Jointed rock specimens with a natural replicated joint surface oriented at a mean dip angle of 60were prepared,and a series of cyclic triaxial tests was performed at different confining pressures and cyclic deviatoric...Jointed rock specimens with a natural replicated joint surface oriented at a mean dip angle of 60were prepared,and a series of cyclic triaxial tests was performed at different confining pressures and cyclic deviatoric stress amplitudes.The samples were subjected to 10,000 loading-unloading cycles with a frequency of 8 Hz.At each level of confining pressure,the applied cyclic deviatoric stress amplitude was increased incrementally until excessive deformation of the jointed rock specimen was observed.Analysis of the test results indicated that there existed a critical cyclic deviatoric stress amplitude(i.e.critical dynamic deviatoric stress)beyond which the jointed rock specimens yielded.The measured critical dynamic deviatoric stress was less than the corresponding static deviatoric stress.At cyclic deviatoric stress amplitudes less than the critical dynamic deviatoric stress,minor cumulative residual axial strains were observed,resulting in hysteretic damping.However,for cyclic deviatoric stresses beyond the critical dynamic deviatoric stress,the plastic strains increased promptly,and the resilient moduli degraded rapidly during the initial loading cycles.Cyclic triaxial test results showed that at higher confining pressures,the ultimate residual axial strain attained by the jointed rock specimen decreased,the steadystate dissipated energy density and steady-state damping ratio per load cycle decreased,while steadystate resilient moduli increased.展开更多
Electrokinetic(EK)treatment is an effective method in accelerating the consolidation and improving the geotechnical properties of fine-grained soils.This method stabilizes the soil and increases the bearing capacity o...Electrokinetic(EK)treatment is an effective method in accelerating the consolidation and improving the geotechnical properties of fine-grained soils.This method stabilizes the soil and increases the bearing capacity of piles by improving the soil shear strength.Changing the soil p H,due to the occurrence of chemical reactions of electrolysis in the soil,can increase its shear strength.However,the electrodes used in this method corrode due to the change in the soil p H,which in turn reduces the electrical potential.Electrode corrosion and loss of electrical potential can significantly reduce the efficiency of the EK method.In addition,when using the EK method to increase the bearing capacity of piles,changing the p H can cause corrosion and damage to the piles.One of the most important factors influencing the change in the p H of soil is the voltage applied during the EK process.It was reported that increasing the voltage affects the intensity of chemical reactions and electroosmotic flow and thus increases the efficiency of EK.However,very limited research has been conducted on the effect of voltage on the performance of EK method.In the present study,the effects of three voltages on soil p H and corrosion resistance of four types of electrodes including iron(Ir),stainless steel(St),copper(Co),and aluminium(Al)were studied.In addition,the effects of p H variations on the corrosion rate of three types of piles including steel pile(SP),reinforced cement concrete pile(RCCP),and reinforced lime-cement concrete pile(RLCCP)were investigated.It was observed that increasing the voltage from a specific limit had no effect on the intensity of electrolysis reactions and the soil p H adjacent to the electrodes did not change more than a specific limit.Moreover,increasing the voltage to higher than 35 V(i.e.45 V)did not increase the volume of drained water from the soil,but caused more electric current than the allowable current for Ir,St,and Al electrodes,and the corrosion intensity of these electrodes increased significantly.RCCP reduced the soil p H to 2.4 within 7 d of curing due to severe corrosion(13%corrosion rate).The soil p H values adjacent to RCCP and RLCCP within 28 d of curing reduced to 3.7 and 3.8,respectively,but the two piles were not damaged.In general,the results of this research showed that selecting an optimized voltage had a significant effect on the efficiency of EK,and increasing the voltage did not always lead to increase in the efficiency of EK process.展开更多
文摘Jointed rock specimens with a natural replicated joint surface oriented at a mean dip angle of 60were prepared,and a series of cyclic triaxial tests was performed at different confining pressures and cyclic deviatoric stress amplitudes.The samples were subjected to 10,000 loading-unloading cycles with a frequency of 8 Hz.At each level of confining pressure,the applied cyclic deviatoric stress amplitude was increased incrementally until excessive deformation of the jointed rock specimen was observed.Analysis of the test results indicated that there existed a critical cyclic deviatoric stress amplitude(i.e.critical dynamic deviatoric stress)beyond which the jointed rock specimens yielded.The measured critical dynamic deviatoric stress was less than the corresponding static deviatoric stress.At cyclic deviatoric stress amplitudes less than the critical dynamic deviatoric stress,minor cumulative residual axial strains were observed,resulting in hysteretic damping.However,for cyclic deviatoric stresses beyond the critical dynamic deviatoric stress,the plastic strains increased promptly,and the resilient moduli degraded rapidly during the initial loading cycles.Cyclic triaxial test results showed that at higher confining pressures,the ultimate residual axial strain attained by the jointed rock specimen decreased,the steadystate dissipated energy density and steady-state damping ratio per load cycle decreased,while steadystate resilient moduli increased.
基金supported by the Laboratory of Soil and Concrete of Abadgaran Negin Jonoobshargh Company(ANJ Co.)Chem Concrete Pty Ltd.Australia(117/3C-1397)。
文摘Electrokinetic(EK)treatment is an effective method in accelerating the consolidation and improving the geotechnical properties of fine-grained soils.This method stabilizes the soil and increases the bearing capacity of piles by improving the soil shear strength.Changing the soil p H,due to the occurrence of chemical reactions of electrolysis in the soil,can increase its shear strength.However,the electrodes used in this method corrode due to the change in the soil p H,which in turn reduces the electrical potential.Electrode corrosion and loss of electrical potential can significantly reduce the efficiency of the EK method.In addition,when using the EK method to increase the bearing capacity of piles,changing the p H can cause corrosion and damage to the piles.One of the most important factors influencing the change in the p H of soil is the voltage applied during the EK process.It was reported that increasing the voltage affects the intensity of chemical reactions and electroosmotic flow and thus increases the efficiency of EK.However,very limited research has been conducted on the effect of voltage on the performance of EK method.In the present study,the effects of three voltages on soil p H and corrosion resistance of four types of electrodes including iron(Ir),stainless steel(St),copper(Co),and aluminium(Al)were studied.In addition,the effects of p H variations on the corrosion rate of three types of piles including steel pile(SP),reinforced cement concrete pile(RCCP),and reinforced lime-cement concrete pile(RLCCP)were investigated.It was observed that increasing the voltage from a specific limit had no effect on the intensity of electrolysis reactions and the soil p H adjacent to the electrodes did not change more than a specific limit.Moreover,increasing the voltage to higher than 35 V(i.e.45 V)did not increase the volume of drained water from the soil,but caused more electric current than the allowable current for Ir,St,and Al electrodes,and the corrosion intensity of these electrodes increased significantly.RCCP reduced the soil p H to 2.4 within 7 d of curing due to severe corrosion(13%corrosion rate).The soil p H values adjacent to RCCP and RLCCP within 28 d of curing reduced to 3.7 and 3.8,respectively,but the two piles were not damaged.In general,the results of this research showed that selecting an optimized voltage had a significant effect on the efficiency of EK,and increasing the voltage did not always lead to increase in the efficiency of EK process.
