TECHNOLOGY OF MANUFACTURING CENTRIFUGAL CONCRETE PIPE WITH ABSORBING HOLES
The process of implementation of projects such as dam construction land, the water tunnels, bridges, flood release tunnels, stadiums, irrigation works, retaining wall, residential areas, buildings sports etc.. It is often designed underground drainage system to lower the saturation to reduce the instability of the ground water level rises due.
There are many solutions to collect and remove water to the solution that works in lower groundwater levels can be closed style described by some as typical solutions of the following models:
TECHNICAL REGULATIONS APPLICATION AND ACCEPTANCE TEST pile
The soft soil treatment technology in Vietnam
The foundation of the construction of housing, roads, dikes, dams and other works on some soft ground often poses a series of problems to be solved, such as low load bearing capacity of the foundation, the large subsidence and stability of the large area. Vietnam is known to be home to several major land, particularly the Red River and the Mekong River. Many cities and towns are important in the formation and development of soft ground with very complex conditions of the ground, along the rivers and coast. This fact requires the formation and development of appropriate technologies and advanced to handle soft ground.
This article presents some typical characteristics of soft soil, the problems posed by soil and some background processing technology. At the time of presentation and refers to the soil treatment solutions have been used in Vietnam. Some new background processing technology is presented and discussed. Some solutions to the foundation on soft soil conditions suitable for Vietnam and development
Some treatment technologies mentioned the following
+ Handle with Melaleuca and bamboo poles.
+ Reflect pedestal pressure treatment to improve stability and slope protection works of roads and dikes.
+ Preloaded with the aim to increase and decrease the intensity of the settlement.
+ Preload ground with vertical drain: technology enables accelerated consolidation process, shorten the distance and duration of water movement in the soil under the effect of load can be covered or soil suction vacuum.
+ Lime and soil piles of soil cement: lime or cement mixed with soil in the form of injection and spin in place. Technology enables the creation of soil lime, cement soil with lower intensity of conventional piles. This solution is suitable for deep soft ground handling, catering for the construction of roads, ports, industrial parks, repair and rehabilitation of dykes, dams ...
Cement + sand piles: using technology to create piles of sand holes, sand cement mix dress with vibrator system and casing holes.
+ Rock piles and piles of sand compaction: Technology allows increased intensity, soil bearing capacity and reduce settlement of the works. This solution is reinforced deep background. Suitable for work with large construction area, highways, ports, new land reclamation and polders.
+ Try to work: Concrete dumbbell weighing 10-15 tons, falling at an altitude of 10-15m by crane, allowing compacted soil and adding the sand pit through dress. Appropriate technology for background processing for the new land reclamation.
+ Background processing technology in small piles: piles with a diameter of 100-200mm is constructed with closed technology, injection molding or drilling. Technology transfer load to allow more in-depth work with materials cost optimization of reinforced concrete. This is the appropriate technology solutions to handle soft ground for the construction of houses, roads, land and buildings Savior works damaged by the foundation.
The cities in Vietnam such as Hanoi, Hai Phong, Ho Chi Minh City. Ho Chi Minh City are located in the basin of the Red River Delta and the Mekong River. These areas have relatively thick alluvial soil and clay major focus. With the goal of urban development, much needed choice of solutions and treatment technologies appropriate for the conditions of Vietnam.
Characteristics of soft soil should be improved to serve the practical needs of the construction and use of buildings. Weak soils often have high humidity and undrained shear strength is low. Land consolidation in the form of normal and low water permeability. In the ground water table often lies close to the surface, from 0.5 to 2.5 m. Some cases of soft soil with high organic content and the peat layer. For some types of land subsidence due to secondary accounts for 10-25% of total subsidence. In some areas of the city, geotechnical section that covers the ground with soil density, hardness, thickness and permeability different.
Generally weak clay soils are low bearing capacity and high compressibility subsidence. Some typical indicators of weak soil is presented below for reference:
- Humidity: 30% or greater for sandy soil
50% or greater for clay.
100% or greater organic soil.
- The number of regular N the standard 0-5
- Undrained shear strength: 20 - 40Kpa
- A shaft unconfined compression: 50kPa or less.
The determination of structures on soft soil out of the ground characteristics depend on the type of work (home, road, dam, dam, railway ...) and the size of the project.
2. The issues raised with weak foundations
Nail of roads, railways, buildings and other structures as set on soft ground usually pose the following problem to be solved:
+ The settlement: The settlement is great value, negative friction acting on piles due to compression of the ground.
+ Stability: Load capacity of foundations, stability of embankment, slope stability, earth pressure on retaining walls, horizontal load bearing capacity of the pile. The problem must be considered by the load capacity and the intensity of not big enough.
+ Greatly Cat unlucky, absorbent damaged by seepage problems and the effects of pressure under water.
+ Liquid Chemistry: Soil liquefaction is due to the load of trains, cars and earthquakes.
In the current conditions of Vietnam, the following practical issues are concerned:
- Construction of roads, irrigation, dikes and buildings on soft soil base
- Handling and reinforcing the dike roadbed on soft ground and exploring the use of technology requires deep processing.
- Handling landslides or river and sea dykes.
- Scuba diving and construction works on the sea.
- For the treatment of industrial parks built along rivers and coastal areas.
- Soil treatment to living with floods in the Mekong Delta.
3. Some treatment methods Soil
3.1. Melaleuca and bamboo poles
Melaleuca and bamboo poles are technological solutions to traditional processing platform for small load works on soft ground. Melaleuca and bamboo poles in length from 3 - 6 meters close to the ground reinforced with the aim to increase the load bearing capacity and reduce settlement. According to experience, often 25 bamboo or mangrove poles are close to 1m2. However should estimate bearing capacity and settlement of pile foundations bamboo or mangrove poles calculated by the method in practice. The use of mangrove poles in the ground conditions and load requires unreasonable anti piles sunk by small sections.
3.2. Reflect pedestal pressure
Reflect pedestal pressure is used to increase the stability of the embankment of the road blocks or the dike on soft ground. The method is simple but is limited to parts of the settlement arises reflect pedestal pressure and land area to build counter-pressure pad. The height and width of the counter-application platform is designed from the indicators of weak soil shear strength, thickness, depth of soft soil and the weight of the counter-pressure pad. Reflect pedestal pressure is also used to protect dykes, sparkling sand and sparkling control circuit.
Preloading method in technology solutions is often most economical to handle soft ground. In some cases pre-loading method does not use vertical drainage wells still succeed if time and conditions allow ground. Load in preload can be equal to or greater than the work load in the future. During loading and subsidence monitoring of water pressure. Class preloading embankment to be unloaded when the end of the settlement or basically happened. Preloading method is used to handle before the foundation of the Central Circus (Hanoi, the Swedish Institute for Children (Ha Noi), Maritime University (Hai Phong) and a series of works in the south.
Preload is simple technology, but it is necessary to examine in detail the ground. Some thin soil layer, sandwiched difficult to identify by conventional methods. Use measuring devices through static pore water pressure drilling and sampling ongoing. In some cases, due to the short duration loads, lack of monitoring and evaluation of adequate and after construction, land subsidence continues and damaged buildings.
3.4. Preload vertical drainage
In many cases, preload duration needed to be shortened construction, so the speed is increased coherence of the pile by using sand or water. Piles of sand are close by vibrating tube technology to occupy the land, then sand filled tube and shake to compaction. Piles of sand 30-40cm in diameter. It can be constructed to 6-9m. Solution pile of sand was applied to a number of foundation treatment works in the city. Ho Chi Minh City, Vung Tau, Hai Phong, Ha Noi.
The resin is used to handle soft ground in Vietnam since the 1980s. Equipment and technology used by Sweden to the plastic construction. Technology allows increased intensity and ground decreased coherence time.
At the Saigon river has built a tank with geometric dimensions and loads 43m diameter, 15m height, weight 20,000 tons. Foundation works with a thickness of soft soil treated with a resin base vertical drainage combined with vacuum preloading with. The depressions are approximately 1.0 m. Results subsidence after 2 times the actual load in the 3.26 m (first settlement by 2.4 m and 0.86 times after the settlement by m), there are differences between measured and estimated results. The difference may be due to the process not to mention calculation of the horizontal deformation and work place conditions along the river.
In background processing technology with preloaded in the vertical drainage is essential place subsidence monitoring system.
3.5. Lime soil pile and soil cement
Equipment and Swedish technology used to make the soil cement and lime soil. The results of laboratory studies and field application show that:
- Lime soil pile and soil cement drainage role and reinforced base. This is the appropriate technology solutions to deep soft soil reinforcement.
- Indicators of strength, deformation depends on time, the soil type, organic content, particle size and concentration of cement and lime used.
- The use of cheaper cement in Vietnam conditions than lime. The percentage used is 8-12% and the percentage of cement is 12-15% dry weight of soil.
- Equipment capable of Swedish soil cement piles.
- Can be used with their equipment regularly to check the quality stakes.
- Pile soil cement is used to reinforce road base, floor, industrial park, the dike ...
The effect of temperature on the intensity of ground limestone.
3.6 Piles of sand cement
Sand pile construction equipment can be used to cement the sand piles, steel pipe is closed and shake the ground and take the place of soft soil. Sand and cement are mixed to flow into the casing. Compacted sand with cement and casing vibration.
3.7. Piles and piles of sand compacted stone
In order to reduce land subsidence and weak intensity, sand piles or piles have been used dung.Cat compacted and compacted stone by vibrating system and can use technology in tube dress. Technology Used sand piles and piles of stones to build a building in the city, Ho Chi Minh City, Hanoi, Hai Phong and Vung Tau. Load capacity of the sand piles depends on the pressure exerted on the soft soil deposits. According to Broms (1987) critical pressure of 25 Cu with Cu = 20kPa, Ф 40cm sand pile bearing capacity is critical 60KN. The safety factor of 1.5 can be used.
3.8. Trying to close
Try to play and allows enhanced load capacity and the reduction of the settlement. Technology is used to reinforce soft ground in Hanoi, Hai Phong and Ho. HCM. Fruit punch with precast concrete blocks weighing from 10-15 tons lifted by crane and dropped down from the surface to 15m high 10-compacted base. The distance between the holes dress 3x3, 4x4 or 5x5m. The depth of compaction affects cohesion is calculated by:
D = 0.5 √ WH
In due: D - depth is effectively compacted
W - Weight punch, attack
H - height fell fists, m
After compaction at a point a few times and kicked sand filled pits dress. The mobile phase to reinforce the soft soil simple and economical, suitable for new phenomena and land leveling up. necessary to check the effectiveness of compacted before and after using the device regularly dress or horizontal compression in the drill hole.
3.9. Soil reinforced with piles for small section
Pile section is meant to be the kind of small-diameter poles or edges from 10 to 25cm. Small piles can be constructed by building technology, presses, injection drilling. Small piles are used to reinforce the foundations for buildings, roads, land cover and other structural forms. Small pile is a good solution to handle soft ground for effective economic and technical. Small piles technology for reducing the cost of materials, simple construction, and the work load transfer to the weaker soils, reduce total settlement and the settlement of the differences.
4. Solution Selection process in soft ground reinforced the case must satisfy the conditions bearing capacity, settlement allows stable. Necessary geotechnical monitoring and comparing the results predicted, laboratory experiments, field experiments.
+ For more than 10 years through a series of soft soil treatment technologies are applied in Vietnam. Demand for research and technological development soft ground handling increasing. The main challenge is the complex ground conditions and limited infrastructure of our country. in the coming years technological ground handling will certainly constantly evolving to meet the building of roads, ports, land reclamation and other infrastructure projects;
+ Errors mostly of works damaged foundation is caused by the wrong choice of design solutions to land and foundation design.
+ The method commonly used to handle soft ground in Vietnam are using bamboo and mangrove poles. This is an economical solution for the ground conditions and load relatively favorable. Due to the limited length of the pile, so practical applicability is limited. Need for evaluating bearing capacity and settlement of pile foundation reinforced with short by the usual methods. The conventional solution. The solution only works for independent housing. Do not use backfill with large width.
+ Method in preload is usually economical solution to handle soft ground. Need for evaluating the stability under load effects. Should conduct monitoring subsidence and water pressure. Do not use the concept of forward settlement and subsidence compensation. To control the settlement. Consideration should be secondary to the settlement and expected.
+ Preload combined with plastic or water wells in the sand. Impact load can be replaced with vacuum technology. Currently, the devices can plug into the plastic on the 20m depth. It is necessary to monitor the settlement, pore water pressure, horizontal displacement compared to estimates
Pile soil + lime, soil cement should be used extensively to reinforce deep ground. This is useful solutions, not to waste time, enhance the stability of the background.
+ Compacted sand piles allows increased load capacity and shorten the time constant of the ground. Equipment now allows sand piles piles with a diameter of 40-70cm and a length of 25m. This is the appropriate solution technology, economy and allow deep processing. The compacted sand piles at the pile tip location allows increased efficiency reinforcement.
+ Try to be the least expensive solution for background processing. Large size reinforced construction can be handled in a short time. The effectiveness of the solution should be checked with the survey equipment. This technology is suitable for reinforcing the soil is not compacted embankment.
+ We make the necessary surveys, measurement, design, quality control and set up systems for principles to handle the soft ground. It can refer to the process of drafting embankment on soft soil.
+ Be the formation of a national program of research and review, technology transfer, building regulations and norms in the field of soft soil treatment. Essential learning experiences and draw on international experience to local information widely. the Soil Mechanics and Geotechnical works Vietnam (VSSMGE) and Consulting Company AA (sponsored by VSSMGE) expect to receive multiple documents, survey reports, survey, design, monitoring , experimental foundation treatment works on the soft soil of the project / work specific (Case Histories) to make the document public.
+ Forming strong geogrids, a collection of geotechnical experts from Vietnam and international cooperation aimed at solving the problem of soil mechanics and geotechnical complex nature.
Source: synthetic xaydungvietnam
Technology for basement waterproofing construction of high buildings
Background Currently, office buildings, commercial centers and especially the condominiums being built in urban Vietnam. In Hanoi and HCMC. HCM has built 33 storey high buildings. In high-rise buildings, the underground is an indispensable part. The basement structure in addition to strength requirements as other structures, require a certain level of proof to satisfy the performance requirements set by the designer.
1. Basement Waterproofing for reinforced concrete (RC) also ensure that steel reinforcement in concrete from corrosion. Thus, for structural concrete basement waterproofing requirements is not only required, but is used to ensure that the conditions are the necessary durability. However, until this point there is no indication or criteria guiding the design and construction of high-rise building basement. Records engineering design as well as design and construction of high-rise include only architectural design, structural drawings, technical systems. The waterproof design for buildings in general and in particular the basement just a few lines of comment with the general instructions. The construction units perform basement waterproofing on their own experiences to each unit there is a way. Consequently, most of the basement of high-rise buildings are being absorbed. Introducing technology basement waterproofing concrete monolithic structure to remedy the situation.
2. Principle waterproof
Basement Waterproofing buildings based on the following principles:
- Enhance the ability of structural waterproofing concrete basement floor and walls of concrete waterproofing;
- Waterproof outer basement supplemented by the elastic material, prefabricated waterproofing sheet;
2.1. Improved waterproofing of concrete structures reinforced
This measure should be considered when designing the first basement waterproofing concrete structures. Enhance the ability of concrete waterproofing basements using active mineral additives ultrafine not only for the effective waterproofing of underground works, but also to protect steel reinforcement from corrosion and ensures durability 's works. So far, the structures are often specified minimum compressive strength of concrete at 28 days of age without regard to the other properties of concrete. Meanwhile, the durability of concrete depends very much on the porosity and pore distribution in diameter. Mineral fillers such activity silicafume microsilica or rice husk ash when put into concrete components will significantly reduce the total porosity and especially capillary porosity (pore diameter of greater than 10-4mm). To achieve this, concrete waterproofing components should be designed by professional design agencies.
When choosing a level of waterproofing for concrete construction walls and the basement floor need to pay attention to the texture and thickness of the water table height. The relationship between the thickness and the reinforced concrete structure with a height of groundwater level waterproofing of concrete needed.
The proof required
H - The height of the water table;
δ - thickness of reinforced concrete structures.
The data in Table 1 show that the higher the level of waterproofing concrete thickness of the structure as
small, or the water table height greater. Therefore, in the design process to make choices consistent with waterproof building practice.
In the case of ratio H / δ is too large and improving levels of Concrete waterproofing, you can not effectively use the additional layer waterproof outer reinforced concrete structure. Also, due to the safety requirements, the economics of waterproofing solutions, to consider the additional waterproofing.
2.2. Additional Waterproofing
In the case of enhanced waterproofing concrete basement structures did not meet the requirements (level of waterproofing, safety factor and the economics of solution) may consider measures against additional proof. That is the technical solution to covering the entire outer reinforced concrete structure with precast panels or waterproof membrane elasticity.
During the design and construction should also pay special attention to the technical solutions and construction measures to improve waterproofing of joints positions as construction joints, bolt holes, pipe techniques through the basement walls and floor.