A number of investigations into application of polymers for macro-morphological modification of tool surface have been carried out. These researches, with extensive stress on convex or domed protuberations as one of t...A number of investigations into application of polymers for macro-morphological modification of tool surface have been carried out. These researches, with extensive stress on convex or domed protuberations as one of the widely used construction units, have tried to harness benefits from using polymers in agriculture. Ultra high molecular weight polyethylene （UHMW-PE） has proved an emerging polymer in its application to reduce soil adhesion. This research was conducted to study the effect of shape （flat, semi-spherical, semi-oblate, semi short-prolate and semi long-prolate） and dimensions （base diameter and dome height） on sliding resistance and normal adhesion of biomimetic plates. To incorporate both shape and size, a dimensionless ratio of height to diameter （HDR） was introduced to characterize the effect of construction unit＇s physique. Experiments were conducted in Bangkok clay soil with dry （ 19.8% d.b.）, sticky （36.9% d.b.） and flooded （60.1% d.b.） soil conditions respectively. Soil at sticky limit exhibited the highest sliding resistance （77.8 N） and normal adhesion （3 kPa to 7 kPa）, whereas these values were 61.7 N and 〈0.2 kPa in dry, and 53.7 N and 0.5 kPa to 1.5 kPa in flooded soil conditions. Protuberances with HDR ≤ 0.5 lowered sliding resistance by 10% - 30% and the same reduced normal adhesion by 10% - 60%. The amount of reduction in both sliding resistance and normal adhesion was higher in flooded soil. Lighter normal loads obviously produced lesser resistance and adhesion.展开更多
The non-smooth surface morphology of dung beetle, Copris ochus, was analyzed. The bulldozing plates with bionic geometric non-smooth or the chemical uneven surface were designed for the soil sliding test based on the...The non-smooth surface morphology of dung beetle, Copris ochus, was analyzed. The bulldozing plates with bionic geometric non-smooth or the chemical uneven surface were designed for the soil sliding test based on the simulation of the bumpy surface of the dung beetle. Special black metals— with different contents of alloys of manganese, silicon, chromium, copper and rare earth— were developed for making geometric non-smooth and chemical uneven surfaces by means of surface welding at the surfaces of a middle carbon steel plate. Four metals, with different surface properties including hardness and water contact angle were used to make the bulldozing plates for measuring the soil sliding resistance. Test results of soil sliding resistance indicate that all the geometric non-smooth plates and the chemical uneven plates reducing soil friction. Considering the materials and surface morphology, the bionic plate can reduce the soil sliding resistance from 18.1 % up to 42.2%, compared to the traditional smooth bulldozing plate made from middle carbon steel. The test results also show that the smaller the normal load, the greater effect on resistance reduction by the bionic non-smooth surface plates.展开更多
Anti-slide pile is one of the important methods to administer landslide geological disaster because of its advantages.It plays important role in administering landslide.It is a premise of reasonable economy and techno...Anti-slide pile is one of the important methods to administer landslide geological disaster because of its advantages.It plays important role in administering landslide.It is a premise of reasonable economy and technological advance to know the distribution rule and feature of the force between anti-sliding pile and surrounding rock.To determine the sliding force and remnant resistant sliding force,according to need of study,this paper sets up the geological model and mechanics model in term of a typical landslide,and analyzes the effect rule of sliding body distortion,strength and gravity to the pushing force and remnant resistant sliding force by use of the numerical model.The distribution rule of pushing force and remnant resistant sliding force of the type of landslide is given.展开更多
The Three Gorges Project is one of the essential key projects for flood controlling and water resources regulation in the Yangtze River. The project includes a river-crossing dam, underground powerhouses, and navigati...The Three Gorges Project is one of the essential key projects for flood controlling and water resources regulation in the Yangtze River. The project includes a river-crossing dam, underground powerhouses, and navigation structures. Because of the huge size and complicated construction technologies, the project faced a series of challenging engineering issues. In terms of rock mechanics, there are many key technical issues, including the sliding resistance and stability of the dam section along the foundations of powerhouses No.l-5, the ,,;lope stability of the double-line five-stage shiplock, excavation of large-scale underground powerhouses, and curtain grouting under the dam. With decades of scientific research and 16 years of practical construction experiences and reservoir operations, these key technical issues in construction of the Three Gorges Project are successfully resolved, which will attribute to the development of hydropower technology. On the basis of the monitoring data during construction and normal operation periods of the Three Gorges Project, this paper presents a systematic analysis of these key rock mechanical issues in terms of behaviors, solutions, dynamic controlling, monitoring arrangement and integrated assessment.展开更多
Austenitic 316L stainless steel has good corrosion resistance l however, the relative softness often limits its application. Severe adhesive wear often occurs between the 316L stainless steel and the metal counterpart...Austenitic 316L stainless steel has good corrosion resistance l however, the relative softness often limits its application. Severe adhesive wear often occurs between the 316L stainless steel and the metal counterpart. Cu-10Sn alloy is often used to improve the wear resistance of powder metallurgy 316L stainless steel. The influence of Cu-10Sn on sintering behavior and wear resistance of powder metallurgy 316L stainless steel was investigated. The pa-rameters investigated included sintering temperature and volume percent of Cu-10Sn. A maximum relative density of 97% was achieved with 25% （in volume percent） Cu-10Sn content at a sintering temperature of 1 300 ℃ for 60 min. The irregular and sharp angles of 316L stainless steel particles become round, and the pores are removed completely as a result of large amount of liquid phase formed during sintering. The minimum friction mass loss was achieved with 25% Cu-10Sn content.展开更多
Microstructure and high-temperature dry sliding wear at 600 ~C in ambient air of austenitic heat-resistant steel ZG40Cr25Ni20 with different contents （mass percent） of AI （0 to 7.10~） have been investigated. The r...Microstructure and high-temperature dry sliding wear at 600 ~C in ambient air of austenitic heat-resistant steel ZG40Cr25Ni20 with different contents （mass percent） of AI （0 to 7.10~） have been investigated. The results show that microstructures of 4.68% and 7.10% A1 addition content consist of the matrix and reinforcement of inter- metallic compound y＇ and carbide, while microstructures of ZG40Cr25Ni20 without A1 and with A1 of 1.68% are ab- sent of y＇. Higher wear resistance than the original ZG40Cr25Ni20 alloy is achieved in alloys with higher content of A1 under the same high-temperature wear test condition. The wear rates of Fe-25Cr-20Ni-7.10A1 and Fe-25Cr-20Ni- 4.68A1 are only 20.83% and 45.83% of that of Fe-25Cr-20Ni, respectively. Heat-resistant steels with higher con- tents of AI （4.72% and 7.10%） have higher hardness than those with lower contents of AI （1.68% and 0）. Wear mechanisms of ZG40Cr25Ni20 are considered as severe plough plastic deformation and slight adhesive. However, wear mechanisms of Fe-25Cr-20Ni 4.68A1 are light micro-cutting and oxidation-wear, while that of Fe-25Cr-20Ni- 7. 10A1 are severe adhesive transfer and oxidation-wear_展开更多
文摘A number of investigations into application of polymers for macro-morphological modification of tool surface have been carried out. These researches, with extensive stress on convex or domed protuberations as one of the widely used construction units, have tried to harness benefits from using polymers in agriculture. Ultra high molecular weight polyethylene （UHMW-PE） has proved an emerging polymer in its application to reduce soil adhesion. This research was conducted to study the effect of shape （flat, semi-spherical, semi-oblate, semi short-prolate and semi long-prolate） and dimensions （base diameter and dome height） on sliding resistance and normal adhesion of biomimetic plates. To incorporate both shape and size, a dimensionless ratio of height to diameter （HDR） was introduced to characterize the effect of construction unit＇s physique. Experiments were conducted in Bangkok clay soil with dry （ 19.8% d.b.）, sticky （36.9% d.b.） and flooded （60.1% d.b.） soil conditions respectively. Soil at sticky limit exhibited the highest sliding resistance （77.8 N） and normal adhesion （3 kPa to 7 kPa）, whereas these values were 61.7 N and 〈0.2 kPa in dry, and 53.7 N and 0.5 kPa to 1.5 kPa in flooded soil conditions. Protuberances with HDR ≤ 0.5 lowered sliding resistance by 10% - 30% and the same reduced normal adhesion by 10% - 60%. The amount of reduction in both sliding resistance and normal adhesion was higher in flooded soil. Lighter normal loads obviously produced lesser resistance and adhesion.
文摘The non-smooth surface morphology of dung beetle, Copris ochus, was analyzed. The bulldozing plates with bionic geometric non-smooth or the chemical uneven surface were designed for the soil sliding test based on the simulation of the bumpy surface of the dung beetle. Special black metals— with different contents of alloys of manganese, silicon, chromium, copper and rare earth— were developed for making geometric non-smooth and chemical uneven surfaces by means of surface welding at the surfaces of a middle carbon steel plate. Four metals, with different surface properties including hardness and water contact angle were used to make the bulldozing plates for measuring the soil sliding resistance. Test results of soil sliding resistance indicate that all the geometric non-smooth plates and the chemical uneven plates reducing soil friction. Considering the materials and surface morphology, the bionic plate can reduce the soil sliding resistance from 18.1 % up to 42.2%, compared to the traditional smooth bulldozing plate made from middle carbon steel. The test results also show that the smaller the normal load, the greater effect on resistance reduction by the bionic non-smooth surface plates.
文摘Anti-slide pile is one of the important methods to administer landslide geological disaster because of its advantages.It plays important role in administering landslide.It is a premise of reasonable economy and technological advance to know the distribution rule and feature of the force between anti-sliding pile and surrounding rock.To determine the sliding force and remnant resistant sliding force,according to need of study,this paper sets up the geological model and mechanics model in term of a typical landslide,and analyzes the effect rule of sliding body distortion,strength and gravity to the pushing force and remnant resistant sliding force by use of the numerical model.The distribution rule of pushing force and remnant resistant sliding force of the type of landslide is given.
文摘The Three Gorges Project is one of the essential key projects for flood controlling and water resources regulation in the Yangtze River. The project includes a river-crossing dam, underground powerhouses, and navigation structures. Because of the huge size and complicated construction technologies, the project faced a series of challenging engineering issues. In terms of rock mechanics, there are many key technical issues, including the sliding resistance and stability of the dam section along the foundations of powerhouses No.l-5, the ,,;lope stability of the double-line five-stage shiplock, excavation of large-scale underground powerhouses, and curtain grouting under the dam. With decades of scientific research and 16 years of practical construction experiences and reservoir operations, these key technical issues in construction of the Three Gorges Project are successfully resolved, which will attribute to the development of hydropower technology. On the basis of the monitoring data during construction and normal operation periods of the Three Gorges Project, this paper presents a systematic analysis of these key rock mechanical issues in terms of behaviors, solutions, dynamic controlling, monitoring arrangement and integrated assessment.
文摘Austenitic 316L stainless steel has good corrosion resistance l however, the relative softness often limits its application. Severe adhesive wear often occurs between the 316L stainless steel and the metal counterpart. Cu-10Sn alloy is often used to improve the wear resistance of powder metallurgy 316L stainless steel. The influence of Cu-10Sn on sintering behavior and wear resistance of powder metallurgy 316L stainless steel was investigated. The pa-rameters investigated included sintering temperature and volume percent of Cu-10Sn. A maximum relative density of 97% was achieved with 25% （in volume percent） Cu-10Sn content at a sintering temperature of 1 300 ℃ for 60 min. The irregular and sharp angles of 316L stainless steel particles become round, and the pores are removed completely as a result of large amount of liquid phase formed during sintering. The minimum friction mass loss was achieved with 25% Cu-10Sn content.
文摘Microstructure and high-temperature dry sliding wear at 600 ~C in ambient air of austenitic heat-resistant steel ZG40Cr25Ni20 with different contents （mass percent） of AI （0 to 7.10~） have been investigated. The results show that microstructures of 4.68% and 7.10% A1 addition content consist of the matrix and reinforcement of inter- metallic compound y＇ and carbide, while microstructures of ZG40Cr25Ni20 without A1 and with A1 of 1.68% are ab- sent of y＇. Higher wear resistance than the original ZG40Cr25Ni20 alloy is achieved in alloys with higher content of A1 under the same high-temperature wear test condition. The wear rates of Fe-25Cr-20Ni-7.10A1 and Fe-25Cr-20Ni- 4.68A1 are only 20.83% and 45.83% of that of Fe-25Cr-20Ni, respectively. Heat-resistant steels with higher con- tents of AI （4.72% and 7.10%） have higher hardness than those with lower contents of AI （1.68% and 0）. Wear mechanisms of ZG40Cr25Ni20 are considered as severe plough plastic deformation and slight adhesive. However, wear mechanisms of Fe-25Cr-20Ni 4.68A1 are light micro-cutting and oxidation-wear, while that of Fe-25Cr-20Ni- 7. 10A1 are severe adhesive transfer and oxidation-wear_
