Evaluation Theory And Application For Health Condition Of Tunnel And Underground Engineeri

With the rapid development of traffic infrastructure construction and city scale expansion, China has become the country with the most quantity, most complicated, most rapidly developing in the future of tunnels and underground engineerings in the world. However, the maintenance technique for tunnels and underground engineerings started relatively late in our country, it is not optimism that the health of operation tunnels. At present, the most common method of health diagnosis for these concrete structures is monitoring model basing on monitoring data, although some success has been taken out in the practice using the Statistical Model, Deterministic Model, Mixed Model and so on, but single measuring points data is dealt in most models, and the judgment basis of the evaluation of health for structures is qualitative description or static evaluation, it is not sufficient at the system and comprehensiveness, and it will bring some difficulty to correctly guide the daily maintenance and repair to use above results. In the paper, combined with practical work, puts forward index system that can basically correct reflect the tunnel health states, combining quantitative and qualitative, and the final result being evaluated quantitatively. Giving the judging standards and weight of corresponding indexes; Establishing dynamic evaluation model of health states of tunnel and underground engineerings by inducting the method of dynamic fuzzy comprehensive evaluation; At the final, verifying and modifying part criterions of health diagnosis indexes by the method of indoor similar model test, validating the correctness of evaluation system and model proposed. The main research results as follow:1. Analyzing the supports and various structural breakage forms and influencing factors under operation basing on the rule of diagnostic index in its system, combing the practical engineering requirement and the specific characteristics of comprehensive diagnosis of tunnel and underground engineering health. Choosing and ascertain six diagnostic indexes (including supporting structure crack, water seepage, material degradation, cavities behind the lining, variation, ling peeling off and exfoliation of tunnel and underground engineering) and sub-index, constituting a comparatively complete diagnostic index system of the structure health.2. According to the diagnostic index and final diagnostic targets, designing the health evaluation sets of comprehensive diagnosis system of tunnel and underground engineering thinking over the corresponding criterion, existing methods, practical experience, medically health divided and other factors, the operation states are divided as four ranks:health, sub-health, disease and sick into death.3. It is relative that the various qualitative or quantitative index standards in the practice engineering, so distinguishing the results of structures using the combine of judgement standard with the works monitoring data and examining results. Giving the judgement standards of correspond index system combing the home and abroad engineering experience and criterion and so on.4. In the paper, the concept of health value is proposed, it makes the evaluation of various levels and its various indexes have a uniform meaning. Studying relatively thorough the method of initial data standardization of quantitative and qualitative diagnostic indexes, basically solved the difficult problem of intercomparison of diagnostic indexes in the same level resulting different each other from expression method, value range, measure method and measure units.5. According to the weight characteristic of diagnostic indexes and the comparative study of existing weight methods of tunnel and underground engineering, introduced multiplication scale method to determine the scale-weight of index layer, and comprehensively applied with the multiplication scale method and fuzzy artificial neural network to determine the six scale weight of criterion layer. At the same time, basing on the optimization principle, adopted combined weight method to determine the scale-weight, of criterion layer, it can effectively avoid artificial error caused by single method, and lay the foundation for the latter judgment.6. Puting forward dynamic fuzzy comprehensive evaluation of tunnel and underground engineering according to the characteristic that it commonly takes into account the evaluation indexes as constant and almost not considers change with time of eigenvalue. Putting forward variable fuzzy set theory, relative difference function model, variable fuzzy evaluation model. Constructing membership function of dynamic fuzzy comprehensive evaluation method, and constructing attractive matrix (main), range domain matrix and point value matrix linking practical physical meaning.7. Studying the application of dynamic fuzzy comprehensive evaluation method in the tunnel and underground engineering linking the practical example of bayi and xiangyang tunnel in Chongqing, China, it realized dynamic comprehensive evaluation of the tunnel and underground engineering. The results shows that it is more stable to evaluate the health states of the tunnel and underground engineering than other methods and it is propitious to reasonable judgment and maintenance by stage and batch to the same class engineering.8. Basing on indoor similar model test liking the practical engineering example, respectively studying the failure regularity and ultimate bearing capacity of the surrounding rock and supporting structure under the state of lining thinning, cavities behind the vault lining and correlative combination of them, and under the role of vertical stress, the criterion at every healthy subsection has been obtained. The bearing capacity curves show obviously S shape or inverse s-shaped and they can be divided into three degraded stages:slowly, rapid and completed, it is corresponding between tunnel health state with the stage, and it can offer basis and methods for judgment of tunnel supporting structure. The results show that it has a good correlation between structural health criterions, which getting from the test, with that using in the practical engineering, the former can correct the latter, and it can make the judgment more close to reality and be more scientific and rational for structural health judging and practical engineering result if combinedly use correlative criterions.