剛性基礎(chǔ)下剛性長(zhǎng)短樁復(fù)合地基樁土空間作用效應(yīng)研究
發(fā)布時(shí)間：2018-07-14 18:01
【摘要】：樁與土的空間作用效應(yīng)，使相同基礎(chǔ)沉降下小承臺(tái)板長(zhǎng)短樁復(fù)合地基的承載性狀與大承臺(tái)板長(zhǎng)短樁復(fù)合地基的承載性狀之間存在差異。這種差異使得，目前用長(zhǎng)短4樁復(fù)合地基靜載荷試驗(yàn)結(jié)果驗(yàn)證長(zhǎng)短樁復(fù)合地基承載力和沉降計(jì)算理論存在一定問(wèn)題。而現(xiàn)實(shí)中，受場(chǎng)地和加載條件限制，多數(shù)情況下又僅能進(jìn)行長(zhǎng)短4樁復(fù)合地基靜載荷試驗(yàn)。為解決理論與現(xiàn)實(shí)之間的矛盾，需要研究樁土空間作用效應(yīng)問(wèn)題。 本文在CFG樁-PHC管樁長(zhǎng)短4樁復(fù)合地基靜載荷試驗(yàn)研究的基礎(chǔ)上，，首先，通過(guò)數(shù)值模擬方法，探討樁土間的空間作用效應(yīng)問(wèn)題，挖掘其與剛性基礎(chǔ)下剛性長(zhǎng)短樁復(fù)合地基承載性狀的相關(guān)性。分析了剛性基礎(chǔ)下剛性長(zhǎng)短樁復(fù)合地基中荷載-沉降、樁-土應(yīng)力、樁端阻比及樁刺入變形隨樁數(shù)變化的規(guī)律，并給出了擬合函數(shù)表達(dá)式。研究表明：在相同荷載水平下，樁數(shù)越多，承臺(tái)板沉降越大；隨著荷載水平增加，同等荷載水平下，各模型承臺(tái)板沉降差逐漸增大；相同承臺(tái)板沉降下，樁數(shù)越多，長(zhǎng)短樁復(fù)合地基所承擔(dān)的荷載水平越小；隨著承臺(tái)板尺寸（樁數(shù)）增加，地面和深層土體水平位移量和應(yīng)力擴(kuò)散范圍逐漸增大，最大水平位移逐漸向土層深部傳遞，長(zhǎng)樁、短樁樁頂和樁端應(yīng)力逐漸減�。浑S著承臺(tái)板沉降增大，承臺(tái)板等沉下不同模型中長(zhǎng)樁或短樁樁頂和樁端應(yīng)力差異逐漸減小，樁頂平面和長(zhǎng)樁樁端平面土應(yīng)力逐漸減小，短樁樁端平面土應(yīng)力逐漸增加，長(zhǎng)樁端阻比逐漸增大，中心短樁和長(zhǎng)樁上刺入變形逐漸減小，角樁長(zhǎng)樁上刺入變形逐漸增加，下刺入變形逐漸減小。 其次，詮釋了樁長(zhǎng)、樁間距及褥墊層厚度變化對(duì)剛性基礎(chǔ)下剛性長(zhǎng)短樁復(fù)合地基中荷載-沉降、樁-土應(yīng)力、樁端阻比及樁刺入變形隨樁數(shù)變化的規(guī)律的影響，并評(píng)判了影響度及其變化規(guī)律。研究表明：相同承臺(tái)板沉降下，樁長(zhǎng)變化對(duì)長(zhǎng)短樁復(fù)合地基中短樁樁端平面土應(yīng)力、樁頂應(yīng)力、樁上下刺入變形隨樁數(shù)變化的規(guī)律的影響顯著；而對(duì)長(zhǎng)短樁復(fù)合地基中荷載-沉降、樁端應(yīng)力隨樁數(shù)變化規(guī)律的影響在現(xiàn)場(chǎng)試驗(yàn)或工程設(shè)計(jì)時(shí)可以不予考慮；相同承臺(tái)板沉降下，樁間距變化對(duì)長(zhǎng)短樁復(fù)合地基承載力的影響，隨著荷載增加逐漸增大，對(duì)長(zhǎng)短樁復(fù)合地基中樁頂土應(yīng)力、短樁端阻比隨樁數(shù)變化的規(guī)律影響顯著，且隨著樁數(shù)增加，其影響程度逐漸減小，對(duì)樁刺入變形、樁頂和樁端應(yīng)力、樁端阻比隨樁數(shù)變化規(guī)律的影響在現(xiàn)場(chǎng)試驗(yàn)或工程設(shè)計(jì)時(shí)可以不予考慮；相同承臺(tái)板沉降下，褥墊層厚度變化對(duì)長(zhǎng)短樁復(fù)合地基中樁頂和樁端應(yīng)力隨樁數(shù)變化的規(guī)律影響顯著，且隨著樁數(shù)增加，其影響程度逐漸減小，而對(duì)于荷載-沉降、樁頂和樁端平面土應(yīng)力、樁端阻比、樁頂和樁端刺入變形隨樁數(shù)變化規(guī)律的影響在現(xiàn)場(chǎng)試驗(yàn)或工程設(shè)計(jì)時(shí)可以不予考慮。 最終，基于Boussinesq和Mindlin解，提出了長(zhǎng)樁下刺入變形和下臥層附加應(yīng)力計(jì)算方法；以長(zhǎng)樁控沉為沉降計(jì)算理念，同時(shí)考慮樁土空間作用效應(yīng)、長(zhǎng)樁上下刺入變形、長(zhǎng)樁樁頂褥墊層壓縮變形及樁端下臥層壓縮變形，提出了剛性基礎(chǔ)下剛性長(zhǎng)短樁復(fù)合地基沉降計(jì)算理論方法；通過(guò)工程實(shí)例計(jì)算與分析，驗(yàn)證了該計(jì)算方法的合理性與可行性。
[Abstract]:The spatial action effect of pile and soil makes the bearing characters of the small bearing plate long short pile composite foundation differ from the bearing characters of the long short pile composite foundation with the large bearing platform. This difference makes the calculation of the bearing capacity and settlement of the long short pile composite foundation by the static load test results of the long short 4 pile composite foundation. In fact, in reality, under the limitation of site and loading condition, the static load test of 4 pile composite foundation can only be carried out in most cases. In order to solve the contradiction between theory and reality, it is necessary to study the effect of the spatial effect of pile and soil.
In this paper, based on the static load test of CFG pile -PHC pipe pile 4 pile composite foundation, first, through the numerical simulation method, the spatial effect effect between pile and soil is discussed, and the correlation between the bearing behavior of rigid long short pile composite foundation under rigid foundation is excavated and the load sedimentation in rigid long short pile composite foundation is analyzed. Down, pile soil stress, pile end resistance and pile thrust deformation change with the number of piles, and give a fitting function expression. The study shows that under the same load level, the more the pile number, the greater the settlement of the platform plate; with the increase of load level, the settlement difference of the model bearing plate increases gradually under the same load level; the same bearing platform settlement, The more the pile number, the lower the load level of the long and short pile composite foundation. With the increase of the plate size (pile number), the horizontal displacement and the stress diffusion range of the ground and deep soil gradually increase, the maximum horizontal displacement gradually passes to the depth of the soil layer, and the stress of the long pile, the short pile top and the pile end gradually decreases; with the increase of the settlement of the platform plate, the bearing capacity is increased. The stress difference between the top and the pile ends of the long pile or the short pile gradually decreases, the stress of the pile top plane and the long pile end decreases gradually, the stress in the end plane of the short pile increases gradually, the end resistance ratio of the long pile increases gradually, the piercing deformation of the short pile and the long pile gradually decreases, and the spiny deformation on the long pile pile increases gradually. The deformation of the lower stab gradually decreases.
Secondly, the influence of pile length, pile spacing and cushion thickness on load settlement, pile soil stress, pile end resistance ratio and pile number change with pile number in rigid foundation pile composite foundation under rigid foundation is explained, and the influence degree and change law are judged. The stress of the short pile at the end of the pile composite foundation, the stress of the pile top, the deformation of the pile on the pile and the pile number change with the number of piles, and the effect of the load settlement on the pile and the change law of the pile number in the pile composite foundation can not be considered in the field test or the engineering design; the pile spacing is changed under the same settlement plate settlement. The influence on the bearing capacity of the long and short pile composite foundation increases with the increase of load. The influence of the pile top soil stress and the short pile end resistance ratio with the number of piles in the long and short pile composite foundation is significant, and with the increase of pile number, the influence degree gradually decreases, the deformation of pile, the stress of the pile top and the pile end and the pile end resistance ratio change with the number of piles. The influence on field test or engineering design can not be considered. Under the same slab settlement, the change of cushion thickness on pile top and pile end stress changes with the number of piles in the composite foundation of long and short pile, and with the increase of pile number, the influence degree gradually decreases, and the stress on the load settlement, pile top and pile end plane soil stress, pile The influence of the end resistance ratio on the deformation of pile top and pile tip with the variation of pile number can not be considered in field test or engineering design.
Finally, based on the Boussinesq and Mindlin solutions, the calculation method for the additional stress of the long pile under the spiny deformation and the lower lying layer is proposed, and the long pile controlled settlement is considered as the settlement calculation, and the space action effect of the pile and soil, the deformation of the long pile up and down, the compression deformation of the bedding cushion and the compression deformation of the lower lying layer are put forward, and the rigidity under the rigid foundation is put forward. The theoretical method of settlement calculation for long short pile composite foundation is verified and verified by engineering examples.
【學(xué)位授予單位】：鄭州大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2014
【分類(lèi)號(hào)】：TU473.1
本文編號(hào)：2122510
[Abstract]:The spatial action effect of pile and soil makes the bearing characters of the small bearing plate long short pile composite foundation differ from the bearing characters of the long short pile composite foundation with the large bearing platform. This difference makes the calculation of the bearing capacity and settlement of the long short pile composite foundation by the static load test results of the long short 4 pile composite foundation. In fact, in reality, under the limitation of site and loading condition, the static load test of 4 pile composite foundation can only be carried out in most cases. In order to solve the contradiction between theory and reality, it is necessary to study the effect of the spatial effect of pile and soil.
In this paper, based on the static load test of CFG pile -PHC pipe pile 4 pile composite foundation, first, through the numerical simulation method, the spatial effect effect between pile and soil is discussed, and the correlation between the bearing behavior of rigid long short pile composite foundation under rigid foundation is excavated and the load sedimentation in rigid long short pile composite foundation is analyzed. Down, pile soil stress, pile end resistance and pile thrust deformation change with the number of piles, and give a fitting function expression. The study shows that under the same load level, the more the pile number, the greater the settlement of the platform plate; with the increase of load level, the settlement difference of the model bearing plate increases gradually under the same load level; the same bearing platform settlement, The more the pile number, the lower the load level of the long and short pile composite foundation. With the increase of the plate size (pile number), the horizontal displacement and the stress diffusion range of the ground and deep soil gradually increase, the maximum horizontal displacement gradually passes to the depth of the soil layer, and the stress of the long pile, the short pile top and the pile end gradually decreases; with the increase of the settlement of the platform plate, the bearing capacity is increased. The stress difference between the top and the pile ends of the long pile or the short pile gradually decreases, the stress of the pile top plane and the long pile end decreases gradually, the stress in the end plane of the short pile increases gradually, the end resistance ratio of the long pile increases gradually, the piercing deformation of the short pile and the long pile gradually decreases, and the spiny deformation on the long pile pile increases gradually. The deformation of the lower stab gradually decreases.
Secondly, the influence of pile length, pile spacing and cushion thickness on load settlement, pile soil stress, pile end resistance ratio and pile number change with pile number in rigid foundation pile composite foundation under rigid foundation is explained, and the influence degree and change law are judged. The stress of the short pile at the end of the pile composite foundation, the stress of the pile top, the deformation of the pile on the pile and the pile number change with the number of piles, and the effect of the load settlement on the pile and the change law of the pile number in the pile composite foundation can not be considered in the field test or the engineering design; the pile spacing is changed under the same settlement plate settlement. The influence on the bearing capacity of the long and short pile composite foundation increases with the increase of load. The influence of the pile top soil stress and the short pile end resistance ratio with the number of piles in the long and short pile composite foundation is significant, and with the increase of pile number, the influence degree gradually decreases, the deformation of pile, the stress of the pile top and the pile end and the pile end resistance ratio change with the number of piles. The influence on field test or engineering design can not be considered. Under the same slab settlement, the change of cushion thickness on pile top and pile end stress changes with the number of piles in the composite foundation of long and short pile, and with the increase of pile number, the influence degree gradually decreases, and the stress on the load settlement, pile top and pile end plane soil stress, pile The influence of the end resistance ratio on the deformation of pile top and pile tip with the variation of pile number can not be considered in field test or engineering design.
Finally, based on the Boussinesq and Mindlin solutions, the calculation method for the additional stress of the long pile under the spiny deformation and the lower lying layer is proposed, and the long pile controlled settlement is considered as the settlement calculation, and the space action effect of the pile and soil, the deformation of the long pile up and down, the compression deformation of the bedding cushion and the compression deformation of the lower lying layer are put forward, and the rigidity under the rigid foundation is put forward. The theoretical method of settlement calculation for long short pile composite foundation is verified and verified by engineering examples.
【學(xué)位授予單位】：鄭州大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2014
【分類(lèi)號(hào)】：TU473.1
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