| A large number of old drainage pipes and canals in China have suffered structural damage due to long-term disrepair,which has seriously endangered the safety of urban areas.To meet the requirements of sustainable development of existing cities,it is urgent to repair and transform them.Most of the old drainage pipes are located in the old urban areas with dense buildings and complex geological conditions.It is not feasible to build new drainage pipes in the old urban areas.Therefore,trenchless methods are often used to repair them.However,the existing trenchless technology does not consider the bearing capacity of the original structure but simply adds new lining pipes to meet the requirement of bearing capacity,which has a great influence on the flow capacity of the pipeline.As a non-excavation technology for semi-structural repair,pressure grouting has been widely used owing to its advantages of improving the strength of the original pipe canal sidewall and greatly reducing the water-passing area of the pipe canal.As the main consumable material for pressure grouting,high-performance grouting material has a high unit price.Meanwhile,due to the rainwater erosion,the internal structure of the sidewall of the original drainage pipe is complicated and the consumption of grouting material fluctuates greatly,which brought huge problems to the cost management of construction enterprises.Therefore,a reasonable and accurate prediction for the consumption of high-performance grouting can provide guidance for the material cost management of construction enterprises and references for the dynamic cost management in the construction process,which has important practical significance.Relying on old drains restoration project in Changsha,this study carries out the predictive research on the consumption of high-performance grouting material in old drains restoration projects.The mainly completes are as follows:(1)Research on key factors affecting the consumption of high-performance grouting.The factors affecting the consumption of grouting materials are initially identified by using the literature research method.On this basis,orthogonal simulation experiments were carried out to screen out the key influencing factors.Using the restoration project in Changsha for instance,the key factors that affect the consumption of grouting material are the fullness of the mortar,the grouting pressure,and the inclination rate of the grouting hole.(2)Research on numerical prediction of high-performance grouting material consumption.Using the GRNN neural network,a high-performance numerical prediction model of grouting material consumption is established with key factors as input variables and grouting material consumption as output variables,and the 5-fold cross validation algorithm is used to optimize the model.Next,the established model is verified with the collected project data.The results show that the average relative error of the prediction model is 6.96%,which indicates that the model has a significant improvement co MPared with the traditional BP neural network.(3)Research on interval prediction of high-performance grouting material consumption.To guide the construction more effectively and reduce the waste of materials in the construction process,an interval prediction model of grouting slurry consumption based on the LSTM and the quantile regression is established.The analysis results show that the model has good reliability and accuracy.(4)Based on the above-mentioned high-performance grouting material consumption prediction research,the material cost management application framework of the old drainage pipe and channel repair project construction enterprises is proposed,which provides a powerful tool for designers,construction site personnel,and cost management personnel.Next,it is proved that the framework has strong application potential in practical engineering applications. |
