【摘要】：隨著我國(guó)西部建設(shè)的高速發(fā)展，公路、橋梁、港口碼頭等實(shí)際工程建設(shè)中會(huì)更多地遇到巖溶地質(zhì)條件。因此巖溶區(qū)基樁與溶洞相互作用關(guān)系、基樁嵌入溶洞頂板的深度、溶洞頂板的穩(wěn)定性以及最小安全厚度等問(wèn)題成為巖溶區(qū)橋梁樁基研究的熱點(diǎn)。由于巖溶地質(zhì)條件的復(fù)雜性與不確定性使得巖溶區(qū)樁基的研究尤為困難。本文在已有研究的基礎(chǔ)之上，結(jié)合國(guó)家自然科學(xué)基金項(xiàng)目“巖溶區(qū)基樁豎向承載機(jī)理及其設(shè)計(jì)計(jì)算方法研究”（項(xiàng)目編號(hào)：51278187）對(duì)巖溶區(qū)樁基及溶洞頂板做了如下研究工作： 本文首先對(duì)巖溶區(qū)樁基已有的研究做了簡(jiǎn)要的概括，繼而基于普通嵌巖樁的樁端荷載傳遞機(jī)理，結(jié)合巖溶區(qū)基樁與溶洞頂板相互作用的特點(diǎn)，假定出不同頂板厚度情況下樁端荷載傳遞方程，并通過(guò)室內(nèi)大比例尺模型試驗(yàn)進(jìn)行驗(yàn)證。考慮基樁嵌巖段巖石性質(zhì)的差異性，分別提出了軟巖與硬巖條件下嵌巖深度計(jì)算模型并推導(dǎo)出了最小嵌巖深度解析解。通過(guò)某室內(nèi)試驗(yàn)以及某現(xiàn)場(chǎng)工程實(shí)例對(duì)本文方法進(jìn)行對(duì)比驗(yàn)證，并對(duì)影響嵌巖深度的計(jì)算參數(shù)進(jìn)行了參數(shù)分析。 為深入研究巖溶區(qū)橋梁樁基豎向承載機(jī)理與溶洞頂板破壞模式，基于相似定理設(shè)計(jì)出巖溶區(qū)基樁與頂板作用大比例尺室內(nèi)模型試驗(yàn)，通過(guò)多組配合比試驗(yàn)確定頂板模擬材料，根據(jù)溶洞頂板厚度的不同分別設(shè)計(jì)了四組大比例尺室內(nèi)模型試驗(yàn)。對(duì)厚度分別為0.5d、1d、2d以及3d的溶洞頂板進(jìn)行豎向加載，獲得了不同頂板厚度條件下基樁荷載傳遞規(guī)律、溶洞頂板荷載位移曲線以及頂板的破壞形式，最后對(duì)試驗(yàn)現(xiàn)象以及試驗(yàn)數(shù)據(jù)進(jìn)行了理論分析。采用FLAC3D有限差分軟件模擬室內(nèi)模型試驗(yàn)，并將樁頂位移以及實(shí)際頂板破壞形式與有限差分模擬結(jié)果進(jìn)行對(duì)比分析，，從而進(jìn)行相互驗(yàn)證。針對(duì)室內(nèi)模型試驗(yàn)沒(méi)有考慮溶洞頂板厚跨比變化對(duì)于頂板豎向承載影響的不足，最后利用FLAC3D數(shù)值模擬軟件對(duì)于不同厚跨比的溶洞頂板進(jìn)行數(shù)值模擬分析，以期獲得厚跨比變化對(duì)于溶洞頂板豎向承載影響的變化規(guī)律，從而對(duì)室內(nèi)模型試驗(yàn)做進(jìn)一步的補(bǔ)充。
[Abstract]:With the rapid development of the construction of the western part of China, more karst geological conditions will be encountered in the construction of highway, bridge, port and wharf. Therefore, the interaction between pile and karst cave in karst area, the depth of pile embedding into karst cave roof, the stability of karst cave roof and the minimum safety thickness have become the hot spots in the research of bridge pile foundation in karst area. Because of the complexity and uncertainty of karst geological conditions, the study of pile foundation in karst area is especially difficult. On the basis of the existing research, Combined with the project of National Natural Science Foundation of China, "Research on Vertical bearing Mechanism and Design calculation method of pile Foundation in Karst area" (Project No.: 51278187), the research work on pile foundation and karst cave roof in karst area has been done as follows: first of all, this paper has done the following research work: The existing research on pile foundation in karst area is briefly summarized. Then, based on the load transfer mechanism of common rock socketed pile, combined with the characteristics of interaction between pile and karst cave roof in karst area, the load transfer equation of pile tip under different roof thickness is assumed. And through the indoor large-scale model test to verify. Considering the difference of rock properties of rock-socketed section of pile, the calculation models of rock-socketed depth in soft rock and hard rock are put forward, and the analytical solution of minimum rock-socketed depth is deduced. Through a laboratory test and a field engineering example, the method is compared and verified, and the parameters affecting the depth of rock socketed are analyzed. In order to deeply study the vertical bearing mechanism of bridge pile foundation in karst area and the failure mode of karst cave roof, a large scale indoor model test of the interaction between pile and roof in karst area was designed based on the similarity theorem, and the roof simulation material was determined by multi-group mix ratio test. Four groups of large scale indoor model tests were designed according to the different thickness of cave roof. When the roof thickness is 0.5 d, 1 d, 2 d and 3 d respectively, the load transfer law of foundation pile, the load displacement curve of karst cave roof and the failure form of roof are obtained under the condition of different roof thickness, and the vertical loading is carried out on the roof of karst cave under the condition of different roof thickness. Finally, the experimental phenomena and experimental data are analyzed theoretically. The FLAC3D finite difference software is used to simulate the indoor model test, and the pile top displacement and the actual roof failure form are compared and analyzed with the finite difference simulation results, so as to verify each other. In view of the inadequacy of indoor model test which does not consider the influence of roof thickness-span ratio change on the vertical bearing capacity of the roof, the numerical simulation analysis of the karst cave roof with different thickness-span ratio is carried out by using FLAC3D numerical simulation software. In order to obtain the variation rule of the influence of the ratio of thickness to span on the vertical bearing capacity of the roof of the karst cave, further supplement to the indoor model test is made.
【學(xué)位授予單位】：湖南大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類(lèi)號(hào)】：U443.15

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