Karst Tunnel Reinforcement System for Mud Inrush Stability
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Solution Overview
Problem
Construction of railway tunnels through karst caves with large dip angles faces challenges such as ground collapse, water inrush, and safety hazards due to limited anti-buffering capacity of filling sand and difficulties in non-blasting excavation, especially with deep pile foundations and prolonged settlement observation.
Innovation Solution
A reinforcement system comprising an umbrella arch, concrete layer, flexible buffer layer, protective layer, arch bridge, emptying culvert, cross passage, and circuitous passage is implemented, along with anchor cables and a vertical bearing wall, to effectively discharge falling rock and water, enhance stability, and facilitate construction and maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If filling sand is used as buffer layer, then construction is simplified, but anti-buffering capacity is limited and water accumulates
Solution Approach 1:
The patent replaces single-material filling sand with a composite buffer layer system consisting of multiple layers including sandbags, concrete layers, and drainage materials. This composite structure combines the advantages of different materials to achieve both ease of construction and high anti-buffering capacity while preventing water accumulation through integrated drainage channels.
2Object-affected harmful factors
If non-blasting excavation is used, then safety is improved, but excavation difficulty increases due to limestone covering
Solution Approach 1:
The patent applies preliminary action by using water jetting and mechanical breaking methods to pre-fracture the limestone covering before main excavation. This preliminary treatment reduces the hardness and compactness of the rock, making subsequent non-blasting excavation significantly easier while maintaining safety by avoiding blasting operations entirely.
3Productivity
If blasting excavation is used, then excavation efficiency is improved, but safety hazards increase due to rock damage and mud inrush
Solution Approach 1:
The patent replaces the chemical-mechanical blasting system with a purely mechanical excavation system using hydraulic breakers, water jets, and mechanical digging equipment. This substitution eliminates the harmful effects of blasting (rock damage, mud inrush, gas emissions) while maintaining acceptable excavation efficiency through the combined use of these mechanical methods.
4Stability of the object's composition
If deep pile foundations are constructed, then structural stability is improved, but construction period is extended
Solution Approach 1:
The patent applies preliminary action by pre-construction of the arch bridge structure and preliminary stabilization of the foundation area before constructing the deep pile foundations. This allows overlapping of construction activities and reduces the waiting time for foundation completion, thereby shortening the overall construction period while maintaining the required structural stability.
5Reliability
If settlement observation is conducted, then structural safety is monitored, but construction time is prolonged
Solution Approach 1:
The patent implements continuous automated settlement monitoring systems that operate throughout the construction process and after completion. This continuous monitoring provides real-time safety data without requiring prolonged interruption of construction activities, thus maintaining structural safety monitoring while minimizing construction time delays.
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 provides enhanced stability and safety by buffering impact forces, discharging water and rock, and allowing for the safe laying of ballastless tracks, addressing the challenges of mud inrush and water accumulation, and reducing construction time.
Implementation Method 1
a flexible buffer layer... to effectively discharge falling rock and water, enhance stability, and facilitate construction and maintenance
Implementation Method 2
an emptying culvert parallel to the main tunnel, a bottom surface of the emptying culvert is lower than the bottom plate in height in a vertical direction, which is conducive to discharge of the falling rock and the inrush water
Data Source
AI summary
The present invention relates to a reinforcement system at a railway tunnel section passing through a karst cave with a large dip angle and a construction method. The reinforcement system of the present invention can solve the problems of downward mud filling, watertightness, etc. of a top through structures of an umbrella arch, a concrete layer, a flexible buffer layer and a protective layer at the top, at a karst cave, of a tunnel, solve the problem of upward mud inrush at a bottom through structures of an anchor cable, a ring beam and a foundation pad at the bottom of the tunnel, guarantee stability of an arch bridge by erecting “a triple arch bridge” in a middle and adding a vertical bearing wall under the arch bridge, and make a railway safely cross the mud-inrush karst cave by safely laying a ballastless track on the bridge.