導(dǎo)截流工程中的幾個隨機性問題的研究
發(fā)布時間：2019-07-08 12:27
【摘要】：本文以隨機性為大的研究背景和研究主題,針對施工導(dǎo)截流過程中的三個由隨機性所引發(fā)的工程問題,在分析了各問題自身特點的基礎(chǔ)上,分別應(yīng)用了三種不同的隨機性分析方法,使各問題從與以往不同的角度得到了新的認(rèn)識和一定程度上的解決。具體地,本文所分析的三個隨機性問題分別為：A.受水文和水力隨機性共同影響時的導(dǎo)流風(fēng)險分析問題；B.由水流脈動隨機性以及塊體在床面所處位置隨機性所產(chǎn)生的,截流塊體的隨機性起動問題；C.在脈動水壓作用下的閘門的隨機振動問題。對以上三個問題的研究,分別構(gòu)成了本論文的第三、四、五章。 1)對于隨機性問題A,本文應(yīng)用了一種概率密度演化的方法,以達到“既能對受多重隨機因素影響時的風(fēng)險演化過程進行分析,又能獲取最終的導(dǎo)流風(fēng)險率”的研究目的。 鑒于上游圍堰的堰前水位能綜合地體現(xiàn)出水文和水力隨機性的共同影響,因此,本文以堰前水位作為導(dǎo)流風(fēng)險的載體,試圖采用概率密度演化方法對堰前水位分布在各時刻的概率密度進行求解,以期能據(jù)此對導(dǎo)流風(fēng)險的演化過程進行分析。為此,在第三章中,基于概率密度演化方法的研究思路,首先根據(jù)水庫蓄量平衡關(guān)系,為該方法的應(yīng)用提供了一個關(guān)于堰前水位的狀態(tài)方程。然后,在分析了水文和水力不確定性的基礎(chǔ)上,通過對各隨機參數(shù)進行以設(shè)計值為均值的正態(tài)分布假設(shè),向狀態(tài)方程中引入了水文和水力隨機性。根據(jù)此狀態(tài)方程,本章隨后建立了針對堰前水位的廣義概率密度演化方程,并介紹了基于此方程的對堰前水位分布的概率密度進行求解的計算流程。同時,通過在該計算流程中添加吸收壁邊界條件,提出了導(dǎo)流風(fēng)險率的計算方法。本章最后,以某水電工程為例,通過數(shù)值求解帶有7個隨機變量的廣義概率密度演化方程,成功地獲取了3個典型流量水平下的堰前水位分布在計算時段內(nèi)各時刻的概率密度,并對各流量水平下的導(dǎo)流風(fēng)險率進行了計算,為了對比驗證,該風(fēng)險率還與由Monte-Carlo法所得到的風(fēng)險率進行了比較。 通過以上對實例的分析,可以發(fā)現(xiàn),應(yīng)用概率密度演化方法能夠方便地獲取由傳統(tǒng)方法所不易得到的堰前水位分布的概率密度及其隨時間的變化情況,可以直觀、實時地從蘊含有豐富概率信息的該變化過程中,對導(dǎo)流風(fēng)險進行分析與判斷。另外,通過與Monte-Carlo法的計算結(jié)果進行對比,說明了基于概率密度演化方法還可以對導(dǎo)流風(fēng)險率進行有效的求取。 2)對于隨機性問題B,本文根據(jù)對塊體隨機性起動現(xiàn)象的一種描述,應(yīng)用Monte-Carlo法,對處于多種情況下的截流塊體的起動概率進行了計算。 具體地,在第四章中,首先僅以瞬時流速作為隨機參數(shù),對處于無阻擋無遮掩這一簡單情況下的截流塊體的起動概率用Monte-Carlo法進行了計算,并通過與該情況下的理論解進行對比,說明了Monte-Carlo法在計算塊體起動概率方面的可行性。然后,對塊體處于更復(fù)雜、受更多隨機性因素影響下的情況,仍用Monte-Carlo法計算了其起動概率。此處,這些情況包括：有阻擋無遮掩以及有阻擋有遮掩的情況。另外,為能更加合理地反映出截流塊體的實際起動情況,本章還首次應(yīng)用Monte-Carlo法對塊體在三維空間內(nèi)的起動概率進行了計算,得到了塊體在該情況下的一些起動規(guī)律,并與在二維情況下的相同計算進行了比較。 通過以上的一系列計算,顯示了Monte-Carlo法可以方便且有效地求取受多重隨機性因素影響的截流塊體的起動概率,使截流塊體在動水作用下的起動難度(或穩(wěn)定性)可以從概率的層面上進行量化,為截流塊體的選取及其帶來的相關(guān)的風(fēng)險估計提供了依據(jù)。 3)對于隨機性問題C,本文應(yīng)用正交展開的方法,使脈動水壓從頻域內(nèi)的隨機過程轉(zhuǎn)化為時域內(nèi)的隨機過程,從而為由脈動水壓所引起的閘門振動問題建立了激勵模型。通過與目標(biāo)隨機過程在均值、方差以及功率譜層面的比較,驗證了該激勵模型的準(zhǔn)確性。進一步地,本章以一個簡單的平板結(jié)構(gòu)作為閘門受力體,將由激勵模型所生成的252條激勵樣本作用于該結(jié)構(gòu),并通過概率密度演化方法對該結(jié)構(gòu)進行了動力響應(yīng)分析,得到了結(jié)構(gòu)任意位置處的振動位移量在計算時段內(nèi)任意時刻的概率分布情況,為閘門振動研究提供了一種“頻域到時域的激勵建�！怕拭芏妊莼椒ǖ捻憫�(yīng)分析”的研究模式。
[Abstract]:Based on the analysis of the characteristics of each problem, three different stochastic analysis methods are applied to the research background and the research topic of the randomness, and based on the analysis of the characteristics of each problem, So that the problems can be solved in a new way and a certain degree from the angle different from that of the past. In particular, the three stochastic problems analyzed in this paper are: A. The problem of the analysis of diversion risk in the case of the mutual influence of the hydrological and hydraulic randomness; B. the randomness of the flow pulsation and the randomness of the block in the position of the bed surface, and the random starting of the shut-off block; C. The random vibration of the gate under the action of pulsating water pressure. The third, fourth and fifth chapters of this thesis are respectively formed in the research of the above three problems. 1) For the problem of randomness A, a method of probability density evolution is applied in this paper to reach the aim of the "The risk evolution process of multiple random factors can be analyzed, and the final diversion risk rate can be obtained.". In view of the fact that the pre-weir water level of the upstream cofferdam can comprehensively reflect the mutual influence of the hydrological and hydraulic randomness, this paper, taking the pre-weir water level as the carrier of the diversion risk, tries to adopt the probability density evolution method to the probability density of the pre-weir water level distribution at all times. The line is solved with a view to the evolution of the diversion risk accordingly. To this end, in the third chapter, based on the research thinking of the method of probability density evolution, firstly, according to the reservoir volume balance relationship, a shape of the water level before the weir is provided for the application of the method. Then, on the basis of the analysis of the hydrological and hydraulic uncertainties, the hydrologic and hydraulic power is introduced into the state equation by assuming a normal distribution hypothesis with a mean value of the design value for each random parameter. In this chapter, the generalized probability density evolution equation for the water level of the weir is set up in this chapter, and the probability density of the water level distribution before the weir is calculated based on the equation. in addition, by adding that boundary condition of the absorption wall in the calculation flow, the invention provides a flow-guide risk ratio meter, In the end of this chapter, a general probability density evolution equation with 7 random variables is solved by means of a numerical solution, and the general probability density evolution equation with 7 random variables is solved by numerical solution. The rate density is calculated and the risk rate of the flow at each flow level is calculated. In order to compare the verification, the risk ratio is also compared with the risk rate obtained by the Monte-Carlo method. By the analysis of the above examples, it can be found that the probability density of the pre-weir water level distribution which is not easily obtained by the conventional method and the change of the time with time can be conveniently obtained by using the probability density evolution method. and the diversion risk can be intuitively and real-time from the change process containing abundant probability information, In addition, by comparing with the calculation results of the Monte-Carlo method, the probability density evolution method can also be used to carry out the flow-diversion risk rate. In this paper, based on the description of the random starting phenomenon of the block, the method of Monte-Carlo method is applied to the start-up of the shut-off block in many cases. The probability is calculated. In the fourth chapter, only the instantaneous flow rate is used as the random parameter, the start-up probability of the shut-off block under the simple condition without blocking is calculated by the Monte-Carlo method, The theoretical solution is compared, and the Monte-Carlo method is used to calculate the block. The feasibility of the dynamic probability. Then, the block is in a more complex and more random factor, and the Monte-Carlo method is still used. The start-up probability is calculated by the method. Here, these conditions include: In addition, the start-up probability of the block in three-dimensional space is calculated by using the Monte-Carlo method for the first time in order to more reasonably reflect the actual start-up of the block. some of the starting laws of the state, and in the two-dimensional case Through the above series of calculations, it is shown that the Monte-Carlo method can conveniently and effectively obtain the starting probability of the shut-off block affected by the multiple random factors, so that the starting difficulty (or stability) of the shut-off block under the action of moving water can Quantization from the level of probability, the selection of the closure block and the phase brought by it In this paper, the stochastic process of the pulsating water pressure from the frequency domain to the random process in the time domain is applied to the stochastic problem C, which is caused by the pulsating water pressure. The excitation model is established by the vibration of the gate. By comparison with the mean, variance and power spectral level of the target stochastic process, Further, this chapter uses a simple plate structure as the force body of the gate, and the 252 excitation samples generated by the excitation model act on the structure, and the probability density evolution method In this paper, the dynamic response analysis of the structure is carried out, and the probability distribution of the vibration displacement in any position of the structure at any time in the calculation period is obtained, and a kind of "The Response Analysis of the Method for the Modeling of the Frequency Domain to the Time Doai" is provided for the gate vibration research.
【學(xué)位授予單位】：武漢大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2014
【分類號】：TV551
本文編號：2511582
[Abstract]:Based on the analysis of the characteristics of each problem, three different stochastic analysis methods are applied to the research background and the research topic of the randomness, and based on the analysis of the characteristics of each problem, So that the problems can be solved in a new way and a certain degree from the angle different from that of the past. In particular, the three stochastic problems analyzed in this paper are: A. The problem of the analysis of diversion risk in the case of the mutual influence of the hydrological and hydraulic randomness; B. the randomness of the flow pulsation and the randomness of the block in the position of the bed surface, and the random starting of the shut-off block; C. The random vibration of the gate under the action of pulsating water pressure. The third, fourth and fifth chapters of this thesis are respectively formed in the research of the above three problems. 1) For the problem of randomness A, a method of probability density evolution is applied in this paper to reach the aim of the "The risk evolution process of multiple random factors can be analyzed, and the final diversion risk rate can be obtained.". In view of the fact that the pre-weir water level of the upstream cofferdam can comprehensively reflect the mutual influence of the hydrological and hydraulic randomness, this paper, taking the pre-weir water level as the carrier of the diversion risk, tries to adopt the probability density evolution method to the probability density of the pre-weir water level distribution at all times. The line is solved with a view to the evolution of the diversion risk accordingly. To this end, in the third chapter, based on the research thinking of the method of probability density evolution, firstly, according to the reservoir volume balance relationship, a shape of the water level before the weir is provided for the application of the method. Then, on the basis of the analysis of the hydrological and hydraulic uncertainties, the hydrologic and hydraulic power is introduced into the state equation by assuming a normal distribution hypothesis with a mean value of the design value for each random parameter. In this chapter, the generalized probability density evolution equation for the water level of the weir is set up in this chapter, and the probability density of the water level distribution before the weir is calculated based on the equation. in addition, by adding that boundary condition of the absorption wall in the calculation flow, the invention provides a flow-guide risk ratio meter, In the end of this chapter, a general probability density evolution equation with 7 random variables is solved by means of a numerical solution, and the general probability density evolution equation with 7 random variables is solved by numerical solution. The rate density is calculated and the risk rate of the flow at each flow level is calculated. In order to compare the verification, the risk ratio is also compared with the risk rate obtained by the Monte-Carlo method. By the analysis of the above examples, it can be found that the probability density of the pre-weir water level distribution which is not easily obtained by the conventional method and the change of the time with time can be conveniently obtained by using the probability density evolution method. and the diversion risk can be intuitively and real-time from the change process containing abundant probability information, In addition, by comparing with the calculation results of the Monte-Carlo method, the probability density evolution method can also be used to carry out the flow-diversion risk rate. In this paper, based on the description of the random starting phenomenon of the block, the method of Monte-Carlo method is applied to the start-up of the shut-off block in many cases. The probability is calculated. In the fourth chapter, only the instantaneous flow rate is used as the random parameter, the start-up probability of the shut-off block under the simple condition without blocking is calculated by the Monte-Carlo method, The theoretical solution is compared, and the Monte-Carlo method is used to calculate the block. The feasibility of the dynamic probability. Then, the block is in a more complex and more random factor, and the Monte-Carlo method is still used. The start-up probability is calculated by the method. Here, these conditions include: In addition, the start-up probability of the block in three-dimensional space is calculated by using the Monte-Carlo method for the first time in order to more reasonably reflect the actual start-up of the block. some of the starting laws of the state, and in the two-dimensional case Through the above series of calculations, it is shown that the Monte-Carlo method can conveniently and effectively obtain the starting probability of the shut-off block affected by the multiple random factors, so that the starting difficulty (or stability) of the shut-off block under the action of moving water can Quantization from the level of probability, the selection of the closure block and the phase brought by it In this paper, the stochastic process of the pulsating water pressure from the frequency domain to the random process in the time domain is applied to the stochastic problem C, which is caused by the pulsating water pressure. The excitation model is established by the vibration of the gate. By comparison with the mean, variance and power spectral level of the target stochastic process, Further, this chapter uses a simple plate structure as the force body of the gate, and the 252 excitation samples generated by the excitation model act on the structure, and the probability density evolution method In this paper, the dynamic response analysis of the structure is carried out, and the probability distribution of the vibration displacement in any position of the structure at any time in the calculation period is obtained, and a kind of "The Response Analysis of the Method for the Modeling of the Frequency Domain to the Time Doai" is provided for the gate vibration research.
【學(xué)位授予單位】：武漢大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2014
【分類號】：TV551
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