本文選題：多層土工加筋體 + 巖溶塌陷　； 參考：《長沙理工大學(xué)》2015年碩士論文

【摘要】：巖溶區(qū)塌陷易對高速公路路基造成不利影響,采用多層土工格柵加筋形成加筋墊層進(jìn)行防治具有顯著優(yōu)勢,但目前設(shè)計計算理論遠(yuǎn)遠(yuǎn)落后于工程實(shí)踐,極大阻礙了其發(fā)展和應(yīng)用,有必要對其展開系統(tǒng)的理論和試驗研究。為此,本文擬基于土性試驗、加筋體拉拔試驗、土筋界面試驗等手段,實(shí)測各材料的計算參數(shù)及筋土界面本構(gòu)關(guān)系;在可模擬工況塌陷的模型箱內(nèi)進(jìn)行模型試驗,實(shí)測塌陷產(chǎn)生時各層加筋體的變形和應(yīng)變值,在此基礎(chǔ)上,分析各層土工格柵上的荷載分布模式及荷載傳遞規(guī)律;然后采用三維數(shù)值計算軟件FLAC3D對試驗結(jié)果進(jìn)行驗證計算,并對各影響因素進(jìn)行敏感性分析。綜合分析研究得到下面規(guī)律和結(jié)論,為實(shí)際工程中格柵加筋體設(shè)計提供依據(jù)。(1)數(shù)值模擬得出的規(guī)律和模型試驗基本保持一致,驗證了試驗數(shù)據(jù)的可靠性,對土工格柵加筋體的設(shè)計及施工具有一定的指導(dǎo)意義。(2)數(shù)值模擬各種工況下各層格柵其變形規(guī)律和模型試驗相同,格柵撓度曲線接近符合拋物線規(guī)律。(3)同等條件下,巖溶塌陷坑寬度越寬,格柵的撓度會越大。即同樣規(guī)格的土工格柵對于巖溶塌陷坑寬度差異表現(xiàn)出不同的適應(yīng)性,具體是在滿足要求的最大格柵撓度前提下,潛在巖溶塌陷坑寬度越小,格柵的拉伸強(qiáng)度需求越低。(4)加筋層數(shù)達(dá)到一定值時,即本實(shí)驗中加筋層數(shù)為四層時,單純的增加加筋層數(shù)對于原有格柵受荷性能影響不大,我們可以尋求其它改變來改善格柵的受荷性能。本次數(shù)值模擬同時也表明了四層格柵加筋是最經(jīng)濟(jì)合理的。(5)塌陷坑上方格柵變形規(guī)律符合拋物線關(guān)系,且變形量由上往下依次遞減,非底層土工格柵變形范圍不完全與陷坑范圍一致�？傮w來說,多層加筋墊層相對單層加筋可有效減小變形量。(6)相同格柵規(guī)格和格柵間距條件下潛在巖溶塌陷坑的寬度大小對各層格柵荷載分擔(dān)系數(shù)影響不大。
[Abstract]:Collapse in karst area is easy to cause adverse effect on highway roadbed. It has obvious advantages to use multi-layer geogrid reinforcement to form reinforced cushion layer, but the design and calculation theory is far behind engineering practice at present. Its development and application are greatly hindered. It is necessary to carry out systematic theoretical and experimental research on it. Therefore, based on the soil test, the drawing test of reinforced body and the interface test of soil reinforcement, the calculation parameters and the constitutive relation of the interface of each material are measured, and the model test is carried out in the model box which can be collapsed under simulated working conditions. The deformation and strain values of each layer reinforced body are measured when the collapse occurs. On this basis, the load distribution mode and load transfer law on each layer geogrid are analyzed, and the test results are verified and calculated by using 3D numerical calculation software FLAC3D. Sensitivity analysis of various influencing factors was carried out. The following laws and conclusions are obtained from the comprehensive analysis and research, which provide the basis for the design of grid stiffened body in practical engineering. (1) the law obtained by numerical simulation is basically consistent with the model test, and the reliability of the test data is verified. It has certain guiding significance for the design and construction of geogrid reinforced body. (2) the deformation law of each layer grid is the same as the model test under various working conditions, and the deflection curve of the grid is close to the parabola law. (3) under the same conditions, the deformation law of the grid is the same as that of the model test. (3) under the same conditions, The wider the width of karst collapse pit, the bigger the deflection of grid. That is to say, the same size geogrid has different adaptability to the difference of karst collapse pit width, in particular, under the premise of satisfying the maximum grid deflection, the width of potential karst collapse pit is smaller. (4) when the number of stiffened layers reaches a certain value, that is, when the number of stiffened layers is four layers in this experiment, simply increasing the number of stiffened layers has little effect on the original grid load performance. We can look for other changes to improve the grid's load performance. The numerical simulation also shows that the four layer grid reinforcement is the most economical and reasonable. (5) the deformation law of the grid above the collapse pit accords with the parabola relation, and the deformation decreases from top to bottom. The deformation range of the non-bottom geogrid is not completely consistent with that of the pit. In general, multi-layer reinforced cushion can effectively reduce deformation relative to single-layer reinforcement. (6) the width of potential karst collapse pit has little effect on the load sharing coefficient of each layer under the same grid size and grid spacing.
【學(xué)位授予單位】：長沙理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：U416.16

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