Horizontal Drilling Jet Grouting for Unstable Soil Stability
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Solution Overview
Problem
Horizontal directional drilling methods are unsuitable for unstable ground conditions, where the borehole may become unstable or collapse, making it difficult to maintain stability and prevent settlement.
Innovation Solution
Integration of nozzle jet elements (DSE) into the drill pipe for injecting a binder into the soil using a jet spray method, creating a stable binder column around the borehole, which stabilizes the soil and prevents settlement, allowing for continuous drilling and expansion without interruption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If horizontal directional drilling is used in unstable soil, then the borehole becomes unstable or collapses, but the method avoids the need to excavate a trench
Solution Approach 1:
A jet grouting element is introduced as an intermediary component between the drill string and the surrounding soil. This element injects binder material into the soil to create a stabilized borehole wall, acting as a mediator that prevents direct contact between the unstable soil and the borehole, thereby maintaining borehole stability while preserving the trenchless drilling advantage
Solution Approach 2:
The jet grouting element performs preliminary stabilization of the borehole wall during the drilling process itself, before the borehole could become unstable or collapse. By injecting binder material into the surrounding soil in advance, the system prevents future instability rather than addressing it after it occurs
2Productivity
If the soil shrinks the breakthrough after drilling, then the forces on the reamer are too great to guide it through, but horizontal directional drilling creates a pilot hole for pipe installation
Solution Approach 1:
The jet grouting element acts as an intermediary that prevents soil shrinkage and breakthrough collapse by stabilizing the borehole wall during the reaming process. This mediation reduces the forces acting on the reamer, making it possible to guide the reamer through the breakthrough while maintaining the ability to install pipes
3Ease of manufacture
If the borehole collapses in unstable soil, then pipe pulling becomes impossible, but horizontal directional drilling enables trenchless pipe installation
Solution Approach 1:
The jet grouting element serves as a mediator that prevents borehole collapse by injecting binder material to stabilize the surrounding soil. This creates a stable passage that allows pipe pulling operations to proceed successfully while maintaining the trenchless construction advantage
Solution Approach 2:
The system performs preliminary stabilization of the borehole wall during drilling, preventing collapse before it occurs. This advance action ensures that the borehole remains open and stable for subsequent pipe pulling operations, making trenchless construction feasible in unstable soil conditions
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
Enables the production of stable horizontal boreholes in unstable soils, preventing settlement and allowing for the installation of pipes and tunnels without the need for trench digging, even in challenging geological conditions.
Implementation Method 1
with which DSE binder introduced into the drill string is injected into the soil surrounding the borehole using a jet grouting process
Implementation Method 2
If the soil stability permits, at least one DSE can be inserted between the drill head and the drill rod. This allows steps 1) and 2) to be performed simultaneously.
Data Source
Figure 1~3
Figure 4~6
Figure 7~9
AI summary
The invention relates to a horizontal drilling method comprising the following steps: 1) Creating a pilot bore in which a drill head on a drill string (15) with a plurality of coupled drill rods (17) is driven from a starting pit (25) to a target pit (27) in the ground and bentonite is conveyed via the drill string (15) to the drill head, thereby creating a borehole (11); 3) Replacing the drill head with a reamer in the target pit (27) and widening the borehole (11) by pulling the reamer from the target pit (27) to the starting pit (25); and 4) Optionally repeating step 3) with further reamers for stepwise widening of the borehole (11).A further step 2) is the integration of at least one jet peening element (DSE) (31) into the drill string (15), with which binder introduced in the drill string (15) is injected into the soil surrounding the borehole (11) using a jet peening process before step 3) or during step 1), thereby creating a column of binder (39) around the borehole (11).