On Oct. 22 and 23, 2020, NHRI Office of National Key Special Projects organized a meeting of performance evaluation on 6 special projects of the national key research and development program, Capacity Improvement and Safety Guarantee Technology for Long Distance Water Supply Projects in Highly Cold Areas. More than 60 people attended the meeting, including invited experts, program leaders, special project administrators and technical backbones.

Special project 1—Performance Evolution and Disaster Mechanism of Water Supply Channels in Highly Cold Areas

A regression model on temperature and freezing and melting indexes, a standard contour map of thawing indexes, a distribution map of the maximum seasonal freezing depth, and a freezing damage risk grading map of water channels in Northern Xinjiang have been developed. The 3D fissuring evolution characteristics of channel base soil under the coupling effect of dry-wet and freezing-thawing cycles and the effect law of ice membrane formation on interface mechanics have been revealed. A 1D interface constitutive model of viscosity-damage-friction has been set up. Devices for freezing-thawing cycle test of soil under variable temperatures and loads have been developed. The relation between frost heaving rate and overlying load, and the internal stress mechanism of base soil deformation development during freezing-thawing process have been revealed. Equipment for centrifugal simulation test under dry-wet and freezing-thawing conditions and a numerical simulation system for channel water-heat-force coupling have been developed, with which the degradation and disaster process of channel base under the conditions of dry-wet and freezing-thawing cycles has been analyzed and reproduced, providing a technical platform for the design, operation and safety assessment of channels in highly cold areas. A frost heaving mechanical model of channel lining structure has been established, with which the influence of groundwater depth, freezing depth and channel depth on frost heaving damage of lining structure has been revealed, and the technical requirements for lining joints have been put forward.

Special project 2—Theory and Technology of Water Supply Efficiency Improvement and Structure Optimization of Channels in Highly Cold Areas

A new design method of structure optimization for channel sections in highly cold areas has been established, by which a new, trapezoidal and arc-bottomed channel section structure, featured with many advantages such as strong capability of recovery from frost heaving and thawing settlement, even stress distribution and high efficiency of water conveyance has been developed. The controlling technology of compatible deformation of old and new channel slopes, the technology of connecting old and new anti-seepage bodies and high efficient drainage of channel leakage water, and the technology of channel upgrade and maintenance have been developed. A new type of water-stop material with frost and salt resistance, and concrete material for channel lining, the technology for fast channel repair, and a complete set of construction equipment have been developed for highly cold areas.

Special project 3—Key Technology of Water Delivery at Low Temperature and Channel Operation Control in Winter in Highly Cold Areas

A hydraulic-control simulation system of digital channel and the dispatching rules for water conveyance in highly cold areas have been produced for freezing period. A new kind of structure and material for thermal insulation board used on channels has been invented. This material is featured with heat preservation, low weight, rapid construction, durability and corrosion resistance. The structure design method has also been created. An auxiliary heating technology using channel base rubble, and three other channel ice-melting technologies utilizing solar energy, i.e. floating solar blanket covering ice surface, thermal storage lining with phase change material and channel base energy preservation, have been developed. The emergency electrical heating technology for ice-melting, based on skin effect and used in the key parts of long distance water delivery channels, has been optimized.

Special project 4—Monitoring, Early Warning and Diagnosis Technology of Long Distance Water Supply Channels in Highly Cold Areas

An index system of channel safety monitoring and evaluation in highly cold areas and sensor elements that can accurately measure channel frost heaving amount and heaving force in highly cold areas have been developed. A distributed optical fiber testing technology which can accurately locate the sections with abnormal leakage and deformation damage of long distance channels has been developed and applied in practice. A compatible intelligent system for channel monitoring, forecasting and early warning and a rapid detection and interpretation method for the main hidden dangers of channels have been set up. Vehicle-mounted intelligent equipment for field inspection has been integrated, and a quantitative health evaluation system for long distance channel operation in highly cold areas has been established.

Special project 5—Emergency Dispatching and Rescuing Technology for Water Supply Channels in Highly Cold Areas

A scheme and a set of technology for accident risk tracking have been developed after researching such techniques and methods as remote inspection aerial image acquisition, dynamic BIM model construction of engineering operation safety, interactive roaming of dynamic BIM virtual scene and aerial video, and intelligent identification of risk images. A multi-process numerical simulation model of channel water volume, quality and velocity and a risk factor and event analysis model based on correlation matrix have been constructed. The adaptive emergency dispatching technology for sudden water quality risk has been put forward after studying the variation process and characteristics of channel water quality under emergency working conditions in highly cold areas. A decision supporting platform for whole-process emergency dispatching of water supply channels in highly cold areas has been built. Emergency rescue equipment such as tipping bucket elevator and filter material distributor have been developed.

Special project 6—Integrated Demonstration of Capacity Improvement and Safety Guarantee Technology for Water Supply Channels in Highly Cold Areas

A complete set of technology and equipment for upgrading, rebuilding, maintaining and rescuing full channel section, a decision making platform for channel safety operation and management, and a system platform for all-weather unmanned safety monitoring, forecasting and early warning of channels, all used in highly cold areas, have been integrated and demonstrated, verifying the rationality and effectiveness of the complete set of technical measures for low-temperature water conveyance, heat preservation and ice-melting. These achievements have been successfully applied in large water supply projects in Northern Xinjiang, increasing the frost resistance capacity of channel lining by 60% and the water supply capacity 25%. Standards such as Technical Code for Channel Safety Monitoring in Cold Areas and Evaluation Guidelines for Freezing Damage of Channels in Cold Areas have been formed. With a promising application prospect, these achievements may also be used in other major projects of water conservancy and transportation in cold areas.

The expert group unanimously agreed that the above-mentioned special projects passed the performance evaluation.