From October 27 to 30, CISMGE 2023, the 14th National Academic Conference on Soil Mechanics and Geotechnical Engineering of the China Civil Engineering Society, was grandly held at the China Optics Valley Convention & Exhibition Center (Wuhan). About 4,000 participants from across the country attended the conference, including construction enterprises for underground space and foundation engineering, machinery and equipment manufacturing enterprises, survey and design institutes, research institutes, industry associations, experts and scholars.

▲Conference site

As a quadrennial event, the National Academic Conference on Soil Mechanics and Geotechnical Engineering of the China Civil Engineering Society is one of the most influential academic gatherings in China's geotechnical engineering field. This conference was hosted by the Soil Mechanics and Geotechnical Engineering Branch of the China Civil Engineering Society and organized by the Wuhan Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, and the State Key Laboratory of Geomechanics and Geotechnical Engineering. With the theme of "Green, Intelligent, Resilient" geotechnical engineering, the conference exchanged and discussed the latest achievements and development trends in China's soil mechanics and geotechnical engineering fields, explored the path of green, low-carbon and resilient high-quality development of the geotechnical engineering industry, and led disciplinary development and promoted industry progress.

▲Conference site

As a company with inherited craftsmanship and a century-long history, the specially invited guest of the conference—Gong Xiugang, General Manager of Shanghai Engineering Machinery Factory Co., Ltd.—attended the opening ceremony. On site, the project "R&D and Application of TRD Construction Method Equipment" won the Mao Yisheng Geotechnical Engineering Technology Innovation Award - Team Award. He was also invited to give a conference report at the Mao Yisheng Award Forum entitled "R&D and Application of Construction Equipment for Equal-Thickness Cement-Soil Mixing Walls," focusing on technical topics such as "Introduction to the Equal-Thickness Cement-Soil Mixing Wall Method, CSM and TRD Equipment Technology Innovation, and Typical TRD Application Cases."

▲General Manager Gong Xiugang of Shanggong Machinery attending the conference opening ceremony

▲Receiving the Mao Yisheng Geotechnical Engineering Technology Innovation Award - Team Award on site

▲Award ceremony for the Mao Yisheng Geotechnical Engineering Technology Innovation Award - Team Award

▲Group photo of the winners of the Mao Yisheng Geotechnical Engineering Technology Innovation Award - Team Award

Overview of the Equal-Thickness Cement-Soil Mixing Wall Method

The report described that the conventional construction methods for waterproof curtains in building foundation pits under the equal-thickness cement-soil mixing wall method mainly include the TRD method and the CSM method, etc. They are widely used in projects such as pit bottom reinforcement, continuous wall joint waterproofing or deepening, newly added waterproof curtains, and projects with high requirements for controlling deformation of the surrounding environment.

TRD method:A square box equipped with a chain of cutting tools is inserted underground and advanced laterally to form a trench, while the tool chain performs vertical cutting and mixing, and cement slurry is injected from the front cutting head into the original foundation soil, so that the soil in the original foundation is fully mixed and stirred with the injected cement slurry to form an equal-thickness, seamless cement-soil mixing continuous wall.

CSM method:The cutter soil mixing technology is configured with two milling wheels at the bottom end of the drilling tool. The two sets of milling wheels rotate and mix vertically along the axis; by sinking to form a trench and lifting to form a wall, they forcibly cut and loosen the soil vertically, while combining injection of cement, water and high-pressure air, mixing and stirring to form an equal-thickness, overlapping cement-soil mixing continuous wall.

▲General Manager Gong Xiugang of Shanggong Machinery giving a conference report

CSM and TRD Equipment Technology Innovation

The report first provided an overview of CSM equipment technology. The Shanggong Machinery MS45 dual-wheel mixing drilling rig adopts pure electric drive, variable-frequency speed-regulation motors with direct drive for high efficiency and low operating cost, replacing the hydraulic transmission system, with low procurement cost; its operating cost is 2/3 that of hydraulic systems, power consumption is as low as 8 kWh per cubic meter, time-of-use emergency overload capacity is 1.5 times, and it features forced motor cooling technology and other technical innovation points. Then it elaborated and introduced advanced technologies such as CSM equipment technology innovation—drill pipe combination, which changes the traditional CSM slurry pipe, air pipe, coolant pipe and grease pipe routes from hoses to hard pipes integrated in the drill pipe, greatly improving drill pipe splicing efficiency.

▲General Manager Gong Xiugang of Shanggong Machinery giving a conference report

▲Construction case of the MS series dual-wheel mixing drilling rig

Secondly, the report introduced the development history of TRD method technology, the expansion of TRD method application fields, the TRD equipment market size, and the background of continuous research on the TRD method. Shanggong Machinery independently developed China's first TRD equipment with 61 m construction capability in 2012. It has now formed three major series: TRD-60/70/80 (dual power system). Among them, the TRD-80E (pure electric drive) method machine set a world record with a maximum construction depth of 86 m. In 2022, the product series was further expanded with the launch of the TRD-C50 method machine, and this year the pure electric drive TRD-C40E was launched. The "value competitiveness" of Shanggong Machinery's segmented products has been fully demonstrated, further consolidating its leading position in the TRD industry.

After that, the report shared in detail the innovative technologies of TRD method equipment:

● Main and auxiliary dual power systems, safer and more energy-saving;

● Diesel and electric dual power cabinets, for broader adaptability;

● Ultra-deep curtain solutions: upper and lower dual grouting technology and dual-channel inclinometer technology, for higher wall quality;

● Cutting box wedge connection technology, safer and more reliable;

● Remote control technology, safer and more efficient;

● Remote construction monitoring system, making management simpler.

▲General Manager Gong Xiugang of Shanggong Machinery giving a conference report

▲Construction case of the TRD method machine

Typical TRD Application Cases

Finally, through the advantages of the TRD method and new ultra-deep TRD technologies, the report listed the excellent performance of multiple typical construction cases across the country, deeply analyzed the main technical features, new technologies and new intelligent control technologies of Shanggong Machinery's TRD method machine equipment and how to ensure wall quality, and comprehensively introduced the core advantages of TRD method equipment in the field of equal-thickness cement mixing wall construction. Secondly, the report further outlined the expansion of TRD method applications—the TAD method, its advantages, cases, and the latest application of the TRD method in ultra-deep steel section composite retaining walls (trial).

▲General Manager Gong Xiugang of Shanggong Machinery giving a conference report

▲No. 5 shaft of the Hard X-ray project of ShanghaiTech University

▲Underground transportation hub and supporting projects in the south area of Pudong Airport

▲Xiong'an New Area Xiongxin High-Speed Railway Project

▲Ganjiang Tailu Comprehensive Regulation Project

▲Ultra-deep reinforcement project for the tunnel portal of the shield receiving shaft on Yunling West Road, Shanghai

▲Phase I project of key polder embankment reinforcement in the Dongting Lake area

In recent years, in order to promote the sustainable development of the construction industry, it is necessary to adhere to a green, low-carbon, energy-saving and emission-reduction development path. The industrialization of foundation pit engineering is an effective means of achieving energy conservation and emission reduction. In construction projects such as building engineering, underground engineering, deep foundation pit retaining, revetment engineering, tunnels, dams and other underground structure and space utilization projects, as the scale of underground space structure development develops toward large, deep, tight, complex and changeable conditions, it also provides a broad stage for the theories and technologies of underground structure and space utilization.

The national "14th Five-Year Plan": accelerate digital transformation, promote green development, comprehensively improve urban quality, and deeply advance low-carbon transformation in construction and other fields. Shanggong Machinery's serialized method equipment has contributed to numerous underground space engineering construction and urban building deep foundation pit engineering applications across the country. To meet the engineering needs of ultra-deep foundation pits, it has made unremitting efforts toward the development direction of intelligent, visual, informatized and low-environmental-impact construction equipment.