The main method of trenchless restoration (reconstruction and repair) of underground pipelines for various purposes- application of internal protective coatings (lining, shells, shirts, membranes, inserts, etc.) along the entire length of the pipeline or in some of its places.
According to the modern international classification, internal protective coatings can be made in the form of spray casings, continuous coatings, spiral casings, point (local) coatings.
The most common methods of restoration of water supply and drainage networks by trenchless methods:
- application of cement-sand coatings (CPP) on the inner surface of the restored pipeline;
- pulling a new pipeline into a damaged old one (with its destruction and without destruction) using special devices, for example pneumatic punches;
- pulling through a flexible polymer pipe (pre-compressed or folded U-shape) inside the pipeline being repaired;
- pulling through continuous protective coatings from various polymeric materials;
- the use of flexible elements made of sheet material with a toothed fastening structure;
- the use of a flexible combined sleeve (stocking), which allows molding a new composite pipe inside the old one;
- the use of roll winding (endless profile tape) on the inner surface of the old pipeline;
- application of spot (local) coatings, etc.
Each of the listed restoration methods has specific features and has its own advantages that determine the scope of its application. The expediency of using a particular method is specified after detailed diagnostic examinations and technical expert opinions. In each specific case, the condition of the pipeline, its size, the type of the transported medium, the surrounding underground infrastructure, the type of soil, the presence of groundwater and a number of other factors that can influence the choice of the recovery method are subject to consideration.
Imagine short description some methods of trenchless restoration of water supply and drainage networks.
Application of cement-sand coatings on the inner surface of pipelines (spray method). The use of the spraying method by applying cement-sand coatings must be considered from a historical perspective,
Over time, as a result of intensive operation of the pipeline, mechanical or chemical destruction of the protective layer is possible. Mechanical destruction of the coating is caused by the following factors: excessive permeability of the coating, which is excluded when its density is 300-400 kg / m 3; the appearance of cracks - mainly due to a violation of the preparation and coating technology (for example, due to non-compliance with the water-cement ratio, the lack of special plasticizer additives); erosion, which manifests itself at a speed of water flow through pipes of more than 4 m / s or at large temperature differences.
In turn, the chemical destruction of coatings can be caused by the following reasons: the aggressiveness of C0 2, the impact strong acids high concentrations of ammonia, sulfates, strong alkalis, as well as biological corrosion with the formation of hydrogen sulfide H2S. drainage - both mechanical and chemical, which largely determines the feasibility of using protective cement-sand coatings in drainage networks transporting wastewater aggressive to the coatings.
It should be noted that the application of the method of repairing pipelines with the application of cement-sand coatings is not always possible or ineffective with a branched network, including pipelines of different diameters. In these cases, when applying cement-sand coatings, blockage of branches (bridges) with smaller flow sections can occur.
On the other hand, if there is an alternative to using two methods of renovating the network - laying a new pipeline from the central heating station or repairing the old one with applying the central heating station on site, then the latter is more often preferred. The fact is that it is very difficult to avoid damage (during transportation or laying) of new pipelines with pre-applied CPP (i.e., in the factory). Pipelines coated with CPP can be loaded with a bend radius of at least 500 times the pipe diameter (German DIN 2614).
V recent times An alternative to the application of cement-sand coatings on the inner surface of pipelines is the spraying of rapidly hardening in air special compounds resistant to aggressive substances, for example, according to the Triton method developed by the CUES company (USA). Unlike cementing, in which a sufficiently thick layer of the protective shell is applied and it cannot be ruled out that it will slip under the influence of gravity, the Triton cladding, which includes more than 20 various substances, has a thickness of 1 mm and hardens in 30 minutes, while the cement-sand coating hardens in 24 hours.
Spray methods of restoration of drainage pipelines have another advantage. It manifested itself only in last years when solving issues of combining the renewal of drainage collectors with the laying of fiber-optic cables in them. Any type of cured in place lining facilitates reliable fastening of special modules with cables for various purposes in the upper part of the inner surface of the pipeline. Thus, a double effect is achieved: an economical trenchless repair of the pipeline network is carried out and the commercialization of the empty space in the upper part of the pipelines.
Dragging a new pipeline into a damaged old one (with its destruction and without destruction). The main advantage of this method is the ability to restore badly damaged pipelines by laying a new one, for example, low pressure polyethylene (HDPE), in place of the old one. Pulling a new pipeline into an old one is most promising in cases where a complete replacement of a dilapidated pipeline with an increase in the diameter of the network is required.
In domestic and foreign practice, the method of destruction of old pipes along the route between two wells is widely used, with individual tubular modules being pulled into the vacated space (Fig. 1.26).
After the destruction of old pipelines, their place can be taken by new ones from various materials, as a rule, of a slightly larger diameter than the failed ones. The trenchless method of replacing pipes by breaking and pulling new ones has some advantages over others: an increase in the pipe diameter leads to an increase in its throughput; When implementing the method, a pipeline made of polymeric materials can be used, which does not have butt joints and can withstand heavy loads with a service life of 50-100 years. In addition, the method can be used in unstable soils with minimal development during the reconstruction period.
Destruction of an old pipeline and pulling a new one out of individual modules using a pneumatic impact machine
1 - pneumatic winch; 2 - compressor; 3 - sections (modules) of the new pipeline; 4 - working well; 5 - air outlet hose; 6 - pneumatic impact machine; 7 - new pipeline; 8 - expander; 9 - replaceable pipeline; 10 - anchor; 11 - receiving well; 12 - winch cable
Pulling a new pipeline with parallel destruction of the old one can be carried out using pneumatic impact machines or pneumatic punches equipped with destructive sleeves with appropriate knives (Fig. Below). The energy required to move the device along the route of the old pipeline is supplied from the compressor. The cracking knife destroys the old pipe and compacts the debris into the surrounding natural soil. The expander creates an enlarged profile for the new pipe, which is pulled into the vacant space simultaneously with the destruction process.
A set of a pneumatic punch of the company "GRUNDOKRACK" with a destructive sleeve and an expander
1 - winch cable; 2 - guide rod; 3 - destructive sleeve-knife; 4 - expander; 5 - terminals; 6 - high pressure hose
In recent years, a number of facilities in Russia have used the technology of replacing dilapidated non-metallic pipelines after their destruction with polyethylene pipelines with the help of rolling machines. This technology provides for the use of a special working body - a power-driven unroller. The unroller is installed in a working pit by a crane or manually. After ensuring the alignment of the rolling machine and the pipeline to be destroyed, the rolling machine is screwed into the pipeline and the fragments of the destroyed pipe are pressed into the walls of the well being formed. In this case, the soil is displaced in the radial direction and a compacted soil zone is formed around the well. Practice shows that the surface layer of soil 10-15 mm thick in the borehole walls is so compressed that its strength is comparable to that of a concrete pipe of the same thickness. After the working body exits into the receiving pit and is disconnected, a polyethylene pipe (solid or in separate sections) is connected to the end of the drive rods, which is pulled into the formed well by the return stroke of the rods.
It should be noted that the main disadvantage of these two methods of pulling through pipelines with the help of pneumatic punchers and roll-out tools is that shock waves, which can damage communications located in the immediate vicinity of the restored pipeline, or disrupt the vault around them, which subsequently leads to various defects, up to the destruction of intersecting communications. To exclude these phenomena, the geological conditions of the area must be studied in detail and preliminary drilling must be carried out, confirming or refuting the presence of neighboring communications at a safe distance.
Currently, methods of destruction of old pipes made of asbestos-cement, cast iron, ceramics and plastic are widely used in a number of countries. At some domestic and foreign objects of renovation for destruction steel pipes The wire used a shattering tip that acts like a can opener and cut the pipeline in half. The average speed of movement of the installation with a destructive tip is about 80 m / h. A slight decrease in speed is observed only when the tip passes through the threaded pipe connections.
Trenchless replacement of old pipelines with new ones can be carried out without destroying them; a diagram of pulling through a new polymer pipeline into the old one is shown in the figure below. V in this case a new polymer pipeline is used, unwound from a reel (coil, drum) and pulled with a pneumatic winch and a cable through a case and a well into a dilapidated section of the water supply network. Given the predisposition of polyethylene pipes to cuts by accidental solid inclusions in the channel during pulling, to minimize the possibility of damage to the outer surface of the pipeline, special short plastic segments and slats can be used, which are put on the pulled pipeline at regular intervals.
To prevent cuts on the outer surface of polyethylene pipes, following ways: factory applied thickened outer shell so that possible damage affects only her; the use of polyethylene pipes with a mechanical damage-resistant outer polypropylene sheath.
In some cities of Russia, when restoring the drainage network without destruction and with destruction, short pipe polymer modules are widely used. At the same time, special attention when using them for trenchless restoration is paid to the designs of the connecting nodes. For example, the connection of pipes made of polyvinyl chloride (PVC) is performed on sockets with sealing with rubber rings, as well as gluing. Adhesive joints have a long technological pause (the time between the end of the process and the admissibility of the application of assembly loads to ensure the appropriate strength): from 0.5 hour (with artificial heating of the adhesive joint) to a day (when the adhesive joint is formed under natural conditions, without heating).
Restoration of a section of a dilapidated water supply network without destruction using polymer pipes
Plastic segments and slats of the company "Metafrax" for the protection of pipelines during pulling
The main method for joining polyolefin pipes is butt-butt welding. To obtain a high-quality connection, a long technological pause is also required (20 minutes). In fig. below shows a machine for welding pipes with a diameter of 900 mm in a string in the field.
Socket connections with rubber O-rings do not require a process pause. However, a significant drawback of such connections is their external dimensions. When pulling a new pipeline into the cavity formed by the destruction of the walls of the pipeline being replaced, powerful equipment (for example, pneumatic impact machines) is required, since a larger expander is used in size and power. In addition, the presence of flared protrusions on the surface of a new pipeline, commensurate with fragments of destroyed pipes (for example, sharp ceramic), can facilitate their capture and uncontrolled dragging along the surface of plastic pipes, which will cause the appearance of cuts on the surface of the pipe. Such defects for free-flow pipelines are not as dangerous as for pressure ones. Nevertheless, when deep longitudinal cuts are located near the shells of plastic pipes, they may ovalize under the action of soil and transport loads, which, in turn, can lead to premature failure of the pipeline.
Fragment of preparation of polymer pipes for welding
For trenchless assembly of pipes made of polymer materials, locking and threaded connections are used. They, as well as bell-shaped ones, do not require a technological pause. Threaded connections can be different both in cross-section (triangular, rectangular, trapezoidal, rounded), and in the dimensional characteristics of the constituent elements of the thread and the connection as a whole (height, length and pitch, number of turns, presence of runaway and lead-in part and its place location).
The main advantage of the described recovery methods by pulling in pipes is their rather high productivity with relative simplicity of operations. However, the disadvantage of the method of pulling through without destroying the dilapidated pipeline is the reduction of its inner diameter after repair.
It should be noted that when choosing a method of pulling and fixing polymer shells or pipes in a previously destructible pipeline for trenchless renovation of networks, it becomes necessary to thoroughly diagnose the state and structure of the soil around the repair section of the network.
Pulling deformed polymer pipes and protective shells inside the pipeline being repaired. When applied to the inner surface of the pipeline, shells in the form of deformed (profiled, flattened) polymer pipes ensure not only the tightness of the walls, but also their high resistance to dynamic loads. The introduction into the pipeline and the fixing of the containment in it can be achieved in two ways.
The first method is to pull through a seamless polymer material, for example, a plastic profiled pipe, the cross-section of which has a U-shape, along the entire length of the repair section between two wells, followed by pressing it against the inner wall by supplying a coolant under pressure (for example, steam, hot water ), including for making coated round shape... This technology was developed by Preussag and named Slip Lining. With the help of this technology and its modifications, over 800 km of pipelines have been restored in different countries the world. The advantage of the technology is that during the renovation, thin polyethylene pipes are used, which make it possible to restore the networks practically without reducing the free cross-section of the pipelines.
Fragment of introducing a profiled pipe into the well (a) and its location in the pipeline (b)
The second method is the introduction into the old pipeline of a previously compressed (deformed) over the entire section (deformed) new polymer pipeline, which has a "thermal memory" of assuming the required shape over time (Swage Lining technology). Repairs are performed by welding sections of polyethylene pipes to each other and pulling them through a punch or a special narrowing die with a smaller diameter than the diameter of the polymer pipe (Fig. Above). After that, the lash is introduced into the old pipe using a cable and a winch installed in the well next to the pipe.
Over time, the compressed pipe straightens to its natural state and adjoins the inner surface of the restored pipeline (Fig. Below). The polymer pipe expands until its outer diameter reaches the size of the inner diameter of the old pipeline and forms a tight connection with its wall. This eliminates the need to use cement mortar or special hardeners.
Pulling through continuous protective coatings made of various polymeric materials. Protective internal coatings (shells, membranes, sleeves) can be applied to the sanitized pipelines of water supply and sewerage systems, which ensure the complete tightness of the walls, as well as their high resistance dynamic loads.
Passing a polymer pipe through a matrix to temporarily reduce the diameter
New polyethylene pipe after taking its original shape in the old pipeline
The introduction of the shell into the pipeline and fixing it in it can be achieved either by pulling the seamless coating over the entire length of the repair section between two wells, followed by pressing it with a special load in the form of a balloon and supplying hot air or water vapor under pressure, or by gradually introducing it into the repair section a shell in the form of a stocking (liner) twisted into a roll by pressing it against the wall with a liquid supplied under pressure. The shell is introduced into the pipeline through the open hatch of the well.
Internal protective coating of flexible plastics
1 - the restored section of the pipeline; 2 - protective coating; 3 - guide roller;
4 - winch; 5 - cable; b - container with hot air (steam); 7 - special cargo
Application of an internal protective coating according to the "Entrepose" technology
1 - pipeline to be restored; 2 - a protective covering in the form of an outward-turning stocking; 3 - guide rollers
As a result of the polymerization process, a solid protective shell solidifies, after which all devices and liquid are removed from the pipeline. Communications can be put into operation a few days after the described operations. This method is widely used by a number of Western European companies, in particular: Sosa, Entrepose T. R., Le Joint Jnterne, etc.
Special attention from a technical point of view deserves the technology of applying continuous polymer sleeves "Phoenix", which is one of the effective ways restoration of the inner surface of worn out pipelines of water and gas supply systems.
The use of flexible elements made of sheet material with a toothed fastening structure. This method of restoring drainage networks is based on the use of polymer cladding. from elements of longitudinal section, forming, when connected to each other, an internal protective shell pipeline. The method was developed by the German company "Trolining". The technology of applying a protective coating consists in pulling flexible and high-strength polyethylene blanks from the well through the defective section of the pipeline, which are connected inside the pipeline by means of extrusion welding. For tight fixation of the lining to the inner surface of the pipeline, a cementing material is injected into the annular cavity between the pipe wall and the lining, and water is injected into the pipeline, which straightens the lining and presses it against the walls.
Installation of sheet polymer gear sections using the "Trolining" technology
a - basic installation system (with one toothed section and filling the voids between the inner surface of the pipe and the toothed elements);b - the same with the use of an intermediate protective layer; c - the same with the use of an additional elastic element around the toothed section; d — installation system with two toothed sections;1 - damaged pipe; 2 - Trolining injector; 3 - toothed section; 4 - protective layer; 5 - elastic element
The system of internal flexible segments "Trolining" allows the use of Various types sections that differ from each other in the structure of the surface (single-layer, multi-layer and combined with protective layers).
Use of a flexible combined sleeve (stocking). The essence of this restoration method consists in the formation of a new composite thin-walled pipe inside the repair section of the pipeline, which has a sufficiently independent bearing capacity with a minimum reduction in the diameter of the existing pipeline.
To implement the method, a combined sleeve is passed through the inspection wells inside the dilapidated pipeline, which is a reinforcing material impregnated with a thermosetting binder (fiberglass, synthetic felt). Then, a coolant (steam, hot water), which straightens the sleeve, presses it against the inner surface of the pipeline and polymerizes the binder, forming a new composite pipe.
The inversion and advancement of the combined sleeve in the pipe-conduit can be carried out using a flexible element (cable), a liquid or gaseous medium supplied under pressure, as well as the combined use of both methods.
The main advantages of the combined sleeve pulling method are the simplicity and availability of technology and equipment for its implementation, high quality and durability of the protective coating, the possibility of repairing sufficiently worn-out pipelines (regardless of the material of manufacture) in a wide range of their diameters and lengths. With the plastic combination sleeve, round, oval and special pipe profiles can be restored.
The use of roll winding (endless profile tape) on the inner surface of the old pipeline. For the renovation of gravity drainage pipelines, the "Ribloc" and "Expanda-Pipe" methods can be used. They allow you to cover the inner surface of pipelines with PVC tape. For this, a special machine is installed in the well, which performs several functions: application (winding) of an endless tape along the inner diameter of the pipeline, its fastening; pouring adhesive resin; pushing the formed PVC frame into the pipeline repair section, expanding the frame to fix it on the restored structure. After the winding process, the remaining free annular space between the rehabilitated pipe and the new frame is filled special solution and compacted with a rammer to increase static strength.
A fragment of the application of a tape protective coating using the "Ribloc" technology from a well
According to the Panel Lok technology, developed by Camit Ltd (Australia), a special profiled PVC tape is used for winding, which has T-shaped corrugations on the outside. The corrugations increase the structural surface and provide mechanical adhesion to the cement slurry injected between the lining and the wall of the pipeline being repaired. The profiled tape can be used for round, oval and rectangular sections pipelines with a diameter of 900 mm or more, with sufficient bearing capacity.
When using some modifications of the roll-to-roll method, the functioning of the pipeline may not stop.
Spot (local) protective coatings. This type of coatings is typical for the elimination of single (point) through, including peripheral, cracks caused by soil movement (for example, when carrying out excavation near the routes, impacting pipelines with excessive loads from traffic, earthquakes, etc.) , as well as local corrosion of pipeline walls. Spot repair coatings can also be used as sealed connections for individual pipes in the implementation different ways trenchless restoration of networks.
Local damage caused by chemical erosion of pipeline walls can develop very quickly and lead to premature pipeline failure. Statistics show that this kind of damage is about 10% of the length of the pipeline.
Coatings for local repair can be supplied in the form of: liquid solutions, hardening after application operations on damaged surfaces; solutions of a semi-liquid consistency; fibrous materials impregnated with resins (polyester, epoxy and polyurethane); profile rubber seals; sleeves from of stainless steel; elastic sleeve blanks; tubular liners, etc.
Before implementing any of the above methods of repairing existing networks and water supply or drainage facilities, it is necessary to lay temporary external bypass pipelines. For example, in cases of restoration of water supply networks, bypass pipelines must ensure the supply of household and drinking water to the consumer for the period of repair in the required quantity and of the appropriate quality. In addition, bypass pipelines must meet certain requirements set forth in the technical conditions for the production of repair work, they must be quickly assembled and dismantled and ensure the appropriate sanitary and hygienic indicators of the transported water. Because these pipelines are routed externally along sidewalk boulders, they must be able to withstand the impact of vehicle tires and also be designed to withstand the full hydrodynamic pressure of the water. At the same time, it is very important to adapt the bypass pipelines to standard fittings, control and regulation and shut-off valves.
Table 1.2 presents data on the most common methods of trenchless restoration of water supply and drainage pipelines with detailed technical, technological and operational indicators. Analysis different methods trenchless restoration of pressure and free-flow networks indicates that there is no universal approach to the repair or replacement of pipelines. Each of the proposed methods is limited by the corresponding framework of application, which must satisfy the existing technical conditions at various facilities, as well as the material and other capabilities of the organizations operating the networks.
It should be noted that with many positive aspects of modern technologies for trenchless restoration of pipelines, one should not allow the "euphoria of sanitation", which may be the result of subjective and not fully justified decisions, unreasonable criteria or the dictates of the fashion for trenchless technologies. Absolute priority to the use of trenchless repair technologies can be given only in cases where the engineering communications requiring repair are located below other urban underground structures and their excavation is associated with significant difficulties. For example, in Hong Kong, some sewers are laid below subway lines. This circumstance clearly gives preference to trenchless methods in case of need for repair or replacement of networks.
Usage: replacement and repair of underground pipelines. The essence of the invention: when trenchless replacement of a pipeline with a repair coupling, the old pipeline is removed from the assembly well with an impact mechanism with its destruction and the formation of a well with a diameter exceeding the outer diameter of the old pipeline. Eliminate the latter in parts until the repair coupling from two opposite assembly wells. Elimination of the remaining part of the old pipeline and knocking out the coupling into a free well is combined with the retraction of the new pipeline. 3 ill.
The invention relates to the construction industry and can be used for trenchless replacement of old underground pipelines, for the repair and reconstruction of underground utilities. There is a known method of trenchless replacement of underground utilities (RF patent N 2003911 C1), which consists in breaking the pipeline being replaced, pressing its fragments into the soil mass with the formation of a well and pulling a new pipeline into it using a pneumatic impact mechanism. Disadvantage this method replacement is the need to carry out additional ground work in the event that a repair metal sleeve is located on the outer surface of the old pipeline, which requires large energy efforts to remove it. The pneumatic hammer mechanism is not always able to cut it. Also in the method of replacing an underground pipeline (RF patent N 2003909), which includes cutting longitudinal grooves on an old pipeline and applying concentrated destructive forces to its walls using cutting edges located on the body of a pneumatic impact tool, in the presence of a repair metal sleeve on the old pipeline, jamming of the tool due to the all-metal cast structure of the coupling. In practice, in these cases, the soil is excavated at the location of the coupling, it is removed, and then the replacement work continues. This leads to large time losses and costs. physical labor. The closest in technical essence is the method of trenchless replacement of an underground pipeline (RF patent N 2003918), which consists in eliminating the old pipeline being replaced under the impact of the shock load and ramming its fragments into the ground, followed by retraction of the new pipeline. The disadvantage of this replacement method is that if the impact mechanism meets the repair metal coupling and a significant shock load is applied, a forced stop of the impact mechanism may occur when it comes into contact with the metal repair coupling, which will lead to the need for open ground work and slow down the replacement process. The technical problem solved by this invention is to accelerate the method of replacing the pipeline. The proposed method of replacement, including the elimination of the old pipeline and the retraction of the new pipeline from the installation wells, is that the removal of the old pipeline is carried out to the repair coupling from each of the wells, and then the coupling is knocked out into one of the installation wells. It is advisable, when removing the old pipeline from the side of the well, into which the coupling is knocked out, to form a well with a diameter larger than the diameter of the coupling. Replacing the pipeline in this way significantly speeds up the time of replacement work, since it eliminates the need to break a section of the route at the location of the coupling and remove it using physical labor. FIG. 1 shows a longitudinal section of a replacement pipeline with one of possible options devices for implementing the proposed method. The essence of the proposed method is shown on the example of a specific use. A device that implements this method is placed inside the old replaceable pipeline 1 from the installation well 2, consists of an impact mechanism 3, for example, a pneumatic punch. In the head part of the percussion mechanism 3, there is an expander 4 with a tapered section, the diameter of which is greater than the inner diameter of the old pipeline 1 and greater than the outer diameter of the newly laid pipeline 5. At the front of the body of the percussion mechanism 3, a cable 6 is fixed, passing inside the old pipeline 1 and connected to the traction mechanism 7 (for example, a winch) located in the opposite well 8. On the outer surface of the old pipeline 1 there is a repair sleeve 9. To implement this method, the device is placed in the assembly well, which is closest to the repair sleeve 9 located on the pipeline 1. Implemented way as follows. Under the action of the shock impulses of the mechanism (pneumatic punch) 3 and the efforts of the traction mechanism (winch) 7, transmitted by the traction cable 6, the device moves along the old pipeline 1 to the repair sleeve 9, breaking the old pipeline 1 with the expander 4, pressing its fragments into the ground. After driving this section of the route, the device and the traction mechanism 7 are dismantled and the driving is carried out in the same way with a new pipeline attached to it from the assembly well 8 to the repair coupling 9 (Fig. 2). After contact with the clutch, the penetration is continued until the repair clutch 9 is pushed into the well 2 and the old pipeline is completely replaced throughout the entire section (Fig. 3). Driving of this section is easy, since the diameter of the sleeve is less than the diameter of the well from the side of the first well. Then, due to the fact that the well has a larger diameter in comparison with the diameter of the old pipeline 1 and coupling 9, the latter is easily knocked out into the installation well 2.
Construction of pipelines using trenchless methods
The main advantage of the construction of canals underground, by using HDD equipment, is that it is possible to carry out laying even in extreme, inaccessible places and conditions, in particular, under railway rails and large suburban transport routes, tram lines, reservoirs - lakes and rivers, as well as ravines. It is possible to carry out work in the conditions of specific soil and dense buildings in the city center. When using the HDD method, many experts note that the durability and reliability of pipelines increases several times, which is explained by several things - first of all, the integrity of the pipe is not violated during the work, due to which premature leaks and disconnection of joints do not occur. Pipes are laid deep underground, in the soil mass, which also contributes to their long-term operation due to protection from negative impact environment.
Regardless of what is required - to make a puncture under the highway or to clean the pipes from accumulated deposits, to rehabilitate the pipes, berstlining or relining, it is recommended to use modern equipment, with the help of which the work is carried out quickly and easily. During its entire service life, any pipeline, even the most reliable one, may need to be repaired or even replaced.
By using closed line-laying and drilling technologies, workers can perform even the most complex work, bypassing various obstacles on the way of laying the pipeline route. It also becomes possible to create almost any trajectory when drilling a hole in the ground.
If necessary, choose the method of laying pipes side by side, in parallel, which is also carried out by the HDD method. The use of modern technologies when laying communications - gas pipelines, water pipelines or oil pipelines, in particular, the HDD method, it becomes possible to save as much as possible cash and reduce the time of work. Also, the likelihood of accidents, both at the construction site and during the operation of the pipeline, is reduced several times.
When using the installation for HDD, the customer can reduce the amount of costs up to six times, while the productivity of the work does not decrease, but, on the contrary, greatly increases. It should be noted that when carrying out work using HDD installations, pollution can be prevented natural environment and the emission of gases into the atmosphere, leave intact forests, parks and various private plantings - trees and shrubs, flower beds in the city. Most importantly, there is no pollution of communications. The customer has the opportunity to get a quick result without wasting time on the restoration of asphalt, roads, urban infrastructure.
Sitting at the HDD unit, the operator monitors the movement of the drill head and receives an electromagnetic signal, which is emitted by a special sensitive transmitter built into the drill head. This signal passes through the layers of the earth and is received by the locating system. The locating system allows not only to locate the drill head, but also to calculate the incline and drilling depth used, which makes it possible to make corrections in time. It is also possible to use the indications of the locating system with parallel laying of pipelines. In this case, the direction of the drill head can be controlled by a computer equipped with a laser guidance system. The soil developed in the course of work is immediately removed from the ground due to the work of the auger mechanism.
There are many benefits from the use of modern equipment and, in particular, HDD installations. With their help, you can go through and bypass all known obstacles, without making an exit to the outside. The HDD method can be used to carry out work in areas with dense residential development, a major highway, railways and water barriers.
To lay communication pipelines for any purpose, you can use one of the currently known methods - trench or trenchless laying of pipelines. The method of trenching is traditional and is characterized by the need to open the ground and carry out earthworks, in particular, at the initial and the last stage... Despite the many positive aspects, the number of disadvantages of this method is off the charts. First of all, the disadvantage is that in the process of work, the entire ground structure is destroyed - fertile soil with green spaces, roads and railways, all flower beds and trees are completely destroyed. Due to the need to carry out restoration work. The price for such work, in particular, for the open laying of highways and collectors, increases significantly.
To avoid all negative consequences Today, the technology of a closed, underground installation of networks is used, due to which it became possible to lay pipes, not only without disturbing the coating of roads and sidewalks, but also preserving the integrity of the foundations of residential and industrial buildings. It is also possible to carry out work under water bodies, highways and other objects of urban infrastructure.
An excellent opportunity is that, using the method of closed laying of communications, it is possible to carry out work underground on large territory without resorting to soil opening. The necessary equipment is pushed underground, without harm to the road surface and other channels at different depths. Many customers today prefer a closed type of construction, mostly due to the fact that the use of this method allows you to save money. HDD work can be carried out in any season, in winter or summer. But care must be taken to ensure that the safety of workers on the construction site is properly ensured.
At the first stage of work, the preparation of the starting pit and the receiving pit is carried out. Punching a pipe underground begins with one pit, through which the pipe is fed into the ground and then pushed.
Today, there are several widely used technologies that allow you to quickly build pipes underground, make a puncture or push a pipe into the ground. Drilling is also often used. Especially one can single out such a method as restoration or rehabilitation of networks, which has a different name - relining.
Rehabilitation is carried out in the event that a leak or other malfunction is detected that must be urgently eliminated, but the pipes are so outdated that they need to be updated, and simple repair is impossible. Remediation is carried out through a previously laid pipeline, most often for the repair of individual damaged areas. However, this method can also be used to completely replace the pipeline, without removing the old one. Using the relining method, it is possible to replace the pipeline, destroying or leaving the old pipe in its previous state. You can resort to increasing the diameter of the new pipeline.
Exists latest technology, pipe puncture, which is used mainly on loamy and clay soils, as well as in cases where it is necessary to replace the pipe in a small area, avoiding obstacles, for example, under a highway or a railway. To carry out a puncture, powerful, hydraulic equipment is used - winches and jacks, without which it is impossible to lay a new pipe and destroy the old one. The puncture method is suitable for replacing medium-diameter pipes in a small area.
It is also possible to carry out work on pushing the soil and laying pipelines. Use a water power jack. In this case, it is possible to replace large canals in an area of about one hundred meters.
Directional, underground drilling piping is the most popular method for a variety of reasons. With the help of HDD installations, horizontal drilling of soil is carried out for subsequent laying of pipelines in the formed trench.
The essence of the method lies in the use of modern powerful equipment, drilling rigs, thanks to which not only high accuracy of laying is achieved, but also high speed of work, as well as an affordable democratic price.
The laying of pipelines using the HDD method takes place in several stages: first of all, the site is prepared, and the well is drilled, then it is expanded and the pipes are pulled. In this case, the length of the pipeline broach using the HDD method can reach up to several kilometers. Large diameter pipes are allowed.
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Trenchless laying of pipelines is used when crossing various natural or artificial obstacles. Depending on the category of soil and the diameter of the pipes being laid, the methods of trenchless laying are divided into: puncture- for pipes of small diameters in clay and loamy soils, a variety are vibro-puncture and hydro-puncture; pushing; pneumatic punch, horizontal drilling(vibration vacuum method), shield and adit- for underground tunnels and collectors.
Way puncture used for laying in cohesive soils in the absence of stones and gravel in them. For puncture, pressurized pumping and jacking units are used, consisting of one or two coupled hydraulic jacks mounted on a common frame.
The pipes are pressed in during the puncture process cyclically by alternately switching the jacks to forward and reverse. The indentation occurs at a stroke length of 1.3 m. The stem is returned to its original position, and another pipe of double length is inserted (Fig. 2.10). During hydro-piercing, a water jet, escaping under pressure from a special conical nozzle in front of the pipe, washes away the soil and forms holes in it with a diameter of up to 500 mm. Vibration puncture is based on the use of additional vibration longitudinally directed influences in the process of puncturing a pipe with a diameter of up to 500 mm.
Rice. 2.10.
- 1 - persistent reinforced concrete wall; 2- hydraulic jack;
- 3- push-in branch pipe 1 m long; 4 - the same, 3 m long; 5- steel pipe to be laid; 6- steel tapered tip;
- 7 - pit; 8- guide frame; 9- push frame; 10- welded support pad; 11 - picking up from boards; 12- fastening I-piles; 13 - hydraulic jack pump
When punching the pipe to be laid with an open end equipped with a knife, it is cut into the soil mass, and the soil entering the pipe in the form of a dense core (plug) is developed and removed from the face. The soil is removed manually with a shovel with a shortened handle or mechanized - with a shovel or a cart installed inside the pipe, moved with the help of winches. When the pipe moves, the frictional forces of the soil along its outer contour and the cutting of the knife part into the soil are overcome. For punching pipes, pressure pumping and jacking units of two, four, eight or more hydraulic jacks are used. For jacks, strong thrust walls are arranged in the pit.
When laying steel pipes using pneumatic punches, a tapered tip is attached to the front end of the pipe, while there are two options for performing work: driving the pipe into the ground and driving the pipe into the leading well.
Shield laying of pipes, used in the construction of collectors and tunnels, provides for the development of soil under the cover of the shield and the fastening of the tunnel with prefabricated cast-iron and reinforced concrete tubing, in-situ concrete or ceramic blocks -
mi (Fig.2.11). Shield penetration is carried out using a shield consisting of three parts: front - cutting wedge-shaped; middle - support, where the jacks are located, and rear - tail. The shield is pressed into the ground with jacks, and the ground is worked out manually or mechanically. For shield tunneling, mechanized, partially mechanized and non-mechanized tunneling shields are used. The work is carried out in three stages: the device of the initial (assembly) shaft for lowering the shield with a crane into the face; moving the shield with jacks, including the development of the soil, the advance of the shield, the installation of a block or the construction of a monolithic lining; device tray, if the tunnel is used as a gravity collector.
a"" i 9 s and
Rice. 2.11. Construction of a transport tunnel by a shield method (dimensions in m): a - diagram of a mechanized shield with a flat washer; b - General view of the head of the shield with a plan-washer; c - general diagram of the shield tunneling method; 1 - shield body; 2- washer plan; 3- thrust rollers; 4 - drive unit; 5- movable bed; 6- dump bridge; 7- fixed bed; 8- feed jack; 9 - conveyor; 10- incisal windows; 11 - shield body; 12- block layers; 13- conveyor; 14 - lining the walls of the tunnel; 15 - trolleys; 16 - electric locomotive; 17 - attachment of the mine blade; 18 - metal frame
Horizontal drilling is performed in sandy and clayey soils. Laying is carried out using an eccentric drilling unit with cyclic soil removal with a bucket, drilling is performed with a milling head, and soil removal is performed with a screw conveyor (Fig. 2.12).
The vibro-vacuum method for laying pipes with a diameter of 200-500 mm in horizontal wells is as follows: a pipe consisting of a glass, a vibrator and a rod is pressed against the wall of a pre-dug trench with an open end using a winch. Then air is pumped out of the ground, the vibrator is turned on, and under the influence of the difference atmospheric pressure and vibration, the pipe cuts into the ground. After that, it is removed, the soil is removed and the bar is lengthened for a second operation.
The laying of the working pipeline in the case is carried out at the section of the underpass. For this, steel pipes with a wall thickness of 25% greater than the wall thickness of the main pipeline are used. Laying is carried out by pushing for pipes with a diameter of up to 1020 mm and pulling through for pipes with a diameter of more than 1020 mm. Before pushing along the bottom of the pit, a path is made of sleepers, corners and rails, along which the pipeline is pushed. A pull-off block is attached to the end of the case, a traction rope with a hook is passed. The hook is put behind the wall of the working pipeline, and the other end of the rope is hooked onto the crane hook. When pulling through, a track is also arranged, the traction cable is attached to the tip or bracket, welded to the front end of the pipeline.
Rice. 2.12.1 - cutting head; 2- scoop; 3 - block holder; 4 - support wall; 5 - guide frame; 6- capture; 7- unloading and traction device; 8- capacity;
9 - unloading check valve
The end of the cable is pulled through the pulling block, fixed in the excavation from the side of the traction mechanisms, and the pipeline is pulled through.
PAGE 4
TOPIC No. 4. CONSTRUCTION OF UNDERGROUND ENGINEERING NETWORKS
BY EXTREME WAYS
- Arrangement of pipelines by means of soil puncture.
- Arrangement of pipelines by means of punching.
- Arrangement of pipelines by the method of horizontal drilling.
- Construction of tunnels with shield boring.
- Promising methods of laying underground engineering networks.
1 DEVICE OF PIPELINES BY PUNCHING SOIL
On streets and squares with heavy urban traffic, at the intersection of tram lines, automobile and railways, as well as in undeveloped areas of the city at great depths(more than 5 m), closed (trenchless) pipelines should be used.
Currently, four methods of trenchless laying of underground networks are used. Depending on the method of work, they are distinguished: sinking by shields, punching, puncture, horizontal drilling.
Geological and geodetic surveys, as well as the development of design estimates and careful horizontal and vertical breakdown on site in accordance with the approved project, precede the work on the trenchless method of laying underground networks.
A puncture is a method of penetration in which a hole for a pipe is formed due to radial compaction of the soil, without its development.
The puncture method can be used to lay pipes with a diameter of up to 500 mm in soils with compressibility (clay, loam). The penetration length is 30-40 m, and for pipes of small diameters (150-200 mm), taking into account the longitudinal bending of the pipes, it is 20-25 m. The penetration rate when using powerful hydraulic jacks is 2-3 m / h.
Piercing can be performed using jacks, winches, tractors, levers and other mechanisms capable of developing forces from 25 to 300 tf.
The force is imparted to the pipe to be laid by pushing nozzles through the rear end. Pressure nipples are pipe sections with a length equal to the stroke of the jack rod. Flanges are welded to their ends using gussets. The jack, through the pressure connection and the lining, presses directly into the end of the pipe. After pressing the pipe into the ground for the length of the jack rod stroke (for example, 1 m), the rod returns to its original position and another double-length pipe is inserted into the resulting space. Thus, using a combination of 1 and 2 m long pressure sleeves, the first pipe link is pressed in. Then the second pipe link is laid and welded to the previous one. Then the processes are repeated until the penetration is brought to the design length.
To install piercing mechanisms on the route, a pit 1.2-2.5 m wide is being developed. The length of the pit is assigned such that the link of the pipes being laid, the support pad, the jack and the stop can freely fit. A free space of 0.8-1 m is also envisaged, thus, the total length of the pit is about 10 m (with a link length of 6 m). The depth of the pit is determined depending on the location of the pipeline.
A stop is installed to the back wall of the pit. With low piercing forces, the stop can be made of wood. With great effort, it is advisable to put a metal inventory stop.
To reduce the resistance of the pipe (frictional forces) when puncturing the soil, a conical tip is used, the base diameter of which is 25-35 mm larger than the outer diameter of the pipe. An increase in the base of the tapered tip reduces the frictional force of the lateral surface of the pipes against the ground.
2 DEVICE OF PIPELINES BY PUSHING METHOD
Punching is a method of trenchless laying of engineering networks in which individual pipe links are successively pressed into the ground, which are connected to each other in the process of welding, with the development of the bottom hole inside the pipe and soil removal through the pipe being laid. This method can be used to push pipes with a diameter of 200 to 3600 mm and more.
Most widespread For pushing pipes, currently received installations with hydraulic jacks with a long stroke and a high speed of indentation. The transfer of pressure to the pipe is carried out by means of pressure pipes with a length equal to the stroke of the jack rod or double the length of the rod.
Punching is possible with manual excavation and mechanized methods.
In manual excavation of the soil (for pipes with a diameter of more than 800 mm), workers are inside the pipe and shovels with short cuttings load the soil into a trolley, which is pulled from the pipe being laid by a cable and rises to the surface. For pipes with a diameter of up to 700 mm, the excavation is carried out from the working pit with bailers, the handles of which are increased as the length of the penetration increases.
With the mechanized method, it is possible to use an installation with a cylindrical excavation of the soil by a shuttle. It is used for steel pipes (cases) with a diameter of 529 to 1420 mm.
3 DEVICE OF PIPELINES BY THE METHOD OF HORIZONTAL DRILLING
The horizontal drilling method is used for trenchless laying of pipes with diameters from 325 to 1220 mm for a length of 40-60 m, it is used for the development of hard soils.
Horizontal drilling rigs of the UGB type can be used. At the same time, a link of the pipe to be laid with a cutting head and augers is placed in the working pit on the roller supports. A machine is attached to the auger shaft, which, during installation and operation, is suspended on the hook of the pipelayer. In the working pit at the beginning of the well, a thrust bar with pulley blocks is reinforced. The forward movement of the pipe is carried out by a winch, which winds the chain hoist cable. During operation, when the pipe moves forward, the pipelayer moves in the same direction to support the machine. Cutters are installed on the cutting head. The cutting head is equipped with folding blades, which allow increasing the borehole diameter by 30-40 mm more than the diameter of the pipe being laid. Remove the screws and the head through the pipe when folding the blades and rotating the head in the opposite direction.
4 CONSTRUCTION OF TUNNELS WITH A PANEL PASSAGE
Shield is such an underground tunneling, in which the excavation of the soil and the construction of the walls of the tunnel are carried out under the protection of the cylindrical shell of the shield.
Driving with a shield is carried out in this sequence. The shield inserted into the face is pressed into the ground in the horizontal direction (along the axis of penetration) with the help of jacks.
When pressed, the soil enters its cutting part, which has the shape of a cylindrical wedge. The soil pressed into the inside of the shield is worked out manually or mechanically and loaded onto carts that roll back along the tunnel. In the front part, the shield has a visor protruding forward, which serves to prevent soil from falling into the shield (in case of weak soils). After the soil pressed into the shield has been fully developed and removed, the shield moves forward again.
The forward advancement of the shield with the introduction of its cutting part into the ground is carried out using hydraulic jacks located along the perimeter of the shield. The block lining of the tunnel serves as an emphasis for the jacks. After moving the shield forward and sampling the soil in the tail part of the shield, lining blocks are laid along its perimeter under the protection of the tail shell of the shield.
For the lining of tunnels, blocks are used: ceramic, concrete and reinforced concrete.
The soil can be worked manually using picks, crowbars and bayonet shovels, as well as mechanically. The developed soil is loaded into trolleys and removed from the tunnel.
Panel penetrations for water supply and sewerage networks are made with panels with an outer diameter of 2.1 to 5.63 m.
