dynamic and static stresses were conducted on the MTS815 Rock Mechanics Testing System. Surface asperity was investigated by scanning the specimen surfaces before and after testing. The results show that the roughness of fracture surface has a great influence on the permeability when the axial displacement is not enough to cause the fracture rock to slip. Moreover, the rougher fracture surface leads to severer surface damage as indicated by the more gouge productions. The accumulation of gouge materials on larger roughness fracture surfaces causes a slow drop in permeability. The fracture surfaces experience larger degradations, but it has small weights of gouge materials on fracture surface after testing under axial dynamic stress. The reason is that the gouge material transport and mobilization tend to occur in process of dynamic loading. Therefore, the permeability drops of axial dynamic stress are larger than those of axial static stress.
Publisher: Elsevier BV
Date: 08-2020
Publisher: Elsevier BV
Date: 09-2018
Publisher: Springer Science and Business Media LLC
Date: 11-2011
Publisher: Hindawi Limited
Date: 26-11-2018
DOI: 10.1155/2018/5796086
Abstract: The crack characteristic and permeability change in six compacted clay liners (CCLs) under dry-wet cycles were studied. Results show that as soil liquid limit (LL) increases, the crack block (CB) number, crack ratio (CR), and crack length (CL) of the CCLs increase under the dry state. The CB sizes of all the six CCLs correspond to normal distribution. A piecewise linear relationship exists between crack parameters and soil LL, and the slope at LL 50 is larger than the slope at LL 50. The size of the representative elementary volume (REV) of cracked CCL decreases linearly with the increase in soil LL when LL 50. The linear fitting result is REV = 90.5 – 1.6 LL, whereas REV change is inconspicuous with a mean value of approximately 10 cm when LL 50. The s le size of the CCLs for the permeability test must be larger than REV. Before and after three dry-wet cycles, the permeability ratio ( K 3 / k 0 ) initially increases and eventually decreases as soil LL increases, and LL at the peak value of K 3 / k 0 is 36.1%. However, linear relationships exist between permeability D-value ( K 3 − k 0 ) and soil LL in a semilog coordinate system when LL 50%, whereas the change in the permeability D-value is inconspicuous with a mean value of approximately 1.67 × 10 −8 cm/s when LL 50%. The volume and mean width of unclosed cracks are two main factors that determine the increase in permeability after dry-wet cycles. After three dry-wet cycles, these factors decrease as soil LL increases, thereby reducing the permeability D-value.
Publisher: Elsevier BV
Date: 03-2017
Publisher: Springer Science and Business Media LLC
Date: 10-06-2020
Publisher: Elsevier BV
Date: 2017
DOI: 10.1016/J.CHEMOSPHERE.2016.09.059
Abstract: Long-term leaching behavior of contaminant from stabilization/solidification (S/S) treated waste stays unclear. For the purpose of studying long-term leaching behavior and leaching mechanism of lead from cement stabilized soil under different pH environment, semi-dynamic leaching test was extended to two years to investigate leaching behaviors of S/S treated lead contaminated soil. Effectiveness of S/S treatment in different scenarios was evaluated by leachability index (LX) and effective diffusion coefficient (D
Publisher: Elsevier BV
Date: 03-2023
Publisher: Oxford University Press (OUP)
Date: 20-06-2017
DOI: 10.1093/GJI/GGX270
Publisher: Elsevier BV
Date: 12-2011
Publisher: The Royal Society
Date: 08-2018
DOI: 10.1098/RSOS.180346
Abstract: Upward mining of the residual coal seam over an abandoned pillar working is one of the effective measures to alleviate the contradiction between limited resources and increased consumption. Interburden stability over an abandoned pillar working plays a significant role in guaranteeing the safety of upward mining however, it has not yet been extensively studied and understood. In this study, the vertical stress of the interburden over an abandoned pillar working was first investigated. The mechanical model of the interburden was established and the damage conditions were analysed. Then, the stability of the interburden over 38502 abandoned workings in Baijiazhuang coal mine was determined by mechanical analysis and field monitoring. The results show that: (i) Vertical stress of the interburden over abandoned mining zones is clearly lower than the initial stress, indicating the existence of a de-stressed effect. Moreover, vertical stress of the interburden over residual coal pillars is greater than the initial stress, which is the evidence of a stress concentration effect. (ii) The interburden over an abandoned pillar working should be regarded as an elastic rectangular plate supported by generalized Kelvin bodies in mechanical modelling. (iii) The interburden over abandoned mining zones may experience two damage stages. In the first stage, initial plastic damage appears at the central region of interburden. In the second stage, the plastic damage evolves from the central point to the surrounding areas. (iv) The mechanical analysis and field monitoring both indicate the initial damage occurred at the central region over 38502 abandoned workings in Baijiazhuang coal mine before upward mining. Related rock control measures should be implemented in that region to guarantee the safe mining of the residual coal seam.
Publisher: Wiley
Date: 31-03-2020
DOI: 10.1002/NAG.3071
Start Date: 2014
End Date: 2018
Funder: Australian Research Council
View Funded ActivityStart Date: 2014
End Date: 2016
Funder: Australian Research Council
View Funded ActivityStart Date: 05-2015
End Date: 12-2019
Amount: $761,579.00
Funder: Australian Research Council
View Funded ActivityStart Date: 2023
End Date: 12-2025
Amount: $532,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 12-2021
End Date: 12-2025
Amount: $360,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 2014
End Date: 12-2018
Amount: $425,000.00
Funder: Australian Research Council
View Funded Activity