1, clay blanket method
Clay blanket construction method is very simple, and its technical requirements are not high; The water surface construction scene is large, the throwing speed is fast, and the purpose of fast plugging and gas sealing can be achieved without rolling; Clay blanket has good flexibility, can be integrated with fill, bank slope and cast-in-place concrete structure, and has strong adaptability to foundation deformation.
With the continuous deposition of sediment, the anti-seepage effect is increasingly enhanced, which is a good anti-seepage measure for permeable foundation in temporary cofferdam water retaining buildings and some permanent buildings. In many cofferdams of water conservancy and hydropower projects, clay blanket method has been well applied.
After the cohesive soil is thrown into the water, the soil aggregate absorbs water and expands, resulting in uneven stress on the soil, gradual dissolution of colloid, thickening of water film of aggregate, reduction of internal friction and cohesion, gradual destruction of soil aggregate structure and disintegration into small clods or even loose particles.
After that, under the action of its own weight, the weight of the upper fill and seepage pressure, the water is drained bi-directionally or unidirectionally, gradually consolidated and compacted, the compactness and water content gradually become uniform, and the impermeability gradually improves.
2. Selection conditions of clay
Underwater clay blanket is mainly used for seepage control of weir foundation. Therefore, the thrown soil material should be able to soak, disintegrate and consolidate under water to form an impervious body with certain anti-seepage ability, anti-scouring, seepage stability and slope stability requirements.
Common quality problems in water conservancy project construction;
1, the subcontracting level is low.
Combined with the present situation of water conservancy projects in China, water conservancy projects are usually subcontracted to construction units in the actual construction process. Subcontracting has certain advantages and can effectively reduce the construction cost, but there are security threats. At present, many migrant workers from construction units have spontaneously formed in the market.
Many migrant workers have low professional status, so it is difficult to determine the technical points of each construction link of water conservancy projects. Many construction workers have been working alone for a long time. They have no sense of teamwork and management of rules and regulations, and it is difficult to attach importance to construction safety, which directly affects the construction quality and safety of water conservancy projects.
In addition, many construction teams pay too much attention to the construction time and shorten the construction time for their own economic interests. In addition, subcontractors do not have perfect construction management standards, imperfect mechanisms and imperfect supervision and management mechanisms, which directly affect the quality of water conservancy projects.
2. Lack of reasonable construction planning
In the construction of water conservancy projects, many construction units will carry out comprehensive construction planning in combination with the drawings of water conservancy projects, and there is no perfect planning for the construction content. In addition, some construction units rushed to work blindly, which led to serious interruption of construction. Even some construction units have the problem of shortening the construction period at will or without approval for their own interests.
It is difficult to guarantee the construction quality of water conservancy projects, and even cause rework, which can not guarantee the quality of water conservancy projects and cause unnecessary human, material and economic losses. Therefore, before the construction of soil and water conservation project, we must strictly control the construction content, make overall planning and construction, make clear the construction sequence, design, monitor and manage all links of water conservancy project as a whole, and comprehensively improve the quality of water conservancy project.