Model-based Design Powers China Dam Construction
Harnessing power from moving water has the benefit of slowing and controlling flow in order to prevent natural disasters, providing water for human consumption and crop irrigation, slowing soil erosion, and supplying clean power. Hydropower is a low-cost source of renewable energy that is very flexible as it can be ramped up or down quickly to meet demand. The topography of China, with its many mountain ranges and rivers, lends itself well to dam construction, and the country is on an aggressive push to achieve all of these objectives.
China has been the leading producer of hydroelectric power in the world since the late 1990s, with roughly 17 percent of the country’s power coming from this source. The pace of growth of dams in China has been phenomenal with only 22 dams in the country in 1949, and now more than 50,000 dams larger than 15 meters. Dam building continues on an accelerated course with a $635 billion (US) investment in water infrastructure planned by 2020, with a third of that going to dam and reservoir building efforts. In addition to domestic projects, China also exports this dam building expertise to other countries, with projects getting larger and producing more energy.
The Three Gorges Dam that was completed in 2012 is the most famous of these huge projects, but the pace of current hydropower development in the country is the equivalent of building seven more dams of that size by 2015. One such dam is the Huangdeng Hydropower Station in the southwestern Yunnan Province, a seven-year project now underway at a cost of approximately $3 billion (US).
Preparations and Planning
The Huangdeng Hydro Power Station on the Lancang River is a concrete gravity dam being built in a narrow river gorge, with a maximum height of 203 meters, a total capacity of 1.5 billion cubic meters of water, and an installed capacity of 1,900 megawatts of power. The dam will cover approximately 20 square kilometers.
HYDROCHINA Kunming (KHIDI) is the award-winning1 survey, design, construction and engineering firm responsible for the construction of this project. They have completed more than 200 hydropower projects since their start in 1957, continuously fine tuning their process to make the most of the latest technology.
In conventional design, specialists across disciplines communicate and coordinate by issuing a design change notification form, a paper-based process where it’s difficult to quickly convey design changes or catch conflicts, resulting in a serious waste of resources. KHIDI leadership, with the full support of the project professionals across disciplines, decided to base this and future projects on a Building Information Modeling (BIM) process, using solutions from Autodesk in order to improve business productivity and gain competitive advantage. (See the sidebar gallery for an overview of the different Autodesk software tools applied in this project.)
A project of this magnitude is complicated, given the number of engineering disciplines and design elements, including power production, living quarters, processing plants, and auxiliary facilities linked by a network of infrastructure and roads. The project includes complicated retaining structures, underground factories, and diversionary structures, as well as very large and complex equipment and a multitude of supporting utilities. With an integrated, intelligent 3D model, engineers are able to speed the understanding of the hydrology, to calculate the volume of material that needs to be removed along with grading plans, to calculate the amount of cement needed, the location of structures, and the interconnecting infrastructure between the facilities.
KHIDI is using model-based BIM workflows to support collaborative design, coordination, and planning across the various disciplines involved in the project, including surveying, hydrotechnics, mechanical and electrical engineering, and construction.
The first step of the project is the creation of an accurate 3D model of the area. To create this model, satellite imagery provides a basemap, aerial photography and LiDAR provided more details along with a colorized 3D point cloud for accurate capture of reality, and survey measurements provide a ground truth to ensure that the resulting model is accurate for engineering.
Upon this basemap, KHIDI developed intelligent 3D models for a range of activities and purposes. Models have helped achieve a multi-discipline engineering design, one that allows for clash detection within the model rather than at the construction phase, and detailed project visualizations that inform better design decisions. Model-based design has also improved the efficiency of drawing production, with higher quality construction documentation.
“Up to now the integration of sub-project models has not been possible,” said Harry Luo, application engineer manager, Autodesk Software (China). “Autodesk InfraWorks (formerly Autodesk Infrastructure Modeler) helps to integrate the models into one view. At the primary stage, each domain sets up their model respectively with different software, then they are linked together.”
All together, more than 50 engineers and technicians from multiple design disciplines created and interact with the models. This project isn’t the first one where KHIDI used a model-based BIM approach, but it is the first time they have used InfraWorks.
This new tool has proven particularly useful during primary design stages to quickly model roads, bodies of water, vegetation, buildings, and the landscape, and to integrate basemap data and the models from various Autodesk software products. The KHIDI process has proven that InfraWorks provides a powerful means to integrate and organize the design of hydropower projects.
A major advantage of the model-based BIM approach is that each component of the design models can be updated individually, with just the affected design documents modified and communicated. With integration centralized in InfraWorks, the whole model can be automatically updated for a central overview and a reduced workload to amend design documents and update the individual models. The central model provides the overall construction site layout and communicates design intent so that each discipline is aware of the work of others, and how their own work integrates with the overall project plan.
Autodesk’s AutoCAD Civil 3D provides tools to model terrain, and to perform the 3D calculations needed to design road grading and takeoff processes. With its land shaping tools, AutoCAD Civil 3D proves very useful in dam design for such elements as reservoir planning, the design of the area where material will be disposed of, the dam foundation, and overall excavation. AutoCAD Civil 3D is also the tool for site plans of the living quarters and other buildings.
The volume and slope capabilities within AutoCAD Civil3D marries well with the visualization capabilities of InfraWorks. For instance, base lines created in AutoCAD Civil 3D for the creation of slopes in dam base excavations, waste pits and material storage facilities, can be displayed accurately through InfraWorks, with grading surfaces and construction volumes calculated automatically. When the base lines are adjusted, the software can automatically update relevant surfaces and volumes and carry out analysis of the topography, generating accurate construction drawings and engineering volumes.
The integration of AutoCAD Civil 3D and InfraWorks wasn’t the only powerful coupling of model-based design tools for the project. In addition, Autodesk Inventor and Autodesk Revit proved a powerful duo for the layout of complex mechanical details along with the facility design, providing detail as well as context, and automating the production of traditional design schematics.
For the mechanical and electrical engineering fields, Inventor and Revit MEP improve the speed of design creation, once a relevant parametric model pool is created. After the baseline of components have been established, design of complex pipelines, mechanical and electronic equipment can be quickly turned into blueprints or shown within the context of the other design software. Again, any changes in the design can be automatically updated, greatly improving design efficiency.
While InfraWorks provides the visual representation of the entire structure within context, Navisworks provides the means for modeling project steps in 3D along a timeline for 4D visualization. In Navisworks, the users are able to do walkthroughs and to see the assembly of the design over time in order to discover any conflicts or flaws in the assembly sequence. This 4D visualization also provides the means to coordinate equipment layout among the various phases, enhancing construction efficiency and quality.
A BIM approach has helped KHIDI improve design efficiency and to reduce collaborative costs and miscommunication among the various fields of expertise, improving design quality. Thanks to integrated workflows among the different Autodesk BIM design software, KHIDI was able to convert, assemble and integrate 3D models across different professional formats and informational models.
At this point in KHIDI’s model integration, 2D layout and blueprints are the main outputs from the models, although they have adopted 3D in design and layout for some time. KHIDI are now considering adopting mobile devices to allow for access to the 3D models in the field, further enhancing project efficiency.
“It’s an ongoing process for KHIDI to improve collaboration, management, and integration of technology and software step-by-step.” said Luo. “The quality of the project is definitely improved, and I believe that the efficiency and quality will be further improved after the staff are fully adapted to this design approach.”
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Autodesk InfraWorks (formerly Autodesk Infrastructure Modeler) was used for conceptual design, basemap data integration, and overall project visualization.
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Autodesk AutoCAD Civil 3D was used for surveying, hydrological design, reservoir planning, foundation design, grading excavation, design of disposal areas, land formation details and construction.
Autodesk Inventor was used for the detailed and complex metal structures design, such as the gate of lock and ship lift in the image at left.
Autodesk Revit MEP, Structure and Architecture were integrated to model the complex mechanical and electronic equipment as well as the overall building design.
Autodesk Navisworks was used for visual analysis of project component, coordination, 4D construction simulation, clash detection, and virtual project walkthroughs, and review.
1 Over the past years, HYDROCHINA Kunming has been awarded many honorable titles issued by both provincial and central government authorities, including: Civilized Unit of Yunnan Province; National Advanced Unit for Quality and Economic Benefits; National Excellent Enterprise of Power Sector; National Advanced Unit of Power Sector for Implementation of Customers’ Satisfaction Scheme; Enterprise up to Satisfaction of Customers; Advanced Unit for Poverty Alleviation among Central State Organizations; National Model of Corporate Social Accountability; Outstanding Enterprise of Construction Sector of Yunnan Province; as well as Winner of May 1st Labor Certificate of Yunnan Province. In addition, this project took the top prize in Autodesk’s inaugural Excellence in Infrastructure Competition (http://www.infrastructure-excellence.com), for the best usage of Autodesk technology to plan, design, build or manage civil infrastructure projects. The prize was awarded in the fall of 2012.