Underground Engineering Waterproof Technique in Renovation Project

(1. School of Engineering and Military Engineering, PLA University of Science and Technology, 210007 Nanjing; 2. Nanjing Huanli Construction Engineering Co., Ltd., 210087 Nanjing) has conducted various technical studies. In construction, the effect of waterproofing of concrete structures should be fully exerted, attaching importance to the structure of additional waterproof layers, multi-channel protection, and comprehensive management.

(3) The structural detail waterproof design is unreasonable. Such as deformation joints, construction joints and other improper structure, as well as improper selection and other reasons, making it the main hidden dangers of the tunnel project leakage.

(4) Leakage caused by changes in the surrounding environment. At present, large-scale infrastructure construction is being carried out around the tunnel. Because these projects are adjacent to each other and are in close proximity to each other, it will inevitably cause changes in the groundwater movement around the tunnel, which will cause significant changes in the water pressure acting on the tunnel structure.

(1) With the popularization and application of commercial concrete, the principle of the preparation of waterproof concrete is difficult to achieve, in particular, the slump of pumped concrete is large, the water-cement ratio often exceeds the limit, and some methods are satisfied by increasing the amount of cement. The requirements of large slumps require higher construction requirements. Otherwise, due to the increased shrinkage of concrete, cracks tend to occur and cause leakage. If you simply rely on the waterproof function of concrete itself, it will cause greater leakage.

(2) Unclear understanding of the performance, function, and application of the waterproof material used. If slag cement or ordinary cement is used in waterproof concrete, UEA composite expansive agent, alumite, and expansive cement are used mechanically. The construction maintenance is still unable to meet the requirements according to the traditional construction process or conservation, resulting in failure to obtain the desired waterproof effect. .

(3) The quality of the waterproof material used does not meet the design requirements, or does not meet the conditions of use of the special underground engineering environment, causing leakage.

(1) Uneven settlement of the foundation resulted in structural fracture.

(2) Waterproof structure Because of the poor adhesion of waterproof membranes, a tunnel project for corners and stays was built in 1996. It was constructed by open cut method. The tunnel floor is reinforced concrete, and the wall is underground continuous wall + color steel plate lining. The top plate is a reinforced concrete prefabricated plate. At present, there are different degrees of leakage in various parts of the tunnel. To ensure the safety and durability of the tunnel and improve the conditions of use of the tunnel, a comprehensive analysis and study of the tunnel's waterproof system must be conducted to completely resolve its existence. The leakage of water can meet the requirements of the project.

1 Analysis of Engineering Leakage Water 1.1 Design factors have insufficient understanding of groundwater movement laws and water pressure. Due to the high groundwater table, when the depth of the local engineering project exceeds the groundwater level, the pressure of the water level will cause osmotic pressure. In addition, the groundwater is a complex solution and often contains some harmful gases and minerals. And organic matter etc. will erode the concrete structure when it exceeds a certain limit.

The waterproof solution chosen is not reasonable. The tunnel mainly relies on the concrete structure to be waterproof. There are no internal and external waterproof layers penetrating the entire tunnel at the tunnel floor and side walls. Only waterproof measures are added at the joints, and the top plate adopts prefabricated panels. These are the causes of leakage of the project. Water's immediate danger. :2006-03-01 Cheng College, Lecturer.

Inadequate handling or scratches on the waterproof layer.

When pouring waterproof concrete, only pay attention to grading and admixture while ignoring the construction quality, the water-cement ratio is not strict, the vibration is not true, resulting in honeycomb, pitting, holes and other ills.

The construction of deformation joints or through-wall pipes, etc., did not take the positioning of the water stop belt seriously. When the concrete was poured on both sides, any collision occurred, and the water stop belt was deflected, resulting in poor connection and leakage.

The quality of backfill soil has a great influence on the waterproof performance of underground works. When the backfill soil is not dense and real-time, due to the atmospheric precipitation and the replenishment of the surrounding surface water, the backfill soil layer will form an upper layer of water with a large water content. This layer of stagnant water will generate hydrostatic pressure on the project. Leakage of the project.

1.4 Other factors As a subproject of the main project, waterproof engineering is often not fully understood for its importance. In addition, improper management and supervision personnel who are not familiar with waterproof supervision will cause leakage of the project.

Waterproofing is an important factor that affects the quality of waterproofing.

2 Research on waterproof technology of underground engineering 2.1 Fully exploiting the self-waterproof effect of concrete structures Waterproofing of underground projects must be based on the quality of waterproof concrete of the main structure in order to play a complementary and mutual overall waterproof effect. Concrete structures are self-waterproof to the entire underground works. The waterproof plays a decisive role. Waterproof concrete shall be prepared by adjusting the mix ratio, adding admixtures and admixtures, and its impermeability rating shall not be less than P6. Concrete cushion of waterproof concrete structure floor, the strength grade shall not be less than C15, the thickness shall not be less than 100mm, In the soft soil layer should not be less than 150mm, and the thickness of the waterproof concrete structure should not be less than 250mm. Under the conditions of ensuring the material and design quality, the construction quality of the waterproof concrete must be guaranteed to ensure that no leakage occurs.

In the preparation of waterproof concrete, in addition to cement, sand and other raw materials to meet the requirements of waterproof concrete, according to the needs of the project can be mixed with water reducing agent, swelling agent and other additives, its type and dosage should be determined according to the test; In addition can be mixed A certain amount of admixtures such as fly ash and silica fume can also be blended with steel fibers or synthetic fibers according to engineering requirements to formulate structural waterproof concrete with waterproof effect and strength grade that meet the requirements.

2.2 Attachment to Concrete Structures Additional Waterproof Layers There are multiple leaks in the sidewalls, floor, etc. of the tunnel. One of the important reasons is that no additional waterproof layer is provided. In addition, the tunnel structure is in a saturated water-bearing stratum. At the same time, the joint force between the retaining wall of the underground continuous wall and the inner lining and the structural characteristics of the slab need to be provided with an additional waterproof layer, and an additional waterproof layer is provided to strengthen the joints against water and cracks and water (such as construction. The effects of seams, expansion joints, etc. are obvious, and it is necessary to strengthen the long-term protection and durability of concrete structures.

The installation of additional waterproof layers for underground works is divided into external waterproof and internal waterproof. The two methods have their own roles and scope of use, and should be determined according to the situation. The comparison is shown in Table 1.

Table 1 Waterproof and Waterproof Comparison Project Waterproof Inner Waterproof Definition Waterproof layer is set on the outside of the underground structure, also known as waterfront waterproofing. The waterproof structure is set on the inner side of the underground structure, also known as the waterproof function of the backwater surface. It is often used in new construction projects; Protect steel from corrosion; prevent concrete from being eroded by groundwater, extend the service life of the concrete, stop leaking and stop water, and it is often used in maintenance or reconstruction projects. National standard fortification requires self-waterproofing; set rigid or flexible additional waterproof layer on the outside of the structure. Remedial measures taken in case of failure The engineering quality standard does not permit water seepage, and there is no wet stain on the surface of the structure. For first-grade waterproof grades, the material of the water-permeable waterproof layer is not allowed to be selected according to the fortification requirements and construction conditions, and the waterproof material suitable for it is selected according to the characteristics of different parts and Leakage situation, select the appropriate waterproof material system to synthesize external waterproof and structural waterproof concrete at the same time construction, through mutual interaction, complement each other concrete waterproof and additional waterproof layer joint action, additional waterproof multi-channel fortification, comprehensive treatment of other pouring concrete cushion After that, you can The water layer construction does not occupy the construction period within the structure and occupy a certain period of time; when the interior decoration is easy to destroy the inner waterproof layer of the construction, the outer waterproof structure is either fully enclosed or partially closed, and its purpose is to pass through the waterproof material in the structure. The surface of the waterfront forms a barrier to water repellency beyond the main body of the project structure. This approach is feasible in design, and the actual operation often results in unsatisfactory results. In addition to product quality, there are several problems: (1) Excessive structural deformation or excessively wide cracks, which exceeds the elongation rate of the material and breaks the waterproof layer; (2) External waterproofing of the structure, if used with coils or coatings A joint and the head problem, especially the overlap and the head of the coil waterproof layer is difficult to operate, it is difficult to ensure that the groundwater does not penetrate through the overlap and the head; (3) the adhesion and destruction of the waterproof layer and the base surface is also outside The main problem of waterproof leakage. When the waterproof layer is applied, it is generally required that the base surface is smooth, dense, non-leaven, and dry, or the moisture content is within the allowable range. However, external waterproof failure is often caused by lax construction requirements, lack of explicit requirements, and the time for grabbing.

With regard to the waterproof layer in underground engineering, developed countries in Europe and the United States pay more attention to laying a complete waterproofing layer on the outside of the envelope structure to form a flexible waterproof lining, and it is a double-layered coiled material and presets plugging facilities. This type of waterproof liner has good water resistance, tensile strength, extensibility, and certain repairability. Within a certain deformation range of the concrete structure, it must be small, with good irrigation, and can be filled with fine cracks. To have good flexibility and hydrophilicity, at the same time, the cured product should have a certain degree of compression resistance. 71994-2015 ChinaAcademic can not only enhance the impermeability, but also prevent the concrete from cracking or not being dense and suffer from harmful media in groundwater or surface water. Erosion and destruction. However, this type of waterproofing is usually used for new construction. For the maintenance and renovation of old constructions, the inner waterproof layer is often added to achieve the purpose of waterproofing. The commonly used additional waterproof layer materials are two types of coil waterproof layer (waterproof board) and paint waterproof layer.

2.3 The single material can not meet the waterproof requirements At present, many new types of waterproof material, but have their own characteristics, are not perfect, it is difficult to rely on a single material to solve the leakage of water, especially for the waterproof level of a tunnel renovation project, must According to the characteristics of different parts of materials and engineering, while considering the waterproof effect, ease of construction, cost and other factors to choose. In the design, coatings or coils are generally used as the additional waterproof layer. Among them, the waterproof layer of the coating is mostly made of cement-based penetrating crystalline waterproof coating, followed by the reactive polyurethane waterproof coating; and the waterproofing layer of the coil is generally selected by SBS. Asphalt waterproofing membranes, PVC waterproofing membranes, etc. The advantage of waterproofing membranes is that the thickness and quality of the material are easy to control, and the ability to adapt to the cracks in the base layer is strong, but the disadvantage is that it is easy to drown and the detailed treatment is a weak link; the advantage of the waterproof coating is the ability to adapt to the surface of the complex base layer, and it is not easy. Drainage, the disadvantage is that the thickness of the material, the quality is difficult to control, and poor ability to adapt to the base layer cracks.

The general principle of selection is: large-area flat (such as the top surface) is dominated by coils, the structure is complex, and the wall surface of the underground wall is mainly painted with wet surface (such as polyurethane coating). In the rainy season, the ceiling must meet the requirements of the construction period. Additional waterproof material can be polymer mortar and so on.

2.4 Multiple fortifications, comprehensive management To meet the waterproof requirements of the tunnel remodeling project as a level one, multiple defenses are required, and composite waterproofing is necessary. The waterproof materials used in the coiled materials and the waterproof materials used in the coatings are used together to give full play to their advantages and achieve the goal of preventing seepage and plugging.

When selecting materials, it is necessary to investigate whether the waterproofing membrane matches the waterproof coating, whether the binding of the membrane, coating or sealing material and the base surface is matched, whether the grouting material matches the base surface, and whether the construction method of the waterproof material is matched or not. Problems. After considering the influencing factors of cost, duration, and construction environment impact, the materials to be used should be tested for material properties and related indicators after coordination to determine whether the materials used match each other and determine the best waterproof material. Match each other's reasonableness and operate in accordance with appropriate standards and specifications during the construction process.

In the construction process, for a large area, a layer of waterproof paint may be applied first, and then the paint is used as an adhesive, and the waterproof material compatible with the paint is pasted, and an excellent comprehensive effect will be obtained. In the deformation joints, construction joints and other parts will be based on the actual leakage of the situation, carry out multiple protection, comprehensive management.

3 Comprehensive study of plugging materials and construction techniques As the tunnel faces the lake water in the south, the groundwater pressure is large, and the walls and floors are thicker and may have deeper cracks. Different treatment methods should be adopted according to the actual leakage conditions investigated. The principle is the combination of blocking and prevention, the combination of palliative and permanent cure, and the use of multiple defenses to ensure safety and reliability.

In view of the existing leakage of the tunnel, grouting water plugging technology should be used first to plug the leakage point, and then the appropriate waterproof coating and sealing material should be selected for further sealing. When it is used, it can use resin mortar, resin concrete and other repairing and filling, polymer mortar, polymer coating (having the function of self-healing and self-closing cracks), spraying and sealing to achieve multiple protections and comprehensive treatment.

3.1 Selection of grouting materials Grouting is a practical and engineering technology with a wide range of applications. At present, grouting materials with good waterproof plugging effect mainly include: polyurethane and epoxy resin.

The grouting material can adopt hydrophilic epoxy grouting material, which has better permeability, adhesion and physical and mechanical properties, and has double functions of reinforcement and plugging. In addition, the low-expansion, hydrophilic polyurethane also has the dual function of reinforcing and sealing water. Of course, its fillability and strength are inferior to those of epoxy grouting materials. However, for large leakage of water, the effect of plugging of polyurethane is better than that of polyurethane. In the epoxy grouting material, since the grouting fluid can form an elastic body, the plugging effect of deformation joints, construction joints and the like which will continue to be deformed is better.

3.2 Research on materials, construction and technology In the treatment of seepage water in underground engineering, the key is to find out the cause of leakage and the degree of damage caused by water seepage to the project and find out the exact location of water seepage. The leakage of underground engineering is mainly the leakage and large-area leakage of “three-seam” cracks, construction joints and deformation joints. For a large area of ​​serious leakage of water, generally adopt a comprehensive approach to management, that is, rigid and flexible combination of multiple lines of defense.

Crack leakage water can take corresponding measures according to the amount of water leakage and water pressure. For cracks with less water seepage, the cracks can be cut into V-shaped grooves, compacted with quick-setting material, and grouted for cracks with large water seepage. , and then use surface-enhanced water-repellent mortar, polymer waterproof mortar or paint to enhance waterproofing.

For multi-channel fortification, grouting and leakage shall be performed on the leakage area first, a layer of inorganic rigid waterproof coating shall be applied, and polymer cement mortar shall be used for surface protection, etc. The plugging of thicker parts may adopt high pressure grouting method. The thin part can use the traditional grouting method. Among them, the water-soluble polyurethane plugging agent is a grouting plugging material with good effect, and the inorganic rigid waterproof coating can use the cement-based penetrating crystal waterproof coating with simple construction. A rigid waterproof coating should not be used at the deformation joints to prevent new deformations caused by continued deformation.

Research on Wall Insulation Technology of Cold-Reclaimed Round-wood Small Residential Buildings Yang Yong, Yu Xia (Heilongjiang Institute of Science and Technology, Harbin, 150027) Progress of the work, good wall stability, and strong earthquake resistance. Through the use of different caulking practices during construction, the airtightness of the wall was solved and the insulation performance of the external wall was ensured.

As one of the types of wooden structures, round logs are favored for their good ecological and renewable resources. However, because of the large amount of wood used, they are often used in small residential buildings such as high-end villas and resort hotels. . It is the first choice for small residential buildings that do not shape the round wooden building, which is simple and natural, rough and unrestrained, and meets the requirements of authentic rural life pursued by small villas such as high-class villas. Based on the above reasons, the Golf Resort Mountain Resort was developed and developed in Harbin Erlongshan National Scenic Area, and it is the first batch of independent domestically shaped round residential buildings ().

Fund Project: Heilongjiang Institute of Science and Technology introduces the talented person to fund the project 1 The problem of not shaping the round wooden small residential building The round wooden building refers to using the round wood as the wall construction material, the round side of the round wood is grooved, and the layers are piled on each other as the weight bearing. The water resistance of walls, vertical and horizontal walls that overlap and bite underground works is system waterproof. From the structural level, waterproofing requires cooperation and convergence between the upper and lower levels; from the specific operation point of view, the strength and adhesive strength of 71994-2015 China Academician are to be well established. The water-soluble polyurethane slurry is poured.

Sealing materials should be able to adapt to the deformation caused by temperature changes and have a strong bonding properties, such as the use of elastic epoxy mortar.

In places with severe leakage, high-pressure jet grouting can also be used to form curtain water interception, or a certain part of the structure outside (as far as possible to form a closed form) to spin the spray, this can change the mechanical parameters and permeability coefficient of the loose soil layer, reinforcement Soft ground, cut off the source of water seepage, to achieve the purpose of sealing.

Waterproofing requires not only good waterproof materials and accessories, but also perfect waterproof design and careful waterproof construction. At present, there are more and more waterproof renovation projects for underground works. It is necessary to carry out relevant waterproof technology research for such waterproof projects first. On this basis, the corresponding processes of waterproof materials, design, and construction can be correctly performed. To achieve the goal of imperviousness and ensure the quality of the project.

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