Application of resonant petrochemical crushing in cement bridge engineering
Published on.
2022-12-27 14:51
I. Preface
Since the 1990s, China's concrete plaster has developed rapidly due to the high strength and long design time of concrete. With the year by year improvement of traffic performance, more and more old cement plaster is under construction, the pre-concrete plaster should be the rapid growth of China's economy in recent decades, the traffic volume and axle load increased year by year, various structural forms are also increasing. l Old concrete pavement also occurred damage, causing serious damage, at the same time, the burden of dust on the injured citizens is high, not conducive to environmental protection.
However, asphalt concrete has the characteristics of smooth surface, comfortable driving, low noise, wear resistance, etc. Shanghai gradually changed the cement smear to asphalt. At present, there are two ways to change the cement plaster to asphalt: one is the old cement concrete surface asphalt concrete n layer, that is, "white to black", the other is the old cement concrete "white to black" for excavation and transformation. It is not recommended to assume that the "white-to-black" procedure should be considered first whenever possible.
Practice has shown that the biggest and most fundamental problem with the "white to black" program is the reflection spell. Large displacements of the old concrete surface near joints or cracks lead to a concentration of tension in the asphalt mixture. Vertical displacements due to expansion or contraction of cement concrete caused by temperature changes and vertical displacements due to traffic loads. The shear tension of the asphalt coating at the joint is high, leading to the tension concentration of the coating at the joint and the formation of reflection cracks.
According to the research results and practical experience at home and abroad, the prevention and control of reflection cracks are mainly considered from two aspects: pressure dissipation and asphalt surface reinforcement.
Resonant crushing of concrete slabs is one of the most effective measures to avoid stress concentration and avoid reflection.
Concrete pulverizer crusher powder so far, more than half of the United States has a total of more than 300 crushers, Sinopec B in 2003 in Shandong Province, the first time the introduction of this technology, followed by Zhejiang, Jiangsu, Anhui and other provinces took over the technology for the transformation of cement mortar, Shanghai has been carried out more than 50 times. 2005 Shanghai to Qingping Highway 0 m test section, 2006 Jinshan Avenue renovation and 2007 Shanghai to the southern line of the highway renovation, the technology was taken over. Therefore Minhang District is also gradually implementing the resonance suppression process. As the maintenance, upkeep and management unit of the tram in Minhang District, it is necessary to use Zerkle to analyze and study the inertia and petrifaction technology, to summarize the experience, and to lay the foundation for the smooth development of similar projects in the future.
II. Resonance reduction petrochemical mechanism
The working principle of reducing resonance is to use the resonance device to continuously generate high-frequency, low-amplitude vibration energy, which is transferred to the cement slab by the hammer head. e. The cement slab works to ensure that the whole slab is polished smooth, the size and direction of the fragments are extremely regular, and the internal reinforcement is completely removed from the concrete. It is different from the impact of a heavy hammer on a cement board. That is, the "cracks" on the surface of the cement slab should be immediately and evenly distributed at the bottom of the slab and should not damage the basic structure. The crack of the cement slab is 35-40 angle m. This unique torsional force and pre-buried structure significantly improves the load-bearing capacity of the structure after breaking the petrifaction. The T process does not damage the base because the impact force of high frequency and low amplitude is very small and the crack only reaches the material limit.
After the concrete slab resonance shrinkage, the teeth are embedded and pressed together, which can be divided into two layers, the upper layer is a fine crushed stone layer, and the lower layer is a better shaped crushed petrified layer, but with more cracks. Cement slab crushed petrified, similar to crushed stone, used as a flexible base layer of the road, coupled with an asphalt surface layer. However, the thickness of the asphalt layer should be at least 15 cm or more, otherwise the surface may be damaged due to insufficient strength.
There are two types of machines used for cement mortar resonance crushing, one is a single-head resonance breaker and the other is a multi-head impact crusher.
Single-head resonance breaker is a high-frequency, low-amplitude principle, the impact on the underground pipeline is small, the noise is relatively small, suitable for the higher price of the city streets; multi-head bumper instead of Prince IP, low-frequency, high amplitude. h component price, high vibration intensity, the impact on the underground pipeline is large, the noise is relatively high, suitable for roads and breaks. Lower unit price.
Three. Resonance crushing construction technology
3.1. investigation and preparation before the crushing petrochemical
(1) Identify the geology of road transportation, underground pipelines along the line, mark out the location of all pipelines, and communicate with maintenance units to negotiate protection measures.
(2) Identification of street houses
3.2. Investigation and preparation after crushing petrochemical
(1) Determine the geological conditions of the road, identify the underground pipelines along the route, mark the location of all pipelines, and maintain them.
2. Resonance dismantling mechanism
(1) The principle of reducing resonance is to use the resonance device transmitted from the hammer head to the cement slab to continuously generate high-frequency, low-amplitude vibration energy. e. The cement slab is worked by grinding smooth, the total size and direction is very regular, and the internal steel reinforcement is completely removed from the concrete. It is different from the impact of a heavy hammer on a cement board. In other words, the "cracks" on the surface of cement board. The crack of cement slab is 35~40 angular m. This unique rotational force and pre-built structure significantly improves the load bearing capacity after structural damage. High frequency low amplitude is very small, the crack only reaches the material limit, so that the T process does not damage the substrate.
(2) After the resonance of shrinkage concrete slab, the teeth are compressed and can be divided into two layers, the upper layer is fine gravel layer and the lower layer is crushed petrified layer, which is in better shape but has many cracks. The concrete slab is similar to gravel, which is crushed and used as a flexible pavement and asphalt surface. However, the thickness of the asphalt layer should be at least 15cm or thicker, otherwise the surface may be damaged due to insufficient strength.
(3) There are two types of machinery used to reduce the resonance of cement mortar, one is a head impinger and the other is a multi-head buffer.
(4) purchase resonance interference machine is a high-frequency low-frequency principle, the impact on the underground pipeline is small, the noise is relatively small, suitable for the higher price of urban roads; multi-head bumper with low-frequency high R amplitude instead of prince IP. H components of high price, high vibration intensity, the impact on the underground pipeline is large, the noise is larger, suitable for roads and breakage. The unit price is much lower.
(5) resonance crushing needs to have: multi-hammer head cement road crusher, door type cement road crusher, cement road rammer, asphalt road milling machine, etc.
Four. Three resonant drilling techniques
3.1. Investigation and preparation before crushing petrochemical
(1) Geological survey of road transport and underground pipelines along the route, marking the location of all pipelines, communicating with maintenance units and negotiating protective measures.
(2) Apartment marking (street)
3.2. Investigation and preparation before crushing petrochemical
(1) Determine the geological conditions of the road, identify underground pipelines along the route, mark and maintain the location of all pipelines.
(2) Dust control before shredding and petrifaction using water sprinklers to sprinkle water on the road surface, which needs to be shredded to control the dust phenomenon in the building. The jump time of water and the resonance of the crushed petrochemical should be regulated within half an hour.
(3) The construction sequence to reduce resonance usually starts from the outer track and stops along the road. The crushing width is about 0.2 m per track. A period of crushing will cause some crushing in an adjacent area of about 5 cm. The distance between the second crushing period and the first crushing period can be 24 cm.
(4) During the construction process, the driver should monitor the operation of the cement pavement crusher and the fracture performance of the hammer head at all times and adjust the braking parameters to achieve better braking effect.
(5) When steel and concrete pavement is used for the old pavement, the crushing parameters should be adjusted, such as increasing the vibration energy and separating the steel from the concrete after crushing.
(6) send special personnel to observe the buildings and structures around the crushing and petrification and petrification site. When deformation or cracks occur in the surrounding buildings and structures, the construction should be stopped immediately and the solution should be analyzed and checked in conjunction with the monitoring unit and the construction unit.
3.3.Resonance crushed petrifaction reserve technology
(1) When the pavement is crushed, the loose filler and large gravel between the joints of the old pavement should be removed, and graded gravel should be used for filling.
(2) Protection of fracture layer
(3) Transportation control
For broken petrified layer, try not to drive, let the vehicle brake and start, and also monitor the construction machinery running on it.
(4) Rainwater control
For the broken petrified layer, we should do a good job of waterproofing. If the asphalt layer cannot be crushed immediately after the crushed petrified layer, it should be covered and drainage measures should be taken if necessary.
(5) Local reinforcement
In the local section, the old roadbed has been damaged and should be reinforced.
(6) Rolling
Under the action of not less than 9 tons of two-wheel vibration steam, after 25 times of compaction, water spray compaction, can make the coagulation effect enhanced. The roller can press the fine particles into the cracks of the pavement, so that the concrete module after the crushing and lithification is wider, and improve and stress the smooth soil conditions acting on the asphalt layer.
3.5 Concrete asphalt pavement overlay construction
(1) Interval time
After crushed petrochemical, asphalt repair must be carried out within 48 hours to reduce the damage to the crushed petrochemical layer by vehicle traffic and to avoid rain.
(2) The interface between the petrochemical transformation section of crushed petrochemical and other sections
In the joints and other treatments of petrochemical crushed petrochemical section, the joints are treated with additional geotechnical materials to avoid stress concentration causing reflection cracks.
(3) Combination of petrochemical coating of crushed petrochemicals and asphalt coating
The asphalt layer after crushed petrochemical can be directly beaten square, or the penetrating oil can be sprayed on the surface of the crushed petrochemical layer. A layer of crushed rock slag can be evenly distributed on the crushed rock layer, and the crushed rock layer can be stabilized by light roller paving.
IV. Application of resonance crushing technology
In April 2012, the Jindu Road (Urban Road S4) renovation project was approved to treat the asphalt pavement after reducing the highway resonance. At present, the project has passed the acceptance test and has been put into operation with good treatment effect. take difference is the reduction of most of the sections less than 0.35mm, which meets the design requirements. Before and after inspection photos are as follows.
Jindu Road has the following characteristics, so it is assumed to reduce the resonance on the engine track.
(1) Both sides of the road are residential fences, no load-bearing façade, and the road height has height conditions.
(2) Jindu Road of this project is the only access along Longwu Road to Xinzhuang Industrial Zone, west of Humin Road and Wujing Industrial Zone, with high traffic flow. Therefore, the treatment plan should have the characteristics of short duration.
V. Conclusion
(1) Resonant crushing system is an effective treatment program for asphalt cement plastering renovation. It is a new technology. This utility model has the advantages of short construction time, comfortable construction, moderate cost and low environmental protection rate of carbon dioxide, etc. It should be actively promoted in future renovation projects, especially in road sections with high traffic flow, in order to solve the problem of "C". Lost traffic.
(2) Before implementing the MRI treatment plan, the design drawings and construction measures should be strictly reviewed and the surrounding and underground structures should be familiarized.
(3) In the implementation of the reduction of resonance, should strengthen the detection and observation of the surrounding buildings and underground pipelines, and timely handling of problems found.
(4) It is strictly prohibited to disconnect resonance in rainy days.
Cement bridges,Bridge Engineering
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