1 Selection of earthwork filling materials
Generally, the materials in the construction site are uneven, the distribution of soil materials is complex, the change is great, and the layer thickness is uneven, so the available soil materials are separated by large-scale mechanical excavation during construction. Even if some construction workers with professional qualifications are set up to direct excavation and loading, the qualified soil samples are put in backhoe, which is convenient for backhoe operators to compare the qualified soil samples during excavation and loading. In addition, quality inspectors are arranged in the filling area to conduct secondary inspection on the materials. If inferior soil materials are mixed into the construction site, it will affect the filling quality. To maximize the quality of earthwork filling, high-quality materials are the primary factor.
2 field rolling test
It is necessary to conduct a comprehensive and complete exploration of the topography and geomorphology of the construction site, and send the soil samples to the laboratory, and all the relevant indicators are determined and tested in accordance with the requirements of the specification to determine the maximum dry density and optimal water content of the soil. After the test, the next rolling test should be carried out by using the relevant data obtained from the test, mainly to obtain data such as water content control range, soil paving thickness and rolling times. The first purpose of the test is to check the working state of the compactor to meet the construction requirements. Secondly, it is necessary to check whether the compacted soil reaches the designed compacted dry density value. Third, we should memorize the technical requirements and testing methods of quality control. Fourthly, it is necessary to clarify various parameters, including the limit particle size of clods, the suitable range of water content, compaction methods, compaction times, etc. Rolling test alone is the basic requirement. Different compaction machines should be used according to the characteristics of each operation area. For the fourth time, the sample was extracted by ring knife method and the dry density value was determined. Once the unqualified parts appear, they should be compacted again to achieve the qualified goal. It is more scientific and reasonable to finally determine the parameters after determination. It should be specially noted that due to the different locations of soil borrowing and mining methods, the parameters such as dry density and water content will be directly deviated, and the construction site environment and construction conditions will be different from those in the test area. If other problems are added, the compaction effect obtained in the test process is almost impossible to achieve. In this case, only by selecting the parameters of rolling times and soil thickness more carefully and leaving enough room can the quality be guaranteed to meet the standard.
3 Construction preparation stage
3. 1 construction technical disclosure
Technical disclosure is an essential step before construction. It is necessary to introduce the compaction parameters, transverse slope, width, elevation and other parameters of filling control to the construction personnel one by one, so that every construction personnel can understand the construction technology and the places that should be paid attention to, so as to better carry out related construction.
3.2 Construction survey and lofting
Before construction, a series of work should be carried out, including re-measuring traverse, center line and elevation, rechecking leveling points and quantity, determining the positions of subgrade edge, slope toe, side ditch, berm, borrow pit and spoil ground, marking them clearly one by one, and then reporting them to the supervision unit for examination and approval. The control piles of the road center line and roadside line are standard piles, with a section pile for the straight section 50m and a section pile for the flat curve section 20m-30m. At the same time, placing a cement mileage pile with the height of 15cm× 15cm and 1m every 50cm on the roadside is beneficial to the smooth inspection.
3.3 Clean up the site
Before construction, trees, garbage and obstacles that are not conducive to driving sight should be removed from the construction site. These rubbish should not be thrown away at will, but should be put in a designated place.
4 Construction process quality control
4. 1 Control of soil water content
It is necessary to detect the moisture content of soil after the operation of soil laying process. If the moisture content is high, turn it over. On the contrary, if it is small, it must be increased, and sprinkling water on the working face is an ideal operation method. Sprinkle water with a sprinkler, use the combination of pressure water and compressed air to spray in the form of fog, so that the spilled water is more uniform, and then use a tractor to pull the disc harrow.
4.2 Unloading mode and soil laying thickness control
In water conservancy construction, many heavy trucks usually work at the same time, and the fill layer is easy to be squeezed, forming some damage points. This requires that the materials should be discharged in strict accordance with the regulations and leveled with bulldozers. After the bulldozer leveled the filler, it was leveled and reshaped with a grader, and a certain cross slope was trimmed, mainly for the convenience of drainage. The paving width is 50cm larger than the design width of each subgrade. The paving thickness is calculated by measuring the fixed-point elevation, and the water content is detected at the same time.
4.3 Control of walking speed and rolling times of rolling equipment
Once the rolling test is inconsistent with the control of the running speed and rolling times of rolling equipment, there will be problems such as pressure leakage, under-pressure or over-pressure, which will lead to uneven compaction quality and difficult to guarantee the quality of filling construction. In addition, it is necessary to continuously strengthen the management of quality inspectors, strengthen quality supervision, and set up special personnel to monitor the quality of the whole process.
4.4 Testing and detection
After the compaction of each layer is completed, the relevant inspection personnel shall conduct sampling inspection on the filling surface. Once it is found that it does not meet the requirements of the specification, it cannot be ignored, because a small problem may cause great security risks. Therefore, in order to reduce the occurrence of problems, the supervisor should be invited to witness the sampling, and the inspection results should be truthfully reported to the on-site quality inspector, so that the soil materials can be effectively treated. After obtaining the consent of the supervision engineer, proceed from the actual situation of construction, and do a good job in dealing with the joint surface.
5 other control of engineering quality
5. 1 personnel control
Engineering quality is always the first. In order to obtain good quality, we must have experienced construction personnel, put every responsibility into practice, and organize relevant training to ensure the construction quality.
5.2 Control of seasonal construction
Pay special attention to seasonality in construction. In rainy season, the loose soil on the surface should be quickly compacted with flat rollers in advance to ensure the smoothness of the filling surface, mainly to prevent rainwater from infiltrating downward to produce water. Construction can only be carried out on the qualified filling surface. Also pay attention to protect the filling surface. When it rains, it is not allowed to trample on the filling surface, and no vehicle can pass at will. In order to ensure the normal filling water content of soil materials, the construction should be stopped in the case of heavy rainfall, and the surface should be covered with impervious materials. The soil yard should reserve enough qualified soil materials, and take drainage and rainproof measures. In winter, earthwork filling should be avoided as far as possible, and positive temperature soil should be adopted to carry out processes such as soil loading, soil spreading and rolling, so that continuous operation can be completed in a short time.
5.3 Implement measures to ensure peak intensity.
The construction of a water conservancy project should not only formulate a complete construction organization design, but also have enough technical, production, management and other personnel to use those mechanical equipment with excellent performance and regularly maintain these equipment to ensure that it can have a good working condition. We should also do a good job of communication with other construction units and put forward corresponding construction opinions according to the construction progress.
6 concluding remarks
Through the analysis of this paper, we can fully realize that earthwork filling is an indispensable part to ensure the construction quality of water conservancy projects to meet the standards. Relevant construction personnel should focus on its construction quality, always regard high quality as the fundamental starting point and foothold of construction, and create one excellent project after another.
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