Fixed price contract is usually employed in the engineering-procurement-constmction (EPC) hydropower project. However, project cost is difficult to manage because many uncertainty factors exist. There is a risk for the general contractor to accomplish an EPC project with a fixed price contract. Therefore, it is important for a general contractor to make quantitative analysis of uncertainty factors related to project cost in order to give a competitive bidding with reasonable contract price and then implement effective cost control during the whole construction period.rnFirst, this paper identifies main cost risks of an EPC hydropower project and proposes a contractor's cost model by considering price uncertainty, interest rate, natural condition, engineering technology and owner's credit. The cost contains not only the budgetary estimate of design (A) , but also the additional expected costs including materials price inflation cost ( a) , and the interest of contractor's advanced cash because of owner's overdue payment ( G) , and the increased cost of modification design that are susceptiblernto natural condition and engineering technology risks (L).rnSecond, we discuss the methods used to calculate materials price inflation cost, the interest of contractor's advanced payment and the increased cost. We estimate the price inflation cost a and predict the price fluctuation by using the average growth of main materials price index of hydropower project. Considering unfavorable natural conditions of engineering geology, hydrology and climate, and project technique risks, PERT (Program Evaluation and Review Technique) and Three Point Evaluation methods are employed to measure the increased cost of modification design L. Additionally, the maximum delayed months and monthly repayment probability are determined by experts according to owner's credit and financial capability. The interest of contractor's advanced payment during the whole construction period G can be calculated to estimate the monthly budgetary of design and the repayment probability.rnFinally, the complex contractor's cost model with some random variables is solved by the Monte-Carlo method. The cost distribution and monthly expected cost cash-flow, as well as the cost control risk of general contractor can be simulated quantitatively. Furthermore, the general contractor cost of an EPC hydropower project in Yunnan province China is analyzed using the proposed methods. The finding provides strong support for the general contractor to make reasonably decision on bidding price, risk compensation, and cost control in the construction process.%水电工程EPC模式中通常采用固定总价合同,但由于工程实施过程中存在众多不确定因素,使得工程成本具有较大的不确定性,所以固定总价合同对总承包商来说具有很大风险.本文在辨识影响水电EPC项目总承包成本变动的主要风险因素基础上,建立了综合物价、利率、自然条件和工程技术、业主资信等不确定因素影响下的总承包商工程成本模型,提出了考虑物价随机波动的工程成本变动分析方法、自然条件及工程技术不确定性下基于PERT三值估计的成本变动分析方法以及工程款拖欠风险下的总承包商垫资利息分析方法,并采用Monte-Carlo方法求解有着众多随机变量的总承包商成本模型,定量模拟了各种不确定性因素影响下总承包商的成本变化规律和成本控制风险,从而可为总承包商合理确定合同报价、风险补偿金以及施工过程中的成本控制提供科学依据.
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