Technique Of Dynamic Monitor On Forming Process Of Subgrade System

The subgrade is a kind of three-dimensional belt-shaped structure, it is the infrastructure of road and railway, and has very important function. The performance of subgrade structure is formed in the course of its shaping process, it is determined by selecting the fine filling and plenty compaction. This article takes the thoughts of system science as the instruction, and the elastic-plastic dynamic theory and modern dynamic testing technology as basis, made a research on the problem of continuous dynamic monitoring in the forming process of subgrade structure, and initially formed a set of real-time, continual dynamic monitoring technology, which take the vibration roller as its driving source, and carried on a quite successful application, especially in compacting controlling about coarse grain.The method of conventional compaction quality control primarily bases on the non-continual testing, and most part of which doesn't fit for the problem of coarse grain compaction. On the basis of the generalization and analyze on existing controlling method of subgrade compaction quality, it emphasis on analyzing the overseas compactor method, which is a kind of continue compaction control method based on vibration roller, it has got the extensive application in the Euro-American region, after pass by continuously perfect since 1978. It can realizes quantity control completely and rapid, and this is impossible that the normal method do it. The method appraises the compacting quality through the evaluating index of harmonic ratio. However, both the theoretical and practical researches show that this method has certain limitations, and it's difficult for compacting appraisal of coarse grain. So establishing the continue control method that is suitable for a more broad range is to become the core of this article.Firstly, according to the system science theory, established a general concept of subgrade structure system. The performance of subgrade system is restricted by its consisting factors—grain and the connecting way of them. But the state of coarse grain subgrade system is expressed by the indexes of its density, module and shearing strength. The change of system state can be represented by its change of structure resistance on macroscopic view. According to elastic-plastic meachnics and system theory, analyzed the evolvement principles of which the subgrade system on its forming process, and discussed the qualitative relations between the plasticdeformation and the resistance of the subgrade structure, laid a foundation for accurately estimating the subgrade system's compacting state in its compacting process.Secondly, analyzed and discussed the interacting problems between the compaction machine and compacted materials. It gives a vertical displacement solution on theory under the periodic load, and emphatically conducted the value simulated analysis to the vibration roller's response, indicated the distinction and relation between the compacting force and exciting force. On the basis of which established the dynamic model of compacting machine in the compacting process, under the linear and non-linear conditions, made the solution and analysis to the equation. Pointed out the relation between system resistance and its acceleration is linear, therefore defined the resistance index—acceleration, its goal is for the convenience of real-time measuring and fast monitoring. On the basis of theoretical research, studied the testing technology of the compacting process, introduced the composition, characteristics and the signal processing method of compaction process monitoring system which independently developed. According to control theory, produced the principle, content and implementing method of compaction quality control, and laid foundations for practical project application.Finally, made researches on the monitoring technology's applied problem in the stone ballast subgrade compacting process. To guarantee vibration roller conducting its compacting tasks on rated parameters is the precondition to use it as driving force to conduct compacting quality testing and controlling. Therefore, made the real-time supervision on the key parameters—excited frequency which can affect the compacting craft, the control method is throttling. Through changing the size of throttling, to realize the working frequency is near the rated value. On the basis of which analyzed the quality monitoring problem of the degree of stone ballast subgrade compaction and its uniformity. To the degree of compaction, should comprehensively apply standardization and relative method to implement the quality supervision, that is to distinguish the change and stability of subgrade plastic deformation by the dynamic responsive signal changes of vibrating wheel in the course of neighboring two times compaction, according to this determined whether finished compacting work on this kind of craft;Through the standardization distinguished whether achieved existing request, whether need to change the craft tocontinue the compaction. The applied example showed the change of compacting craft and the improvement of padding attribute is extremely effective for increaseing the compacting degree and the stability. The compacting uniformity is an extremely complex question, what kind of variation level by controlling involves to the influencing question of the subgrade structure's long-term service performance.This article used mathematical statistic principle for controlling, separately carried on the discussion from the point of view of the distribution of the whole variability and the partial non-uniformity, analyzed the padding changeability is the primary factor which affect the subgrade uniformity. Changing padding attribute and the compacting craft really can reduce the changeability. By conducting the contrast analysis between the dynamic measuring compacting data and the result of correspondingly conventional experiment such as deflection and the module, confirmed that the relation between them is one kind of direct-way relations, ulteriorly explained the feasibility of using the dynamic method.The monitoring technology established by the dynamic concept and the method in this article is feasible which proved by practice, it is helpful for the improvement of the whole roadbed construction level, and has the good application prospect and the high extension value.