Full-Round Tunnel Formwork for Pressure-Limited Secondary Lining

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Solution Overview

Problem

Existing tunnel formwork systems cause damage to the primary lining during secondary lining construction due to unsupported loads, leading to delays and overcosts from repairs.

Innovation Solution

A formwork system with hydraulic cylinders and pressure sensors that maintain the load on the primary lining below a predefined threshold, using a master-slave cylinder arrangement and a system controller to distribute pressure evenly, ensuring the system rolls on a cylindrical surface with balanced loads.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If existing full round tunnel formworks are used to cast secondary lining, then the secondary lining can be formed, but the primary lining of dowels is damaged due to excessive loads and overpressures

Engineering Contradiction:

Improvesecondary lining formationVSAvoiddamage to primary lining

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The patent introduces a load distribution system with multiple support points and hydraulic cylinders that act as intermediaries between the formwork and the primary lining. This system distributes the pressing loads across multiple dowels rather than concentrating force on single points, preventing damage while enabling secondary lining formation.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The formwork is divided into multiple articulated formwork elements that can be independently supported by separate hydraulic cylinders. This segmentation allows each element to be pressed against the primary lining with controlled, distributed loads, avoiding excessive pressure on any single dowel while maintaining overall formwork stability.

Inventive Principle:

Principle #1Segmentation

2Stability of the object's composition

If hydraulic pressure is increased to ensure formwork stability during concrete casting, then formwork stability improves, but the risk of damaging the primary lining increases

Engineering Contradiction:

Improveformwork stabilityVSAvoidoverpressure on primary lining

Core Design Contradiction:

Stability of the object's compositionVSObject-affected harmful factors

Solution Approach 1:

The patent employs a dynamic load distribution system where multiple hydraulic cylinders can independently adjust their pressure output. The system dynamically balances the loads across different support points, maintaining formwork stability while preventing any single cylinder from applying excessive pressure that could damage the primary lining.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes the pressure parameters by distributing the total required support force across multiple hydraulic cylinders rather than using high pressure from fewer cylinders. Each cylinder operates at a lower, safer pressure level while collectively providing the necessary stability for formwork during concrete casting.

Inventive Principle:

Principle #35Parameter changes

3Productivity

If traditional formwork moving solutions are used, then the formwork can be repositioned for step-by-step casting, but execution delays occur due to repairs from primary lining damage

Engineering Contradiction:

Improvecasting execution speedVSAvoiddelays from repairs

Core Design Contradiction:

ProductivityVSLoss of time

Solution Approach 1:

The patent incorporates a control system that monitors the loads applied to the primary lining and provides feedback to the hydraulic cylinder operation. This feedback mechanism ensures that pressure limits are not exceeded, preventing damage to the primary lining and eliminating the need for repairs that would cause execution delays.

Inventive Principle:

Principle #23Feedback

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

The system prevents damage to the primary lining, enabling faster execution and reducing construction costs while ensuring safety and efficiency in tunnel lining processes.

Implementation Method 1

a hydraulic cylinder coupled with the formwork element to exert pressure on it towards a tunnel surface like the primary lining

Methodology Applied

Scientific EffectHydraulic pressure: Hydraulic Press

Implementation Method 2

at least one pressure sensor for measuring pressure exerted by the hydraulic cylinder

Methodology Applied

Scientific EffectPressure measurement: Pressure Increase

Data Source

PatentUS12398642B2Full round travelling formwork for secondary lining of tunnels

Publication Date: 2025.08.26 GRP EMPRESARIAL TECOZAM SL

AI summary

A formwork system is specifically adapted to be full-round tunnel lining formwork systems. The system includes at least one formwork element having a surface shaped to conform a part of a tunnel lining, and hydraulic cylinder coupled with the formwork element to exert pressure on it towards a primary lining, and at least one load sensor for measuring load exerted by the hydraulic cylinder. The system further includes a system controller that operates the hydraulic cylinder based on measurements of the pressure sensor, and maintains the pressure exerted by the formwork element on a primary lining during concrete forging, equal or below a predefined pressure to avoid damaging an external tunnel lining or structure. The formwork system speeds up execution work and avoids budget overcost caused by damages and repairs.