巖質(zhì)邊坡傾斜樁基橫向承載性能的模型試驗(yàn)研究
發(fā)布時(shí)間：2019-01-12 07:04
【摘要】：西南地區(qū)地貌多變、地質(zhì)條件復(fù)雜,需建設(shè)大量鐵路網(wǎng)、公路網(wǎng),當(dāng)線路跨越河流、溝谷或者山區(qū)時(shí),往往需要修筑橋梁以連接線路,需要布設(shè)橋梁樁基礎(chǔ)�，F(xiàn)階段對樁橫向承載性能的研究主要還是針對在水平地基中的樁,對于巖質(zhì)邊坡上的斜樁基礎(chǔ)橫向受力機(jī)理,研究文獻(xiàn)非常少,沒有系統(tǒng)的理論和方法對其進(jìn)行分析,本文主要以模型試驗(yàn)為研究手段,通過數(shù)值模擬對模型試驗(yàn)結(jié)果進(jìn)行對比分析,得到一些結(jié)論,希望對實(shí)際工程實(shí)際和理論研究能起一定參考價(jià)值。主要得到以下幾點(diǎn)結(jié)論(1)巖質(zhì)邊坡上傾斜樁基礎(chǔ)在橫向受荷的情況下,彎矩整體分布趨勢呈由地面沿樁身先增大后減小再最后衰減為零的非線性分布,當(dāng)樁埋深在14D～17D時(shí),最大彎矩分布在坡面到(6D～9D)之間,且隨橫向荷載增加,彎矩值不斷變大,但不改變其分布規(guī)律,樁身坡面處橫向位移隨橫向加載量級增大而增加,部分位移曲線隨荷載增加曲線斜率增加。(2)軸力對巖質(zhì)邊坡上傾斜樁基礎(chǔ)橫向受荷性能影響:先有軸力作用的斜樁橫向承載能力提高,樁承受的軸向壓力相當(dāng)于預(yù)先給樁施加了預(yù)應(yīng)力,使得其橫向抗彎剛度提高,橫向承性能加強(qiáng)。(3)滑帶對巖質(zhì)邊坡上傾斜樁基礎(chǔ)橫向受荷性能影響:滑帶的存在使得同級荷載下的樁彎矩更大,滑帶造成樁周巖土介質(zhì)不連續(xù),降低了邊坡的穩(wěn)定性,使得邊坡上的斜樁橫向承載能力變?nèi)?所以在進(jìn)行基樁設(shè)計(jì)時(shí),要充分考慮巖體性質(zhì)。(4)抗彎剛度對巖質(zhì)邊坡上傾斜樁基礎(chǔ)橫向受荷性能影響:樁身抗彎剛度越大,彎矩值越大,地表橫向位移越小;樁身抗彎剛度越小,彎矩值越小,地表橫向位移越大,橫向力由樁身剛度大的樁分擔(dān)的比率大于剛度小的樁分擔(dān)的比率。提高抗彎剛度,可以有效提高樁基的橫向承載能力。(5)坡體推力對巖質(zhì)邊坡上傾斜樁基礎(chǔ)橫向受荷性能影響:巖質(zhì)邊坡樁滑面以上坡體推力沿樁身整體分布呈拋物線型,滑面以上樁前土壓力分布呈增大的三角形分布;滑面以下土抗力呈倒三角形分布。a、樁地面位置彎矩接近零,其彎矩分布形式和單獨(dú)橫向荷載作用、有軸壓作用時(shí)的橫向加載作用下的內(nèi)力分布規(guī)律不一樣。坡體推力作用時(shí)樁身嵌固越深,樁抵御坡體推力能力提高愈明顯,合理地增加傾斜樁基嵌固深度,對于提高其抗坡體推力承載性能有較大的改善。b、坡體推力和橫向力共同作用時(shí),樁橫向位移發(fā)展較快,對于坡體推力作用下橫向受荷下巖質(zhì)邊坡斜樁受力性能并不是將坡體推力單獨(dú)作用與橫力單獨(dú)作用進(jìn)行簡單的疊加,要考慮二者耦合的影響,二者的耦合使得彎矩更大,將對斜樁的橫向承載性能不利。因此在設(shè)計(jì)相類似的橋梁樁基時(shí),對可能存在的坡體推力要引起重視。
[Abstract]:The geomorphology of southwest area is changeable and the geological conditions are complicated. A large number of railway and highway networks are needed. When the lines cross rivers, valleys or mountain areas, it is often necessary to build bridges to connect the lines, and to set up bridge pile foundations. At present, the research on the lateral bearing capacity of pile is mainly aimed at the pile in the horizontal foundation. The research literature on the lateral force mechanism of the inclined pile foundation on the rock slope is very few, and there is no systematic theory and method to analyze it. This paper mainly takes the model test as the research means, through the numerical simulation carries on the contrast analysis to the model test result, obtains some conclusions, hopes to have certain reference value to the actual engineering practice and the theory research. The main conclusions are as follows: (1) when the slope pile foundation on the rock slope is subjected to transverse load, the overall distribution trend of bending moment is a nonlinear distribution, which increases first along the pile body and then decreases to zero at last. When the pile buried depth is 14D~17D, the maximum bending moment is distributed between slope surface and (6D~9D), and with the increase of transverse load, the bending moment value increases continuously, but does not change its distribution law, and the lateral displacement of pile slope increases with the increase of transverse loading order. The slope of partial displacement curve increases with the increase of load. (2) the influence of axial force on lateral load performance of inclined pile foundation on rock slope: the lateral bearing capacity of inclined pile with axial force is increased. The axial pressure on the pile is equivalent to prestressing the pile in advance, so that the lateral bending stiffness of the pile is increased. (3) the influence of slip zone on lateral load performance of inclined pile foundation on rock slope: the existence of slip zone makes the bending moment of pile under the same load greater, and the slip zone causes discontinuity of rock and soil media around pile, which reduces the stability of slope. The lateral bearing capacity of inclined pile on slope becomes weaker, so when designing foundation pile, the rock mass property should be fully taken into account. (4) the flexural stiffness of inclined pile foundation on rock slope is affected by transverse load performance: the greater the bending stiffness of pile is, The larger the bending moment is, the smaller the lateral displacement is. The smaller the bending stiffness of pile is, the smaller the bending moment is and the greater the lateral displacement is. The ratio of lateral force shared by pile with large stiffness is larger than that of pile with small stiffness. The lateral bearing capacity of pile foundation can be improved effectively by increasing flexural stiffness. (5) the lateral load behavior of inclined pile foundation on rock slope is affected by slope thrust. The distribution of earth pressure in front of piles above the sliding surface is triangular. The resistance of the soil below the sliding surface is distributed in an inverted triangle. A, the bending moment of the pile is close to zero, and the distribution of the bending moment is different from that of the single lateral load, and the distribution law of the internal force under the lateral loading under axial compression is different. The deeper the pile body is embedded in the slope body, the more obvious the resistance of the pile to the slope body thrust is, and the more reasonable increase in the embedded depth of the inclined pile foundation is, the greater the bearing capacity of the slope body thrust can be improved. The pile lateral displacement develops rapidly when the slope body thrust and transverse force act together, so the slope pile under lateral loading is not simply superposed by the slope thrust and the transverse force. The influence of coupling between them should be considered, which makes the bending moment bigger, which will be unfavorable to the lateral bearing capacity of inclined pile. Therefore, in the design of similar bridge pile foundation, attention should be paid to the possible slope thrust.
【學(xué)位授予單位】：西南交通大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：U443.15
本文編號：2407489
[Abstract]:The geomorphology of southwest area is changeable and the geological conditions are complicated. A large number of railway and highway networks are needed. When the lines cross rivers, valleys or mountain areas, it is often necessary to build bridges to connect the lines, and to set up bridge pile foundations. At present, the research on the lateral bearing capacity of pile is mainly aimed at the pile in the horizontal foundation. The research literature on the lateral force mechanism of the inclined pile foundation on the rock slope is very few, and there is no systematic theory and method to analyze it. This paper mainly takes the model test as the research means, through the numerical simulation carries on the contrast analysis to the model test result, obtains some conclusions, hopes to have certain reference value to the actual engineering practice and the theory research. The main conclusions are as follows: (1) when the slope pile foundation on the rock slope is subjected to transverse load, the overall distribution trend of bending moment is a nonlinear distribution, which increases first along the pile body and then decreases to zero at last. When the pile buried depth is 14D~17D, the maximum bending moment is distributed between slope surface and (6D~9D), and with the increase of transverse load, the bending moment value increases continuously, but does not change its distribution law, and the lateral displacement of pile slope increases with the increase of transverse loading order. The slope of partial displacement curve increases with the increase of load. (2) the influence of axial force on lateral load performance of inclined pile foundation on rock slope: the lateral bearing capacity of inclined pile with axial force is increased. The axial pressure on the pile is equivalent to prestressing the pile in advance, so that the lateral bending stiffness of the pile is increased. (3) the influence of slip zone on lateral load performance of inclined pile foundation on rock slope: the existence of slip zone makes the bending moment of pile under the same load greater, and the slip zone causes discontinuity of rock and soil media around pile, which reduces the stability of slope. The lateral bearing capacity of inclined pile on slope becomes weaker, so when designing foundation pile, the rock mass property should be fully taken into account. (4) the flexural stiffness of inclined pile foundation on rock slope is affected by transverse load performance: the greater the bending stiffness of pile is, The larger the bending moment is, the smaller the lateral displacement is. The smaller the bending stiffness of pile is, the smaller the bending moment is and the greater the lateral displacement is. The ratio of lateral force shared by pile with large stiffness is larger than that of pile with small stiffness. The lateral bearing capacity of pile foundation can be improved effectively by increasing flexural stiffness. (5) the lateral load behavior of inclined pile foundation on rock slope is affected by slope thrust. The distribution of earth pressure in front of piles above the sliding surface is triangular. The resistance of the soil below the sliding surface is distributed in an inverted triangle. A, the bending moment of the pile is close to zero, and the distribution of the bending moment is different from that of the single lateral load, and the distribution law of the internal force under the lateral loading under axial compression is different. The deeper the pile body is embedded in the slope body, the more obvious the resistance of the pile to the slope body thrust is, and the more reasonable increase in the embedded depth of the inclined pile foundation is, the greater the bearing capacity of the slope body thrust can be improved. The pile lateral displacement develops rapidly when the slope body thrust and transverse force act together, so the slope pile under lateral loading is not simply superposed by the slope thrust and the transverse force. The influence of coupling between them should be considered, which makes the bending moment bigger, which will be unfavorable to the lateral bearing capacity of inclined pile. Therefore, in the design of similar bridge pile foundation, attention should be paid to the possible slope thrust.
【學(xué)位授予單位】：西南交通大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：U443.15
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