發(fā)布時(shí)間：2019-03-04 19:06

【摘要】：土體是在復(fù)雜地質(zhì)構(gòu)造運(yùn)動(dòng)和應(yīng)力歷史下形成的沉積物,這使得其在空間中不同位置的物理力學(xué)性質(zhì)具有不同程度的差異,其在空間上通常具有不規(guī)則成層分布的特性,并且同一土層內(nèi)部的巖土參數(shù)具有空間變異性。因此,巖土工程結(jié)構(gòu)設(shè)計(jì)之前需要在建筑場地內(nèi)進(jìn)行地質(zhì)勘探以得到所需要的地質(zhì)資料。然而,通過地質(zhì)勘探所獲得的地質(zhì)數(shù)據(jù)是離散的,不能完全確定場地內(nèi)未勘探區(qū)域的地質(zhì)數(shù)據(jù)。為了給工程設(shè)計(jì)提供充足可靠的依據(jù),基于有限鉆孔對土體成層結(jié)構(gòu)及空間變異性進(jìn)行研究很有必要。土體成層結(jié)構(gòu)研究方面,空間插值法不能用于復(fù)雜的土層模擬,變差函數(shù)法雖然可以模擬復(fù)雜地層的分布,然而其所模擬的地層連續(xù)性較差。相比之下,耦合馬爾可夫鏈模型則可以克服以上問題,但是該模型無法模擬具有不同傾斜方向的地層交界面,也不能準(zhǔn)確模擬地層中的棱鏡體。本文對耦合馬爾可夫鏈模型進(jìn)行了改進(jìn),編制了相關(guān)程序,并驗(yàn)證了程序的正確性。改進(jìn)的耦合馬爾可夫鏈模型能夠較好地模擬地質(zhì)剖面內(nèi)不同傾斜方向的地層交界面及變異地層(如棱鏡體)。基于耦合馬爾可夫鏈模型研究了鉆孔布置方案對地層模擬結(jié)果的影響,鉆孔的位置對耦合馬爾可夫鏈模擬復(fù)雜土體成層結(jié)構(gòu)可能產(chǎn)生較大的影響,并且同一土層內(nèi)部出現(xiàn)變異的概率會隨著鉆孔間距的增加而增加。本文還分析了獲得幾種常見的土體成層結(jié)構(gòu)的穩(wěn)定模擬結(jié)果所需要的鉆孔數(shù)量。同一土層內(nèi)的空間變異性可以通過隨機(jī)場理論進(jìn)行研究,然而隨機(jī)場會高估土體的空間變異性,這是因?yàn)樗鼘Φ刭|(zhì)勘探點(diǎn)的數(shù)據(jù)仍然采用隨機(jī)模擬的方式生成。因此,本文研究了能夠充分利用場地內(nèi)實(shí)測值,并有效減小巖土參數(shù)空間變異性的三維條件隨機(jī)場方法,編制了相應(yīng)程序并驗(yàn)證了程序的正確性�；谌S條件隨機(jī)場的方法,本文還研究了鉆孔位置和鉆孔數(shù)量對巖土參數(shù)空間變異性的影響,發(fā)現(xiàn)當(dāng)巖土參數(shù)的相關(guān)性符合指數(shù)平方型相關(guān)函數(shù)時(shí),條件隨機(jī)場內(nèi)勘探數(shù)據(jù)的主要約束距離約為該方向波動(dòng)范圍的一半,并且條件隨機(jī)場預(yù)測值的精度受預(yù)測點(diǎn)周圍的鉆孔數(shù)量以及巖土參數(shù)變異系數(shù)的共同影響。
[Abstract]:Soil mass is a sediment formed under the complex geological tectonic movement and stress history, which makes the physical and mechanical properties of different positions in space different, and it usually has the characteristics of irregular stratified distribution in space. And the geotechnical parameters in the same soil layer have spatial variability. Therefore, geological exploration should be carried out in the construction site before the structural design of geotechnical engineering to obtain the required geological data. However, the geological data obtained from geological exploration are discrete, and the geological data of the unexplored area in the site cannot be determined completely. In order to provide sufficient and reliable basis for engineering design, it is necessary to study layered structure and spatial variability of soil based on finite drilling. In the study of layered structure of soil, the spatial interpolation method can not be used to simulate the complex soil layer. Although the variation function method can simulate the distribution of complex strata, the continuity of the simulated strata is poor. In contrast, the coupled Markov chain model can overcome the above problems, but the model can not simulate the stratigraphic interface with different inclined directions, nor can it accurately simulate the prism in the stratum. In this paper, the coupling Markov chain model is improved, and the related program is compiled, and the correctness of the program is verified. The improved coupled Markov chain model can well simulate the stratigraphic interface and variation strata (such as prism) in the geological section with different tilting directions. Based on the coupling Markov chain model, the influence of borehole layout scheme on the simulation results is studied. The location of borehole may have a great influence on the layered structure of complex soil mass simulated by coupled Markov chain model. And the probability of variation in the same soil layer increases with the increase of borehole spacing. The number of holes needed to obtain the stability simulation results of several common layered soil structures is also analyzed in this paper. The spatial variability in the same soil layer can be studied by random field theory, but the random field overestimates the spatial variability of soil because it still generates the data of geological exploration points by random simulation. Therefore, this paper studies a three-dimensional conditional random field method which can make full use of the measured data in the site and effectively reduce the spatial variability of geotechnical parameters. The corresponding program is compiled and the correctness of the program is verified. Based on the method of three-dimensional conditional random field, this paper also studies the influence of borehole location and number on spatial variability of geotechnical parameters. It is found that when the correlation of geotechnical parameters conforms to exponential square type correlation function, The main constraint distance of exploration data in conditional random field is about half of the range of fluctuation in this direction, and the accuracy of conditional random field prediction is affected by the number of holes around the predicted point and the coefficient of variation of geotechnical parameters.
【學(xué)位授予單位】：哈爾濱工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TU43

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