典型黃土地區(qū)橋梁樁端后壓漿鉆孔灌注樁受力特性研究
發(fā)布時(shí)間：2019-04-03 15:25
【摘要】：目前鉆孔灌注樁技術(shù)在高層建筑和大承載力的基礎(chǔ)中已廣泛應(yīng)用，但受樁端軟弱土層的影響會(huì)大大消弱樁基的的承載力和穩(wěn)定性，尤其對(duì)于黃土區(qū)橋梁，由于黃土結(jié)構(gòu)的特殊性，會(huì)對(duì)橋梁樁基產(chǎn)生一系列的病害。采用樁端后壓漿技術(shù)能解決樁端軟弱層帶來(lái)的不足，但目前的研究只建立在半經(jīng)驗(yàn)半理論的基礎(chǔ)上，因此確定黃土區(qū)樁端后壓漿樁基承載力是目前橋梁樁基設(shè)計(jì)中亟待解決的關(guān)鍵問(wèn)題。本文結(jié)合西安—咸陽(yáng)機(jī)場(chǎng)專用高速段工程樁端后壓漿鉆孔灌注樁的現(xiàn)場(chǎng)靜載試驗(yàn)，以研究后壓漿樁基的受力機(jī)理為主線，以確定樁基承載性能為目標(biāo)，在總結(jié)國(guó)內(nèi)外研究現(xiàn)狀的基礎(chǔ)上，采用現(xiàn)場(chǎng)試驗(yàn)、理論分析和數(shù)值模擬相結(jié)合的技術(shù)手段，對(duì)典型黃土地區(qū)橋梁樁端后壓漿樁承載特性進(jìn)行系統(tǒng)的研究，期望填補(bǔ)樁端后壓漿樁在黃土區(qū)橋梁樁基受力分析方面的空白，為實(shí)際工程需求提供理論及方法支撐，主要研究?jī)?nèi)容如下： 1.運(yùn)用Vesic球形擴(kuò)張?jiān)韺?duì)樁端后注漿樁基進(jìn)行分析，對(duì)Vesic法中的剛度系數(shù)指標(biāo)進(jìn)行修正，，克服了原公式不能考慮樁端沉渣、土層空隙等施工過(guò)程中帶來(lái)的影響，得出后壓漿樁基在施工過(guò)程中，確定土層發(fā)生剪切破壞前的水泥漿凝固半徑和樁端產(chǎn)生的塑性區(qū)范圍。 2.基于樁端后壓漿的受力機(jī)理分析，明確了荷載傳遞的主要影響因素及承載力計(jì)算應(yīng)考慮的因素，確定了注漿體直徑、注漿體高度與樁徑之比的控制范圍，為黃土地區(qū)橋梁樁端后壓漿鉆孔灌注樁的設(shè)計(jì)與施工提供了比較合理的技術(shù)指標(biāo)。 3.考慮黃土的濕陷變形受土體模量、濕陷厚度和濕陷系數(shù)等不同因素的影響，基于彈性理論，結(jié)合樁端后壓漿鉆孔灌注樁的荷載傳遞機(jī)理分析，提出了典型黃土地區(qū)橋梁樁端后壓漿的樁基承載力和沉降計(jì)算公式，并通過(guò)與依托橋梁實(shí)測(cè)數(shù)據(jù)的對(duì)比分析，驗(yàn)證了理論公式的適用性和可靠性。 4.分別對(duì)后壓漿和未壓漿的試樁進(jìn)行現(xiàn)場(chǎng)試驗(yàn)，測(cè)試在不同荷載下樁身軸力、樁側(cè)和樁端阻力的分布，并對(duì)試驗(yàn)數(shù)據(jù)進(jìn)行對(duì)比分析，探討了樁端后壓漿樁基的荷載傳遞規(guī)律，對(duì)采用后壓漿技術(shù)的鉆孔灌注樁的工作機(jī)理進(jìn)行了系統(tǒng)的研究，為典型黃土區(qū)橋梁鉆孔灌注樁的設(shè)計(jì)和施工提供了合理的技術(shù)指標(biāo)。 5.結(jié)合現(xiàn)場(chǎng)試驗(yàn)，采用非線性有限元分析軟件對(duì)后注漿樁基的承載性能進(jìn)行了數(shù)值分析，根據(jù)模擬計(jì)算結(jié)果與現(xiàn)場(chǎng)試驗(yàn)結(jié)果對(duì)比，基于黃土地區(qū)橋梁樁端后壓漿鉆孔灌注樁在設(shè)計(jì)荷載作用下的荷載沉降機(jī)理，對(duì)樁端后壓漿、樁側(cè)壓漿以及樁端與樁側(cè)同時(shí)壓漿等不同工況對(duì)灌注樁承載性能的影響進(jìn)行了研究，并分析了樁端土變形模量提高后及漿液沿樁側(cè)不同程度的上升機(jī)率對(duì)橋梁樁基沉降的影響。
[Abstract]:At present, bored cast-in-place pile technology has been widely used in high-rise buildings and the foundation of large bearing capacity, but under the influence of weak soil layer at the end of pile, the bearing capacity and stability of pile foundation will be weakened greatly, especially for bridges in loess area. Because of the particularity of loess structure, a series of diseases will be produced to bridge pile foundation. The technology of post-grouting at pile tip can solve the problem of weak layer at pile end, but the current research is only based on the semi-empirical and semi-theoretical basis. Therefore, determining the bearing capacity of post-grouting pile foundation in loess area is a key problem to be solved in the design of bridge pile foundation. Based on the field static load test of the post-grouting bored pile at the end of the special high-speed section of Xi'an-Xianyang Airport, the main line is to study the stress mechanism of the post-grouting pile foundation and to determine the bearing capacity of the pile foundation. On the basis of summarizing the present research situation at home and abroad, the bearing characteristics of post-grouting pile at the end of bridge pile in typical loess area are systematically studied by means of field test, theoretical analysis and numerical simulation. It is expected to fill the gap of post-grouting pile in the analysis of pile foundation in loess area, and provide theoretical and methodological support for practical engineering demand. The main research contents are as follows: 1. The Vesic spherical expansion principle is used to analyze the post-grouting pile foundation at the end of the pile, and the stiffness coefficient index in the Vesic method is modified. The original formula can not take into account the influence caused by the pile end sediment and the space in the soil layer, etc. It is concluded that during the construction of post-grouting pile foundation, the solidification radius of cement slurry before shear failure of soil layer and the range of plastic zone produced at the end of the pile are determined. 2. Based on the analysis of the stress mechanism of the post grouting at the end of the pile, the main influencing factors of the load transfer and the factors to be considered in the calculation of the bearing capacity are defined, and the control range of the grouting body diameter, the ratio of the grouting body height to the pile diameter is determined. It provides a reasonable technical index for the design and construction of post-grouting bored pile at the end of bridge pile in loess area. 3. Considering that the collapsible deformation of loess is affected by different factors such as soil modulus, collapsible thickness and collapsibility coefficient, based on elastic theory, the load transfer mechanism of post-grouting bored cast-in-place pile at the end of pile is analyzed. The formulas for calculating the bearing capacity and settlement of pile foundation after grouting at the end of bridge pile in typical loess region are put forward, and the applicability and reliability of the theoretical formula are verified by the comparison and analysis with the measured data of the bridge. 4. The field tests of the post-grouting pile and the unpressed pile were carried out to test the distribution of the axial force of the pile body, the resistance of the pile side and the end of the pile under different loads, and the experimental data were compared and analyzed, and the load transfer rule of the post-grouting pile foundation at the end of the pile was discussed. The working mechanism of bored cast-in-place pile with post-grouting technology is systematically studied, which provides a reasonable technical index for the design and construction of bridge bored cast-in-place pile in typical loess area. 5. Combined with the field test, the bearing capacity of post-grouting pile foundation is numerically analyzed by using nonlinear finite element analysis software. According to the simulation results and the field test results, the simulation results are compared with the field test results. Based on the mechanism of load settlement of post-grouting bored pile at the end of bridge pile in loess area under the design load, the post-grouting at the end of the pile is analyzed. The influence of pile side grouting and simultaneous grouting of pile end and pile side on the bearing capacity of cast-in-place pile is studied, and the influence of soil deformation modulus of pile end and the rising probability of slurry along pile side on the settlement of bridge pile foundation is analyzed.
【學(xué)位授予單位】：長(zhǎng)安大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2014
【分類號(hào)】：U443.15
本文編號(hào)：2453326
[Abstract]:At present, bored cast-in-place pile technology has been widely used in high-rise buildings and the foundation of large bearing capacity, but under the influence of weak soil layer at the end of pile, the bearing capacity and stability of pile foundation will be weakened greatly, especially for bridges in loess area. Because of the particularity of loess structure, a series of diseases will be produced to bridge pile foundation. The technology of post-grouting at pile tip can solve the problem of weak layer at pile end, but the current research is only based on the semi-empirical and semi-theoretical basis. Therefore, determining the bearing capacity of post-grouting pile foundation in loess area is a key problem to be solved in the design of bridge pile foundation. Based on the field static load test of the post-grouting bored pile at the end of the special high-speed section of Xi'an-Xianyang Airport, the main line is to study the stress mechanism of the post-grouting pile foundation and to determine the bearing capacity of the pile foundation. On the basis of summarizing the present research situation at home and abroad, the bearing characteristics of post-grouting pile at the end of bridge pile in typical loess area are systematically studied by means of field test, theoretical analysis and numerical simulation. It is expected to fill the gap of post-grouting pile in the analysis of pile foundation in loess area, and provide theoretical and methodological support for practical engineering demand. The main research contents are as follows: 1. The Vesic spherical expansion principle is used to analyze the post-grouting pile foundation at the end of the pile, and the stiffness coefficient index in the Vesic method is modified. The original formula can not take into account the influence caused by the pile end sediment and the space in the soil layer, etc. It is concluded that during the construction of post-grouting pile foundation, the solidification radius of cement slurry before shear failure of soil layer and the range of plastic zone produced at the end of the pile are determined. 2. Based on the analysis of the stress mechanism of the post grouting at the end of the pile, the main influencing factors of the load transfer and the factors to be considered in the calculation of the bearing capacity are defined, and the control range of the grouting body diameter, the ratio of the grouting body height to the pile diameter is determined. It provides a reasonable technical index for the design and construction of post-grouting bored pile at the end of bridge pile in loess area. 3. Considering that the collapsible deformation of loess is affected by different factors such as soil modulus, collapsible thickness and collapsibility coefficient, based on elastic theory, the load transfer mechanism of post-grouting bored cast-in-place pile at the end of pile is analyzed. The formulas for calculating the bearing capacity and settlement of pile foundation after grouting at the end of bridge pile in typical loess region are put forward, and the applicability and reliability of the theoretical formula are verified by the comparison and analysis with the measured data of the bridge. 4. The field tests of the post-grouting pile and the unpressed pile were carried out to test the distribution of the axial force of the pile body, the resistance of the pile side and the end of the pile under different loads, and the experimental data were compared and analyzed, and the load transfer rule of the post-grouting pile foundation at the end of the pile was discussed. The working mechanism of bored cast-in-place pile with post-grouting technology is systematically studied, which provides a reasonable technical index for the design and construction of bridge bored cast-in-place pile in typical loess area. 5. Combined with the field test, the bearing capacity of post-grouting pile foundation is numerically analyzed by using nonlinear finite element analysis software. According to the simulation results and the field test results, the simulation results are compared with the field test results. Based on the mechanism of load settlement of post-grouting bored pile at the end of bridge pile in loess area under the design load, the post-grouting at the end of the pile is analyzed. The influence of pile side grouting and simultaneous grouting of pile end and pile side on the bearing capacity of cast-in-place pile is studied, and the influence of soil deformation modulus of pile end and the rising probability of slurry along pile side on the settlement of bridge pile foundation is analyzed.
【學(xué)位授予單位】：長(zhǎng)安大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2014
【分類號(hào)】：U443.15
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