Research On Satability Evaluation Criterion And Method For Engineering Treatement Rock Slope

Recently, fast progress of traffic construction projects being carried at the mountain areas in western China, a large number of high-steep slopes were formed during the engineering constructions. Statistically, there are more than700slopes higher than30m that need to be evaluating the treatment effect.182slopes had loose stability and been treated while constructing along the area between Yuan-Jiang to Mo-Hei expressway (147km distance).Therefore, finding scientific methods that can maintain of high-steep slopes is of great importance for the safety of the proposed highway operation. Although local and external scholars have reached great achievements on stability evaluation for the untreated engineering slope at present, the studies on the post evaluation of the stability of engineering slope and the engineering treatment effects are relatively scarce. The evaluation methods for treatment effect in most of the current published literatures are normally using the traditional methods to re-evaluate the slope stability, or calculating the engineering economic indicators.Based on the western traffic science and technology project 《Researth on evaluation of treatment effect and the countermeasure for Yunnan YuanMo expressway》, this thesis concerned mainly to systematically study the criterion, evaluation method on the treatment effect of anchors engineering. The main contents are as follows:(1) The concept and content of post evaluation of the treatment effect were put forward from the point of view the highway operation, management and maintain, considering the difference between the stability evaluation of the untreated and post treatment effect of engineering slope.(2) Considering the risk of engineering, scale and extent of influence on operation of the treated slopes, and based on the failure type, the classification criterions for treatment effect evaluation of the slope engineering were designed, and solving measures were proposed.(3) According to the characters of anchor engineering, classification criterions were established for evaluation of treatment effect for the engineering slope, which based on three coefficients of safety (1.00,1.10and1.20). Furthermore, the suitability of anchorage engineering in different aspects of slope failure such as rock fall, collapse, landslide, deformation failure in slope were analyzed, considering the mechanical parameters of rock mass and the anchorage engineering mechanical behaviors.(4) The accuracy of strength parameters of structural planes in rock slope were discussed with the method of laboratory direct shear test and empirical evaluation method. The results show that the Barton model can determine the strength parameters of structural planes easily and accurately. However, the value of cohesion gained from the laboratory test is significantly higher, and it is proper to take one tenth of the laboratory test value or less in practical application. (5) Mechanical behaviors and design depth of anchorage segment was synthetically analyzed through theoretical analysis、empirical equations and normative recommended methods. In addition the calculated data was also compared with practical data collected from field test. The result suggests that the design parameters recommended by the current norms is evident conservative, and the value of design depth is2.2-5.1times as much as which gained through practical monitoring and theoretical calculations.(6) Based on3D geological information and numerical calculation model, which compiled in Fish language was constructed to analyze the failure model of slope before and after treatment. The results of calculations show that the method of numerical simulation can accurately simulate the treatment effect. In addition, it also proves that the pre-stress anchor cable can efficiently prevent the potential sliding trend and achieve the good treatment effect.(7) The trend changing of the pre-stress in the course of the construction anchorage and working stage was predicted by means of second order curve, GM(1,1) and exponential smoothing. The results show that the stress changes of anchorage segment accord with the characters of the second order curve, but the GM(1,1) and exponential smoothing models can predict the changes trend of pre-stress accurately, therefore, they can be used in risk prediction of treatment effect for the slope.(8)Base on the fuzzy mathematics theory and project risk evaluation contents, a comprehensive evaluation model for the slope engineering treatment effect was established. This model considers three aspects (nine evaluation factors), which include slope geological condition, slope prevention engineering and macroscopic indications. Then the index weight at every level was established by the analytic hierarchy process method. The treatment effect of119slopes along Yuan-Mo highway is evaluated. This research is approved that this model can effectively distinguish the treatment effect of evaluation levels, so it can be widely used to evaluate the treatment effect of the slope engineering.(9)Based on the content, objectives and method of the slope engineering treatment effect evaluation, a monitoring and early warning system were developed. This is the first time to construct a slope basic and monitory information database from the angle of slope treatment effect evaluation, and to establish an interactive query mechanism in different database. This work can realize both the single factor and comprehensive evaluations for the treatment effect of slope engineering. Moreover, it can make the early warning on the analysis of the real-time data.