In the past 50 years, underground engineering waterproof technology in China has not allowed water seepage due to various types of underground construction at different times. The surface of the structure and lining structure may have a small amount, see the wet building housing basement: the total wetted area should not exceed 1/1000 of the total waterproof area (including the roof, wall, floor); any 100m2 wet area on the waterproof area does not Over one place, the maximum area of ​​a single wet collapse is not more than 0.1m2. Other underground works: The total wet collapse area should not exceed 6/1000 of the total waterproof area; No more than 4 wet collapses on any 100m2 waterproof area, single wet stain The maximum area is not more than 2m2m level with a small amount of leakage points, no cable flow and no leakage of sediment, no leakage point of 00m2 in the waterproof area shall not exceed 8 points, the maximum leakage of a single leakage point shall not exceed 3L/d, a single wet collapse The maximum area is not greater than 0.4m2. There is a leakage point in class IV. The average leakage of the whole project of cable flow and leakage sediment shall not be greater than any 100m2. The average leakage of water shall not exceed 4L/(m2-d> note. When a lining structure is used for a Grade II project, the waterproof rating of the envelope structure can be reduced by one level.
Table 2 Applicable scopes of different waterproof grades Waterproof grades Scope of application Project site Class 1 personnel's long-term stay places; Storage sites with bad or occasional wet collapse will cause items to deteriorate, fail, and seriously affect the normal operation of equipment and endanger project safety Location of operations; extremely important battle-ready project housing, offices, hospitals, hospitals, hotels, entertainment venues, shopping malls, grain storages, vaults, archives, cultural relics, communications engineering, computer rooms, power station control rooms, generator rooms , power distribution rooms, higher-demand production workshops, railway passenger stations, luggage rooms, underground railway stations, command engineering, protection professional team projects, military underground libraries, etc. In the case of , items that do not deteriorate or damage the items, and places that do not substantially affect the normal operation of the equipment and the safe operation of the project; the important battle-planning general production workshop, air-conditioning room, fuel storage, cold storage, storage, underground garage, Electrified iron and steel tunnels, high-speed railways and highways, cold and cold regions, railways and highways, subways Intermediary tunnels, urban roads, underwater pavilions, general road tunnel arches, urban tunnels, pump rooms, personnel shelters, and other places of temporary activities for m-class personnel; general battle engineering cable tunnels, urban common ditch, water tunnel, non- Electrified railway tunnels, general highway tunnel side walls, strategic preparations such as raceways and evacuation arterial roads, etc. Class w water drainage channels, rural pedestrian passages, culverts, etc. that do not have strict requirements for seepage water Note: 1 Underground works waterproof rating, except press In addition to the division of engineering categories, it is also possible to achieve remarkable progress based on the development of the constituent units.
The basic status and characteristics of the development of waterproof technology for underground engineering in China are as follows: With the rapid development of petroleum, chemical and building materials industries and achievements in science and technology, waterproof materials have moved from a few species to a multi-type and multi-variety structure. Synthetic germanium molecular materials, polymer modified asphalt materials, waterproof concrete, polymer cement mortar, cement-based waterproof coating materials, and various plugging and sealing materials have been widely used in various types of waterproofing projects. Waterproof design in general affirmed the principle of "prevention, drainage, cutting, blocking, rigid-flexible combination, suiting measures to local conditions, comprehensive management" and insisting on the principle of "multi-channel fortification, multiple materials and composite use", and summarizing different types of projects. In the use of anti-distribution combination (or blocking, supplemented with sparse), waterproof material and construction waterproof combination, flexible waterproof material (coil, paint) and joint sealing material complementary and other design methods. The construction technology and process equipment are becoming more and more mature. Basically, they can adapt to the development of various types of new waterproof materials, master the use requirements and conduct standardized operations. The National Standards for Waterproofing of Underground Works (GBJ108-87) and “Code for Construction and Acceptance of Underground Waterproofing Works†(GBJ208-83) formulated in the 1980s provided the basis for design and construction units to select the waterproof standard and waterproof method. With guidelines. The development of these waterproof technologies has played an important role in comprehensively improving the waterproof quality and reliability of underground projects.
Classification of Underground Works and Their Major Waterproofing Measures 1.1 Classification of underground works According to the construction environment, the types of underground works include crossing mountain bodies, and can be roughly classified as Rugao according to the construction methods and uses within the body, under the ground, and underwater.
Tunnel Engineering: railways, highway tunnels, underground railways, cross-river tunnels, and hydraulic and cable tunnels.
Underground structures: military, civil defense projects, t-city sharing ditch, hydraulic structures, storage tanks, swimming pools, etc.
Underground buildings: buildings (multipurpose) basements, underground buildings, warehouses, garages, subway stations, urban tunnels, commercial streets, etc.
Due to the different site, environment, hydrology, and geology of each type of project, construction methods vary, and can be divided into open excavation methods and undercut methods as a whole, including special construction methods: shield tunnels, caisson, underground Continuous wall, reverse structure, spray anchor support, pipe jacking, etc., so the requirements for waterproof technology are not the same. Under different conditions of use, the design of more underground works not only needs to be well-prepared for waterproofing, but it must be ensured that no leakage or leakage occurs. It is also necessary to comprehensively consider the problems of drainage, moisture prevention, ventilation, heat preservation, heat insulation, and noise.
1.2 Classification of Underground Works Waterproof Grade Underground works have long been affected by the change of groundwater level or surrounded by water. If leakage is caused by improper waterproofing measures, it will not only be difficult to repair and affect the normal use of the project, but will also cause corrosion of the main structure and sinking of the foundation. It is even submerged, endangering the safety of the project. Therefore, strict requirements should be placed on the waterproofing of underground works. The national standard "Waterproofing Technical Requirements for Underground Works" (hereinafter referred to as "the Code") under revision is still considering classifying the waterproofing rating of underground works into four levels, and increasing the quantification of each waterproof rating standard, which is very necessary (Table 1).
1.3 Application scope of different waterproof grades The design unit should select the waterproof grade according to the project's importance according to the importance of the project and the waterproofing requirements in use. See Table 2. According to the requirements in Table 2, the underground building waterproof grade is taken as an example. Most projects should meet Class I standards, and some projects should meet Class II standards. The classification of the waterproof rating and the scope of its application in the “Specifications†reflect the requirements of the applicable project, facilitating the qualitative and quantitative inspections and ensuring the quality and reliability of the waterproof project.
1.4 Waterproof Measures for Underground Works Currently, the waterproof measures taken in underground projects in China are various. According to engineering classification, the type of enclosure structure, main waterproofing scheme and selection of waterproof materials used in the design can be roughly summarized in Table 3. Analysis of waterproof measures and functions of underground works in various types of underground works mainly depends on enclosures. The structural waterproof design scheme includes the waterproof treatment of various seams and joints, the selection and quality of waterproof materials, and the construction technology level. Now take the form of various types of engineering envelope structure as the theme, and analyze some waterproof measures taken today.
Divide; 2 For projects that require more separation from the lake, in addition to the flood protection level, the corresponding preventive measures shall be taken.
Table 3 Waterproofing Measures for Various Underground Projects Engineering Type Enclosure 2.1 Tunnel Engineering The lining materials of the tunnel engineering envelope structure are mainly reinforced concrete. Therefore, various measures must be taken to improve the waterproof performance of the concrete itself, and the impervious grade of the waterproof concrete used Must not be lower than P8. At the same time, joint waterproofing of various parts of the lining should be carefully handled, especially the construction joints and deformation joints of the cast-in-place concrete linings, as well as the joints and grouting holes of the precast concrete lining segments, which guarantee the waterproofing of the lining. Quality is more important. The tunnel lining structure has the following three basic forms: (1) shotcrete (spray-anchor support) lining structure or cast-in-place reinforced concrete lining structure; (3) shotcrete lining or now-deflected reinforced concrete lining attached to off-wall ( Lining and application issues.
3.1 Promoting the Application of High-Quality Waterproof Materials In recent years, more and more new materials and new products have been developed and introduced in China. Although their performances are similar, there are no shortages of quality. However, it is difficult for design, construction, and construction organizations to identify them when they are selected. Inherent quality and durability, or due to price factors give up the choice of high-quality waterproof material. For this reason, it is necessary to strengthen the inspection and supervision of product quality, establish a scientific and strict product quality certification system, and ensure that good materials are quality-recognized.
In the early days, the concrete used for these three kinds of structures was mainly made of water-repellent concrete using a grading method, and some projects also added appropriate amount of water repellent. Among them, sprayed concrete and cast-in-place concrete linings are generally not prone to large-area leakage in the case of pre-grouting waterproofing and careful treatment of construction joints and deformation joints. When linings and joints have holes or pores locally and gushing water occurs, more grouting and water-proof materials such as A, N, C, etc. are used for post-grouting and better results are obtained. The segmental lining structure is mainly used in cross-river tunnels and subway projects; the wall-type wall structure is more used in tunnel openings, subway stations, underground powerhouses, and military air defense command projects. The waterproof effect of these two types of structures mainly depends on whether they have a correct and reasonable waterproof design scheme and well-conceived construction technical conditions.
In the past 10 years, although the form of the tunnel lining structure has not changed much, there are many new waterproof materials and application technologies available for lining waterproofing and joint waterproofing. For example, waterproof concrete with various types of admixtures, multi-variety grouting materials, troweling materials, synthetic lanthanum molecular waterproofing membranes, and waterproof sheets (more waterproof linings are used in railway tunnels and subway projects), all kinds of water stoppages The application effects of sealing materials such as belts, water-swelling sealing strips, and rubber strips are quite remarkable. Another example is that many construction companies have adopted a large number of engineering practices, summed up and formulated a number of applicable to a variety of environments or parts, to solve the water leakage problems of the operating procedures or waterproof workers, have to play an important role in ensuring the quality of waterproofing projects.
However, it is worth pointing out that when designing the tunnel body waterproofing scheme, it is difficult to fully grasp the hydrological and geological changes in different sections of the project and what leakage conditions and leakage levels will occur during construction. It is due to the randomness of leakage during the construction process, which is often blocked by side construction. A large number of projects require multiple repairs at the end of the construction period and after completion of construction. Therefore, it is necessary for the construction units to undertake such underground projects. The level of qualification and waterproofing technology put forward higher requirements. The "Regulations" under revision takes into account that the treatment of leakage not only exists in the process of project use, but also occurs in the process of project construction. Therefore, the contents of the annex to the original "Code" include the order of governance, material selection, and governance measures. The text of the "norms" is very necessary.
2.2 Underground Structures There are many types of underground structures, and the requirements for waterproof function should be based on the nature of the project, its purpose, and its waterproof rating and standards. According to the current selection of waterproof materials and technical level, it is not difficult to solve a variety of waterproof problems. The key to preventing leakage still lies in the need to take comprehensive measures and focus on the construction of the construction joints, deformation joints, structural nodes, out of population, through-wall fittings, embedded parts and other parts of the waterproof, meticulous construction is a very important part.
2.3 Underground Buildings At present, the level of waterproofing and the requirements for use of underground structures have been increasingly raised. The waterproofing levels of underground constructions for civil buildings and public buildings are to be Class I. Since most of the projects are built in cities, the site is narrow and the construction is difficult. Therefore, both the engineering design and the waterproofing scheme must be considered in conjunction with the site environment and construction conditions. In view of the years of practice of waterproofing of underground buildings at home and abroad, except for waterproof concrete with admixtures commonly used for enclosing structures, one or two kinds of waterproof materials should be used for the main surface of envelops of waterproof grades I and n. Waterproof layer to meet the requirements of multiple defenses. The basic method of external anti-sticking and external anti-sticking methods of the waterproofing layer of the coiled material (or coating film) is still the basic construction method of the coiled material waterproof layer.
Starting from the requirements of technological progress, in order to ensure the bonding quality of the lap joint edge of the waterproof layer of the coiled material, it is necessary to strongly advocate the selection of waterproofing membranes and waterproofing plates that can be used for hot-melting and welding methods to ensure the reliable waterproofing of joints. Sex.
2.3.1 External anti-external sticking method The external anti-sticking method shall be used to lay the waterproof layer on the floor cushion, and after the wall construction of the retaining structure is completed, the facade sheet (waterproof layer) shall be directly paved. Adhere to the outer surface of the envelope structure and then take protective measures. The advantage is that with the passage of time, the concrete of the wall of the envelope structure will gradually dry, which can effectively prevent the indoor humidity, but when the excavation of the foundation pit and the support of the sheet pile are taken, measures shall be taken to solve the influence of the horizontal support site. Waterproof layer construction problem.
2.3.2 External defense inner-laying method construction The outer-defense inner-bonding method is to build a permanent protective wall on the floor cushion first, and then lay the coiled material (waterproof layer) on the permanent protective wall and the floor cushion. Practice. After the waterproof layer is completely finished, the concrete of the envelope structure is finally poured. This is a construction method that has to be adopted in the construction environment is limited, it is difficult to implement the external anti-external sticking method °C 2.3.3 waterproof from the wall lining The program in addition to waterproof in the concrete wall and its inner surface of the envelope structure In addition to the measures, in order to meet the functional requirements, a wall-type interior wall is added on the inner side of the main wall. Although this design scheme is multi-channel fortification and is conducive to drainage, there is a cost problem. The walls of the envelope structure are not easy to be fully dried, and it is difficult to ensure the watertightness of the concrete joints of columns and walls. 2.3.4 Wet environment construction In recent years, some scientific research institutes and material manufacturers have developed waterproof coatings that can be applied to the surface of wet substrates, such as silicone rubber waterproof coatings, cement-based composite waterproof coatings, and cement-based infiltration crystallization. Waterproof coatings, as well as polyurethane waterproof coatings using media base materials, have achieved a good bonding effect, so that waterproof coatings also have a wide range of application prospects in underground waterproofing projects.
2.4 Adhere to multi-channel design principles 2.4.1 Based on the characteristics of the underground engineering structure and the requirements of the environment, it is necessary to adhere to the design principles of multi-channel protection, rigid and flexible waterproof materials, and comprehensive prevention and control in terms of waterproof technology measures.
2.4.2 In order to ensure that the underground engineering envelope structure plays a role in waterproofing and protection, the concrete structure body shall be waterproofed, and the flexible waterproof material waterproof layer shall be enclosed. The multi-channel comprehensive protection for detailed structural joints and joints shall be carried out. Technical measures. Neglecting or unilaterally emphasizing the role of any fortification is not reliable for ensuring the quality of underground waterproof works, and it is also undesirable.
2.4.3 The advantage of using multi-water protection for underground works lies in. The use of waterproof concrete for the envelope structure can exert load-bearing, waterproof, and water-bearing pressure. However, it is not possible to replace the waterproof concrete with the required impermeability grade with high-strength grade concrete. The waterproof body of the waterproof concrete structure is based on the use of flexible waterproof around it. The material waterproof layer, because of its good water resistance, tensile strength and extensibility, within a certain deformation range of the concrete structure, not only can it enhance the impermeability, but also can prevent the groundwater of harmful medium from being cracked or not dense due to the concrete. Or surface water damage and destruction; careful and careful handling of the construction site and joints of various parts of the waterproof, is to avoid leakage of waterproof engineering one of the keys, with very important significance analysis. It is true that the construction unit does not pay attention to the quality of waterproof projects and blindly lowers the cost in various types of underground projects. The design is not thorough and scientific, and the materials are not properly selected. The qualifications of construction units are low, there is no waterproof professional construction team or they do not operate in accordance with regulations. It is not uncommon for problems of mismanagement to cause varying degrees of leakage and economic losses. This is not a problem in the waterproof technology itself, but the new materials, new technologies, and new processes do not have the expanded applications for which the people concerned can correctly master and guide quality products.
3.2 Implementation of the Project Quality Assurance Period System The construction unit shall be the main body. Under the premise of carrying out waterproof project professional contracting or professional construction, a quality assurance period system shall be implemented for all types of waterproof works. It is particularly important to strengthen the cooperation of design and construction. The design unit should draw more and respect the opinions of the construction unit in formulating waterproof solutions and materials.
3.3 Improve Engineering Leakage Maintenance Technology The practice of a large number of underground waterproofing projects has proved that even if the design adopts thorough waterproofing measures and uses high-quality waterproof materials, due to the complicated environment and parts of the waterproofing project and the low detection technology means, it is still difficult to avoid varying degrees. The leakage problem affects the normal use of the project. Therefore, the construction unit must establish a waterproof construction professional team or team, and attach great importance to training personnel, constantly sum up and improve the technical level of construction and maintenance in order to successfully solve all kinds of complex waterproof technology problems, to undertake projects with good reputation for their own construction and Development creates conditions.
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