A suction caisson can be extracted by applying reverse pumping water,which cannot be regarded as the reverse process of installation because of the dramatically different soil−structure interaction behavior.Model test...A suction caisson can be extracted by applying reverse pumping water,which cannot be regarded as the reverse process of installation because of the dramatically different soil−structure interaction behavior.Model tests were first carried out in this study to investigate the extraction behavior of the modified suction caisson(MSC)and the regular suction caisson(RSC)in sand by reverse pumping water.The effects of the installation ways(suction-assisted or jacking installation)and the reverse pumping rate on the variations of the over-pressure resulting form reverse pumping water were investigated.It was found that neither the RSC nor the MSC can be fully extracted from sand.When the maximum extraction displacement is obtained,the hydraulic gradient of the sand in the suction caisson reaches the critical value,leading to seepage failure.In addition,the maximum extraction displacement decreases with the increasing reverse pumping rate.Under the same reverse pumping rate,the final extraction displacements for the RSC and MSC installed by suction are lower than those for the RSC and MSC installed by jacking.The final extraction displacement of MSC is almost equal to that of the RSC with the same internal compartment length.Based on the force equilibrium,a method of estimating the maximum extraction displacement is proposed.It has been proved that the proposed method can rationally predict the maximum extraction displacement and the corresponding over-pressure.展开更多
The modified suction caisson(MSC) is a novel type of foundation for ocean engineering, consisting of a short external closed-top cylinder-shaped structure surrounding the upper part of the regular suction caisson(RSC)...The modified suction caisson(MSC) is a novel type of foundation for ocean engineering, consisting of a short external closed-top cylinder-shaped structure surrounding the upper part of the regular suction caisson(RSC). The MSC can provide larger lateral bearing capacity and limit the deflection compared with the RSC. Therefore, the MSC can be much more appropriate to use as an offshore wind turbine foundation. Model tests on the MSC in saturated sand subjected to monotonic lateral loading were carried out to investigate the effects of external structure sizes on the sand surface deformation and the earth pressure distribution along the embedded depth. Test results show that the deformation range of the sand surface increases with the increasing width and length of the external structure. The magnitude of sand upheaval around the MSC is smaller than that of the RSC and the sand upheaval value around the MSC in the loading direction decreases with the increasing external structure dimensions. The net earth pressure in the loading direction acting on the internal compartment of the MSC is smaller than that of the RSC at the same embedded depth. The maximum net earth pressure acting on the external structure outer wall in the loading direction is larger than that of the internal compartment, indicating that a considerable amount of the lateral load and moment is resisted by the external skirt structure.展开更多
Open caissons are widely used in foundation engineering because of their load-bearing efficiency and adaptability in diverse soil conditions.However,accurately predicting their undrained bearing capacity in layered so...Open caissons are widely used in foundation engineering because of their load-bearing efficiency and adaptability in diverse soil conditions.However,accurately predicting their undrained bearing capacity in layered soils remains a complex challenge.This study presents a novel application of five ensemble machine(ML)algorithms-random forest(RF),gradient boosting machine(GBM),extreme gradient boosting(XGBoost),adaptive boosting(AdaBoost),and categorical boosting(CatBoost)-to predict the undrained bearing capacity factor(Nc)of circular open caissons embedded in two-layered clay on the basis of results from finite element limit analysis(FELA).The input dataset consists of 1188 numerical simulations using the Tresca failure criterion,varying in geometrical and soil parameters.The FELA was performed via OptumG2 software with adaptive meshing techniques and verified against existing benchmark studies.The ML models were trained on 70% of the dataset and tested on the remaining 30%.Their performance was evaluated using six statistical metrics:coefficient of determination(R²),mean absolute error(MAE),root mean squared error(RMSE),index of scatter(IOS),RMSE-to-standard deviation ratio(RSR),and variance explained factor(VAF).The results indicate that all the models achieved high accuracy,with R²values exceeding 97.6%and RMSE values below 0.02.Among them,AdaBoost and CatBoost consistently outperformed the other methods across both the training and testing datasets,demonstrating superior generalizability and robustness.The proposed ML framework offers an efficient,accurate,and data-driven alternative to traditional methods for estimating caisson capacity in stratified soils.This approach can aid in reducing computational costs while improving reliability in the early stages of foundation design.展开更多
The scaled suction caisson repre sents an innovative design featuring a bio-inspired sidewall modeled after snake skin,commonly utilized in offshore mooring platforms.In comparison with traditional suction caissons,th...The scaled suction caisson repre sents an innovative design featuring a bio-inspired sidewall modeled after snake skin,commonly utilized in offshore mooring platforms.In comparison with traditional suction caissons,this bio-inspired design demonstrates reduced penetration resistance and enhanced pull-out capacity due to the anisotropic shear behaviors of its sidewall.To investigate the shear behavior of the bio-inspired sidewall under pull-out load,direct shear tests were conducted between the bio-inspired surface and sand.The research demonstrates that the interface shear strength of the bio-inspired surface significantly surpasses that of the smooth surface due to interlocking effects.Additionally,the interface shear strength correlates with the aspect ratio of the bio-inspired surface,shear angle,and particle diameter distribution,with values increasing as the uniformity coefficient Cudecreases,while initially increasing and subsequently decreasing with increases in both aspect ratio and shear angle.The ratio between the interface friction angleδand internal friction angle δ_(s) defines the interface effect factor k.For the bio-inspired surface,the interface effect factor k varies with shear angleβ,ranging from 0.9 to 1.12.The peak value occurs at a shear angleβof 60°,substantially exceeding that of the smooth surface.A method for calculating the relative roughness R_(N) is employed to evaluate the interface roughness of the bio-inspired surface,taking into account scale dimension and particle diameter distribution effects.展开更多
在Windows环境下,以MSC/PATRAN为平台,利用平台提供的二次开发语言PCL(Patran Command Language),并结合C++语言,通过客户化、增设特定的命令和窗体等技术开发了飞机结构强度静力试验数据实时跟踪与处理系统TestDTAS(Test Data Tracking...在Windows环境下,以MSC/PATRAN为平台,利用平台提供的二次开发语言PCL(Patran Command Language),并结合C++语言,通过客户化、增设特定的命令和窗体等技术开发了飞机结构强度静力试验数据实时跟踪与处理系统TestDTAS(Test Data Tracking,Analyzing and Processing System)。在结构试验进行中,TestDTAS可以实时地监测结构试验件中应力和位移的变化情况,并与理论分析结果进行对比,而在试验结束后,TestDTAS可以进行试验数据回放和分析,从而将试验与理论分析有机的结合在一起,对结构静力试验和结构设计有很高的实用价值。展开更多
目的观察右归饮联合MSCs介入治疗早期股骨头缺血性坏死(avascular necrosis of the femoral head,ANFH)的疗效及促进再血管化、再骨化的作用。方法取健康雄性成年毕格犬24只,体重(10.0±0.5)kg,随机分为4组:A组(模型组)、B组(右归饮...目的观察右归饮联合MSCs介入治疗早期股骨头缺血性坏死(avascular necrosis of the femoral head,ANFH)的疗效及促进再血管化、再骨化的作用。方法取健康雄性成年毕格犬24只,体重(10.0±0.5)kg,随机分为4组:A组(模型组)、B组(右归饮组)、C组(MSCs介入组)、D组(MSCs介入加右归饮组),每组6只。通过液氮冷冻法建立早期ANFH模型。分离、培养并以BrdU标记MSCs。造模3周后,C、D组动脉灌注标记后的浓度为(0.5～1.0)×106个/mL的MSCs1mL,B、D组每天予右归饮100mL灌胃,A、C组以100mL蒸馏水灌胃。连续治疗4周及8周后行股骨头大体观察,DSA和MRI观察股骨头供血血管的数量及直径的变化情况,行组织学及免疫组织化学染色观察VEGF、BrdU阳性表达情况,实时荧光定量RT-PCR检测VEGF mRNA表达。结果治疗后4、8周,A组股骨头外形扁平,呈蘑菇状;B、C、D组股骨头外形基本正常。DSA观察示C、D组治疗后供血血管分支增粗、增多,原阻塞血管再通。治疗后4、8周,C、D组间血管数和血管直径比较差异均有统计学意义(P<0.05);两组血管直径与治疗前比较差异有统计学意义(P<0.05),D组血管数与治疗前比较差异有统计学意义(P<0.05)。MRI检查示B、C、D组较A组明显改善,D组尤为明显,T1W略低信号,T2W略低信号,STIR略高信号。组织病理学及免疫组织化学染色示:B、C、D组较A组结构有明显改善,D组较其他各组的VEGF阳性表达率均明显增高(P<0.05),D组较C组的BrdU阳性率、阳性成骨细胞数、阳性血管数表达均明显增高(P<0.05)。实时荧光定量RT-PCR检测示:D组较其他各组VEGFmRNA表达量增多(P<0.05),B、C、D组的VEGF表达均高于A组(P<0.05)。结论右归饮联合MSCs介入治疗早期ANFH疗效显著,可改善坏死股骨头的血供、促进修复、预防塌陷。展开更多
基金This study was financially supported by the National Natural Science Foundation of China(Grant Nos.51879044 and 51639002)the Shandong Natural Fund(Grant No.ZR2019BEE007)+1 种基金SDUST Research Fund(Grant No.2015TDJH104)the Project oce and Technology Program(Grant No.J18KA184).
文摘A suction caisson can be extracted by applying reverse pumping water,which cannot be regarded as the reverse process of installation because of the dramatically different soil−structure interaction behavior.Model tests were first carried out in this study to investigate the extraction behavior of the modified suction caisson(MSC)and the regular suction caisson(RSC)in sand by reverse pumping water.The effects of the installation ways(suction-assisted or jacking installation)and the reverse pumping rate on the variations of the over-pressure resulting form reverse pumping water were investigated.It was found that neither the RSC nor the MSC can be fully extracted from sand.When the maximum extraction displacement is obtained,the hydraulic gradient of the sand in the suction caisson reaches the critical value,leading to seepage failure.In addition,the maximum extraction displacement decreases with the increasing reverse pumping rate.Under the same reverse pumping rate,the final extraction displacements for the RSC and MSC installed by suction are lower than those for the RSC and MSC installed by jacking.The final extraction displacement of MSC is almost equal to that of the RSC with the same internal compartment length.Based on the force equilibrium,a method of estimating the maximum extraction displacement is proposed.It has been proved that the proposed method can rationally predict the maximum extraction displacement and the corresponding over-pressure.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.51639002 and 51379118)the SDUST Research Fund(Grant No.2015KYTD104)
文摘The modified suction caisson(MSC) is a novel type of foundation for ocean engineering, consisting of a short external closed-top cylinder-shaped structure surrounding the upper part of the regular suction caisson(RSC). The MSC can provide larger lateral bearing capacity and limit the deflection compared with the RSC. Therefore, the MSC can be much more appropriate to use as an offshore wind turbine foundation. Model tests on the MSC in saturated sand subjected to monotonic lateral loading were carried out to investigate the effects of external structure sizes on the sand surface deformation and the earth pressure distribution along the embedded depth. Test results show that the deformation range of the sand surface increases with the increasing width and length of the external structure. The magnitude of sand upheaval around the MSC is smaller than that of the RSC and the sand upheaval value around the MSC in the loading direction decreases with the increasing external structure dimensions. The net earth pressure in the loading direction acting on the internal compartment of the MSC is smaller than that of the RSC at the same embedded depth. The maximum net earth pressure acting on the external structure outer wall in the loading direction is larger than that of the internal compartment, indicating that a considerable amount of the lateral load and moment is resisted by the external skirt structure.
文摘Open caissons are widely used in foundation engineering because of their load-bearing efficiency and adaptability in diverse soil conditions.However,accurately predicting their undrained bearing capacity in layered soils remains a complex challenge.This study presents a novel application of five ensemble machine(ML)algorithms-random forest(RF),gradient boosting machine(GBM),extreme gradient boosting(XGBoost),adaptive boosting(AdaBoost),and categorical boosting(CatBoost)-to predict the undrained bearing capacity factor(Nc)of circular open caissons embedded in two-layered clay on the basis of results from finite element limit analysis(FELA).The input dataset consists of 1188 numerical simulations using the Tresca failure criterion,varying in geometrical and soil parameters.The FELA was performed via OptumG2 software with adaptive meshing techniques and verified against existing benchmark studies.The ML models were trained on 70% of the dataset and tested on the remaining 30%.Their performance was evaluated using six statistical metrics:coefficient of determination(R²),mean absolute error(MAE),root mean squared error(RMSE),index of scatter(IOS),RMSE-to-standard deviation ratio(RSR),and variance explained factor(VAF).The results indicate that all the models achieved high accuracy,with R²values exceeding 97.6%and RMSE values below 0.02.Among them,AdaBoost and CatBoost consistently outperformed the other methods across both the training and testing datasets,demonstrating superior generalizability and robustness.The proposed ML framework offers an efficient,accurate,and data-driven alternative to traditional methods for estimating caisson capacity in stratified soils.This approach can aid in reducing computational costs while improving reliability in the early stages of foundation design.
基金supported by the National Natural Science Foundation of China(Grant Nos.52371301 and 52471289)。
文摘The scaled suction caisson repre sents an innovative design featuring a bio-inspired sidewall modeled after snake skin,commonly utilized in offshore mooring platforms.In comparison with traditional suction caissons,this bio-inspired design demonstrates reduced penetration resistance and enhanced pull-out capacity due to the anisotropic shear behaviors of its sidewall.To investigate the shear behavior of the bio-inspired sidewall under pull-out load,direct shear tests were conducted between the bio-inspired surface and sand.The research demonstrates that the interface shear strength of the bio-inspired surface significantly surpasses that of the smooth surface due to interlocking effects.Additionally,the interface shear strength correlates with the aspect ratio of the bio-inspired surface,shear angle,and particle diameter distribution,with values increasing as the uniformity coefficient Cudecreases,while initially increasing and subsequently decreasing with increases in both aspect ratio and shear angle.The ratio between the interface friction angleδand internal friction angle δ_(s) defines the interface effect factor k.For the bio-inspired surface,the interface effect factor k varies with shear angleβ,ranging from 0.9 to 1.12.The peak value occurs at a shear angleβof 60°,substantially exceeding that of the smooth surface.A method for calculating the relative roughness R_(N) is employed to evaluate the interface roughness of the bio-inspired surface,taking into account scale dimension and particle diameter distribution effects.
文摘在Windows环境下,以MSC/PATRAN为平台,利用平台提供的二次开发语言PCL(Patran Command Language),并结合C++语言,通过客户化、增设特定的命令和窗体等技术开发了飞机结构强度静力试验数据实时跟踪与处理系统TestDTAS(Test Data Tracking,Analyzing and Processing System)。在结构试验进行中,TestDTAS可以实时地监测结构试验件中应力和位移的变化情况,并与理论分析结果进行对比,而在试验结束后,TestDTAS可以进行试验数据回放和分析,从而将试验与理论分析有机的结合在一起,对结构静力试验和结构设计有很高的实用价值。
文摘目的观察右归饮联合MSCs介入治疗早期股骨头缺血性坏死(avascular necrosis of the femoral head,ANFH)的疗效及促进再血管化、再骨化的作用。方法取健康雄性成年毕格犬24只,体重(10.0±0.5)kg,随机分为4组:A组(模型组)、B组(右归饮组)、C组(MSCs介入组)、D组(MSCs介入加右归饮组),每组6只。通过液氮冷冻法建立早期ANFH模型。分离、培养并以BrdU标记MSCs。造模3周后,C、D组动脉灌注标记后的浓度为(0.5～1.0)×106个/mL的MSCs1mL,B、D组每天予右归饮100mL灌胃,A、C组以100mL蒸馏水灌胃。连续治疗4周及8周后行股骨头大体观察,DSA和MRI观察股骨头供血血管的数量及直径的变化情况,行组织学及免疫组织化学染色观察VEGF、BrdU阳性表达情况,实时荧光定量RT-PCR检测VEGF mRNA表达。结果治疗后4、8周,A组股骨头外形扁平,呈蘑菇状;B、C、D组股骨头外形基本正常。DSA观察示C、D组治疗后供血血管分支增粗、增多,原阻塞血管再通。治疗后4、8周,C、D组间血管数和血管直径比较差异均有统计学意义(P<0.05);两组血管直径与治疗前比较差异有统计学意义(P<0.05),D组血管数与治疗前比较差异有统计学意义(P<0.05)。MRI检查示B、C、D组较A组明显改善,D组尤为明显,T1W略低信号,T2W略低信号,STIR略高信号。组织病理学及免疫组织化学染色示:B、C、D组较A组结构有明显改善,D组较其他各组的VEGF阳性表达率均明显增高(P<0.05),D组较C组的BrdU阳性率、阳性成骨细胞数、阳性血管数表达均明显增高(P<0.05)。实时荧光定量RT-PCR检测示:D组较其他各组VEGFmRNA表达量增多(P<0.05),B、C、D组的VEGF表达均高于A组(P<0.05)。结论右归饮联合MSCs介入治疗早期ANFH疗效显著,可改善坏死股骨头的血供、促进修复、预防塌陷。
