A slipline, also known as a slip-lining system, is a method used in tunneling and underground construction to rehabilitate or reinforce existing pipelines or conduits by inserting a new pipe inside the existing one.
Definition:
A slipline, also known as a slip-lining system, is a method used in tunneling and underground construction to rehabilitate or reinforce existing pipelines or conduits by inserting a new pipe inside the existing one. The new pipe, known as the slipliner, serves as a protective and structural element, providing enhanced performance and extending the service life of the pipeline system.
Uses/benefits:
1. Rehabilitation: Sliplining is commonly used for the rehabilitation of deteriorated or damaged pipelines. It provides a cost-effective and minimally disruptive solution compared to excavation and replacement of the entire pipeline.
2. Structural reinforcement: Sliplining improves the structural integrity of the existing pipeline by inserting a new pipe inside it. This enhances the load-bearing capacity and resistance to external loads such as soil movement and ground settlement.
3. Corrosion protection: The slipliner acts as a protective barrier, shielding the existing pipeline from corrosion and preventing further deterioration. This is particularly beneficial in aggressive soil environments or when the existing pipe material is susceptible to corrosion.
4. Flow capacity improvement: By reducing the internal roughness of the pipeline, sliplining can improve the hydraulic performance and flow capacity of the system, allowing for increased conveyance of fluids or gases.
5. Environmental benefits: Sliplining minimizes the need for excavation and disruptive construction activities, reducing the impact on the surrounding environment. It also helps prevent leaks and spills, reducing the potential for environmental contamination.
Specifications:
1. Slipliner material: The choice of slipliner material depends on factors such as the desired strength, corrosion resistance, and compatibility with the existing pipeline. Common materials include high-density polyethylene (HDPE), fiberglass reinforced plastic (FRP), and steel.
2. Diameter and thickness: The diameter and thickness of the slipliner are determined based on the internal dimensions of the existing pipeline and the desired performance requirements. It should provide sufficient clearance and structural support within the existing pipe.
3. Length and joints: The slipliner is typically installed in sections, which are joined together using suitable methods such as heat fusion, mechanical coupling, or adhesive bonding. The length of each section should be determined to facilitate smooth installation and minimize the number of joints.
4. Grouting and sealing: Proper grouting and sealing of the annular space between the existing pipe and the slipliner are essential to ensure a watertight and stable installation. Grouting materials may include cementitious grout or specialized sealing compounds.
5. Access and installation method: The choice of access points and the installation method depend on the specific project requirements and site conditions. Access may be through existing manholes, excavation pits, or specially designed entry points. The installation method can involve pushing, pulling, or jacking the slipliner into place.
Types:
1. Pipe-in-pipe sliplining: This is the most common type of sliplining, where a new pipe is inserted inside the existing pipeline, forming a dual pipe system. The annular space between the two pipes is typically grouted or sealed.
2. Fold-and-form sliplining: In this method, a flexible pipe is inserted into the existing pipeline in a folded or coiled state. Once inside, it is expanded or inflated to conform to the shape of the existing pipe, providing a new structural lining.
3. Inverted sliplining: This technique involves the installation of a new pipe by inverting it into the existing pipeline. The new pipe is turned inside out and pulled or pushed into place, forming a continuous lining.
The selection of a suitable sliplining method and materials depends on factors such as the condition of the existing pipeline, desired performance, and project constraints. Proper planning, design, and installation are critical to ensuring the successful rehabilitation and reinforcement of pipelines in tunneling and underground construction.