Casing pipe construction method
By using the casing construction method, including grouting of the outer casing and milling and welding of the inner lining end face, the limitations of traditional pipe jacking construction have been overcome, enabling efficient and safe construction under complex geological conditions, and reducing engineering risks and ground settlement.
Patent Information
- Application Number
- CN202610059213.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-01-16
- Publication Date
- 2026-02-24
AI Technical Summary
Traditional pipe jacking construction methods have limitations in terms of preliminary preparation, working environment, construction flexibility and equipment operation. They are difficult to adapt to complex geological conditions and site requirements, and there are risks of project interruption, equipment damage and ground subsidence.
The casing construction method is adopted, including surveying and setting out, outer casing construction, external grouting, laying of the bedding layer, inner lining construction, and filling of gaps between casings. Through step-by-step excavation and timely support, fly ash or cement grout is used for grouting. Combined with milling and welding technology of the inner lining, the flexibility and safety of construction are ensured.
It improves construction flexibility and safety, reduces engineering deviations and costs, minimizes construction risks, adapts to narrow spaces, and effectively controls ground settlement.
Smart Images
Figure CN121557338A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of pipe jacking construction technology, and specifically relates to a casing construction method. Background Technology
[0002] With the rapid development of pipeline infrastructure construction in my country, pipe jacking has become one of the most widely used and mainstream trenchless construction technologies both domestically and internationally. Although this technology is relatively mature, it still faces many technical challenges in actual construction.
[0003] First, a thorough and accurate geological and hydrological survey must be conducted before construction. The presence of undiscovered obstacles or geological anomalies can easily lead to project interruption, equipment damage, or even safety accidents. Second, when the pipe jacking distance is long, multiple working shafts are often required, and the construction site must meet the spatial requirements for shaft excavation, jacking equipment installation, pipe section stacking, and soil disposal, placing high demands on the site. Third, pipe jacking construction typically only allows for gentle turns with large radii of curvature, making it difficult to adapt to sharp bends or complex three-dimensional curves, limiting the flexibility of pipeline routing planning. Finally, improper operation of the tunnel boring machine (such as over-excavation or poor earth pressure control) or inadequate grouting and friction reduction techniques can easily cause ground loss and ground subsidence, potentially endangering surrounding structures in densely built-up areas.
[0004] In summary, traditional pipe jacking construction methods have certain limitations in terms of preliminary preparation, working environment, construction flexibility, and equipment operation. Summary of the Invention
[0005] In view of the shortcomings of existing technologies, this invention proposes a casing construction method with low requirements for preliminary preparation conditions, strong adaptability to the working environment, high construction flexibility and low dependence on equipment operation, thereby improving construction flexibility, reducing engineering deviations and costs, and effectively reducing construction risks.
[0006] To achieve the above objectives, the technical solution of the present invention is as follows: A casing construction method, the construction method comprising: Measurement and layout positioning → Determine the crossing location → Outer casing construction → Grouting outside the casing → Laying the bedding layer → Inner lining construction → Filling the gaps between casings; The outer casing construction includes: First, the opening is excavated and assembled in a complete circle. Then, the excavation is carried out in two steps, upper and lower, with the over-excavation amount not exceeding 30mm. The first step is to complete the excavation of the upper semicircle with a length of 50cm, and install the upper semicircle of the outer sleeve. The second step is to complete the excavation of the lower semicircle with a length of 50cm, and install the lower semicircle of the outer sleeve. Then, the entire circle is connected with bolts, and the installation of the entire outer sleeve is completed. The excavation proceeds forward in sequence, eventually forming a complete circular outer casing.
[0007] Preferably, the external grouting of the casing involves injecting fly ash slurry or cement slurry into the gap between the outer wall of the outer casing and the inner wall of the hole. In the fly ash slurry, the weight ratio of fly ash to water is 1:1.5 to 1:3, and in the cement slurry, the weight ratio of water to cement is 1:1 to 1:1.1. The final injection pressure is <0.2 MPa.
[0008] Preferably, the construction of the inner lining pipe includes: Pipe preparation → clamping and positioning → milling end face → determining system drag force → end face welding → cooling and shaping.
[0009] Preferably, the pipe preparation involves preparing the pipes to be connected. Clamping and positioning: According to the specifications of the pipe, equip the corresponding clamping mold, place the two clamps of the welding machine in the maximum opening position, fix the pipe in the two clamps, so that the opposite pipe end face extends 50mm out of the clamp slide plate, move the clamps until the two end faces contact, and correct to make the two end faces completely overlap. Milling the end faces: Open the two clamps, place the milling cutter head in the middle of the clamps, start the milling cutter head, and slowly move the cutter to press the two end faces against the milling cutter head to mill the two butt welding end faces flat; the cutting thickness should not exceed 0.2mm; move the pipe section to be welded to fit the two end faces together, the maximum gap between the two end faces should not exceed 0.5mm, and the misalignment of the two pipe edges should not exceed 10% of the wall thickness; the end faces after milling should be welded immediately. End face welding: Set the temperature of the heating plate; place the heating plate, which has reached the welding temperature, between the two end faces to be welded. Operate the moving clamp to make the two end faces adhere tightly to the heating plate under the action of the butt joint pressure. Observe the molten material gradually overflowing from both sides of the heating plate on the end faces to be welded. When the height of the rolled edge reaches the set value in the parameter table, reduce the heat absorption pressure to P1 by pressing the pressure reduction button. After the heat absorption time is reached, remove the clamp and quickly withdraw the heating plate to weld the two end faces to be welded. Apply linear pressure to make the two end faces fit completely together. At the same time, the overflowing molten material forms two uniform weld rings around the weld seam area.
[0010] Preferably, the gaps between the sleeves are filled by sandblasting to ensure a full and dense filling without any voids. During the casing process, supports are set every 6 meters to stabilize the inner liner. After the casing is completed, the gap between the outer casing and the inner liner needs to be filled. First, one end of the outer casing is fully lined with bricks and plastered with waterproof mortar. Medium sand is blown into the gap using an anchor spraying machine. The spraying pipe is connected with DN100 steel pipe flanges, each section is 3 meters long. Medium sand is moistened with water in a mixer and sprayed from the inside out, spraying 3 meters at a time until the entire pipe section is sprayed. Then, it is fully sealed with bricks.
[0011] This invention enables high-risk underground excavation projects to be carried out in stages with timely support. Under the most unfavorable geological conditions, it offers high construction flexibility and low dependence on machinery operation, safely and accurately constructing reliable underground spaces. It greatly reduces the risk of excavation face collapse, effectively controls ground settlement, provides a safe passage for subsequent operations, facilitates precise alignment and complete circularity to ensure structural integrity, and is adaptable to narrow spaces. Attached Figure Description
[0012] Figure 1 This is a schematic diagram of the outer tube assembly structure of the present invention. Detailed Implementation
[0013] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and embodiments.
[0014] Example 1 A casing installation method includes the following steps: (1) Construction process flow: Measurement and layout positioning → Determine the crossing location → Outer casing construction → Grouting outside the casing → Laying the bedding layer → Inner lining construction → Filling the gaps between casings.
[0015] (2) Determine the crossing route: 1) Based on relevant data (such as geological survey reports, route drawings, etc.) and the actual conditions of the construction site, determine the crossing distance and draw a route map of the guiding trajectory to determine the length and depth of the pipeline to be laid.
[0016] 2) Measurement of directional control parameters: The directional control parameters were calibrated according to the operating procedures (such as CECS 382-2014 Technical Specification for Pipeline Crossing Engineering by Horizontal Directional Drilling). Due to the complex terrain at the site, the parameters were measured at five different locations along the centerline of the pipe to ensure data accuracy.
[0017] (3) Grouting outside the casing: To ensure that the road surface does not settle during and after construction, a Φ33mm silicon core tube is selectively suspended from the top of the steel structure sleeve and the inner wall of the hole, and fly ash slurry or cement slurry is injected. In the fly ash slurry, the weight ratio of fly ash to water is 1:1.5 to 1:3, and in the cement slurry, the weight ratio of water to cement is 1:1 to 1:1.1. The final spraying pressure should be less than 0.2 MPa.
[0018] (4) Steel structure sleeve installation construction: 1) Construction procedure: After excavating 50cm, install the steel structure sleeve → backfill with dense material behind it.
[0019] 2) such as Figure 1 As shown, the first step is to excavate and assemble the entire circle of the first archway, as indicated. Figure 1As shown in 'a'. The excavation is then divided into two steps, upper and lower, with over-excavation not exceeding 30mm. The first step completes the upper semicircle excavation, with a length of 50cm, and installs the steel structure sleeve for the upper semicircle. The second step involves excavating and assembling the upper semicircle as follows... Figure 1 As shown in b; the second step is to complete the excavation of the lower semicircle, with an excavation length of 50cm, install the lower semicircle of the steel structure sleeve, and then connect the entire circle with M8 bolts to complete the entire steel structure sleeve. The next lower semicircle is then excavated, assembled, and bolted to the upper semicircle as shown in the image. Figure 1 As shown in c in the figure.
[0020] The excavation proceeds forward in sequence, eventually forming a well-formed circular casing. 3) Measurement work: Processing and feedback of on-site monitoring and measurement data: All data collected during on-site monitoring and measurement (such as displacement data, stress and pressure data, water level, cracks, etc.) should be promptly plotted as displacement-time curves. The curves should indicate the construction sequence and the distance from the excavation face to the measuring section.
[0021] When the curvature of the displacement-time curve tends to flatten, regression analysis should be performed on the data to estimate the final displacement value and determine the displacement variation pattern. When performing regression analysis, the function form with the optimal correlation should be selected from logarithmic, exponential, and hyperbolic functions, based on the characteristics of the curve's variation.
[0022] The measured relative displacement value between any two points around the pipeline, or the relative value of the final displacement value estimated by regression analysis, should be less than the value in clause 0.2% to 0.8%.
[0023] The selection is based on different geological conditions, pipeline burial depth, and span; Stratigraphic conditions: Poor conditions (low values, such as 0.2%-0.4%): soft soil, fluid clay, gravel (easily collapses), strongly weathered and fractured rock strata, etc. These strata have poor self-stabilizing ability, rapid deformation development, and small allowable deformation.
[0024] Favorable conditions (higher values, such as 0.6%-0.8%): hard rock, dense old loess, well-consolidated soil. Strong self-stabilizing ability, able to withstand large deformations without failure.
[0025] Pipeline burial depth: Shallow burial depth (low value): Extremely sensitive to surface subsidence, directly affecting the safety of upper roads, pipelines, and buildings, and displacement must be strictly controlled.
[0026] Burial depth (a higher value can be selected as appropriate): The overlying soil is thick, forming an "arch effect". It has little impact on the surface, but the deep soil pressure is large, and it needs to be combined with a comprehensive geological assessment.
[0027] Pipe span: Large span (lower value): The equivalent stiffness of the structure is small, and the deformation is greater under the same load, requiring stricter control.
[0028] Small span (take the higher value): The structure has high stiffness and relatively strong deformation capacity.
[0029] When the rate of displacement change does not decrease significantly, but the relative value of the measured displacement is close to 0.2% to 0.8%, and obvious cracks have appeared on the surface of the support concrete; or when the measured displacement rate increases sharply, remedial measures must be taken, such as pre-reinforcement in front of the tunnel face, reinforcement of the support system of the excavated section, strong support behind the tunnel, and changes in construction methods and support parameters. If necessary, excavation should be stopped immediately for treatment.
[0030] (5) Laying the subbase: According to the requirements of the drawings and the elevation requirements of the pipeline, sand, gravel or anti-corrosion padding materials are laid in the sleeve in accordance with the relevant specifications of "GB 50268 Code for Construction and Acceptance of Water Supply and Drainage Pipeline Engineering" or "CJJ / T 81-2013 Technical Specification for Direct Buried Hot Water Pipelines for Urban Heating" and then verified.
[0031] (6) Construction of the inner lining pipe: Install the sewage pipes on the laid bedding layer. After installation, secure the pipe walls to ensure they are stable and do not move.
[0032] 1) PE pipe assembly and connection: ① Process flow: Pipe preparation → clamping and positioning → milling end face → determining system drag force → end face welding → cooling and shaping.
[0033] ②PE pipe assembly and connection Pipe preparation: Prepare the pipes that need to be connected.
[0034] Clamping and positioning: According to the specifications of the pipe, equip the corresponding clamping mold, place the two clamps of the welding machine in the maximum opening position, fix the pipe in the two clamps, so that the opposite pipe end face extends about 50mm out of the clamp slide plate, move the clamps until the two ends contact, and correct to make the two end faces completely overlap.
[0035] Milling the end faces: Open the two clamps, place the milling cutter head in the middle of the clamps, start the milling cutter head, and slowly move the cutter to press the two end faces against the milling cutter head, milling the two butt weld end faces flat. The cutting thickness should not exceed 0.2mm. Move the pipe section to be welded so that the two end faces are in contact, and the maximum gap between the two end faces should not exceed 0.5mm, while the misalignment of the two pipe edges should not exceed 10% of the wall thickness. Otherwise, the above process should be repeated after correction. The milled end faces must not be contaminated, and welding should begin immediately.
[0036] Determining the drag force of the welding pressure system: Move both clamps to the maximum opening position, then set the pressure regulating switch to the minimum, operate the clamp moving handle to close the clamps, and at the same time adjust the pressure regulating knob to gradually increase the pressure. Observe the moving speed of the clamps and determine a suitable value. Keep the pressure knob unchanged and move the two clamps several times to observe the change in system pressure. Finally, record the more accurate system pressure value on the process original record card.
[0037] End face welding: According to GB / T 20674.1-2020 Plastic pipes and fittings polyethylene system welding equipment - Part 1: Hot melt butt welding or the "Pipe Factory Certificate of Conformity" and the accompanying "Welding Process Instruction", set the temperature of the heating plate and control it within the specified range. Set the time parameter using a stopwatch.
[0038] Place the heating plate, which has reached the welding temperature, between the two end faces to be welded. Operate the moving clamp to make both end faces adhere tightly to the heating plate under the action of the butt joint pressure. Observe that the molten material gradually overflows from both sides of the heating plate on the end faces to be welded. When the height of the rolled edge reaches the value in the parameter table, reduce the heat absorption pressure by pressing the pressure reduction button. After the heat absorption time is reached, remove the clamp and quickly withdraw the heating plate to make the two end faces to be welded. Apply linear pressure to make the two end faces fit completely together. At the same time, the overflowing molten material forms two uniform weld rings around the weld seam area.
[0039] To prevent contamination of the heat-fused surface, the heating plate must be wiped clean with a clean cotton cloth (or wiped with lens paper and anhydrous alcohol) before each connection.
[0040] When encountering windy weather, the other end of the pipe should be sealed to prevent ventilation and cooling inside the pipe.
[0041] Cooling and Shaping: After welding is complete, start the stopwatch. Once the cooling time is up, the pipe connection is complete. The cooling process should not be affected by any external force. Any form of artificial acceleration of cooling is prohibited.
[0042] Connection parameter recording: After the pipeline connection is completed, record the following parameters: operator, electrofusion machine model, weather, ambient temperature, drag pressure, heat absorption pressure, docking pressure, temperature, time, heat absorption time, operation time, etc.
[0043] (7) Filling construction of casing gap: The gaps between the sleeves are filled by sandblasting to ensure a dense and full filling without any voids. During the casing process, supports are set every 6 meters to stabilize the inner lining pipe. After the casing is completed, the gap between the outer casing and the inner lining pipe needs to be filled. First, one end of the outer casing is fully lined with bricks and plastered with waterproof mortar. Medium sand is blown into the gap using an anchor spraying machine. The spraying pipe is connected with DN100 steel pipe flanges, each section is 3 meters long. Medium sand is moistened with water in a mixer and sand is sprayed from the inside out, 3 meters at a time, until the entire pipe section is sprayed. Then, it is fully sealed with bricks.
[0044] The dimensions of the casing and inner lining pipe of this invention can be flexibly selected according to the actual engineering conditions; the materials for the external grouting method and the bedding material of this invention can be flexibly selected according to the actual engineering conditions; the casing construction method proposed in this invention is mainly applicable to projects with good geological conditions.
[0045] All aspects not described in detail in this invention can be covered using conventional technical knowledge in the field.
[0046] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to the embodiments, those skilled in the art should understand that modifications or equivalent substitutions to the technical solutions of the present invention do not depart from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.
Claims
1. A casing construction method, the construction method comprising: Measurement and layout positioning → Determine the crossing location → Outer casing construction → Grouting outside the casing → Laying the bedding layer → Inner lining construction → Filling the gaps between casings; The outer casing construction includes: First, the opening is excavated and assembled in a complete circle. Then, the excavation is carried out in two steps, upper and lower, with the over-excavation amount not exceeding 30mm. The first step is to complete the excavation of the upper semicircle with a length of 50cm, and install the upper semicircle of the outer sleeve. The second step is to complete the excavation of the lower semicircle with a length of 50cm, and install the lower semicircle of the outer sleeve. Then, the entire circle is connected with bolts, and the installation of the entire outer sleeve is completed. The excavation proceeds forward in sequence, eventually forming a complete circular outer casing.
2. The casing construction method according to claim 1, characterized in that, The external grouting of the casing involves injecting fly ash slurry or cement slurry into the gap between the outer wall of the outer casing and the inner wall of the hole. In the fly ash slurry, the weight ratio of fly ash to water is 1:1.5 to 1:3, and in the cement slurry, the weight ratio of water to cement is 1:1 to 1:1.
1. The final injection pressure is <0.2 MPa.
3. The casing construction method according to claim 1, characterized in that, The construction of the inner lining pipe includes: Pipe preparation → clamping and positioning → milling end face → determining system drag force → end face welding → cooling and shaping.
4. The casing construction method according to claim 3, characterized in that, Pipe preparation: Prepare the pipes to be connected; Clamping and positioning: According to the specifications of the pipe, equip the corresponding clamping mold, place the two clamps of the welding machine in the maximum opening position, fix the pipe in the two clamps, so that the opposite pipe end face extends 50mm out of the clamp slide plate, move the clamps until the two end faces contact, and correct to make the two end faces completely overlap. Milling the end faces: Open the two clamps, place the milling cutter head in the middle of the clamps, start the milling cutter head, and slowly move the cutter to press the two end faces against the milling cutter head to mill the two butt welding end faces flat; the cutting thickness should not exceed 0.2mm; move the pipe section to be welded to fit the two end faces together, the maximum gap between the two end faces should not exceed 0.5mm, and the misalignment of the two pipe edges should not exceed 10% of the wall thickness; the end faces after milling should be welded immediately. End face welding: Set the temperature of the heating plate; place the heating plate, which has reached the welding temperature, between the two end faces to be welded. Operate the moving clamp to make the two end faces adhere tightly to the heating plate under the action of the butt joint pressure. Observe the molten material gradually overflowing from both sides of the heating plate on the end faces to be welded. When the height of the rolled edge reaches the set value in the parameter table, reduce the heat absorption pressure to P1 by pressing the pressure reduction button. After the heat absorption time is reached, remove the clamp and quickly withdraw the heating plate to weld the two end faces to be welded. Apply linear pressure to make the two end faces fit completely together. At the same time, the overflowing molten material forms two uniform weld rings around the weld seam area.
5. The casing construction method according to claim 1, characterized in that, The gaps between the sleeves are filled by sandblasting to ensure a dense and full filling without any voids. During the casing process, supports are set every 6 meters to stabilize the inner lining pipe. After the casing is completed, the gap between the outer casing and the inner lining pipe needs to be filled. First, one end of the outer casing is fully lined with bricks and plastered with waterproof mortar. Medium sand is blown into the gap using an anchor spraying machine. The spraying pipe is connected with steel pipe flanges, each section is 3 meters long. Medium sand is moistened with water in a mixer and sand is sprayed from the inside out, 3 meters at a time, until the entire pipe section is sprayed. Then, it is fully sealed with bricks.