According to the National Meeting on Power Construction and Cost Control held in Beijing on 26th August 1996, the target for power construction in the period of 9th Five- year Plan is set-up as follows:
The Supervision during construction of Thailand PTA Co-generation, Which was contracted by our country extended into the quality guaranteed period. The supervision during the quality guaranteed period includes the mon...The Supervision during construction of Thailand PTA Co-generation, Which was contracted by our country extended into the quality guaranteed period. The supervision during the quality guaranteed period includes the monitor of the operation and maintenance of power plant,organization of subcontractor to treat the problems and defects occurred in the field in time, technical consultancy and communication in time, delivery of spare parts, and assistance of clearing Contractor’s quality deposit. It is proved by the practice that it is necessary to early out the supervision during quality guaranteed period.展开更多
In order to solve the problem of low accuracy of construction project duration prediction, this paper proposes a CNN attention BP combination model </span><span style="font-family:"white-space:...In order to solve the problem of low accuracy of construction project duration prediction, this paper proposes a CNN attention BP combination model </span><span style="font-family:"white-space:normal;">project risk prediction model based on attention mechanism, one-dimensional </span><span style="font-family:"white-space:normal;">convolutional neural network (1d-cnn) and BP neural network. Firstly, the literature analysis method is used to select the risk evaluation index value of construction project, and the attention mechanism is used to determine the weight of risk factors on construction period prediction;then, BP neural network is used to predict the project duration, and accuracy, cross entropy loss function and F1 score are selected to comprehensively evaluate the performance of 1d-cnn-attention-bp combined model. The experimental results show that the duration risk prediction accuracy of the risk prediction model proposed in this paper is more than 90%, which can meet the risk prediction of construction projects with high accuracy.展开更多
Currently,the water inrush hazards during tunnel construction,the water leakage during tunnel operation,and the accompanying disturbances to the ecological environment have become the main problems that affect the str...Currently,the water inrush hazards during tunnel construction,the water leakage during tunnel operation,and the accompanying disturbances to the ecological environment have become the main problems that affect the structural safety of tunnels in water-rich regions.In this paper,a tunnel seepage model testing system was used to conduct experiments of the grouting circle and primary support with different permeability coefficients.The influences of the supporting structures on the water inflow laws and the distribution of the water pressure in the tunnel were analyzed.With the decrease in the permeability coefficient of the grouting circle or the primary support,the inflow rate of water into the tunnel showed a non-linear decreasing trend.In comparison,the water inflow reduction effect of grouting circle was much better than that of primary support.With the increase of the permeability coefficient of the grouting ring,the water pressure behind the primary lining increases gradually,while the water pressure behind the grouting ring decreases.Thus,the grouting of surrounding rock during the construction of water-rich tunnel can effectively weaken the hydraulic connection,reduce the influence range of seepage,and significantly reduce the decline of groundwater.Meanwhile,the seepage tests at different hydrostatic heads and hydrodynamic heads during tunnel operation period were also conducted.As the hydrostatic head decreased,the water pressure at each characteristic point decreased approximately linearly,and the water inflow rate also had a gradual downward trend.Under the action of hydrodynamic head,the water pressure had an obvious lagging effect,which was not conducive to the stability of the supporting structures,and it could be mitigated by actively regulating the drainage rate.Compared with the hydrostatic head,the hydrodynamic head could change the real-time rate of water inflow to the tunnel and broke the dynamic balance between the water pressure and water inflow rate,thereby affecting the stress state on the supporting structures.展开更多
文摘According to the National Meeting on Power Construction and Cost Control held in Beijing on 26th August 1996, the target for power construction in the period of 9th Five- year Plan is set-up as follows:
文摘The Supervision during construction of Thailand PTA Co-generation, Which was contracted by our country extended into the quality guaranteed period. The supervision during the quality guaranteed period includes the monitor of the operation and maintenance of power plant,organization of subcontractor to treat the problems and defects occurred in the field in time, technical consultancy and communication in time, delivery of spare parts, and assistance of clearing Contractor’s quality deposit. It is proved by the practice that it is necessary to early out the supervision during quality guaranteed period.
文摘In order to solve the problem of low accuracy of construction project duration prediction, this paper proposes a CNN attention BP combination model </span><span style="font-family:"white-space:normal;">project risk prediction model based on attention mechanism, one-dimensional </span><span style="font-family:"white-space:normal;">convolutional neural network (1d-cnn) and BP neural network. Firstly, the literature analysis method is used to select the risk evaluation index value of construction project, and the attention mechanism is used to determine the weight of risk factors on construction period prediction;then, BP neural network is used to predict the project duration, and accuracy, cross entropy loss function and F1 score are selected to comprehensively evaluate the performance of 1d-cnn-attention-bp combined model. The experimental results show that the duration risk prediction accuracy of the risk prediction model proposed in this paper is more than 90%, which can meet the risk prediction of construction projects with high accuracy.
基金supported by the Chongqing Natural Science Foundation(No.cstc2020jcyjmsxm X0904)the Chongqing Talent Plan(No.CQYC2020058263)+3 种基金the Chongqing Technology Innovation and Application Development Project(No.cstc2021ycjh-bgzxm0246)the China Postdoctoral Science Foundation(No.2021M693739)the Sichuan Science and Technology Program(No.2021YJ0539)the Natural Science foundation of Jiangsu higher education institutions of China(Grant No.19KJD170001)。
文摘Currently,the water inrush hazards during tunnel construction,the water leakage during tunnel operation,and the accompanying disturbances to the ecological environment have become the main problems that affect the structural safety of tunnels in water-rich regions.In this paper,a tunnel seepage model testing system was used to conduct experiments of the grouting circle and primary support with different permeability coefficients.The influences of the supporting structures on the water inflow laws and the distribution of the water pressure in the tunnel were analyzed.With the decrease in the permeability coefficient of the grouting circle or the primary support,the inflow rate of water into the tunnel showed a non-linear decreasing trend.In comparison,the water inflow reduction effect of grouting circle was much better than that of primary support.With the increase of the permeability coefficient of the grouting ring,the water pressure behind the primary lining increases gradually,while the water pressure behind the grouting ring decreases.Thus,the grouting of surrounding rock during the construction of water-rich tunnel can effectively weaken the hydraulic connection,reduce the influence range of seepage,and significantly reduce the decline of groundwater.Meanwhile,the seepage tests at different hydrostatic heads and hydrodynamic heads during tunnel operation period were also conducted.As the hydrostatic head decreased,the water pressure at each characteristic point decreased approximately linearly,and the water inflow rate also had a gradual downward trend.Under the action of hydrodynamic head,the water pressure had an obvious lagging effect,which was not conducive to the stability of the supporting structures,and it could be mitigated by actively regulating the drainage rate.Compared with the hydrostatic head,the hydrodynamic head could change the real-time rate of water inflow to the tunnel and broke the dynamic balance between the water pressure and water inflow rate,thereby affecting the stress state on the supporting structures.
