一、工程安全分析评价
Research on the Key Technology……
Research on the Key Technology&Its Application to Reinforcement Project Post-evaluation for Dangerously Weak Dams
Wu，Haizhen，Hong，Wenhao，Hu，Qiang
JiangXi Provincial Institute of Water Sciences
According to the Fuzzy Analytic Hierarchy Process（FAHP）and the project success degree comprehensive evaluation theory，this paper established the judgment matrix with the aid of expert opinions，and put forward the fuzzy comprehensive evaluation theory for reinforcement project post-evaluation of dangerously weak dams.Based on the characteristics of the reinforcement project for dangerously weak dams，as well as on the research of the hierarchical relationships and relative importance among various factors，the paper proposed the main influence factor of reinforcement project which may have impact on the effectiveness and efficacy in each reinforcement stage，derived the weighted value of each index，and gave the scoring methods and scoring details for each index so as to establish the reinforcement project post-evaluation index system for dangerously weak dams.Depending on the total scores of dangerously weak dam reinforcement project，targeting the evaluation of the total effect of reinforcement project and with the aid of expert scores，the paper also studied and determined the fuzzy mapping matrix of each index，judgment matrix and index weight，and put forward a fuzzy comprehensive evaluation method with strong operability and high practical value for dangerously weak dam reinforcement project post-evaluation.The practical engineering application proves that the above-mentioned method is both feasible and rational，and is of high academic value and popularization and application value.
According to the Fuzzy Analytic Hierarchy Process（FAHP）and the project success degree comprehensive evaluation theory，this paper established the judgment matrix with the aid of expert opinions，and put forward the fuzzy comprehensive evaluation theory for reinforcement project post-evaluation of dangerously weak dams.Based on the characteristics of the reinforcement project for dangerously weak dams，as well as on the research of the hierarchical relationships and relative importance among various factors，the paper proposed the main influence factor of reinforcement project which may have impact on the effectiveness and efficacy in each reinforcement stage，derived the weighted value of each index，and gave the scoring methods and scoring details for each index so as to establish the reinforcement project post-evaluation index system for dangerously weak dams.Depending on the total scores of dangerously weak dam reinforcement project，targeting the evaluation of the total effect of reinforcement project and with the aid of expert scores，the paper also studied and determined the fuzzy mapping matrix of each index，judgment matrix and index weight，and put forward a fuzzy comprehensive evaluation method with strong operability and high practical value for dangerously weak dam reinforcement project post-evaluation.The practical engineering application proves that the above-mentioned method is both feasible and rational，and is of high academic value and popularization and application value.
1 Introduction
Safety of reservoir（and hydropower station）dams concerns the national welfare and the people’s livelihood.There are more than 30，000 dangerously weak dams throughout the country，accounting for 36%of the total dams.If any dam failure occurs，it will not only cause damage to the dam structure，but also bring personal injury to the downstream public and lead to serious economic，social and environmental losses.Since 2000，China has been intensifying investment on the reinforcement of dangerously weak reservoirs（hereinafter referred to reinforcement）and launching a massive reinforcement project construction.By 2012，the national total investment on reinforcement exceeded RMB 70 billion Yuan which has been completed basically.After reinforcement，with the significant reduction of the ratio of dangerously weak dams，a large number of reinforced reservoirs begin to produce better social and economic benefits.However，dangerously weak dams have the characteristics of discontinuity and periodicity and they occur and develop in dynamic process.Therefore，the reinforcement should be a long-term，regular and systematic work.Correspondingly，the reinforcement project need huge investment，long construction period and have wide influence，which involve many work links and processes.So reinforcement project quality control，afterwards running condition and performance evaluation，economic benefits and social impact estimation are common concerns to the decision-making departments，engineering construction and operation management units.To solve these problems，it is urgent to establish a scientific，reasonable and feasible project post-evaluation method.In the present study，some post-evaluation methods both at home and abroad for railway engineering，highway engineering and other construction projects have been discussed.Also，some positive explorations have taken place in the field of construction of water conservancy project，and some research results have been achieved.For example，Wen Hui［1］ made some exploratory research on the definition and significance of the post evaluation of water conservancy construction project as well as the characteristics，content，principles and others of the post evaluation，Zhang Rentian and Zhang Jinmiao［2］ studied the post evaluation system for water conservancy construction projects.Han Dong［3］ made pilot study on the application of the post-evaluation methods in the water conservancy construction project post evaluation.Sun Xiangqin and Qian Shanyang［5］ discussed the main contents involved in the the water conservancy construction project post evaluation，including revaluation of fixed assets，socio-economy，finance，engineering，environment，operating management，society and immigrants.However，none of these studies involved reinforcement project.Few research results related to reinforcement project post-evaluation index system，methods and other fields can be found.
Based on the Fuzzy Analytic Hierarchy Process（FAHP）and the Comprehensive Evaluation Theory of Project Success Degree，this paper studies and puts forward the fuzzy comprehensive evaluation of reinforcement project post-evaluation.The paper builds an index system for reinforcement project post-evaluation according to the reinforcement project characteristics.Also，with the aid of expert scores method，the paper determines the fuzzy mapping matrix of each index，judgment matrix and index weight，and puts forward a fuzzy comprehensive evaluation method with strong operability and high practical value to apply it to practical engineering.The main technical route of this paper is shown in Fig.1.
Fig.1 Technical ideas for research on reinforcement project post-evaluation for dangerously weak dams
本文发表于2013年。
2 Post-evaluation methods for dangerously weak dams
2.1 General idea
The effect of reinforcement project is of extensive ambiguity.To achieve the objectives［6］，the membership rule of fuzzy theory is often applied to such uncertainty for quantitative analysis.Also，the method of project success degree can be applied to measure the reinforcement effect.On these bases，with the idea of AHP method and the comprehensive evaluation theory of project success degree，this paper studies and proposes the fuzzy comprehensive evaluation method for proposed reinforcement projects.Its overall outline and implementation steps are described as follows：
（1）Division of project implementation phase.In combination with the features and the main contents of reinforcement project，the project implementation process can be divided into reinforcement preparatory work，reinforcement construction process，engineering operating status after reinforcement and project benefits after reinforcement.
（2）Build-up of evaluation structure model.With the idea of AHP method，the factors affecting reinforcement effect can be classified by properties to establish the hierarchical relationships of its influence，and ultimately to form a four-level analytical structure model.
（3）Establishment of index system.Based on the basic theory of fuzzy comprehensive evaluation method，an evaluation index system can be established for various stages of reinforcement project.
（4）Setup of weight matrix at various levels.Based on the evaluation index system，the judgment matrix will be set up at the appropriate level.With the expert opinions，the weight corresponding to each index at various levels will be derived to build the weight matrix at various levels.
（5）Establishment of scoring details for the bottom indexes.With the expert opinions，based on the scoring details，the comment of reinforcement effect will be converted to the corresponding scores.The fuzzy mapping matrix corresponding to the index will be calculated through the matrix.
（4）The matrix obtained in the previous step will be multiplied by the weight matrix corresponding to its previous level to get the new fuzzy mapping matrix.Through such repeated calculations，the target matrix of this reinforcement project can be obtained.Finally，the target matrix will be multiplied by the score matrix，and this product is just the total scores of reinforcement project.
（7）The overall satisfaction of the reinforcement project will be determined based on Evaluation Level.
Set and Their Corresponding Scores for Overall Satisfaction of Reinforcement Project（Table 1）.
Table 1 Evaluation level set and their corresponding meanings for overall satisfaction of reinforcement project
2.2 Establishment of evaluation structural model
When the hierarchical structure model for evaluation at the reinforcement stage is established with the AHP method，the evaluation object will be methodized and layered.Then，a four-level analytic structure model（Table 2）will be formed in accordance with aggregate combinations at different levels.Among which，the bottom level of the hierarchical structure is the expert score index level.
2.3 Composition of index system
Taking into account of the characteristics of reinforcement project，the post-evaluation index system will be mainly established from four aspects，i.e.，reinforcement preparatory work，reinforcement construction process，operating status after reinforcement and engineering benefits after reinforcement.
Meanwhile，the reinforcement project evaluation index system is divided into four levels，that is，first-level index（target level），second-level index（middle level），third-level index（middle level）and forth-level index（bottom）.
Each level in the index system consists of different indexes.In various levels，determination of indexes depends on the characteristics of the engineering project itself.According to statistics，in a certain reinforcement project post-evaluation index system（see Table 2），there are 179 influence indexes at different levels，including 4 first-level indexes，23 second-level indexes，41 third-level indexes and 111 forth-level indexes.
Table 2 Reinforcement project post-evaluation index system for dangerously weak dams
Note Each index in the table represents a unique letter，such as Q for reinforcement preparatory work，Q1 for safety appraisal，Q2 for preliminary design，and so on.
2.4 Establishment of scoring details for bottom index
In formulating the scoring details of the bottom index（score level），it is necessary to follow the principles of detailed，comprehensive，scientific，reasonable and practical.By reference to the relevant technical regulations，specifications，and considering engineering practice，the scoring details should be determined after repeated discussions and comprehensive analysis，and improving continuously in the process of application.For example，the scoring details of the index of“Qualification of Geological Survey Unit（Q121）”in“Geological Survey Work at Safety Appraisal Stage（Q12）”，which belongs to the first index of“Reinforcement preparatory work of dangerously weak dam”，can be graded from the following two aspects（the total score of this index is 100）：① If the geological survey of large reservoirs undertaken by Class A geological survey units，then medium-sized reservoirs undertaken by Class B ones and small reservoirs undertaken by Class C ones，90%of the total score can be granted to this index.② If the geological survey of medium-sized reservoirs or small reservoirs undertaken by Class A geological survey units，then small reservoirs undertaken by Class B ones，the total score can be granted to this index.
2.5 Build-up of judgment matrix
The pairwise comparisons of the importance among various factors at the same level under a single norm will be carried out.The matrix formed by their coefficients of comparisons is called the judgment matrix，which indicates the relative importance of various factors at this level relative to the previous level［6］.
Assuming there are three second-level indexes C1，C2，C3 under first-level index B1，the experts will be invited to conduct the pairwise comparisons to determine the relative importance.According to the assigned values by the experts based on the“0.1～0.9”metrization in Table 3，the relative importance factors can be obtained，as shown in Table 4.
Table 3 Metrization of judgment matrix elements
Table 4 Relative importance coefficient table of the pairwise comparisons relative to B1
From the above table，the judgment matrix MB1 relative to B1 can be obtained as：
2.6 Calculation of weight related to each index
1.Unification of judgment matrix
The above-mentioned judgment matrix MB1 will be unified to derive the Fuzzy consist ent judgment matrix W：
2.Solution of weight
From W，determine the weight set A=（A1，A2，…，An）to indicate weight distribution of various factors：
in formula，n represents of order of matrix；li represents the importance of index i relative to the previous-level objects.li will be normalized to obtain the weight of each index.
2.7 Formation of fuzzy mapping matrix
According to the expert assessment results，the proportion of each index level will be derived statistically，namely，the degree of membership of each index.The matrix formed by this membership index constitutes the judgment matrix of the fuzzy mapping relationship evaluation.
It is assumed to invite several experts to pass judgment on C1，C2 and C3 at D1 level，resulting in the results shown in Table 5.On this basis，the judgment matrix R1 of fuzzy mapping relationship corresponding to D1 is obtained as follows：
Table 5 Solution of degree of membership
Note rij represents the degree of membership of the i Index Element Ci relative to Index Element j of the comment set.For example，r12 represents proportion of Index C1 to be rated to be GOOD accounting for all ratings of Index C1.
According to the above method，the matrix Rn of fuzzy mapping relationship corresponding to other indices can be obtained.
2.8 Realization of fuzzy comprehensive evaluation
According to the above method，the total fuzzy mapping matrix rQ～X^of various indexes for reinforcement project post-evaluation will be established as：
Total weight matrix of various indexes：AQ～X=［qQ，qG，qY，qX］
Total fuzzy mapping matrix：
Score matrix P：
Synthesis score of reinforcement project post-evaluation（Overall effect）：
According to the scores，based on the meanings listed in Table 1，the overall effect after reinforcement and the reinforcement effect at various stages can be judged.
3 Engineering Applications
3.1 Introduction to engineering
The Hongqi Reservoir［7］ is located in the Wotou Village，Sidu Town，Xiushui County in Jiangxi Province，it is also in the upstream of the Penggu River（tributary of the Xiushui River）.The reservoir can control a drainage area of 10.9km2 above the dam site，with a normal pool level of 152.68m（the Yellow Sea elevation，the same below），with a total capacity of 1231×104m3 and design irrigation area of 11400 mu（1mu≈666.67m2）.Built in 1969，the reservoir dam mainly consists of the dam，spillway，dam culvert pipe，outlet tunnel and top grade power station，etc.，which is a medium-sized reservoir giving priority to irrigation，and combining with flood control，power generation，aquaculture and other comprehensive utilization efficiency.The reservoir was included in the second batch of large and medium-sized dangerously weak dam reinforcement planning projects of Jiangxi Province.Its safety appraisal work was completed in September 2005，and its reinforcement design work was completed in February 2006.The reinforcement construction was started in August 2007，and completed and put into operation in November 2010.The situation after reinforcement is shown in Picture 1 and Picture 2.
Picture 1 Downstream revetment situationsof Hongqi Reservoir after reinforcement
Picture 2 Upstream revetment situations ofHongqi Reservoir after reinforcement
3.2 Implementation process of post-evaluation
According to the actual situation of this project，the bottom indexes will be scored by the expert group.In combination with the index system of the four stages of reinforcement project，each evaluation matrix，index weights and fuzzy mapping matrix will be established to calculate the final scores.
1.Establishment of evaluation matrix and solution of weight sets
With the aid of expert experience，together with the actual situation of this project，the judgment matrix F at the relevant level will be established to derive the corresponding weight A.
2.Setup of fuzzy mapping matrix
The bottom index matrix will be calculated step by step to derive the global fuzzy mapping matrix R of reinforcement project post-evaluation：
3.Correlative matrix operation and computed results
The actual scores of the four stages of reinforcement project post-evaluation of this dam can be computed as 92.40，90.36，90.40 and 80.54 points，with a final synthesis score of 87.10.
3.3 Summing-up
From the computed score results of the four stages，the comprehensive effect of this reservoir dam is rated to be GOOD.Among which，the remaining three stages are in the EXCELLENT level except that the project benefit is totally in a GOOD level.
Through field visits，investigation，survey and interview，as well as access to information of the project，the above-mentioned evaluation results basically comply with the actual conditions of the project，which validates the feasibility and rationality of the relevant theoretical method of reinforcement project post-evaluation of dangerously weak dams proposed in this paper.
4 Conclusion
This paper deeply analyzed the characteristics of reinforcement project process and the contents of post evaluation.On these bases，the paper built the main influence factor set to measure the effectiveness and efficacy of the works at various stages of reinforcement project based on the FAHP and the theory as well as method of comprehensive judgment of project success degree，gave the scoring methods and scoring details for various indexes，established the index system of the four stages of reinforcement project post-evaluation and put forward the fuzzy comprehensive evaluation method for reinforcement project post-evaluation.Practical engineering application has proven such method was feasible and rational.
The research results further enrich，and develop the FAHP and the comprehensive evaluation method of project success degree.They are of important practical significance to：①summerize the experiences and lessons learned at various stages of reinforcement project construction and management；②improve and perfect the reinforcement project approval and decision-making，planning and design，quality control and others of dangerously weak dams；③improve project investment efficiency，fund utilization rate and management level of decision-makers and to promote the virtuous cycle and healthy development of investment in water conservancy projects.
References
［4］Zhang Rui，Yang Gaosheng，et.al.Taihu Lake Basin’s Wangyu River project post-evaluation［J］.Journal of Economics of Water Resources，2005（1）：23-24.
本文发表于2013年。