This paper introduces the application of the composite waterproofing system of polyethylene polypropylene reinforced roll and non curing rubber asphalt coating in the underground engineering of Beijing metro line 15.
Beijing metro line 15 is located in the north of Asian Games Village, extending northeastward to Shunyi district. The line is generally east-west-northeast, starting from Xiyuan in Haidian District in the West and ending at Chaobaihe Hedong District in Shunyi District in the East. The total length of the line is 45.7km, with 2L metro stations. Among them, the underground line is 32 kilometers, and there are 13 underground stations. After completion, it can effectively relieve the traffic pressure in the Olympic center area and the northern area of the Asian Games Village.
Metro line 15 passes between the North Fourth Ring Road and the North Fifth Ring Road. The geological structure of this area is complex. It is the geological structure of multiple layers of cohesive soil, gravel and pebble under the fourth flood alluvial plain in Beijing. Under such geological conditions, the subway is built and waterproof. The building structure is greatly affected by the upper stagnant water, phreatic water and confined water. In order to ensure that the subway structure does not leak and meet the requirements of operation safety and service life of the structure, it is very important to do a good job of permanent waterproofing of the subway structure.
Characteristics of composite waterproofing system of polyethylene polypropylene reinforced roll and non curing rubber asphalt coating
Polyethylene polypropylene reinforced coiled material has strong impermeability, high tensile strength, uniform surface, easy to bond, good low temperature flexibility, large friction coefficient, small linear expansion coefficient, good stability, strong deformation adaptability, long service life, wide application range, non-toxic, odorless, green and environmental protection and other excellent technical and economic comprehensive properties. The non curing rubber asphalt waterproof coating is a new type of waterproof material, which can keep the sticky paste and has the creep in the application state for a long time.
The coating can seal the cracks and pores of the base course, adapt to the complex construction work surface, do not solidify for a long time after contacting with the air, and always keep the characteristics of sticky gum. It has strong self-healing ability, adheres when touching, and is difficult to peel. It still has good adhesion performance at - 20 ℃. It can solve the problems of waterproof layer fracture, flexural fatigue and aging caused by cracking stress of base course. At the same time, the problem of water channeling in the waterproof layer and the compatibility of the existing waterproof roll and the waterproof coating are solved, so that the waterproof reliability is greatly improved. The physical and chemical properties of polyethylene polypropylene waterproof roll book shall meet the requirements of Table 1, and the physical and chemical properties of non curing rubber asphalt waterproof coating shall meet the requirements of Table 2.
Advantages of the composite waterproofing system of polyethylene polypropylene reinforced roll and non curing rubber asphalt coating
One The upper and lower surfaces of the polyethylene polypropylene reinforced coiled material are covered with non-woven fabric (which is not possessed by the modified asphalt waterproof coiled material and other polymer waterproof coiled materials) to enhance the tensile strength of the coiled material, increase the surface roughness and friction coefficient, increase the impact resistance and mechanical damage resistance of the core layer, and provide the three-dimensional mesh structure for bonding, which can prevent the impact and mechanical damage with the non curing rubber asphalt Waterborne coatings achieve strong and durable adhesion; non curing rubber asphalt waterproofing coatings have excellent creep properties, super bonding properties, self-healing properties, chemical corrosion resistance and anti-aging properties, and have become the first choice for many large and medium-sized key projects.
2. The use of polyethylene polypropylene reinforced roll and non curing rubber asphalt waterproof coating makes the waterproof layer not only have the advantages of uniform thickness of roll, good quality stability and durability, but also have the advantages of good overall waterproof coating, and complement each other's strengths and weaknesses; at the same time, it solves the compatibility problem when the waterproof roll and waterproof coating are mixed, and can receive good waterproof effect.
The system is non-toxic, tasteless, pollution-free, harmless to the environment and human health, conducive to energy conservation and emission reduction, environmental protection, environmental protection, and sustainable economic and social development. The system is constructed by cold bonding method, no open fire is needed, and there is no fire hazard, which is conducive to fire safety.
Conditions to be met in waterproof construction
1. The project quality of base course shall meet the design and specification requirements. Before the construction of the waterproof project, the quality acceptance of the preceding project must be carried out, and the construction can only be carried out after it is qualified.
2. All kinds of embedded pipe fittings shall be embedded in advance according to the design and specification requirements, and the waterproof and sealing treatment shall be done well.
3. The waterproof construction should not be carried out in rainy days and strong winds above level 5.
Waterproof design and material selection
Waterproof design is usually carried out in the following two ways, as shown in Fig. 1 and Fig. 2.
The waterproofing design of local works shall be in accordance with the requirements of GB 50108-2008 technical code for waterproofing of underground works. The waterproofing grade is determined as grade I. according to the principle of combining rigidity with softness, adjusting measures to local conditions and comprehensive treatment, the waterproofing design combining self waterproofing of concrete structure and waterproof roll shall be adopted. The double-layer fortification scheme (0.8 mm polyethylene polypropylene reinforced coiled material + 1.5 mm non curing rubber asphalt waterproof binder) × 2 is adopted for the base plate, top plate, side wall and other parts of the subway station building.
Through comprehensive analysis, Shengjie company, the undertaking unit of this project, has optimized and refined the design scheme, and put forward key treatment measures and methods for the overlapping of waterproof layers, the ending of waterproof layers and other joints prone to leakage of different materials, in combination with the use of waterproof sealing materials, so as to improve the reliability of waterproof layers. Before waterproof construction, the company conducted safety and technical disclosure to operators.
Waterproof construction preparation
1 tool preparation
Broom (used to clean the base course), punch, blade, (to remove the convex and concave attachments of the base course), brush, scissors, tape measure, scraper, heating bucket (tank), hot melt, holding bucket, non curing rubber asphalt waterproof coating spraying machine and other equipment.
2 preheating preparation of binder
Pour the non curing rubber asphalt waterproof coating into the adhesive heating tank for heating. When the equilibrium temperature of the adhesive rises above 140 ℃, stop heating and maintain the temperature.
3 on site storage requirements for coiled materials
The coiled material shall be handled with care and stored in a proper place on site according to the requirements of the specification. The coiled material shall not be stacked in multiple layers, so as to avoid deformation of the coiled material caused by compression.
Waterproof construction technology
1. Process flow
Base acceptance → base treatment → spraying or scraping non curing rubber asphalt waterproof coating → laying polyethylene polypropylene fiber waterproof roll → node treatment → closing, fixing and sealing → self inspection of waterproof layer → acceptance
2 key points of waterproof construction
(1) Base acceptance and treatment: the base surface shall be solid, flat, clean, dry and free of dust and oil, and the concrete surface shall be free of honeycombs, holes, protruding reinforcement heads and formwork joints. If it does not meet the acceptance requirements, it shall be treated as equality again.
(2) Setting out planning and material preparation: according to the construction area and the amount of coiled material and binder, the setting out planning and nearby scattered materials shall be done to improve the operation efficiency.
(3) Determine the construction method: according to the actual situation of the construction site, determine to use spraying or scraping for construction. Generally, scraping method can be used for the construction of subway station floor, roof and other planes; spray method can be used for the construction of opposite wall, ground beam facade and internal and external corners.
(4) Scrape and apply non curing rubber asphalt waterproof coating and lay coiled material. For the floor and roof of the subway station, evenly scrape and apply 1.5 thick non curing rubber asphalt waterproof coating and lay polyethylene polypropylene fiber reinforced roll. For the double-layer waterproof design requirements, another layer of waterproof layer with the same thickness shall be added on the basis of the first layer to ensure that the waterproof layer meets the requirements of the first level fortification standard. When rolling and laying the coiled material, the surface of the coiled material shall be scraped lightly, and the internal air shall be discharged, so that the coiled material and the non curing rubber asphalt waterproof coating are firmly bonded on the structural base.
When the coiled material construction personnel unfold the coiled material with a length of 20-30 meters, the force on both sides of the coiled material shall be balanced, otherwise, the edge of the coiled material will deviate. When this happens, the deviation must be corrected by cutting method, and then the coiled material shall be bound in strict accordance with the relevant provisions of the joint bonding of the coiled material.
(5) Spray non curing rubber asphalt waterproof coating and lay coiled material. For subway vertical wall, ground beam facade and internal and external corners, the method of spraying non curing rubber asphalt waterproof coating can be used for construction. When spraying the binder, use the non curing rubber asphalt waterproof coating spraying machine to spray the coating evenly. The size of spray nozzle shall be appropriate, the spraying speed shall be uniform, and the spraying thickness shall be uniform. After one spraying, there shall be no exposure or uneven thickness. For some places with insufficient thickness or missing spraying, spray twice or make up spraying until the required thickness of binder is reached.
(6) The overlapping width of polyethylene polypropylene waterproof roll is 100 mm. When the roll is overlapped, the overlapping joints on the two adjacent sides of the bottom layer shall be staggered, and 1 / 2 of them shall be taken for overlapping. The end of the roll shall be firmly bonded to prevent edge warping and cracking. The overlapping edge shall be leveled and compacted with scraper to ensure dense overlapping.
(7) When polyethylene polypropylene waterproof roll is used for single-layer construction, the smooth surface of the roll shall be downward; when double-layer construction is used, the smooth surface of the first layer shall be upward and the smooth surface of the second layer shall be downward.
(8) In the case of basement roof and planting roof waterproof construction, there will be two design situations: first, when the protective layer is directly made on the waterproof roll, the roll lap joint can not be used as a cover strip; second, when the protective layer is not made on the waterproof roll, the roll lap joint can be used as a 10 cm cover strip, and the bonding agent should be sealed with polymer binder.
Measures and methods for strengthening treatment of 3-node
Make different waterproof treatment for each detail node, or strengthen the waterproof reliability of the node by adding additional layer and other measures.
(1) Post cast strip
An additional layer of non curing rubber asphalt coating sandwiched with carcass reinforcement material shall be added to the post cast strip. The additional layer shall extend 300-400mm outward from both sides of the post cast strip, and its waterproof structure is shown in Fig. 7-10.
See Fig. 11-fig. 12 for the waterproof structure of the joint part of the composite waterproof layer constructed by the external anti sticking method of the base plate and the vertical wall.
(2) See Fig. 13 for the waterproof structure of the composite waterproof layer constructed by the method of anti sticking inside outside the base plate and vertical wall.
(3) Wall bushing
The composite waterproof layer at the end of the outer wall through wall pipe shall be clamped tightly and sealed. See Fig. 14 for the waterproof structure.
4. Precautions
(1) The non curing rubber asphalt waterproof coating shall be evenly sprayed, and the adhesion rate between the coiled material and the non curing rubber asphalt waterproof coating shall be ≥ 90%.
(2) The waterproof layer shall be firm, flat and clean without sanding, peeling, hollowing, sharp convex, depression, loosening and cracking.
(3) The coiled material waterproof layer shall be pasted, lapped and sealed in accordance with the design requirements and construction specifications, and shall be firmly pasted, free of defects such as damage, slippage, edge warping and folding, and closely combined with the base course, with uniform thickness.
5 finished product protection
The construction of waterproof works shall be provided with specific protection measures for the finished products of waterproof operation. The operators shall not destroy the finished products of waterproof system at will while constructing. After the completion acceptance of the project, there shall be a special person responsible for the maintenance and management. It is strictly prohibited to drill holes, drill holes and damage the waterproof layer after the acceptance.
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