本文合成了新型疏水缔合两亲共聚物,并对其在溶液中的聚集行为和流变特性进行探究。结果表明:随着两亲单体含量的增加,共聚物表现出更低的临界缔合浓度(CAC),可形成更大聚集数的聚集体,在25℃,剪切速率170 s^(-1)下,0.5%共聚物HPAE10-1...本文合成了新型疏水缔合两亲共聚物,并对其在溶液中的聚集行为和流变特性进行探究。结果表明:随着两亲单体含量的增加,共聚物表现出更低的临界缔合浓度(CAC),可形成更大聚集数的聚集体,在25℃,剪切速率170 s^(-1)下,0.5%共聚物HPAE10-1溶液黏度达205 m Pa·s;触变实验表明疏水缔合作用形成了可逆的网状结构,这种网状结构使共聚物溶液具备了优异的黏弹性能,高频时表现出较高的储能模量和损耗模量;探索了HPAE10-1/有机锆组成的压裂液体系在天然气水合物压裂中的应用性能,发现其对不同粒径的支撑剂都具有良好的悬浮效果、有较低的滤失量,加入破胶剂后在125 min内可使压裂液黏度降低到5 m Pa·s。展开更多
Suction caissons are widely used for anchoring floating platform and offshore wind turbines.Penetration of the suction caisson into the desired position under the combination of its self-weight and applied suction res...Suction caissons are widely used for anchoring floating platform and offshore wind turbines.Penetration of the suction caisson into the desired position under the combination of its self-weight and applied suction resulted from pumping out the encased water is integral to practical engineering.Model tests were carried out to investigate the suctionassisted installation of suction caissons in clay under various undrained shear strengths.It was found that there exists a critical penetration depth value.When the penetration depth is smaller than the critical value,the soil plug undrained shear strength is higher than intact clay(i.e.,clay prior to installation).However,when the penetration depth is greater than the critical penetration depth,the undrained shear strength of soil plug is lower than intact clay.The critical value decreases with the increasing consolidation time and undrained shear strength of clay.During suction-assisted installation,cracks occur around suction caissons.The installation way has little effect on the crack formation.The influence range(i.e.,the maximum distance between the crack and the suction caisson edge)was found to increase with the increasing friction coefficient of interface between the suction caisson wall and soil and decreases with the increasing soil undrained shear strength.In addition,the drained condition of the clay during installation is dominated by the caisson aspect ratio,the undrained shear strength and the friction coefficient between the caisson wall and clay.Equations to estimate the penetration resistance and the required suction to install the suction caisson are summarized.展开更多
This paper presents failure mechanisms of the soil at the caisson-tip with fillet during suction-assisted penetration of suction caissons in undrained clay.Theoretical solutions of resistance factor N_c of the caisson...This paper presents failure mechanisms of the soil at the caisson-tip with fillet during suction-assisted penetration of suction caissons in undrained clay.Theoretical solutions of resistance factor N_c of the caisson-tip are obtained in terms of the caisson-tip geometry ratio of the flat section of the caisson-tip to the caisson wall thickness m/t and adhesion factorsα_i along inside of caisson wall andα_b at the base of the caisson-tip.It is indicated that the factor N_c increases with the increase of m/t,α_i and a_b.The resistance factors N_c for the rough base(α_b=1)are larger by 0.57than that for the smooth base(α_b=0).Besides,the factors N_c of caisson-tip with flat base(m=t)are larger by 1.14 than that with full internal fillet(m=0).The required suction to penetrate suction caissons with various fillets is obtained in terms of the force equilibrium in vertical direction.The finite element limit analysis and centrifuge model test results are used to verify the rationality of the presented failure mechanisms and theoretical predictions.展开更多
文摘本文合成了新型疏水缔合两亲共聚物,并对其在溶液中的聚集行为和流变特性进行探究。结果表明:随着两亲单体含量的增加,共聚物表现出更低的临界缔合浓度(CAC),可形成更大聚集数的聚集体,在25℃,剪切速率170 s^(-1)下,0.5%共聚物HPAE10-1溶液黏度达205 m Pa·s;触变实验表明疏水缔合作用形成了可逆的网状结构,这种网状结构使共聚物溶液具备了优异的黏弹性能,高频时表现出较高的储能模量和损耗模量;探索了HPAE10-1/有机锆组成的压裂液体系在天然气水合物压裂中的应用性能,发现其对不同粒径的支撑剂都具有良好的悬浮效果、有较低的滤失量,加入破胶剂后在125 min内可使压裂液黏度降低到5 m Pa·s。
基金financially supported by the National Natural Science Foundation of China (Grant Nos.52371301,51879044 and 51808325)the Shandong Natural Fund (Grant No.ZR2020QE258)。
文摘Suction caissons are widely used for anchoring floating platform and offshore wind turbines.Penetration of the suction caisson into the desired position under the combination of its self-weight and applied suction resulted from pumping out the encased water is integral to practical engineering.Model tests were carried out to investigate the suctionassisted installation of suction caissons in clay under various undrained shear strengths.It was found that there exists a critical penetration depth value.When the penetration depth is smaller than the critical value,the soil plug undrained shear strength is higher than intact clay(i.e.,clay prior to installation).However,when the penetration depth is greater than the critical penetration depth,the undrained shear strength of soil plug is lower than intact clay.The critical value decreases with the increasing consolidation time and undrained shear strength of clay.During suction-assisted installation,cracks occur around suction caissons.The installation way has little effect on the crack formation.The influence range(i.e.,the maximum distance between the crack and the suction caisson edge)was found to increase with the increasing friction coefficient of interface between the suction caisson wall and soil and decreases with the increasing soil undrained shear strength.In addition,the drained condition of the clay during installation is dominated by the caisson aspect ratio,the undrained shear strength and the friction coefficient between the caisson wall and clay.Equations to estimate the penetration resistance and the required suction to install the suction caisson are summarized.
基金financially supported by the National Natural Science Foundation of China (Grant No.51879044)the Youth Foundation of Shandong Natural Science Foundation (Grant No.ZR2020QE258)+1 种基金Qingdao Postdoctoral Applied Research Project (Grant No.ZX20220202)SDUST Research Fund (Grant No.2015KYJH104)。
文摘This paper presents failure mechanisms of the soil at the caisson-tip with fillet during suction-assisted penetration of suction caissons in undrained clay.Theoretical solutions of resistance factor N_c of the caisson-tip are obtained in terms of the caisson-tip geometry ratio of the flat section of the caisson-tip to the caisson wall thickness m/t and adhesion factorsα_i along inside of caisson wall andα_b at the base of the caisson-tip.It is indicated that the factor N_c increases with the increase of m/t,α_i and a_b.The resistance factors N_c for the rough base(α_b=1)are larger by 0.57than that for the smooth base(α_b=0).Besides,the factors N_c of caisson-tip with flat base(m=t)are larger by 1.14 than that with full internal fillet(m=0).The required suction to penetrate suction caissons with various fillets is obtained in terms of the force equilibrium in vertical direction.The finite element limit analysis and centrifuge model test results are used to verify the rationality of the presented failure mechanisms and theoretical predictions.
