Pulling Head for Parallel Trenchless Cable Laying

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Solution Overview

Problem

Current trenchless cable laying methods, such as Horizontal Directional Drilling (HDD), face challenges with shallow depth installations due to hydraulic pressure issues and heat dissipation requirements, leading to ecological and economic problems, and are not suitable for densely populated areas like agricultural land or sealed surfaces.

Innovation Solution

The method involves creating multifunctional bores that reduce drilling fluid pressure, allowing for precise soil analysis and optimal equipment selection, and using a pulling head with a binding agent to anchor the protective tube, enabling trenchless laying of cables at depths of 1.5 to 4 meters with reduced environmental impact and cost.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of stationary object

If Horizontal Directional Drilling (HDD) method is used for trenchless cable laying, then borehole lengths >2,000 m and borehole diameters >1,000 mm can be achieved, but hydraulic pressure becomes too great causing ground rupture and drilling fluid leakage at shallow depths

Engineering Contradiction:
Improveborehole lengthVSAvoidhydraulic pressure
Core Design Contradiction:
Length of stationary objectVSStress or pressure

Solution Approach 1:

The invention divides the single large-diameter borehole into multiple smaller-diameter boreholes. Instead of drilling one large borehole that requires high hydraulic pressure, the system drills several smaller boreholes that can be used in parallel for drilling and later for removing cuttings, thereby reducing the hydraulic pressure required in each individual borehole and preventing ground rupture.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention uses smaller boreholes nested within or alongside the main drilling path. The multiple smaller boreholes are positioned such that they work together as a system - during drilling, they remove cuttings from the main borehole path, and during the pulling-in phase, they evacuate drilling fluid and provide support, effectively nesting multiple functional boreholes within the overall drilling system.

Inventive Principle:
Principle #7Nested doll (Nesting)

2Length of stationary object

If HDD method is used with shallow laying depths of 1.5-4m for cable installation, then economic and technical requirements are met, but hydraulic pressure causes ground rupture and ecological problems

Engineering Contradiction:
Improvelaying depthVSAvoidground rupture and ecological damage
Core Design Contradiction:
Length of stationary objectVSObject-affected harmful factors

Solution Approach 1:

By segmenting the borehole system into multiple smaller boreholes, the hydraulic pressure in each borehole is reduced to levels that do not cause ground rupture. This allows shallow cable laying at economically viable depths (1.5-4m) while avoiding the harmful effects of excessive hydraulic pressure on the surrounding ground and ecosystem.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The multiple smaller boreholes act as intermediaries that facilitate cuttings removal and provide hydraulic support without directly exposing the ground to excessive pressure. These intermediary boreholes enable the main drilling operation to proceed at shallow depths without causing ground rupture or ecological damage.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Volume of moving object

If larger borehole diameters are used to meet cable laying requirements, then cable installation is feasible, but drilling fluid pressure increases and causes ground rupture

Engineering Contradiction:
Improveborehole diameterVSAvoiddrilling fluid pressure
Core Design Contradiction:
Volume of moving objectVSStress or pressure

Solution Approach 1:

The invention replaces a single large-diameter borehole with multiple smaller-diameter boreholes. The combined cross-sectional area of the smaller boreholes is sufficient to accommodate cable laying requirements, while the smaller diameter of each individual borehole reduces the hydraulic pressure needed to circulate drilling fluid, thereby preventing ground rupture.

Inventive Principle:
Principle #1Segmentation

4Ease of manufacture

If open trench laying is used instead of trenchless methods, then economic costs are lower, but ecological and social acceptance issues arise

Engineering Contradiction:
Improvelaying costVSAvoidecological impact and public acceptance
Core Design Contradiction:
Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The segmented borehole system enables trenchless cable laying that combines the economic advantages of minimal surface disruption with the ecological benefits of avoiding open trenches. By using multiple smaller boreholes, the method achieves cost-effective implementation while maintaining public acceptance through environmentally friendly installation practices.

Inventive Principle:
Principle #1Segmentation

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 approach allows for efficient and economical trenchless laying of cables with improved positional accuracy, reduced soil displacement, and effective heat dissipation, making it suitable for densely populated areas while minimizing ecological and economic drawbacks.

Implementation Method 1

A certain minimum depth is required for the proper use of the method. This is due to the fact that a certain hydraulic pressure is required to generate and maintain the flow of the drilling fluid from the drill head through the borehole to the starting point.

Methodology Applied
Scientific EffectHydraulic pressure: Pressure Increase

Implementation Method 2

a binding agent is supplied for anchoring the protective tube in the ground

Methodology Applied
Scientific EffectAdhesion: Adhesive

Implementation Method 3

a binding agent is supplied for anchoring the protective tube in the ground

Methodology Applied
Scientific EffectCohesion: Cohesion

Data Source

PatentEP3431702B1Method and device for trenchless laying of a cable or pipe in the ground
Publication Date: 2020.04.08 BOHLEN & DOYEN BAU GMBH
  • EP3431702B1 patent drawingFigure 1
  • EP3431702B1 patent drawingFigure 2
  • EP3431702B1 patent drawingFigure 3

AI summary

A pulling head for parallel trenchless pipe and/or cable laying in soil (102) is proposed, comprising: a front connection element (104, 104') for coupling the pulling head to a pulling device (101) in a pilot borehole (103) or a drilling device (130) for a pilot borehole (103), and at least two rear connection elements (106, 106', 106") for coupling the pulling head to a pipe or cable (107) to be laid, wherein at least one of the rear connection elements (106, 106') is arranged parallel to and transversely to a pulling direction relative to the front connection element (104, 104'), wherein the pulling head has a passage area (109) between at least one rear connection element (106, 106') and the front connection element (104, 104'), which is used for laying from an area next to the pilot borehole. (103) soil material is permeable between the rear connecting elements (106, 106', 106").