【摘要】：邊坡工程是巖土工程界的經(jīng)典研究領(lǐng)域之一,其對象是經(jīng)歷了億萬年漫長地質(zhì)史時期的巖土體,其賦存環(huán)境、組成成分、物理、力學(xué)特征等因素存在不同程度的非確定性。在邊坡工程的分析和設(shè)計中,為刻畫這些因素不確定性程度的影響,常采用安全系數(shù)或可靠度指標(biāo)來進(jìn)行表征。但安全系數(shù)側(cè)重揭示平均抗力與平均荷載的相對數(shù)量關(guān)系,而可靠度指標(biāo)提示的是在既定條件下存在需要被動承受失效風(fēng)險的概率。對于存在不確定性影響因素的工程而言,完全消除失效風(fēng)險是不可能的,重點在于明確相關(guān)因素對風(fēng)險的影響程度,依據(jù)具有針對性的方法,通過相應(yīng)的設(shè)計分析,為制訂合理的工程處治措施指明方向,主動將風(fēng)險控制在可接受的范圍之內(nèi)。而目前的相關(guān)分析方法基本上只著重地體現(xiàn)了其中的某個方面,沒有達(dá)到完備地能同時實現(xiàn)上述功能的程度。為此,本文將在現(xiàn)有邊坡穩(wěn)定分析方法的研究基礎(chǔ)上,結(jié)合邊坡工程自身的特征開展一系列的研究工作,進(jìn)而建立起一種基于風(fēng)險主動控制理念的邊坡穩(wěn)定評估新方法。 首先,根據(jù)邊坡破壞時沿規(guī)則滑面滑動和任意滑面滑動的兩類破壞形式,相應(yīng)地從邊坡極限平衡理論體系中挑選出畢肖普模式和簡布模式作為代表,基于風(fēng)險控制理念,利用一次逆可靠度原理,演繹了邊坡穩(wěn)定逆可靠度算法,導(dǎo)出了兩類滑動模式的相關(guān)計算公式,形成了具有可靠度和安全系數(shù)雙重控制指標(biāo)的能完成簡單情況邊坡計算的邊坡穩(wěn)定逆可靠度分析方法框架。該方法基于事先可接受的失效風(fēng)險(目標(biāo)可靠度指標(biāo))設(shè)計影響邊坡穩(wěn)定的各類參數(shù),使可靠度指標(biāo)與穩(wěn)定性系數(shù)相互對應(yīng),達(dá)到主動控制邊坡失效風(fēng)險的目的。 其次,巖土參數(shù)的非確定性描述和邊坡穩(wěn)定狀態(tài)的函數(shù)表達(dá)形式?jīng)Q定著逆可靠度設(shè)計分析方法的實用性及其計算結(jié)果的有效性,影響邊坡穩(wěn)定的眾多參數(shù)在不確定特征上往往又體現(xiàn)為隨機(jī)性、區(qū)間性、灰色性等多樣化現(xiàn)象,同時還表現(xiàn)為各參數(shù)對邊坡穩(wěn)定狀態(tài)影響程度的非均等性。因此,在建立基于充滿空間、多水平、穩(wěn)健性的均勻設(shè)計進(jìn)行試驗樣本提取方法的基礎(chǔ)上,將灰色關(guān)聯(lián)理論嵌入到區(qū)間分析模型之中,求解各因素與響應(yīng)值間的區(qū)間關(guān)聯(lián)度,并通過結(jié)合相對優(yōu)勢度理論對區(qū)間關(guān)聯(lián)度進(jìn)行排序,構(gòu)建出基于不確定性理論的邊坡穩(wěn)定影響因素顯著性綜合評估方法。這一方法既為建立邊坡穩(wěn)定力學(xué)狀態(tài)描述函數(shù)時,合理剔除某些因素、約簡邊坡狀態(tài)模型提供了篩選工具,同時為下一步提高風(fēng)險控制評估方法的實用性準(zhǔn)備了相應(yīng)手段。 結(jié)合邊坡參數(shù)分布形態(tài)各異及參數(shù)間存在相關(guān)性的實際工程特征,從響應(yīng)面函數(shù)模型自身構(gòu)建條件入手,繼續(xù)展開深入的研究與探討。首先,通過引入Nataf變換把邊坡結(jié)構(gòu)中具有多種分布形態(tài)及有相關(guān)性的參數(shù)進(jìn)行獨立正態(tài)化,然后,利用獨立正態(tài)化的參數(shù)來擬合響應(yīng)面函數(shù)模型,據(jù)此構(gòu)造的響應(yīng)面模型能適用于實際邊坡工程中參數(shù)分布形式的多樣性及參數(shù)間的相關(guān)性特征,最后,將前述擬合出的響應(yīng)面模型和一次逆可靠度理論結(jié)合,構(gòu)建出更具合理性和有效性的邊坡失穩(wěn)風(fēng)險主動控制評估方法。 再次,為進(jìn)一步完善并豐富邊坡失穩(wěn)風(fēng)險主動控制評估方法的研究內(nèi)容,提高響應(yīng)面建模手段在處理邊坡工程隱式功能函數(shù)中的適用性,結(jié)合邊坡工程極限狀態(tài)功能函數(shù)復(fù)雜、高度非線性的特征,綜合考慮了響應(yīng)面模型中函數(shù)表達(dá)形式及抽樣方式。在響應(yīng)面模型的選擇上,針對多項式模型適用范圍的局限性,采用理論上更為嚴(yán)謹(jǐn)、操作上更具靈活性、對復(fù)雜非線性問題處理更為有效的Kriging代理模型；對于試驗樣本點的采樣方式,則將對復(fù)雜非線性模型分析效率更高、適應(yīng)性更強(qiáng)的拉丁超立方試驗設(shè)計方法與具有主動搜索最佳訓(xùn)練樣本的主動學(xué)習(xí)法相結(jié)合。上述響應(yīng)面模型與抽樣方式的融合將建立起一種更為完善的邊坡穩(wěn)定逆可靠度響應(yīng)面技術(shù),拓寬了解決邊坡復(fù)雜隱式功能函數(shù)失效風(fēng)險評估方法的適用范圍。 最后,利用本文所構(gòu)建出的一套較為完善、適合不同狀況下的邊坡穩(wěn)定影響因素顯著性辨識方法及失穩(wěn)風(fēng)險主動控制評估方法指導(dǎo)了連接湘北與鄂東的山區(qū)高速公路一通平高速公路沿線大量邊坡的穩(wěn)定性分析及設(shè)計。在第六章中展示了基于上述方法指導(dǎo)的其中兩個路段邊坡的穩(wěn)定性分析過程及主要結(jié)論。工作成果為通平高速公路沿線邊坡提供了實用有效的處治方案,同時驗證了本文所建立的邊坡失穩(wěn)風(fēng)險主動控制評估方法的合理性與適用性。
[Abstract]:Slope engineering is one of the classical research fields in geotechnical engineering. The object of slope engineering is the rock and soil mass which has undergone a long geological history for hundreds of millions of years. The factors such as its occurrence environment, composition, physical and mechanical characteristics are uncertain in varying degrees. The safety factor or reliability index is often used to characterize the failure. But the safety factor focuses on revealing the relative quantitative relationship between the average resistance and the average load, and the reliability index indicates that there is a probability of passive failure risk under given conditions. Risk is impossible, the key point is to make clear the influence degree of the relevant factors on the risk, according to the pertinent method, through the corresponding design analysis, to make reasonable engineering treatment measures to indicate the direction, and actively control the risk within the acceptable range. In this paper, a series of research work will be carried out on the basis of the existing slope stability analysis methods and the characteristics of slope engineering, and a new method of slope stability assessment based on the concept of risk active control will be established.
Firstly, according to the two failure modes of sliding along regular sliding surface and arbitrary sliding surface in slope failure, Bishop model and simple distribution model are selected as representative from the limit equilibrium theory system of slope. Based on the risk control concept, the inverse reliability algorithm of slope stability is deduced by using the principle of primary inverse reliability, and two kinds of inverse reliability algorithms are derived. A framework of inverse reliability analysis method for slope stability with double control indexes of reliability and safety factor is developed. The method is based on the pre-acceptable failure risk (target reliability index) to design various parameters affecting slope stability so as to achieve reliability. The standard and stability coefficient correspond to each other, so as to achieve the purpose of active control of slope failure risk.
Secondly, the non-deterministic description of geotechnical parameters and the functional expression of slope stability state determine the practicability of inverse reliability design and analysis method and the validity of calculation results. Many parameters affecting slope stability are often manifested as random, interval, grey and other diversified phenomena in uncertain characteristics. For the non-uniformity of the influence degree of each parameter on the stability state of the slope, the grey relational theory is embedded into the interval analysis model to solve the interval correlation degree between each factor and the response value, and the relative degree is combined by establishing the method of extracting test samples based on the uniform design which is full of space, multi-level and robustness. The dominance degree theory ranks the interval correlation degree and constructs a comprehensive evaluation method for the significance of the influencing factors of slope stability based on the uncertainty theory. The practicability of the control evaluation method is prepared accordingly.
Combining with the actual engineering characteristics of the different distribution patterns of slope parameters and the correlation between parameters, this paper proceeds with the construction conditions of the response surface function model, and then proceeds to carry on the thorough research and discussion. The response surface function model is fitted by independent normalized parameters, and the response surface model constructed by this method can be applied to the diversity of parameter distribution forms and the correlation characteristics between parameters in practical slope engineering. Finally, the response surface model and the first-order inverse reliability theory are combined to construct a more reasonable and effective response surface model. Active risk assessment method for slope instability risk.
Thirdly, in order to further improve and enrich the research content of active control and evaluation method of slope instability risk, and to improve the applicability of response surface modeling method in dealing with implicit function of slope engineering, the function expression form of response surface model is considered comprehensively considering the characteristics of complex and highly nonlinear function of slope engineering limit state. In response surface model selection, the Kriging proxy model which is more rigorous in theory, more flexible in operation and more effective in dealing with complex nonlinear problems is adopted in view of the limitation of the application scope of the polynomial model. A more adaptable Latin hypercube test design method is combined with an active learning method with active search for the best training samples. The integration of the above response surface model and sampling method will establish a more perfect inverse reliability response surface technique for slope stability, which will widen the risk assessment of failure of complex implicit function of slope. The applicable scope of the method.
Finally, a set of comparatively perfect identification method of slope stability influencing factors under different conditions and assessment method of Instability Risk active control are used to guide the stability analysis and design of a large number of slopes along the mountain expressway-Tongping expressway connecting northern Hunan and Eastern Hubei. The results provide a practical and effective treatment scheme for the slope along the Tongping Expressway, and verify the rationality and applicability of the proposed method.
【學(xué)位授予單位】：湖南大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2014
【分類號】：TU43

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