In worldwide, the most common triggering factor of rock landslides is extended and intense rainfall. However, different from the soil slope failure caused by softening action of infiltration rainwater, the mechanism o...In worldwide, the most common triggering factor of rock landslides is extended and intense rainfall. However, different from the soil slope failure caused by softening action of infiltration rainwater, the mechanism of rock landslide in rainfall is not clear. From the view of fracture mechanics, the propagation of cracks on rock slope and the development of sliding surface were researched. Then based on hydraulics formulas and using Sweden arc method, the influence of crack water on stability of rock slope was quantitatively studied. Finally, an example was given to check the theoretical approach. The result shows that the development of sliding surface of rock slope is mainly caused by crack propagation under hydrostatic pressure when the stress intensity factor KI at crack tip is bigger than the toughness index of rock fractures Klc, and the failure of slope is the result of hydraulic action of crack water and the softening of materials on sliding surface when the depth of crack water is bigger than a minimum value hmin.展开更多
Based on the steady-state seepage method, we used the Mechanical Testing and Simulation 815.02 System and a self-designed seepage instrument for over-broken stone to measure seepage properties of water flows in three ...Based on the steady-state seepage method, we used the Mechanical Testing and Simulation 815.02 System and a self-designed seepage instrument for over-broken stone to measure seepage properties of water flows in three types of crushed rock samples. Three methods of confidence interval in describing permeability coefficients are presented: the secure interval, the calculated interval and the systemic interval. The lower bound of the secure interval can be applied to water-inrush and the upper bound can solve the problem of connectivity. For the calculated interval, as the axial pressure increases, the length of confidence interval is shortened and the upper and lower bounds are reduced. For the systemic interval, the length of its confidence interval, as well as the upper and lower bounds, clearly vary under low axial pressure but are fairly similar under high axial pressure. These three methods provide useful information and references for analyzing the permeability coefficient of over-broken rock.展开更多
In order to realize the safety, high efficiency and rapidity of hard rock tunneling, we propose the drilling &hydraulic impact hard-rock tunneling(DHIHT) technology and method. Based on the LS-DYNA explicit module...In order to realize the safety, high efficiency and rapidity of hard rock tunneling, we propose the drilling &hydraulic impact hard-rock tunneling(DHIHT) technology and method. Based on the LS-DYNA explicit module and APDL programming, the key parameters of DHIHT, including drilling spacing and drilling radius, were investigated. The simulation results show that: the drilling spacing should not exceed0.20 m-larger distances weaken the actual breaking effect; the best drilling radius is about 0.035 m, larger or smaller distances would both decrease the effect of drilling-hole free surfaces. The field impact breaking experiments were conducted in Baitaizi township granite quarry, Jinzhou, Liaoning province,China. The experiment results indicate that DHIHT is a feasible method for hard-rock tunneling, but its efficiency still needs to be further optimized and improved.展开更多
基金Project(2008CB425802) supported by the National Basic Research Program of China Project(40872181) supported by the National Natural Science Foundation of ChinaProject(09R2200200) supported by the West Light Foundation of Chinese Academy of Sciences
文摘In worldwide, the most common triggering factor of rock landslides is extended and intense rainfall. However, different from the soil slope failure caused by softening action of infiltration rainwater, the mechanism of rock landslide in rainfall is not clear. From the view of fracture mechanics, the propagation of cracks on rock slope and the development of sliding surface were researched. Then based on hydraulics formulas and using Sweden arc method, the influence of crack water on stability of rock slope was quantitatively studied. Finally, an example was given to check the theoretical approach. The result shows that the development of sliding surface of rock slope is mainly caused by crack propagation under hydrostatic pressure when the stress intensity factor KI at crack tip is bigger than the toughness index of rock fractures Klc, and the failure of slope is the result of hydraulic action of crack water and the softening of materials on sliding surface when the depth of crack water is bigger than a minimum value hmin.
基金Financial support for this work, provided by the National Natural Science Foundation of China (Nos. 50774083 and 41074040)the Program for New Century Excellent Talents in University (No. NCET-07-0803)the National Key Basic Research Program (No. 2009CB219605)
文摘Based on the steady-state seepage method, we used the Mechanical Testing and Simulation 815.02 System and a self-designed seepage instrument for over-broken stone to measure seepage properties of water flows in three types of crushed rock samples. Three methods of confidence interval in describing permeability coefficients are presented: the secure interval, the calculated interval and the systemic interval. The lower bound of the secure interval can be applied to water-inrush and the upper bound can solve the problem of connectivity. For the calculated interval, as the axial pressure increases, the length of confidence interval is shortened and the upper and lower bounds are reduced. For the systemic interval, the length of its confidence interval, as well as the upper and lower bounds, clearly vary under low axial pressure but are fairly similar under high axial pressure. These three methods provide useful information and references for analyzing the permeability coefficient of over-broken rock.
基金supported by the Staring Project of Youth Team of Taiyuan University of Technology (No. 2013T036)the Qualified Personnel Foundation of Taiyuan University of Technology (No. TYUT-RC201426a)the 2014 Shanxi Coal-based Key Scientific & Technological Project (No. MJ2014-06)
文摘In order to realize the safety, high efficiency and rapidity of hard rock tunneling, we propose the drilling &hydraulic impact hard-rock tunneling(DHIHT) technology and method. Based on the LS-DYNA explicit module and APDL programming, the key parameters of DHIHT, including drilling spacing and drilling radius, were investigated. The simulation results show that: the drilling spacing should not exceed0.20 m-larger distances weaken the actual breaking effect; the best drilling radius is about 0.035 m, larger or smaller distances would both decrease the effect of drilling-hole free surfaces. The field impact breaking experiments were conducted in Baitaizi township granite quarry, Jinzhou, Liaoning province,China. The experiment results indicate that DHIHT is a feasible method for hard-rock tunneling, but its efficiency still needs to be further optimized and improved.
