本文選題：邊坡穩(wěn)定性 + 可靠度分析��； 參考：《西安理工大學(xué)》2017年碩士論文

【摘要】：邊坡的穩(wěn)定性評價是巖土工程中的研究熱點。目前,邊坡穩(wěn)定性評價方法主要包括安全系數(shù)法與可靠度方法,但這兩種方法都存在一些缺點與不足:前者無法考慮巖土參數(shù)以及所受動荷載中存在的不確定性和隨機性,使得邊坡工程的安全水平含混不清,不能提供說明邊坡安全度的評價指標;而后者雖可考慮諸多因素的不確定性,但其在巖土參數(shù)相關(guān)性、小樣本條件下巖土參數(shù)的統(tǒng)計特性及動力可靠度的評判指標等方面尚不完善,導(dǎo)致該法的準確性和實用性較差。本文針對以上幾種問題,提出了相對的解決方法,并在此基礎(chǔ)上編寫了邊坡穩(wěn)定可靠度分析的計算程序,主要研究成果如下:(1)簡單介紹了邊坡穩(wěn)定性分析和可靠度分析的基本理論,并探討了不同可靠度分析方法的優(yōu)劣;提出了基于響應(yīng)面法的邊坡概率臨界滑面搜索方法,使用二次多項式響應(yīng)面函數(shù)代替難以求偏導(dǎo)的安全系數(shù)隱式表達式,從而得到邊坡最小可靠度指標及其對應(yīng)的滑面;通過改變邊坡穩(wěn)定性分析方法和參數(shù)的變異系數(shù)、相關(guān)系數(shù)及其所服從的概率分布,進行了邊坡穩(wěn)定性靜力可靠度的敏感性分析。(2)利用DA-檢驗對3個實際工程中的數(shù)據(jù)進行分析,發(fā)現(xiàn)常用的正態(tài)分布并不一定是c、?所服從的概率分布,對數(shù)正態(tài)、極值I型與Weibull分布都可能是c、?服從的分布,直接使用正態(tài)分布模擬其概率分布將導(dǎo)致較大的誤差。(3)為準確描述參數(shù)間的相關(guān)性引入Copula理論,利用Copula函數(shù)建立參數(shù)的聯(lián)合概率分布并進行邊坡可靠度分析,發(fā)現(xiàn):抗剪強度參數(shù)c、?的負相關(guān)性對可靠度結(jié)果具有很大的影響,不考慮相關(guān)性的邊坡可靠度分析計算結(jié)果偏于保守,帶來不必要的浪費。(4)針對小樣本數(shù)據(jù)條件下的邊坡可靠度分析,首次引入隨機加權(quán)法進行巖土參數(shù)的統(tǒng)計分析,模擬不同備選Copula函數(shù)AIC值及邊坡失效概率的變異性,再利用百分位法得到邊坡失效概率的置信區(qū)間。通過一簡單算例和工程實例說明了上述方法能夠解決小樣本數(shù)據(jù)條件下的可靠度分析。(5)提出以邊坡永久位移作為邊坡穩(wěn)定性動力可靠度的評判指標,在考慮地震動隨機性的基礎(chǔ)上通過Newmark有限位移理論得到永久位移,并通過永久位移的累計概率分布圖得到任意可能發(fā)生的永久變形對應(yīng)的失效概率,使得工程人員能夠根據(jù)邊坡的重要性以及邊坡修復(fù)的難易程度選擇不同的邊坡允許變形作為控制標準,全面協(xié)調(diào)安全與經(jīng)濟的矛盾。(6)在考慮到地震烈度自身隨機性的基礎(chǔ)上,通過地震場地危險性分析得到烈度的概率分布,隨后利用全概法則求得任意邊坡永久位移對應(yīng)的概率;在考慮了巖土參數(shù)不確定性及相關(guān)性的基礎(chǔ)上,研究了不同因素如參數(shù)變異性、參數(shù)分布概型等對動力可靠度結(jié)果的影響。
[Abstract]:Slope stability evaluation is a hot topic in geotechnical engineering. At present, the evaluation methods of slope stability mainly include safety factor method and reliability method, but these two methods have some shortcomings and shortcomings: the former can not take into account the rock and soil parameters and the uncertainty and randomness existing in the dynamic load. The safety level of slope engineering is ambiguous and can not provide an evaluation index to explain the slope safety degree, and the latter can take into account the uncertainty of many factors, but its correlation in geotechnical parameters, The statistical characteristics of geotechnical parameters and the evaluation index of dynamic reliability are not perfect under the condition of small sample, which leads to the poor accuracy and practicability of the method. In view of the above problems, this paper puts forward a relative solution method, and on the basis of this, compiles a calculation program for the reliability analysis of slope stability. The main research results are as follows: (1) the basic theories of slope stability analysis and reliability analysis are briefly introduced, and the advantages and disadvantages of different reliability analysis methods are discussed, and the slope probabilistic critical sliding surface search method based on response surface method is proposed. The quadratic polynomial response surface function is used to replace the implicit expression of safety factor which is difficult to obtain the slope reliability index and its corresponding sliding surface, and by changing the slope stability analysis method and the variation coefficient of the parameters, the minimum reliability index and the corresponding slip surface of the slope are obtained. The correlation coefficient and the probability distribution of the reliability of slope stability are analyzed by using DA-test. It is found that the usual normal distribution is not necessarily cu? The probabilistic distribution, logarithmic normal distribution, extreme type I and Weibull distribution may all be cu? The direct use of normal distribution to simulate its probability distribution will lead to a large error. The Copula theory is introduced to accurately describe the correlation between parameters. The joint probability distribution of parameters is established by using Copula function and the slope reliability is analyzed. Find out: shear strength parameter cu? The negative correlation has a great influence on the reliability results. The calculated results of slope reliability analysis without considering the correlation are conservative and bring unnecessary waste.) for the slope reliability analysis under the condition of small sample data, For the first time, the statistical analysis of geotechnical parameters is carried out by introducing the stochastic weighting method to simulate the variability of AIC value and slope failure probability of different Copula functions, and then the confidence interval of slope failure probability is obtained by using the percentile method. A simple example and an engineering example show that the above method can solve the reliability analysis under the condition of small sample data. The permanent displacement of the slope is proposed as the evaluation index of the dynamic reliability of the slope stability. On the basis of considering the randomness of ground motion, the permanent displacement is obtained by Newmark finite displacement theory, and the failure probability corresponding to any permanent deformation is obtained by the cumulative probability distribution of permanent displacement. According to the importance of slope and the difficulty of slope restoration, engineers can choose different allowable deformation of slope as control standard, and fully coordinate the contradiction between safety and economy. On the basis of considering the randomness of seismic intensity itself, The probability distribution of intensity is obtained by seismic site risk analysis, and then the probability corresponding to permanent displacement of any slope is obtained by using the full probability rule, and the uncertainty and correlation of geotechnical parameters are taken into account. The influence of different factors, such as parameter variability and parameter distribution probability type, on the dynamic reliability results is studied.
【學(xué)位授予單位】：西安理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TU435

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