A trenchless repair and renewal design method for sewer pipelines

Abstract

The application discloses a kind of non-excavation repair updating design methods of drainage pipeline, solve the repair measure of drainage pipeline in prior art mainly according to the unified repair of pipeline evaluation conclusion, do not consider the problems such as economy and other factors, with the beneficial effect of improving the scientific nature and accuracy of repair decision, specific scheme is as follows: a kind of non-excavation repair updating design method of drainage pipeline, including determining the type of defect needing repair and the grade of defect needing repair;Determine repair attribute: according to the length ratio of defect needing repair in the same pipe section, when the ratio is greater than the set value of project, overall repair is adopted, otherwise, local repair is adopted;According to the determination of repair measures according to defect type, grade, repair attribute.

Description

Technical Field

[0001] This invention relates to the field of drainage pipeline engineering technology, and in particular to a trenchless repair and renovation design method for drainage pipelines. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] In past trenchless repair engineering designs for drainage pipelines, there has been a lack of clear design specifications and standards regarding key issues such as which pipeline defects should be addressed through trenchless repair, whether to adopt overall or partial repair methods, and the specific repair and replacement techniques. In actual engineering cases, the need for repair is typically determined based on the "repair level" of the pipeline segment in the pipeline assessment conclusion; and whether to adopt overall or partial repair is determined according to the "type of structural defect," namely "local defect, partial or overall defect, or overall defect." However, these approaches all have the following problems: Pipeline assessment involves statistical calculations of all detected defects. However, different projects differ in their construction objectives, conditions, funding, and timelines, making a uniform assessment standard inappropriate. In pipeline assessment, "overall" and "partial" assessments are results derived from statistical calculations of all defects in a pipeline segment. However, there are significant cost differences between partial and overall pipeline repair. Given different regions and project control prices, a uniform standard cannot be used to determine whether a complete overhaul or partial repair is necessary. Under the premise of achieving the same restoration of pipeline function, existing repair methods do not consider economic factors.

[0004] In addition, the following problems also exist: Pipe sections with the same defects may require different repairs depending on their location. For example, for pipe joint disconnection defects, minor defects of levels 1 and 2 may not need to be repaired temporarily when the pipe is buried at a greater depth or located under a roadway. However, when the pipe is buried at a shallower depth in a green belt, tree roots often grow from the joint and penetrate into the pipe, causing blockage. In this case, repair is necessary, but it is difficult to accurately determine whether pipe structural repair is required based on the pipe assessment results.

[0005] Furthermore, when selecting repair measures, existing repair methods do not select repair measures based on the characteristics of the defect itself. Instead, they select repair measures based on the overall assessment conclusion of the entire pipe section and whether a certain repair measure meets the applicable scope of the pipe section in terms of pipe diameter, pipe material, shape, etc., which lacks specificity and relevance to the characteristics of the defect itself. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the purpose of this invention is to provide a trenchless repair and renovation design method for drainage pipelines. This method does not rely on pipeline assessment conclusions as the primary design basis. Instead, it uses a unified design approach to determine appropriate repair principles and standards based on the characteristics of different projects.

[0007] To achieve the above objectives, the present invention is implemented through the following technical solution: A trenchless repair and renovation design method for drainage pipelines includes the following: Determine the type and severity of the defect requiring repair; Determine the repair attribute: The repair is determined based on the length ratio of the defects to be repaired in the same pipe section. When the ratio is greater than the project setting value, overall repair is adopted; otherwise, local repair is adopted. The remedial measures are determined based on the type and severity of the defect.

[0008] The updated design method described above does not use pipeline assessment conclusions as the main design basis. Instead, it determines the repair based on the length ratio of defects to be repaired in the same pipe section. Under a unified design method, it determines appropriate repair measures based on the defect type, level, and repair attributes, effectively controlling costs. The repair measures provided are more practical while taking into account economic efficiency.

[0009] As described above, in the trenchless repair and renovation design method for drainage pipelines, the length ratio of defects to be repaired in the same pipe segment refers to the ratio of the total length of the defects to be repaired to the total length of the pipe segment where the defects are located. This definition clarifies the quantitative standard for repair judgment and avoids the irrationality of using a uniform standard for all defects to be repaired in the prior art.

[0010] The calculation formula for the length ratio of defects to be repaired in the same pipe segment in the trenchless repair and renovation design method for drainage pipelines described above is as follows:

[0011] In the formula: A – The ratio of the lengths of the same pipe section that require repair of defects; L—Total length of the pipe section where the defect is located; —The longitudinal length of a defect that needs to be repaired in the same pipe section. Defects with a longitudinal length greater than 1m are calculated based on the actual length, while defects with a length less than 1m are calculated as 1m. n – The total number of defects that need to be repaired in the same pipe section.

[0012] This calculation formula achieves a quantitative assessment of the severity of defects by summing the longitudinal length of individual defects and comparing it with the total length of the pipe section. This provides reliable data support for subsequent repair decisions. Defects less than 1m in length are calculated as 1m, which is the smallest construction unit that takes into account the actual repair operation.

[0013] The trenchless repair and renovation design method for drainage pipelines described above determines the type and level of defects to be repaired based on defect detection results, pipeline medium, and investment costs. This embodies the concept of differentiated repair standards, allowing different projects to formulate reasonable repair standards according to their actual situations, avoiding the irrationality of a one-size-fits-all approach, and optimizing economic efficiency while ensuring repair effectiveness.

[0014] The trenchless repair and renovation design method for drainage pipelines described above includes the following defect types requiring repair: cracks, disconnections, deformation, corrosion, misalignment, detachment, undulations, penetration, leakage, and concealed connections. The defect levels requiring repair include Level 1, Level 2, Level 3, and Level 4. These defect types and levels cover common structural defects in drainage pipelines, providing a clear classification basis for repair decisions. Different defect types and levels have different degrees of impact on pipeline function, requiring corresponding repair measures.

[0015] The trenchless repair and renovation design method for drainage pipelines, as described above, involves determining the level of the defect requiring repair based on defect detection results, pipeline medium, and investment costs. This includes the following: If there are cavities around the drainage pipe that needs repair, or if the ground has subsided or collapsed, the level of the defect that needs repair is greater than or equal to 1. For drainage pipes with an average investment of less than 400 yuan per linear meter, when the type of defect to be repaired is penetration and concealed connection, the level of the defect to be repaired is greater than or equal to 1; when the type of defect to be repaired is corrosion, misalignment, disconnection, detachment, unevenness, leakage, cracking and deformation, the level of the defect to be repaired is greater than or equal to 3. For sewage pipes, when the defect type is detachment, disconnection, penetration, leakage, rupture and concealed connection, the level of the defect to be repaired is greater than or equal to 1; when the defect type is corrosion or misalignment, the level of the defect to be repaired is greater than or equal to 2; when the defect type is undulation or deformation, the level of the defect to be repaired is greater than or equal to 3. For rainwater pipes, when the defect type is detachment, penetration, or concealed connection, the level of the defect to be repaired is greater than or equal to 1; when the defect type is corrosion, the level of the defect to be repaired is greater than or equal to 2; and when the defect type is misalignment, disconnection, unevenness, leakage, rupture, or deformation, the level of the defect to be repaired is greater than or equal to 3.

[0016] The above-described trenchless repair and renovation design method for drainage pipelines uses the following criteria for overall repair judgment, considering different pipeline media and pipe materials: As the pipe diameter increases, the cost per meter for overall repair increases more significantly than that for partial repair. Assuming both structural and functional repairs of the pipeline can be achieved, the criteria for overall repair are: the length of the defect to be repaired must be greater than or equal to 50% for pipe diameters greater than or equal to 1200mm; less than or equal to 30% for pipe diameters less than or equal to 600mm; and 30% to 50% for pipe diameters between 600mm and 1200mm. To prevent defects from developing further, considering the structural strength and ring stiffness of the pipe itself, the overall repair decision is based on the length ratio of the defects to be repaired. For rigid pipes, this ratio is 30% to 50%, and for flexible pipes, it is less than or equal to 30%. To reduce environmental pollution, the overall repair criteria are based on the length of the defect to be repaired being less than or equal to 30% for sewage pipes and greater than or equal to 30% for rainwater pipes.

[0017] The trenchless repair and renovation design method for drainage pipelines described above includes the following repair measures: For overall repair: When a pipe section has defects of level 3 or above that require repair, the overall excavation or pipe breaking (fracture) method is used for pipe replacement; for pipe sections that meet the conditions for trenchless overall repair, the in-situ solidification method is preferred for circular pipes; when there is a change in diameter or deflection and no excavation is possible, the thermoplastic molding method is used for repair; when water-based operations are required, the mechanical spiral winding method is used for repair; when the original pipe structure needs to be reinforced and the original pipe has sufficient capacity, the mechanical spiral winding method (sizing type), the padding method, and the short pipe insertion method are used for repair; when the pipe diameter exceeds 2000mm, the mechanical spiral winding method (walking type) and the cement-based material spraying method are used for repair.

[0018] The trenchless repair and renovation design method for drainage pipelines described above further includes the following repair measures: For local repairs: For deformation defects of level 3 or above and / or undulation defects of level 3 or above and / or rupture defects of level 4 or above and / or misalignment defects of level 4 or above with a pipe diameter less than or equal to 800 mm, local excavation repair is adopted; for branch pipe concealed connection defects, the repair method of building a new inspection well is adopted; when there is axial misalignment or pipe deformation, flexible repair material is used to ensure that the inner lining material adheres to the original pipe wall; for level 3 rupture, level 3 leakage, and level 4 disconnection defects that require local repair, stainless steel quick locks are used for repair, but when the defect location is accompanied by axial misalignment or pipe deformation, flexible repair material is used for repair.

[0019] The beneficial effects of the present invention are as follows: This invention is the first to propose the concept of determining whether a defect in a pipe section needs to be repaired. It is more intuitive and convenient, and overcomes the complexity and hidden intermediate data of the existing technology that determines whether the entire pipe section needs to be repaired based on the conclusion formed by the comprehensive evaluation of all defects in the entire pipe section. It can effectively improve the accuracy and efficiency of design. This invention determines repair based on the ratio of the length of defects requiring repair within the same pipe segment, introducing for the first time the concept of "ratio of the length of defects requiring repair," which is the ratio of the total length of defects requiring repair to the total length of the pipe segment. This quantitative indicator determines whether overall or partial repair is needed, overcoming the irrationality of using a uniform judgment standard based on pipeline assessment conclusions in existing technologies. It establishes repair decisions on the basis of quantitative data, avoiding the arbitrariness of subjective judgment, improving the scientificity and accuracy of repair decisions, and enabling repair plans to truly reflect the actual severity of pipeline defects. By comparing the length ratio of the defects to be repaired with the project's set value, overall repair is adopted when the length ratio of the defects to be repaired is greater than the project's set value, and partial repair is adopted otherwise. This fully considers economic factors. In the existing technology, there is a significant difference in cost between partial repair and overall repair. However, the use of a uniform standard for judgment fails to optimize costs while ensuring repair effectiveness. Through a flexible judgment mechanism, the repair method can be reasonably selected under the premise of achieving the same pipeline function restoration, which significantly reduces the investment cost of the repair project and improves the quality and efficiency of the repair. Attached Figure Description

[0020] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0021] Figure 1 This is a schematic diagram of the defects to be repaired in a trenchless repair and renewal design method for drainage pipelines according to one or more embodiments of the present invention.

[0022] The diagram exaggerates the spacing or dimensions between parts to show their positions; the diagram is for illustrative purposes only.

[0023] Among them: 1. Crack defects, 2. Disconnection defects, 3. Deformation defects, 4. Corrosion defects. Detailed Implementation

[0024] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0025] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, unless otherwise expressly indicated by the invention, the singular form is also intended to include the plural form. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof. As described in the background section, existing drainage pipeline repair measures are mainly based on pipeline assessment conclusions for uniform repair, without considering economic and other factors. In order to solve the above-mentioned technical problems, this invention proposes a trenchless repair and renewal design method for drainage pipelines.

[0026] In a typical embodiment of the present invention, a trenchless repair and renovation design method for drainage pipelines is disclosed. This method does not rely primarily on pipeline assessment conclusions as the design basis. Instead, under a unified design methodology, it determines appropriate repair principles and standards based on the characteristics of different projects, focusing on the defect itself rather than the defective pipe segment. The method includes the following steps: determining the type and level of the defect to be repaired; calculating the length ratio of the defect to be repaired; determining the repair attribute based on a comparison between the length ratio and a project-defined value; and determining repair measures based on the defect type, defect level, and repair attribute.

[0027] It should be noted that determining the type and level of defects to be repaired based on defect detection results, pipeline medium, and investment costs reflects the concept of differentiated repair standards. Different projects can formulate reasonable repair standards according to their actual situations, avoiding the irrationality of a one-size-fits-all approach and optimizing economic efficiency while ensuring repair effectiveness.

[0028] Specifically, based on the defect detection results, pipeline medium, and investment costs, the types and levels of defects requiring repair in this project are determined. Defect types include cracks, disconnections, deformation, corrosion, misalignment, detachment, undulations, penetrations, leaks, and concealed connections. Defect levels are categorized into Level 1, Level 2, Level 3, and Level 4. These defect types and levels cover common structural defects in drainage pipelines, providing a clear classification basis for repair decisions. Different defect types and levels have varying degrees of impact on pipeline function, requiring corresponding repair measures.

[0029] Based on different combinations of defect detection results, pipeline medium, and investment costs, the level of defect requiring repair is determined: If there are cavities around the drainage pipe that needs repair, or if the ground has subsided or collapsed, the level of the defect that needs repair is greater than or equal to 1. For drainage pipes with an average investment of less than 400 yuan per linear meter, when the type of defect to be repaired is penetration and concealed connection, the level of the defect to be repaired is greater than or equal to 1; when the type of defect to be repaired is corrosion, misalignment, disconnection, detachment, unevenness, leakage, cracking and deformation, the level of the defect to be repaired is greater than or equal to 3. For sewage pipes, when the defect type is detachment, disconnection, penetration, leakage, rupture and concealed connection, the level of the defect to be repaired is greater than or equal to 1; when the defect type is corrosion or misalignment, the level of the defect to be repaired is greater than or equal to 2; when the defect type is undulation or deformation, the level of the defect to be repaired is greater than or equal to 3. For rainwater pipes, when the defect type is detachment, penetration, or concealed connection, the level of the defect to be repaired is greater than or equal to 1; when the defect type is corrosion, the level of the defect to be repaired is greater than or equal to 2; and when the defect type is misalignment, disconnection, unevenness, leakage, rupture, or deformation, the level of the defect to be repaired is greater than or equal to 3. For pipelines with high media contamination rates, and where leakage would result in significant environmental and treatment costs, the required repair level should be lower. For example, the required repair level for sewage pipelines is generally lower than that for rainwater pipelines. Sewage pipelines with disconnections, leaks, or ruptures require repair at level 1, while rainwater pipelines with disconnections, leaks, or ruptures require repair at level 3. Refer to Tables 1 and 2 for recommended values.

[0030] Table 1 Recommended values ​​for structural defect levels requiring repair of sewage pipelines

[0031] Table 2 Recommended values ​​for structural defect levels requiring repair in stormwater pipes

[0032] For example, a stormwater pipeline project is located beneath a main urban road in a hard clay soil, a type of rigid soil. Excavation and repair costs are high, approximately 10,000 yuan per meter. Based on the above correspondence, the defect levels requiring repair are set according to Table 2. This means that different repair measures can be adopted for different defect levels in this project. This differentiated standard setting ensures both the targeted nature and effectiveness of the repairs, while optimizing the repair plan within limited investment conditions, avoiding the unreasonable practice of applying a one-size-fits-all approach to all defects.

[0033] In addition, some examples consider regional characteristics, primarily referring to soil conditions, including flexible and hard soils. Flexible soils refer to areas with loose, easily excavated soil, such as sandy soil and silt; hard soils refer to areas with firm soil and difficult excavation, such as rock and hard clay. Investment cost refers to the repair cost per unit length of pipe section. Thus, the looser the soil around the pipe, the easier it is for soil erosion to occur, leading to secondary hazards such as road collapse, and the lower the level of defect requiring repair. Defects that easily damage the integrity and structural stability of the pipeline require lower repair levels, such as foreign object penetration, joint material detachment, and concealed branch pipe connections, which require repair level 1.

[0034] In addition, the overall repair criteria are as follows, depending on the different pipeline media and different pipe materials: As the pipe diameter increases, the cost per meter for overall repair increases more significantly than that for partial repair. Assuming both structural and functional repairs can be achieved, the criteria for overall repair should be: the length of the defect to be repaired should be greater than or equal to 50% for pipe diameters greater than or equal to 1200mm; less than or equal to 30% for pipe diameters less than or equal to 600mm; and 30% to 50% for pipe diameters between 600mm and 1200mm. For large-diameter rainwater pipes, due to the higher cost of overall repair, the overall repair threshold should be relatively higher. To prevent defects from developing further, considering the structural strength and ring stiffness of the pipe itself, the overall repair determination is based on the length ratio of the defects to be repaired. For rigid pipes, it is 30% to 50%, and for flexible pipes, it is less than or equal to 30%. For rigid pipes such as concrete pipes, due to their good impermeability and structural performance, the overall repair setting value can be set relatively high, while for flexible pipes such as plastic pipes, the overall repair setting value should be relatively low. To reduce environmental pollution, the overall repair criteria are based on the length of the defect to be repaired being less than or equal to 30% for sewage pipes and greater than or equal to 30% for rainwater pipes.

[0035] Specifically, the ratio of the lengths of defects requiring repair within the same pipe segment is calculated, defined as the ratio of the total length of defects requiring repair to the total length of the pipe segment. The formula is as follows: A = (l1 + l2 + ... + l n ) / L. Where: A is the ratio of the length of the defect to be repaired; L is the total length of the pipe segment where the defect is located, in meters; l iLet l1 be the longitudinal length of a defect that needs to be repaired within the same pipe segment. Defects with a longitudinal length greater than 1 meter are calculated based on their actual length, while defects less than 1 meter are calculated as 1 meter. The unit is meters. n is the total number of defects that need to be repaired within the same pipe segment. For example, if a pipe segment has a total length of 100 meters and there are 3 defects that need to be repaired, with longitudinal lengths of 0.5 meters, 1.2 meters, and 2 meters respectively, then l1 is calculated as 1 meter, l2 as 1.2 meters, and l3 as 2 meters. The ratio of the lengths of defects that need to be repaired is A = (1 + 1.2 + 2) / 100 = 0.042, or 4.2%.

[0036] Next, the calculated ratio of the length of defects requiring repair is compared with the project's set value to determine the repair attribute. If the ratio is greater than the specific value set for the project, overall repair is adopted; otherwise, partial repair is adopted. The project's set value should be set according to the actual situation of the project, comprehensively considering factors such as regional characteristics, investment costs, pipe material type, and media type. For example, for a 500mm diameter concrete drainage pipe project, the project's set value can be set to 30%; if the calculated ratio of the length of defects requiring repair is 4.2%, which is less than 30%, then partial repair is adopted; if the ratio of the length of defects requiring repair is 36%, which is greater than 30%, then overall repair is adopted.

[0037] Finally, the specific repair measures are determined based on the type and level of the defects requiring repair. For deformation defects of level 3 or above and / or crushing defects of level 3 or above and / or rupture defects of level 4 or above and / or misalignment defects of level 4 or above with a pipe diameter less than or equal to 800 mm, if general trenchless methods cannot effectively repair and replace the drainage pipes, partial or overall excavation and replacement or overall pipe breaking (cracking) method replacement shall be adopted; for branch pipe concealed connection defects, the repair method of constructing a new inspection well shall be adopted; for structural defects requiring partial repair, when there is axial misalignment, When a pipeline deforms, flexible repair materials should be used to ensure that the lining material adheres to the original pipe wall, such as point-based in-situ curing or stainless steel double expansion rings. When there is a change in diameter or deflection and no excavation is possible, thermoplastic molding should be used for repair. When underwater operations are required, mechanical spiral winding should be used for repair. When the original pipeline structure needs to be reinforced and the original pipeline has sufficient capacity, mechanical spiral winding (sizing type), padding method, or short pipe insertion method should be used for repair. When the pipe diameter exceeds 2000mm, mechanical spiral winding (walking type) or cement-based material spraying method should be used for repair. For local repairs: For deformation defects of level 3 or above and / or undulation defects of level 3 or above and / or rupture defects of level 4 or above and / or misalignment defects of level 4 or above with a pipe diameter of less than or equal to 800 mm, the drainage pipe cannot be effectively repaired by general non-excavation local repair measures, and local excavation repair should be adopted. For defects in concealed connections of branch pipes, the repair method of constructing new inspection wells should be adopted; For structural defects requiring local repair, when there is axial misalignment or pipe deformation, flexible repair materials such as existing flexible repair agents are used to ensure that the lining material adheres to the original pipe wall, such as point-based in-situ curing or stainless steel double expansion rings. For Class 3 cracks, Class 3 leaks, and Class 4 disconnections that require local repair, repair measures with better structural strength, such as stainless steel quick locks, are adopted. However, when the defect location is accompanied by axial misalignment or pipe deformation, flexible repair materials are used. It should be noted that the repair measures are precisely matched according to the severity and characteristics of the defect, avoiding the conventional design method of selecting repair measures only based on the pipe diameter, material, and cross-sectional shape, without considering the type and characteristics of the defect.

[0038] For example, a 600mm concrete sewage pipe is 30 meters long and has 5 defects. The defect types and longitudinal lengths are as follows: 1 Class 2 misalignment, 1 Class 4 misalignment, 1.5m Class 3 rupture, 14m Class 1 corrosion, and 0.1m Class 1 leakage. According to the values ​​set in Table 1, the defects that need to be repaired are 1 Class 2 misalignment, 1 Class 4 misalignment, 1.5m Class 3 rupture, and 0.1m Class 1 leakage. The calculated ratio of the lengths of defects that need to be repaired is (1 + 1 + 1.5 + 1) / 30 = 0.15, or 15%.

[0039] Next, the overall repair setting value for the project is set according to the pipe material, medium type, and pipe diameter. For a 600mm diameter concrete sewage pipe, the overall repair setting value is set to 30%. The proportion of defect lengths to be repaired is compared with the project setting value to determine the repair attribute.

[0040] The length of the concrete pipe requiring repair is 15%, which is less than 30%, so local repair is deemed appropriate. Then, the repair measures are determined based on the defect type and defect severity.

[0041] Finally, based on the defect type, level, and repair attributes, specific repair measures were determined, including the following: The defects requiring repair in this pipeline include one Class 2 misalignment, one Class 4 misalignment, a 1.5m Class 3 rupture, and a 0.1m Class 1 leak. For the Class 4 misalignment, due to the large axial displacement and small pipe diameter, the trenchless repair airbag could not meet the requirement of sufficient wall adhesion of the lining material, so partial excavation repair was adopted; for the Class 2 misalignment, due to the axial displacement, a two-ring point-like in-situ curing repair with flexible repair material was adopted; for the Class 3 rupture, due to the high degree of rupture, the pipeline strength needed to be strengthened, so a six-ring stainless steel quick-lock repair with rigid repair material was adopted; for the Class 1 leak, a two-ring point-like in-situ curing repair was adopted after pretreatment.

[0042] Using the method of this invention, the project, under limited investment conditions, rationally determined the repair method and accurately selected the repair measures. This ensured that defects such as Level 2 misalignment, Level 4 misalignment, Level 3 rupture, and Level 1 leakage, which are prone to causing environmental hazards and affecting structural safety, were repaired. At the same time, it avoided over-repairing Level 1 corrosion defects that do not affect structural safety. This ensured the repair effect and optimized the economy. The repaired pipeline function was well restored and its service life was significantly extended.

Claims

1. A trenchless repair and renovation design method for drainage pipelines, characterized in that, Includes the following: Determine the type and severity of the defect requiring repair; Determine the repair attribute: The repair is determined based on the length ratio of the defects to be repaired in the same pipe section. When the ratio is greater than the project setting value, overall repair is adopted; otherwise, local repair is adopted. The remedial measures are determined based on the type and severity of the defect.

2. The trenchless repair and renovation design method for drainage pipelines according to claim 1, characterized in that, The length ratio of defects requiring repair in the same pipe segment refers to the ratio of the total length of the defects requiring repair to the total length of the pipe segment containing the defects.

3. A trenchless repair and renovation design method for drainage pipelines according to claim 1 or 2, characterized in that, The formula for calculating the length ratio of defects requiring repair within the same pipe segment is as follows: In the formula: A – The ratio of the lengths of the same pipe section that require repair of defects; L—Total length of the pipe section where the defect is located; —The longitudinal length of a defect that needs to be repaired in the same pipe section. Defects with a longitudinal length greater than 1m are calculated based on the actual length, while defects with a length less than 1m are calculated as 1m. n – The total number of defects that need to be repaired in the same pipe section.

4. The trenchless repair and renovation design method for drainage pipelines according to claim 1, characterized in that, Based on the defect detection results, pipeline medium, and investment costs, determine the type and level of the defect requiring repair.

5. The trenchless repair and renovation design method for drainage pipelines according to claim 4, characterized in that, The types of defects requiring repair include cracks, dislocations, deformations, corrosion, misalignments, detachments, undulations, penetrations, leaks, and concealed connections. The levels of the defects requiring repair include Level 1, Level 2, Level 3, and Level 4.

6. The trenchless repair and renovation design method for drainage pipelines according to claim 4, characterized in that, The determination of the level of the defect requiring repair based on the defect detection results, pipeline medium, and investment cost includes the following: If there are cavities around the drainage pipe that needs repair, or if the ground has subsided or collapsed, the level of the defect that needs repair is greater than or equal to 1. For drainage pipes with an average investment of less than 400 yuan per linear meter, when the type of defect to be repaired is penetration and concealed connection, the level of the defect to be repaired is greater than or equal to 1; when the type of defect to be repaired is corrosion, misalignment, disconnection, detachment, unevenness, leakage, cracking and deformation, the level of the defect to be repaired is greater than or equal to 3. For sewage pipes, when the defect type is detachment, disconnection, penetration, leakage, rupture and concealed connection, the level of the defect to be repaired is greater than or equal to 1; when the defect type is corrosion or misalignment, the level of the defect to be repaired is greater than or equal to 2; when the defect type is undulation or deformation, the level of the defect to be repaired is greater than or equal to 3. For rainwater pipes, when the defect type is detachment, penetration, or concealed connection, the level of the defect to be repaired is greater than or equal to 1; when the defect type is corrosion, the level of the defect to be repaired is greater than or equal to 2; and when the defect type is misalignment, disconnection, unevenness, leakage, rupture, or deformation, the level of the defect to be repaired is greater than or equal to 3.

7. The trenchless repair and renovation design method for drainage pipelines according to claim 1, characterized in that, The criteria for overall repair determination are as follows, depending on the different pipeline media and different pipe materials: The length of the defect to be repaired should be greater than or equal to 50% when the pipe diameter is greater than or equal to 1200 mm, less than or equal to 30% when the pipe diameter is less than or equal to 600 mm, and between 30% and 50% when the pipe diameter is between 600 mm and 1200 mm. Based on the length ratio of the defects to be repaired, the ratio is 30% to 50% for rigid pipes and less than or equal to 30% for flexible pipes. The length of the defect to be repaired is less than or equal to 30% for sewage pipes and greater than or equal to 30% for rainwater pipes.

8. A trenchless repair and renovation design method for drainage pipelines according to claim 5 or 6, characterized in that, Prime number restoration measures include the following: For overall repair: When a pipe section has defects of level 3 or above that require repair, the overall excavation or pipe breaking method is used for pipe replacement; for pipe sections that meet the conditions for trenchless overall repair, the in-situ solidification method is preferred for circular pipes; when there is a change in diameter or deflection and no excavation is possible, the thermoplastic molding method is used for repair; when water-supported operations are required, the mechanical spiral winding method is used for repair; when the original pipe structure needs to be reinforced and the original pipe has sufficient capacity, the mechanical spiral winding method, the padding method, and the short pipe insertion method are used for repair; when the pipe diameter exceeds 2000mm, the mechanical spiral winding method and the cement-based material spraying method are used for repair.

9. A trenchless repair and renovation design method for drainage pipelines according to claim 8, characterized in that, The remedial measures also include the following: For local repairs: For deformation defects of level 3 or above and / or undulation defects of level 3 or above and / or rupture defects of level 4 or above and / or misalignment defects of level 4 or above with a pipe diameter less than or equal to 800 mm, local excavation repair is adopted; for branch pipe concealed connection defects, the repair method of building a new inspection well is adopted; when there is axial misalignment or pipe deformation, flexible repair material is used to ensure that the inner lining material adheres to the original pipe wall; for level 3 rupture, level 3 leakage, and level 4 disconnection defects that require local repair, stainless steel quick locks are used for repair, but when the defect location is accompanied by axial misalignment or pipe deformation, flexible repair material is used for repair.

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