黄土沟谷地区桥梁桩基加固技术的应用研究
发布时间：2018-08-05 11:33
【摘要】：黄土沟谷地区雨水和桥梁上部结构排水长期冲刷作用下，桥梁桩周护坡产生不同程度的冲刷破坏，使单排双柱式桩基产生承载能力不足、沉降与不均匀沉降等诸多问题。直接影响桩基结构的正常使用和安全性，，对桥梁上部结构的正常工作也产生极大隐患。 首先，在对桩基不同冲刷病害进行识别的基础上，结合对典型病害进行的原因分析，建立了桩基水流冲刷破坏过程模型，并在此基础上提出针对冲刷破坏的桩基混凝土结构承载能力和耐久性评估方法。其次，在分析冲刷破坏对桩基竖向和横向承载能力影响时，结合冲刷破坏后桩背侧向土压力对桩身的作用机理，通过建立在竖向力、横向力和弯矩共同作用下的桩基复杂受力模型，得出了基于“m”法的桩身挠曲方程，分析了桩身水平位移、转角、弯矩、剪力和桩侧土抗力的变化规律，分析结果有助于对复杂受力状态下的桩基承载能力及安全状态作出评定。最后，在桩基加固方案初步设计的基础上，通过有限差分软件FLAC3D，使用NULL单元进行冲刷过程模拟、ELASTIC、SHELL和CABLE单元进行加固过程的模拟，建立了桩基典型冲刷病害全程数值模拟桩-土模型，分析了桩-土模型矢量变形、位移、桩身应力、摩阻力、锚杆力在冲刷-加固全程中的变化，对结构体系最大不平衡力和关键点进行了全程跟踪。通过数值计算结果可知，桩周土体冲刷破坏使桩身产生横向挠曲、桩身出现拉应力、产生反弯点、沉降值过大、承载能力不足等诸多问题，使桩基处于极不安全的状态，通过桩底高压喷射注浆形成固结体、土体中打入锚杆和混凝土护面，能够有效改善桩基不利受力，使整个桩-土体系处于较为安全的状态。 本文针对不同冲刷破坏程度提出的加固关键技术和坡面防护技术相结合的加固方案初步设计可操作性强、加固效果明显，能够有效的解决实际工程中的问题，为今后同类问题的解决有借鉴意义。
[Abstract]:Under the long-term scour action of Rain Water and superstructure drainage in loess gully area, the slope protection around the bridge pile produces different degree of scour damage, resulting in many problems such as insufficient bearing capacity of single row double-column pile foundation, settlement and uneven settlement and so on. It directly affects the normal use and safety of pile foundation structure, and also has great hidden danger to the normal work of bridge superstructure. Firstly, on the basis of identifying the different erosion diseases of pile foundation, combined with the analysis of the causes of the typical diseases, the model of pile foundation erosion failure process is established. On this basis, a method for evaluating the bearing capacity and durability of pile foundation concrete structures with scour failure is proposed. Secondly, when analyzing the influence of erosion failure on the vertical and lateral bearing capacity of pile foundation, combined with the action mechanism of lateral earth pressure on pile body after erosion failure, through the establishment of vertical force, The complex force model of pile foundation under the action of transverse force and bending moment is obtained. The deflection equation of pile body based on "m" method is obtained, and the variation law of horizontal displacement, rotation angle, bending moment, shear force and soil resistance of pile side is analyzed. The analysis results are helpful to evaluate the bearing capacity and safety state of pile foundation under complex loading condition. Finally, on the basis of the preliminary design of the reinforcement scheme of pile foundation, through the finite difference software FLAC3D, the NULL element is used to simulate the scouring process and the CABLE element is used to simulate the strengthening process. The pile-soil model for the whole process of typical erosion disease of pile foundation is established, and the variation of vector deformation, displacement, stress of pile body, friction resistance and anchor force in the whole course of scouring and strengthening are analyzed. The maximum unbalanced force and key points of the structure system are tracked in the whole process. The results of numerical calculation show that the soil scour failure around the pile causes the pile body to produce transverse deflection, the pile body appears tensile stress, produces the reverse bending point, the settlement value is too large, the bearing capacity is insufficient and so on, so the pile foundation is in an extremely unsafe state. The consolidation body is formed by high pressure jet grouting at the bottom of the pile, and the anchor rod and the concrete surface are pushed into the soil, which can effectively improve the unfavorable force of the pile foundation and make the whole pile-soil system in a relatively safe state. In this paper, according to different scour failure degree, the key technology of reinforcement and slope protection technology are put forward. The preliminary design of reinforcement scheme is feasible, and the effect of reinforcement is obvious, which can effectively solve the problems in practical engineering. It can be used for reference for solving similar problems in the future.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U443.15;U445.72
本文编号：2165669
[Abstract]:Under the long-term scour action of Rain Water and superstructure drainage in loess gully area, the slope protection around the bridge pile produces different degree of scour damage, resulting in many problems such as insufficient bearing capacity of single row double-column pile foundation, settlement and uneven settlement and so on. It directly affects the normal use and safety of pile foundation structure, and also has great hidden danger to the normal work of bridge superstructure. Firstly, on the basis of identifying the different erosion diseases of pile foundation, combined with the analysis of the causes of the typical diseases, the model of pile foundation erosion failure process is established. On this basis, a method for evaluating the bearing capacity and durability of pile foundation concrete structures with scour failure is proposed. Secondly, when analyzing the influence of erosion failure on the vertical and lateral bearing capacity of pile foundation, combined with the action mechanism of lateral earth pressure on pile body after erosion failure, through the establishment of vertical force, The complex force model of pile foundation under the action of transverse force and bending moment is obtained. The deflection equation of pile body based on "m" method is obtained, and the variation law of horizontal displacement, rotation angle, bending moment, shear force and soil resistance of pile side is analyzed. The analysis results are helpful to evaluate the bearing capacity and safety state of pile foundation under complex loading condition. Finally, on the basis of the preliminary design of the reinforcement scheme of pile foundation, through the finite difference software FLAC3D, the NULL element is used to simulate the scouring process and the CABLE element is used to simulate the strengthening process. The pile-soil model for the whole process of typical erosion disease of pile foundation is established, and the variation of vector deformation, displacement, stress of pile body, friction resistance and anchor force in the whole course of scouring and strengthening are analyzed. The maximum unbalanced force and key points of the structure system are tracked in the whole process. The results of numerical calculation show that the soil scour failure around the pile causes the pile body to produce transverse deflection, the pile body appears tensile stress, produces the reverse bending point, the settlement value is too large, the bearing capacity is insufficient and so on, so the pile foundation is in an extremely unsafe state. The consolidation body is formed by high pressure jet grouting at the bottom of the pile, and the anchor rod and the concrete surface are pushed into the soil, which can effectively improve the unfavorable force of the pile foundation and make the whole pile-soil system in a relatively safe state. In this paper, according to different scour failure degree, the key technology of reinforcement and slope protection technology are put forward. The preliminary design of reinforcement scheme is feasible, and the effect of reinforcement is obvious, which can effectively solve the problems in practical engineering. It can be used for reference for solving similar problems in the future.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U443.15;U445.72
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