本文選題：可靠度理論　切入點(diǎn)：隨機(jī)場(chǎng)理論　出處：《天津大學(xué)》2014年博士論文　論文類型：學(xué)位論文

【摘要】：可靠度理論是一種先進(jìn)的設(shè)計(jì)理論，目前已經(jīng)在結(jié)構(gòu)工程安全評(píng)估中得到廣泛應(yīng)用，而將可靠度理論引入巖土工程穩(wěn)定性分析目前還在探索中，其主要障礙在于由工程勘察獲得的土性指標(biāo)的點(diǎn)方差過大，使計(jì)算的土工結(jié)構(gòu)物（邊坡、結(jié)構(gòu)物地基基礎(chǔ)和擋土結(jié)構(gòu)等）的失效概率過大，與結(jié)構(gòu)物的實(shí)際安全程度不相符。失效概率計(jì)算結(jié)果與設(shè)計(jì)經(jīng)驗(yàn)的差距使人們一度對(duì)可靠度理論能否應(yīng)用于巖土工程設(shè)計(jì)產(chǎn)生懷疑。 采用隨機(jī)場(chǎng)理論，通過考慮土體的空間相關(guān)性來探求土體物理力學(xué)指標(biāo)的真方差，用其代替?zhèn)鹘y(tǒng)的點(diǎn)方差，使計(jì)算的土工結(jié)構(gòu)物的失效概率在合理的范圍內(nèi)，這是建立巖土工程可靠度分析的關(guān)鍵性問題。由于建立隨機(jī)場(chǎng)模型需要大量的相對(duì)比較均勻的土性資料，而積累這種數(shù)據(jù)的難度較大，費(fèi)用較高，因此目前國(guó)內(nèi)外關(guān)于這個(gè)問題的研究進(jìn)展緩慢。 隨著我國(guó)沿海地區(qū)經(jīng)濟(jì)的快速發(fā)展，許多海港碼頭和經(jīng)濟(jì)開發(fā)區(qū)都建在新近圍海造陸形成的陸域。由于這些區(qū)域的開發(fā)時(shí)間比較集中，工程勘察比較密集，容易匯集大量的土層物理力學(xué)指標(biāo)，因而具備了建立地基土性隨機(jī)場(chǎng)模型的有利條件，為在土工結(jié)構(gòu)物設(shè)計(jì)中采用可靠度理論打下了基礎(chǔ)。本文針對(duì)天津?yàn)I海新區(qū)新近圍海造陸區(qū)域的粘性土坡和地基，采用理論研究、現(xiàn)場(chǎng)試驗(yàn)和計(jì)算統(tǒng)計(jì)分析等手段相結(jié)合的方式，對(duì)土性指標(biāo)的隨機(jī)場(chǎng)特性進(jìn)行了比較系統(tǒng)的研究，并討論了其在港工地基和海洋工程結(jié)構(gòu)物地基可靠度分析中的應(yīng)用。對(duì)其可靠度問題進(jìn)行了研究，得到了規(guī)律性較好的研究成果，使之能夠方便的應(yīng)用于工程實(shí)踐。本文的主要研究成果和創(chuàng)新點(diǎn)如下： （1）為建立天津?yàn)I海新區(qū)新近圍海造陸區(qū)域土體物理力學(xué)性質(zhì)的空間隨機(jī)場(chǎng)特性，采用了現(xiàn)場(chǎng)鉆孔取樣、靜力觸探等方法獲取了大量的描述土體物理力學(xué)性質(zhì)的參數(shù)。 （2）將隨機(jī)場(chǎng)理論應(yīng)用于土性指標(biāo)統(tǒng)計(jì)中，發(fā)展了既能考慮土體互相關(guān)性又能考慮自相關(guān)性的土性指標(biāo)統(tǒng)計(jì)方法，，使得計(jì)算結(jié)果更合理。 （3）對(duì)應(yīng)用完全不相關(guān)距離求解折減函數(shù)的計(jì)算方法做出了改進(jìn)，不但理論上有所突破，而且計(jì)算方法更為簡(jiǎn)潔。 （4）根據(jù)提出的土性指標(biāo)統(tǒng)計(jì)方法，對(duì)依托工程的土性指標(biāo)按隨機(jī)場(chǎng)理論進(jìn)行了分析，得到了依托工程的土性指標(biāo)相關(guān)距離、完全不相關(guān)距離和方差折減函數(shù)值。 （5）對(duì)不同土性的折減函數(shù)計(jì)算結(jié)果進(jìn)行分析，得到了方差折減函數(shù)的變化規(guī)律，實(shí)際工程中ω/b值對(duì)應(yīng)的折減函數(shù)值可通過本文得到的折減函數(shù)變化規(guī)律插值計(jì)算，使隨機(jī)場(chǎng)理論更方便的應(yīng)用于實(shí)際工程的可靠度分析。 （6）針對(duì)港口工程中最常見的岸坡穩(wěn)定問題、地基承載力問題，建立了極限狀態(tài)方程，應(yīng)用本文提出的方差折減方法編程計(jì)算了大量工程的失效概率，與直接應(yīng)用可靠度理論計(jì)算的結(jié)果及定值設(shè)計(jì)法的安全系數(shù)進(jìn)行對(duì)比，發(fā)現(xiàn)折減后的結(jié)果更符合實(shí)際。這些工程算例對(duì)應(yīng)的可靠指標(biāo)值將為以后相應(yīng)規(guī)范的制定提供依據(jù)。 （7）港工地基規(guī)范中采用地基土的固結(jié)不排水強(qiáng)度（CU）評(píng)價(jià)地基可靠性，只能評(píng)價(jià)正常運(yùn)營(yíng)狀態(tài)的地基可靠性，對(duì)于施工期地基穩(wěn)定性應(yīng)采用不固結(jié)不排水強(qiáng)度（UU）來評(píng)價(jià)，本文在這方面進(jìn)行了有益的探討。 （8）目前海洋工程中地基可靠度研究較少。本文以溫度應(yīng)力作用下海底管線穩(wěn)定性分析為例，建立了理想海底管線低階屈曲模式的極限狀態(tài)方程，應(yīng)用本文提出的土力學(xué)指標(biāo)的方差折減方法，結(jié)合工程實(shí)例編程計(jì)算了設(shè)計(jì)管線的屈服失效概率。與直接應(yīng)用可靠度理論計(jì)算的結(jié)果及定值設(shè)計(jì)法的安全系數(shù)進(jìn)行對(duì)比，發(fā)現(xiàn)折減后的結(jié)果更符合實(shí)際。相同的方法可用于其他類似的海工結(jié)構(gòu)物地基可靠度計(jì)算。
[Abstract]:Reliability theory is a kind of advanced design theory, has been widely used in structural engineering safety assessment, the reliability theory to the stability analysis of geotechnical engineering is still in the exploration, the main obstacle is that the little square survey of soil index obtained by engineering the difference is too large, the soil structure calculation (the slope structure, foundation and soil retaining structure) the failure probability is too large, the actual safety degree and structure do not match. The calculation results and design experience of failure probability of the gap so that the people were on the reliability theory can be applied to the doubt of geotechnical engineering design.
The random field theory, by considering the spatial correlation of soil to explore soil physical and mechanical indexes of true variance, variance to replace the traditional, the failure probability of soil structure is calculated in a reasonable range, which is the key to establish the reliability analysis of geotechnical engineering. Since the establishment of random field model take a relatively uniform soil data, and the accumulation of such data is difficult, high cost, so the current research progress on this issue at home and abroad slowly.
With the rapid economic development of China's coastal areas, many ports and economic development zones are built in the newly formed land reclamation area. Because of the development time is relatively concentrated, engineering intensive, easy collection soil physical and mechanical indexes of large, and has favorable conditions for the establishment of the foundation soil random field model, laid the foundation for using the reliability theory in soil structure design. According to the Binhai New Area of Tianjin reclamation area newly soil slope and foundation, the theoretical research, field test and statistical analysis of computing means a combination of random field characteristics of soil parameters are studied in the system, and discusses its application in the analysis of port engineering foundation and ocean engineering structures in the foundation. The reliability of the study, obtained a good regularity The research results can be applied to engineering practice conveniently. The main research results and innovation points of this paper are as follows:
(1) for the space establishment of Tianjin Binhai New Area recently reclaimed soil physical and mechanical properties of the regional characteristic of the random field, the field drilling sampling, CPT method to obtain the parameters describing the physical and mechanical properties of soil mass.
(2) the random field theory is applied to the statistics of soil index, and a statistical method of soil index is developed, which can consider the cross-correlation between soil and self correlation, making the calculation result more reasonable.
(3) an improvement is made for the calculation method of reducing the reduction function with complete unrelated distance, which not only has a breakthrough in theory, but also a more concise calculation method.
(4) according to the statistical method of soil index, the geotechnical index based on the engineering theory is analyzed according to the random field theory, and the correlation distance and the complete irrelevant distance and variance reduction function value are obtained based on the engineering.
(5) the results of analysis of different soil reduction function, obtained the reduction function of variance reduction function, the corresponding value can be obtained through the reduction regularity of interpolation function to calculate the Omega /b value in practical engineering, the reliability analysis of the application of random field theory is more convenient in practice engineering.
(6) according to the slope stability of the most common problems in port engineering, the bearing capacity of the foundation, established the limit state equation, this paper presents the application of variance reduction method for programming to calculate the failure probability of a large number of engineering, computing and direct application of the reliability theory and the definite value design method of safety coefficient were compared, found fold after the reduction results more realistic. The reliability index of these examples will be the future value corresponding to the corresponding specification provides the basis for the development.
(7)娓伐鍦板熀瑙勮寖涓噰鐢ㄥ湴鍩哄湡鐨勫浐緇撲笉鎺掓按寮哄害(CU)璇勪環(huán)鍦板熀鍙潬鎬

本文編號(hào)：1628776