Recently, six heavy-cargo trucks fully loaded with the main units and components of SC45 hydraulic milling and mixing drilling rigs set off in a mighty convoy from Shanghai Jintai's Anting headquarters, heading west all the way to a new battlefield. A week later, the convoy arrived at the construction site of the "Dynamic Balance Ecological and Environmental Protection Upgrade and Renovation Project" in Delingha City, Qinghai Province. Unloading, assembly, and commissioning were completed in one smooth sequence. After a brief commencement ceremony, the SC45 steadily drove onto the dam foundation and took its position, immediately commencing construction of the cutoff wall for the No. 3 retaining dam embankment. Set against the blue sky, white clouds, and deep lake waters, it looked especially dazzling and beautiful. This is the first time Qinghai Province has introduced the CSM method and applied it to an ecological and environmental protection project, marking another new milestone for Shanghai Jintai's SC45 hydraulic milling drilling rig on the map of the motherland's infrastructure construction.

The SC45 dual-wheel mixing drilling rig immediately commenced construction after a brief commencement ceremony

As early as 2009, Shanghai Jintai began developing CSM method equipment. The first prototype rolled off the production line in July 2010, and in August of the same year, with the approval of the Hubei South-to-North Water Diversion Construction Administration, it was applied and verified in the foundation treatment works of the sluice gate at the Xinglong Water Conservancy Hub. Subsequently, this method gradually expanded from water conservancy seepage prevention and reinforcement works to fields such as waterproof curtains for urban building foundation pits, underground pollution prevention and control, and reinforcement of trench walls for anchorage foundation pits of large bridges, with its application areas expanding in tandem—north to Heilongjiang, south to Hainan Island, east to Jiangsu, Zhejiang, and Shanghai, and west to Xinjiang—covering almost all provinces in China. During the promotion process, Shanghai Jintai successively developed three SC series platform products—crawler diesel main units, crawler electro-hydraulic main units, and walking electro-hydraulic main units—based on the working conditions, geological characteristics, and design requirements of engineering projects. According to incomplete statistics, since the application of Jintai's SC series products, more than 500 adaptive engineering projects have been completed across the country.

In August 2023, Jintai's CSM method was included in the "2023 Key Promotion Guidance Catalog of Advanced and Practical Water Conservancy Technologies"

In the "Dynamic Balance Ecological and Environmental Protection Upgrade and Renovation Project" in Delingha City, Qinghai Province, the original No. 3 retaining dam embankment foundation adopted a seepage prevention process of geomembrane plus continuous high-pressure jet grouting piles, with a mortar-rubble slope protection on the water-facing side and a dry-laid stone slope protection on the back-water side. The dam body is 641 meters long, with a crest width of 12.5 meters and a foundation width of 58 meters. Through reinforcement of the dam body, structural stability of the dam was achieved. During construction monitoring, obvious seepage was found at the connection between the high-pressure jet grouting piles and the geomembrane. After further investigation and verification, the construction plan was changed to the current approach of "building a cutoff wall using CSM seepage prevention technology on the dam crest." To prevent soil erosion, reduce pressure on the dam body, and ensure dam safety, the design institute constructed a 4-meter-deep interception ditch and two collection wells on the back-water side of the No. 3 dam body.

Overview of the No. 3 project of the "Dynamic Balance Ecological and Environmental Protection Upgrade and Renovation Project" in Delingha City, Qinghai Province

At present, the project is advancing intensely and in an orderly manner, and the project department has unanimously affirmed the construction efficiency and wall quality of Jintai's CSM method equipment. Thanks to the successful demonstration of the SC45, in order to accelerate project progress, the project department has additionally mobilized 7 Shanghai Jintai SC hydraulic milling and mixing drilling rigs and 3 SG series hydraulic grabs, which have successively arrived at the site. It can be foreseen that subsequent works will be even more efficient and faster.

Panoramic view of the construction of the No. 3 project of the "Dynamic Balance Ecological and Environmental Protection Upgrade and Renovation Project"

A little popular science on professional knowledge:

Interception ditchcan effectively intercept rainwater or groundwater on hillsides, preventing water flow from directly scouring the dam body, thereby protecting the stability and safety of the dam. In addition, the interception ditch can reduce the direct impact of rainwater on the dam body, alleviate the water pressure borne by the dam body, and enhance the dam's flood resistance.

Collection wellcan effectively channel the water intercepted by the interception ditch into the collection well, and then discharge this water through the drainage system, avoiding water remaining around the dam body for extended periods and reducing erosion and damage to the dam. At the same time, the installation of collection wells also helps observe the seepage volume of the dam body. By monitoring water level changes in the collection wells, seepage conditions of the dam can be detected in a timely manner, providing a basis for dam maintenance and management.

Building interception ditches and collection wells not only helps protect the stability and safety of the dam body, but also effectively reduces soil erosion and improves the dam's flood resistance and service life.