This technology adopts the “Mechanical Rectangular Pipe Jacking Method” adapted for shallow overburden advancement, replacing large shield tunneling and immersed tube methods. It has successfully overcome a series of key construction challenges in the shallow overburden crossing of the Beijing-Hangzhou Grand Canal vehicular tunnel using large-section, long-distance rectangular pipe jacking. These challenges include the selection and design of rectangular pipe jacking equipment in water-rich, high-water-pressure strata, launching and receiving of rectangular pipe jacking near rivers, prevention of soil backflow and riverbed collapse during shallow overburden crossing under the canal, soil conditioning in water-rich fine sand strata, screw conveyor anti-gushing, combined friction reduction for long rectangular pipe jacking and the setup of intermediate jacking stations, waterproofing, anti-flotation, and dynamic load deformation control of pipe segments. The technology features the following core innovations:
(1) Low-resistance extrusion reaming rectangular pipe jacking machine and supporting construction methods;
(2) Anti-power failure and anti-gushing device for screw conveyors in earth pressure balance rectangular pipe jacking machines for shallow overburden river crossing in water-rich, high-water-pressure strata;
(3) Thixotropic slurry injection anti-backflow structure for earth pressure balance rectangular pipe jacking machines in shallow overburden river crossing;
(4) Sleeve-type mud injection pump + correction cylinder-assisted attitude correction technology;
(5) Soil conditioning system for rectangular pipe jacking in unfavorable ground conditions;
(6) Remote monitoring system and automatic grouting system;
(7) Prestressed longitudinal connection technology for large-section, long-distance rectangular pipe jacking (first-time application);
(8) Sliding-type formwork removal device for extra-large rectangular pipe segments;
(9) Three-level waterproofing structure and waterstop sleeve device;
(10) Combined friction reduction technology using composite thick gel + thixotropic slurry;
(11) Pawl-type anti-retreat device and movable pipe jacking anti-retreat support device and method;
(12) Smart integrated site management system integrating informatization and big data.
Click to read about [Guangzhou Jintu Geotechnical Engineering Technology Co., Ltd.]
