With the development of social economy, the requirements for expressway construction are getting higher and higher. At the same time, the increase of vehicles and loads on the expressway is of great significance to subgrade construction and dynamic compaction. Many road sections have high water content, poor water permeability and unsatisfactory compaction effect. Therefore, in highway subgrade construction, the collapsible loess, low saturation silt and gravel soil are treated by dynamic compaction method, and the dynamic compaction test is carried out in the field to evaluate the dynamic compaction effect. Constantly improve the dynamic compaction mode of expressway subgrade to provide power for promoting the development of expressway construction.
First, the meaning and basic characteristics of dynamic compaction method
Dynamic compaction method is to drop the heavy hammer of 100 ~ 400 kn from the height of 6~40m, which will cause impact energy and vibration to the foundation and compact the foundation. When dealing with the common conditions of expressway foundation, the obvious advantages of dynamic compaction will appear. The reinforcement effect of dynamic compaction method is obvious. Dynamic compaction reduces the compressibility of foundation soil and improves the strength of foundation. At the same time, the influence depth of reinforcement can reach 6 ~ 10m. The construction equipment of dynamic compaction method is very simple, the operation is very convenient, the construction technology is simple, the operability is strong, and the applicability to different soil qualities is strong. Because of the high construction speed and efficiency, the construction period can be shortened and the cost can be reduced, which not only strengthens the quality of foundation construction, but also brings certain economic and social benefits. The noise and vibration during construction are relatively large, which is the deficiency of dynamic compaction method and inconvenient to use in densely populated places.
Second, the dynamic compaction mode of expressway subgrade
Because our country has a vast territory, the expressway foundation soil is regional, the soil properties are complex and diverse, and the deformation state and law of foundation soil under dynamic compaction are different, so different dynamic compaction reinforcement modes of expressway subgrade must be formulated according to specific conditions. In the process of practical application, it is necessary to take corresponding control measures according to actual needs and specific conditions.
(1) Cylinder reinforcement mode
Dynamic compaction mainly produces shear effect on the soil of foundation, causing vertical damage, while the lateral displacement of soil of highway foundation caused by dynamic compaction is relatively small. Based on the test and analysis of the dynamic compaction effect of a highway section, it is assumed that the uplift around the rammed pit is very small, and the lateral deformation of the soil column under the rammed pit is ignored. In this case, the state of dynamic compaction is cylinder, which further simplifies and perfects the cylinder reinforcement mode of dynamic compaction foundation.
(2) ellipsoid reinforcement mode
When dealing with collapsible loess foundation, ellipsoid reinforcement should be adopted. Under the action of dynamic compaction, soil deformation and dynamic response occur. Based on the characteristics and changing process of soil displacement and deformation, the changing range of soil displacement under impact load is studied, and the changing range is ellipsoid. For collapsible loess foundation, the application of this "ellipsoid" reinforcement method can better achieve the effect of tamping and strengthening the foundation.
Through the analysis of dynamic compaction treatment of a highway section, combined with test data and effect evaluation, the shape and characteristics of dynamic compaction reinforcement area are further determined, and the ellipsoid dynamic compaction reinforcement pattern diagram is made for dynamic compaction reinforcement of foundation fill or other soft soil.
Third, the mechanism of subgrade dynamic compaction
According to the propagation law and upward action characteristics of shock wave generated by dynamic compaction foundation, shock wave can be divided into surface wave and body wave. Surface wave propagates from tamping point along the surface direction. The farther away from the source, the more obvious its attenuation is. At this time, the reinforcement of the foundation has basically disappeared, and its vertical stratification will loosen the surface soil. Body wave starts from the tamping point, propagates radially along the wavefront of hemispherical wave, and reaches the depth of foundation. It can tamp and compact the foundation and play the role of shearing and compressing the foundation. Body waves are divided into longitudinal waves and shear waves.
Dynamic compaction will form three areas with different properties in the foundation, namely, loose area, reinforced area and elastic area on the foundation surface. When the soil under the loose area is under the action of body wave, it will compact the upper body and make the upper body settle, thus strengthening the foundation and forming a "reinforced area"; With the change of propagation path and the increase of attenuation range, the shock wave under the reinforcement area will not have enough force to deform the soil, so it will not compact and tamp the foundation. Therefore, this part of the area is called "elastic zone".
The dynamic compaction method is effective in the compaction of expressway foundation, and the operation is simple and easy. The research on a large number of engineering test results shows that the mechanical properties of highway soil strengthened by dynamic compaction have been improved very well, which is very hard and the engineering quality has been improved obviously.
Four. Trial tamping and construction technology
(A) determine the test area
Before trial tamping, the test area should be determined first. These test areas should be representative, and the number should be determined according to the complexity of the construction site, construction scale and building type, which will make the trial ramming more feasible and the detection effect of the trial ramming more ideal.
Determine the use of dynamic compaction machinery through trial tamping, including the quality of rammer and the tamping times in each stage or area; Determine the location and distance where the heavy hammer falls, and determine the tamping energy and compaction degree, so as to better complete the foundation dynamic compaction work and improve the work quality and efficiency.
(2) Mechanical equipment and construction
The thickness of the fill area is generally determined to be 8 ~ 10m, and the tamping should start from the elevation of the basement. Considering the buried depth of the foundation, the elevation of the foundation is at least one or two meters, and the actual maximum reinforcement depth of dynamic compaction is about 7 meters. Mechanical equipment and construction steps are as follows: the whole project will be rammed four times. The first pass and the second pass are point tamping, and the spacing between tamping points should be kept at 3 ~ 4m. The tamping points of the second pass are preferably scattered among the tamping points of the first pass. The first pass and the second pass are generally rammed for 7~ 10 times. The third time is also tamping, and the spacing between tamping points becomes 4 ~ 5m. The tamping points are arranged between the tamping points of the first pass and the second pass, and the tamping times are 4-6 times. The fourth full tamping, hammering overlap about 1/3, falling from 7.5m, tamping twice.
According to the geological drilling data, the dynamic compaction construction is carried out by stages and sections. Dynamic compaction area is divided into areas with different effective reinforcement depths, generally 7 m ~ 10 m area and 4m~7m ~ 7 m area. The thickness and soft and hard conditions of soil should be fully considered, and the topsoil should be cleaned before dynamic compaction.
In the trial tamping stage, a18t heavy hammer is mainly used for dynamic tamping construction, which falls from the height of 1 1m, and the tamping energy is set at about 2,000 kn. M, the tools and methods of auxiliary tamping are the same as the first time. When completely rammed, the hammer weighs l8t and falls from a height of 5.6m The tamping energy is l000kN.m, and the bottom of the rammer should be provided with vent holes.
Conclusion: Based on the study of dynamic compaction reinforcement mode of expressway subgrade, the basic meaning and characteristics of dynamic compaction reinforcement technology are understood. At present, in view of the complexity and particularity of highway subgrade soil in China, various dynamic compaction methods of highway subgrade are briefly described, and different dynamic compaction methods are adopted according to regional characteristics. According to the deformation and displacement of highway foundation soil under impact load, the equipment and construction scheme of dynamic compaction are selected, and the field trial compaction and effect detection are carried out to continuously improve the dynamic compaction reinforcement mode of expressway subgrade. Strengthen the construction of expressway subgrade, improve the quality of expressway engineering, and constantly promote the development of China's highway industry.
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With the official opening of Jide section of Beijing-Fuzhou Expressway in 19971October, as the main artery connecting north and south traffic, the traffic volume is increasing substantially every year. In order to ensure the high-quality operation of the expressway, the maintenance department should invest a certain number of specialized and overhaul projects to maintain the expressway every year, so it is particularly important to maintain the archives of specialized and overhaul projects. Strengthening the scientific management of maintenance engineering archives can better serve the construction and management of expressways.
Take Dezhou Branch of Shandong Expressway Group as an example, there are 3-5 special and overhaul projects every year, and the archives of maintenance projects are numerous, diverse and of high value, which need to be preserved for a long time. These engineering files are an important basis for future highway management and daily maintenance. Maintenance archives management personnel should directly participate in the supervision and guidance of maintenance engineering construction process according to the characteristics of maintenance engineering archives, ensure the integrity, accuracy and systematicness of maintenance engineering archives, and do a good job in the custody of maintenance engineering archives. This paper puts forward the method of archives management of expressway maintenance project.
1, do a good job in file management of special maintenance and repair projects.
1. 1 Strengthening the training of business knowledge is a favorable measure to ensure the quality of maintenance engineering files.
Managers and supervisors involved in special maintenance projects come from all directions, and their understanding and professional level of the importance of engineering archives are uneven. In order to strengthen the orderly management of archival work in various stages of construction and supervision, ensure the integrity, accuracy and systematicness of archival materials, and standardize the collection, sorting, archiving, storage and development and utilization of archival materials, the maintenance department must strengthen the propaganda of archival awareness and the training of archival business knowledge from the beginning of the project, which is stricter than the specification.
1.2 Formulate detailed maintenance project file management methods in line with actual conditions, and clarify standards and requirements.
The Archives Bureau of Shandong Province and the Communications Department have successively issued programmatic documents such as the Implementation Measures for Document Filing of Highway Engineering Projects in Shandong Province and the Notice on Standardizing Traffic Engineering Archives and Accessories, and combined with GB/T 50328-200 1 Specification for Filing and Arrangement of Construction Engineering Documents and related standards, formulated an operational compilation method suitable for the engineering archives of this unit. First, the scope of data collation of maintenance management departments, supervision units and construction units has been refined. The second is to refine the requirements for composing papers, and should follow the natural formation law of documents and materials and the principles of integrity, continuity and systematicness of project files for scientific classification. Thirdly, the composition, format and specific requirements of the document are clarified, which is convenient for the file managers of the construction unit and supervision unit to operate.
1.3 supervise and guide the maintenance special overhaul project.
The archivists of the maintenance management department supervise the construction units and supervision units in a targeted manner, and provide professional guidance on the problems existing in the archives during construction. For example: require the original engineering documents to be filed; The contents of the engineering documents must be true and accurate and conform to the engineering practice; Engineering documents shall be written in durable materials, and shall not be written in faded materials; Engineering documents shall be legible, with clear drawings and neat charts; As-built drawings shall be complete, accurate, clear, standardized and revised in place, consistent with construction drawing design, design change, negotiation, material change, construction and quality inspection records, and consistent with documents, drawings and materials. Thereby improving the quality, completeness and completeness of the maintenance project file submission.
1.4 do a good job in collecting and sorting maintenance and special engineering data.
The maintenance management department shall collect and sort out the relevant information of maintenance overhaul and special projects from scheme formulation and approval to the end of project acceptance. Archives management personnel shall classify, code, file, bind and file the owner's special overhaul project data according to relevant regulations. The file should be composed of the cover and spine of the file, the file in the volume, the borrowing code, the file directory in the volume, the file in the volume and the reference table.
1.5 do a good job of acceptance and sorting of maintenance engineering files carefully.
Maintenance department archives management personnel should focus on the following contents when accepting special and overhaul project files: the project files are complete, systematic and complete; The engineering archives truly and accurately reflect the actual situation of engineering construction activities and projects; Engineering files have been sorted and filed, and the filing conforms to the provisions of relevant specifications; The drawing method, schema and specifications of the as-built drawing meet the professional and technical requirements, and shall be stamped with the completion stamp; For documents that need to be signed by units or individuals, the signing procedures are complete; The material, format and writing of the document meet the requirements. Ensure the standardization and standardization of maintenance project files. Maintenance archives management personnel should systematically sort out the names of this year's special overhaul projects and compile a catalogue of scientific and technological archives for future reference.
2, do a good job of daily maintenance project file management.
2. 1 File management of minor repairs and maintenance projects.
Although there is no clear standard requirement for the file management of minor repairs and maintenance projects, it is as important as the file management of special projects and major repairs. In daily work, strengthen the daily inspection, subgrade and pavement, facilities along the line, bridge inspection, flood control and anti-skid, safety management, minor repair project management and other data collection and sorting. Filing documents and materials must be neatly written, with clear and durable handwriting and lines, and the forms should be unified and standardized. (A4 paper for words and forms) It is forbidden to write with writing tools that cannot be preserved for a long time, such as ballpoint pen, pencil, red ink and pure blue ink.
2.2 Specific management methods.
Maintenance file management personnel will collect and classify the processed documents and materials in time every six months for centralized and unified custody. Collect the formed scientific and technological documents and materials completely, check them accurately, and organize them systematically to form a storage unit. The file should be composed of the cover of the file, the file volume, the borrowing number, the file directory, the file volume and the reference table. The cover, volume and volume of the case file should be kraft paper with similar color to the case file. Print and paste the cover and spine of the case file in the corresponding position. For daily inspection, subgrade, pavement, facilities along the line, bridge inspection, pavement inspection and other materials, the page number of the document is compiled at the end of each year, and it is bound together with the borrowing number, the document catalogue and the reference table by the method of three holes and one line. After binding, paste the file volume. For flood prevention and anti-skid, safety management, various management methods, maintenance documents, superior communication and other materials can not be bound. Make a catalogue of this year's archives for easy reference.
3, do a good job in the management of maintenance engineering files.
Maintenance engineering archives are scientific and technological archives and need to be preserved for a long time. Under the guidance of the principle of centralized and unified management, the custody of maintenance engineering archives scientifically maintains the integrity and safety of maintenance engineering archives, and adopts effective protection technology and management methods to maximize the service life of maintenance engineering archives. Only by keeping the maintenance engineering archives well can the integrity and safety of centralized maintenance engineering archives be reliably guaranteed and the needs of all aspects can be met. Therefore, it is necessary to keep the maintenance engineering archives well.
4, the use of modern technology to do a good job of archives management of maintenance projects.
4. 1 Efficient management with software.
With the rapid development of computer technology, many engineering document management softwares have appeared. These engineering softwares are easy to install, simple to operate and very practical, and can be well applied to the management of maintenance engineering files, making the arrangement of maintenance engineering files faster and more perfect.
4.2 Use the Internet to enjoy * * *.
Through the company LAN, maintenance information can be shared and reliable, detailed and systematic maintenance information can be provided for the whole work, thus improving the work efficiency of all personnel and departments, shortening the retrieval time and saving management funds.
5. Conclusion
Only by having good professional quality, earnestly studying archives laws and regulations and related professional knowledge, and constantly improving the technical level and management ability of archives, can the maintenance archives managers better serve the highway construction and development.
Ideally, to learn more about "Talking about Archives Management of Expressway Maintenance Project", the inquiry of Zhong Da Consulting and Construction Link is simple, convenient and reliable.
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