Subgrade with Local Deep Excavation and Backfilling
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Solution Overview
Problem
In soft soil areas, the lack of targeted control methods for the settlement of overlying backfilling and the original subgrade during underground facility construction leads to differential settlement issues, compromising the stability of road structures.
Innovation Solution
A rapid construction method involving the use of supporting cast-in-place piles, block geobag reinforced fillers, geogrids, and anchor rods, with cement solidified slurry filling and grouting to stabilize the subgrade structure and control settlement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional pile support method is used to ensure underground structure stability, then underground structure stability is improved, but differential settlement control between existing subgrade and backfilled subgrade deteriorates
Solution Approach 1:
The patent applies local quality by implementing different reinforcement strategies for different zones: the existing subgrade receives anchor rod reinforcement at specific intervals, while the backfilled subgrade uses geogrids and cement-soil mixing piles. This localized differentiation addresses the differential settlement issue by tailoring reinforcement to the specific settlement characteristics of each zone.
Solution Approach 2:
The patent employs composite materials including geogrids combined with cement-soil mixing piles, anchor rods with grouting, and block geobag reinforced fillers. These composite solutions provide both immediate structural support and long-term settlement control, resolving the contradiction between stability and settlement control.
2Stability of the object's composition
If comprehensive reinforcement measures are implemented to control settlement, then settlement control is improved, but construction complexity and time increase
Solution Approach 1:
The patent segments the reinforcement system into distinct functional components: support piles for structural stability, anchor rods for existing subgrade settlement control, geogrids for backfill reinforcement, and cement-soil mixing piles for deep soil improvement. This segmentation allows each component to be optimized independently and constructed in a systematic sequence, reducing overall complexity.
Solution Approach 2:
The patent implements preliminary action by pre-installing support piles and preparing the foundation before backfilling operations. The anchor rods and geogrids are positioned in advance to guide the backfilling process, ensuring settlement control is built into the structure from the beginning rather than added as a separate corrective measure.
3Ease of manufacture
If traditional backfilling and compaction methods are used, then construction simplicity is maintained, but settlement control and subgrade stability deteriorate
Solution Approach 1:
The patent introduces geogrids as an intermediary layer between the backfill soil and the underground structure. These geogrids distribute loads evenly and prevent differential settlement while maintaining relatively simple construction procedures. The block geobag reinforced fillers serve as another intermediary that simplifies backfilling while ensuring stability.
4Stability of the object's composition
If anchor rods and geogrids are used to reinforce backfill, then backfill stability is improved, but construction time and cost increase
Solution Approach 1:
The patent implements continuous useful action by integrating anchor rod installation, geogrid placement, and backfilling into a coordinated sequence. The cement-soil mixing piles are constructed continuously along the subgrade, and the anchor rods are grouted in succession, maintaining steady progress without interruptions that would extend construction time.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method effectively stabilizes the subgrade structure, prevents uneven settlement, and reduces construction time and costs by reinforcing the subgrade and backfilled areas, ensuring long-term stability and deformation control.
Implementation Method 1
gaps between the block geobag reinforced fillers are filled with cement solidified slurry
Implementation Method 2
The anchor rods are inserted into the geogrids, the supporting cast-in-place piles and the subgrade structure
Implementation Method 3
backfilling lateral peripheral regions and top peripheral regions of the underground pipe gallery with block geobag reinforced fillers; placing geogrids on the top of the underground pipe gallery
Data Source
AI summary
A subgrade with local deep excavation and backfilling structure and a rapid construction method thereof are provided. Supporting cast-in-place piles are laid at positions where an underground pipe gallery is located in a subgrade structure, and soil there between are longitudinally excavated to form a line-shaped foundation pit. A bottom of the line-shaped deep foundation pit is reinforced to support the underground pipe gallery, and lateral peripheral regions and top peripheral regions of the underground pipe gallery are backfilled with block geobag reinforced fillers. Geogrids are placed on the top of the underground pipe gallery, then backfilling compaction and reinforcing are performed, and the geogrids are fixedly assembled with anchor bolts. The construction method is simple and easy. By using compacted block geobag reinforced fillers and cement solidified slurry, an overall quality of the subgrade structure after backfilling can be ensured, and construction period and cost can be greatly reduced.