【作者】 刘思思；

【导师】 赵明华；

【作者基本信息】 湖南大学 ， 岩土工程， 2010， 博士

【摘要】 基桩自锚静载测试技术是一项以桩底锚固技术为基础的新型基桩静载测试技术。作为一项正处于研制阶段的新技术,其设计计算理论及试验研究分析目前尚处于空白阶段。为填补这一空白,完善和发展基桩自锚静载测试技术,本文结合湖南省交通科技项目(200609),对该技术展开了理论分析及试验数据处理研究,主要研究内容及成果如下:首先对基桩在竖向荷载作用下的工作性状进行了详细的分析和计算。通过建立考虑桩周土卸载情况的多折线模型,结合基于能量原理的桩身能量差分方程,编制了基桩性状计算程序,并提出了引导程序收敛的荷载协调法和最小势能协调法,给出了相应的程序收敛策略。同时,对桩周土发生沉降时桩身产生负摩阻力情况下的基桩工作性状给出了数值计算方法,并结合工程实例对基桩竖向荷载作用下的工作性状进行了计算分析。其次对自锚静载测试中桩底锚杆的工作性状做了深入的分析和计算。以荷载传递法为出发点,利用锚固体计算的能量差分方程,结合工程实例,对拉力型和压力集中型锚杆分别进行了计算和分析。进而,提出了压力分散型锚杆承载单元工作性状的P-s曲线计算方法,并给出在不同张拉工序情况下压力分散型锚杆的工作性状计算方法。接着,对基桩自锚静载测试系统中基桩和锚杆之间的关键介质-地基土,进行了位移求解方法的理论推导及算例计算。基于土体在不同条件下的土压力计算,给出了土中不同深度及变形情况下的剪应力计算方法。同时,基于能量原理,推导了土体的能量法差分方程,进而编制出有限空间下土体位移计算程序。然后,通过算例计算对土体位移进行了影响因素分析,获得了可供实际工程参考的定量分析结论。基于基桩、锚杆及土体的计算理论及程序实现方法,建立了自锚静载测试试验中基桩工作性状的计算分析方法,并结合算例对自锚测试系统中基桩的沉降影响因素进行了分析。同时,基于算例数据对基桩自锚测试试验数据进行了分析,建立了自锚测试系统中桩土荷载传递关系反分析方法,并给出了基桩自锚静载测试试验数据向普通静载测试数据转换的处理方法。为进一步探明基桩自锚静载测试试验的工作机理以及桩、土、锚之间的相互作用关系,本文对基桩自锚静载测试室内模型试验做了详细的说明和介绍,并对试验中所得的模型桩、模型锚及自锚测试情况下模型桩数据做了初步的整理及试验分析。最后为验证文中各计算理论、程序方法及数据处理措施的合理性和准确性,对室内模型试验所得的数据进行了详细的分析计算。首先利用基桩计算程序对模型桩进行计算分析,验证了文中关于荷载传递模型的讨论及基桩性状计算程序的准确性。其次,基于模型锚的荷载传递形态提出了动态折线模型,并通过与实测模型锚数据的对比,验证了动态折线模型锚杆性状计算程序的准确性。再次,通过与实测数据对比,验证了基桩自锚测试工作性状计算程序的准确性。最后,基于自锚测试条件下桩土荷载传递关系反分析方法,对自锚测试情况下模型桩的试验数据进行了分析,并通过与相同条件模型桩试验数据的对比,验证了将自锚测试模型桩试验数据转换为普通静载测试数据处理方法的可行性与准确性。更多还原

【Abstract】 As a new technology, pile foundation self-anchored static loading test technology that was based on under-pile anchoring technology, whose design theories and experiment analysis were still in blank currently. Integrating with trasportation technology project of Hunan province (No. 200609), sufficient researches and analysis about pile foundation self-anchored static loading test technology was done in this thesis in order to improve and develop such technology. Main contents were listed as following:Firstly, pile properties under vertical loading were thoroughly analyzed and calculated. By building multi-broken line model that on conditions of pile-surrounding soil settlement was considered, and integrating pile energy finite difference equation that was based on energy principle, pile properties calculation program was compiled. Then, load coordination method and minimum potential energy coordination method, as well as their corresponding convergence procedure were proposed. At the same time, when settlement of pile-surrounding soil caused pile negative friction, pile properties numerical caculation method was presented. Also, pile properties under vertical loading were calculated basing on a specific project.Secondily, under-pile anchor properties in self-anchored static loading test were deeply analyzed and calculated. Starting from load transfer method, using anchorage body energy finite difference equation, and basing on a specific project, tensile anchor and pressure type anchor were studied respectively. Furthermore, P-s curve of pressure-dispersive anchor bearing unit properties was calculated. Then, properites of pressure-dispersive anchor under different stretching procedures could be obtained.Thirdly, as key medium between pile and anchor in pile foundation self-anchoring static loading test, its theory deduction and calculation method of solving displacement was given. Basing on earth pressure calculation under different conditions, sheering stress in various depth and deformation was also brought out. According to energy principle, soil energy finite difference equation as well as soil displacement calculation programme in a finite sapce were proposed. Through analyzing influencing factors on soil displacement, helpful quantitative conclusions for practical projects could be obtained.Furthremore, calculation metheod of pile properties in self-anchored static loading test were developed, which was based on theories and program implementation methods of pile, anchor and soil. Combining with a calculating example, settlement influencing factors on pile foundation in self-anchored test system were also analyzed. Meanwhile, through data analysis, inverse analysis methods of loading transfer between pile and soil in self-anchored test system, as well as data conversion method from self-anchored static loading test to gereral static loading test, were established.For further exploring working mechanism of pile foundation self-anchored static loading test, and interactions among pile, soil and anchor, a specific laboratory model test was introduced in detail, and its model data were also sorted and analyzed.Finally, all data from laboratory model test were thoroughly analyzed for verification. Above all, through analyzing model pile data, efficiency of loading transfer model and accuracy of pile properties calculation program was evaluated. Subsequently, basing on loading transfer behavior of model anchor, dynamic broken line model was established. By comparing with testing data, accuracy of anchor calculation program of dynamic broken line model and pile calculation program in self-anchored test was measured. According to inverse analysis method of loading transfer between pile and soil in self-anchored test, its model pile testing data were analyzed. Through comparing with testing data on the same conditions, feasibility and accuracy of data conversion method from self-anchored static loading test to gereral static loading test was also verified.更多还原