The technology of expansion fracturing with liquid CO_(2)(EFLCO_(2))has attracted increasing attention due to reduced vibration and damage.The disposable fracturing tube has been developed and is gradually replacing t...The technology of expansion fracturing with liquid CO_(2)(EFLCO_(2))has attracted increasing attention due to reduced vibration and damage.The disposable fracturing tube has been developed and is gradually replacing the Cardox tube.However,there is a lack of impact pressure testing of disposable tubes under real working conditions,selection of gas explosion design parameters,and systematic analysis of blasting vibration.This limitation has constrained the widespread application of disposable fracturing tubes in engineering.A joint monitoring of the pressure-time curves in the disposable tubes and boreholes was conducted.The rock-breaking effect of varying hole spacing parameters in the EFLCO_(2)design was analyzed,and a systematic study was carried out on the vibration peak value,frequency,and energy characteristics.The results show that(1)the pressure distribution characteristics,stress peak value,and duration in the disposable tubes are different from those of Cardox tubes,which show multi-peak distribution,low-pressure peak value,and short duration.The correlation between the pressure in the disposable tube,filling pressure,and liquid CO_(2)weight is established,and a theoretical calculation method for the borehole wall pressure is proposed;(2)The hole spacing in rocks of different hardness is suggested;and(3)At the same scale distance,the peak particle velocity(PPV)caused by EFLCO_(2)(PPVCO_(2))is significantly smaller than that caused by blasting(PPVexplosive).The ratio of PPVexplosive to PPVCO_(2)is a power function related to scale distance,and a distance-related zonality exist in this relationship.The frequency composition of the vibration signal caused by EFLCO_(2)is relatively simple with a narrow frequency band.Its PPV and energy are mainly concentrated in the low-frequency band.This research contributes to the optimization of disposable fracturing tubes,gas explosion design,and vibration hazard control.展开更多
The hole penetrated in thin metallic plates due to hypervelocity impacts of cylindrical projectiles was analyzed by experimental method.The projectile caused a hole-expanding effect when penetrating the target plate b...The hole penetrated in thin metallic plates due to hypervelocity impacts of cylindrical projectiles was analyzed by experimental method.The projectile caused a hole-expanding effect when penetrating the target plate because of dynamic shear failure and extrusion.A new empirical model was presented to predict the perforation diameter in thin plates impacted by high-velocity cylindrical projectiles.The fitting coefficients resulted in a root-mean-square of 0.0641 and a correlation coefficient of 0.991.The errors between the predicted and the experimental values were less than 7.251%,and less than 4.705%for 93.333%cases of the dataset.The accuracy of the proposed model is much higher than that of Hill's model.Compared with historical equations,the new model is more accurate and can well describe the variations of different parameters with the normalized penetrated hole.The model takes into account the strength of materials,which contributes to the excellent results.This paper could provide important theoretical support for the analysis of the perforation process and its mechanism.展开更多
基金financially supported by the National Key R&D Program of China(Grant No.2020YFA0711802)the Wuhan Science and Technology Bureau of China(Grant No.2023020201010081)the National Nature Science Foundation of China(Grant No.U22A20239).
文摘The technology of expansion fracturing with liquid CO_(2)(EFLCO_(2))has attracted increasing attention due to reduced vibration and damage.The disposable fracturing tube has been developed and is gradually replacing the Cardox tube.However,there is a lack of impact pressure testing of disposable tubes under real working conditions,selection of gas explosion design parameters,and systematic analysis of blasting vibration.This limitation has constrained the widespread application of disposable fracturing tubes in engineering.A joint monitoring of the pressure-time curves in the disposable tubes and boreholes was conducted.The rock-breaking effect of varying hole spacing parameters in the EFLCO_(2)design was analyzed,and a systematic study was carried out on the vibration peak value,frequency,and energy characteristics.The results show that(1)the pressure distribution characteristics,stress peak value,and duration in the disposable tubes are different from those of Cardox tubes,which show multi-peak distribution,low-pressure peak value,and short duration.The correlation between the pressure in the disposable tube,filling pressure,and liquid CO_(2)weight is established,and a theoretical calculation method for the borehole wall pressure is proposed;(2)The hole spacing in rocks of different hardness is suggested;and(3)At the same scale distance,the peak particle velocity(PPV)caused by EFLCO_(2)(PPVCO_(2))is significantly smaller than that caused by blasting(PPVexplosive).The ratio of PPVexplosive to PPVCO_(2)is a power function related to scale distance,and a distance-related zonality exist in this relationship.The frequency composition of the vibration signal caused by EFLCO_(2)is relatively simple with a narrow frequency band.Its PPV and energy are mainly concentrated in the low-frequency band.This research contributes to the optimization of disposable fracturing tubes,gas explosion design,and vibration hazard control.
基金supported by the National Natural Science Foundation of China(No.11772269).
文摘The hole penetrated in thin metallic plates due to hypervelocity impacts of cylindrical projectiles was analyzed by experimental method.The projectile caused a hole-expanding effect when penetrating the target plate because of dynamic shear failure and extrusion.A new empirical model was presented to predict the perforation diameter in thin plates impacted by high-velocity cylindrical projectiles.The fitting coefficients resulted in a root-mean-square of 0.0641 and a correlation coefficient of 0.991.The errors between the predicted and the experimental values were less than 7.251%,and less than 4.705%for 93.333%cases of the dataset.The accuracy of the proposed model is much higher than that of Hill's model.Compared with historical equations,the new model is more accurate and can well describe the variations of different parameters with the normalized penetrated hole.The model takes into account the strength of materials,which contributes to the excellent results.This paper could provide important theoretical support for the analysis of the perforation process and its mechanism.
