Research On Application Of Noumenon Sampling Method To Quality Control Of Winter Construction Project

At present, along with China’s economic development going into the fast lane, maintaining regional economy balance became the focus of the development. As the relatively backward region from the point of view of the whole country economic development, during the "12th Five-Year Plan", the development strategy of "revitalizing the northeast old industry base" will continue to implement vigorously in the northeast. However, the Northeast Area locates in the subfrigid zone where winter lasts about5months. The construction cycle in the northeast only covers7months or so if not taking winter construction into consideration, which can not satisfy the demand of economic development in this region. In order to complete the project as soon as possible for the full play of its economic benefit and social benefit, winter construction is the only choice. But because winter construction has its particularity and complexity, and the technology level of the construction team in our country is uneven, so the construction quality problems occur frequently in winter. Consequently, how to guarantee the project quality of winter construction has become a key problem for all the project participations.As the most important structure form at present, the concrete structure is widely used and its dominant position is growing continuously. We can say that the quality of concrete engineering will affect the quality of the whole engineering. The compressive strength is main basis for the concrete quality control, relating to the evaluation and acceptance for the project. Also, the engineering quality accidents have direct relationship with the the compressive strength of concrete not up to the requirements of design. So, to test the strength of concrete structures rapidly, accurately and scientifically is very important for ensuring the project quality. With the research and development of the detection technology, a variety of concrete strength detection methods appeared, such as the same curing condition of specimen, Rebound method, Ultrasonic-Rebound combined method, Drilled core method, Pull-out post-insert method and so on. Most of these methods calculate the strength of concrete structure entity indirectly based on the relationship between the concrete strength and some physical quantities. So it is difficult to achieve a high precision. Drilled core method is recognized as the most direct and accurate method, but this method may damage the structure even damage the rebar. Consequently, all the methods can not become acceptable because of its limitations. In order to overcome the disadvantages of the existing testing methods, and realize the more accurate and valid inspection for the concrete structure strength, this paper used the patent technology of noumenon sampling (abbreviated as noumenon sampling method) to test the concrete structure strength in winter construction. This method is to place the sampling boxes into the structures before concreting, so realizing the same molding conditions and maintenance effect as the structure entity. Also this metod effectively ruled out the interference of human factors. Therefore, the strength of the specimens obtained by this patent technology (abbreviated as noumenon sampling specimens) is very close to the real strength of the structure entity.This paper analyzes the factors which influence the strength of concrete structure in winter construction. Also the advantages and disadvantages of the existing concrete strength testing methods are pointed out. Based on the application of the noumenon sampling method for inspection the concrete strength in winter construction, a large number of strength data for the standard maintenance specimens and noumenon sampling specimens were obtained. And the relationship between the two kinds of strength is studied by using the conversion coefficients, linear regression and some other statistical methods. According to the grey system theory, the GM (1,1) prediction model for the strength of noumenon sampling specimens is established. Because the strength of noumenon sampling specimens is so close the strength of structure entity. So the model can be used to predicte the strength growth situation of the concrete structure entity in winter construction. Research shows that the method and theory expounded in this paper have great use value, so can provide some helpful reference on strengthening the concrete quality control of winter construction and reducing the construction cost for project managers.