The static drill rooted nodular pile is a new type of pile foundation consisting of precast nodular pile and the surrounding cemented soil.This composite pile has a relatively high bearing capacity and the mud polluti...The static drill rooted nodular pile is a new type of pile foundation consisting of precast nodular pile and the surrounding cemented soil.This composite pile has a relatively high bearing capacity and the mud pollution will be largely reduced during the construction process by using this type of pile.In order to investigate the bearing capacity and load transfer mechanism of this pile,a group of experiments were conducted to provide a comparison between this new pile and the bored pile.The axial force of a precast nodular pile was also measured by the strain gauges installed on the pile to analyze the distribution of the axial force of the nodular pile and the skin friction supported by the surrounding soil,then 3D models were built by using the ABAQUS finite element program to investigate the load transfer mechanism of this composite pile in detail.By combining the results of field tests and the finite element method,the outcome showed that the bearing capacity of a static drill rooted nodular pile is higher than the bored pile,and that this composite pile will form a double stress dispersion system which will not only confirm the strength of the pile,but also make the skin friction to be fully mobilized.The settlement of this composite pile is mainly controlled by the precast nodular pile;meanwhile,the nodular pile and the surrounding cemented soil can be considered as deformation compatibility during the loading process.The nodes on the nodular pile play an important role during the load transfer process,the shear strength of the interface between the cemented soil and the soil of the static drill rooted pile is larger than that of the bored pile.展开更多
针对齿轮箱的振动噪声问题,提出了一种基于齿轮载荷静态传递误差(load static transfer error,LSTE)优化的减振降噪方法。通过建立齿廓修形齿轮的时变啮合刚度解析模型,并采用Timoshenko梁单元构建齿轮-转子-轴承耦合动力学模型,系统揭...针对齿轮箱的振动噪声问题,提出了一种基于齿轮载荷静态传递误差(load static transfer error,LSTE)优化的减振降噪方法。通过建立齿廓修形齿轮的时变啮合刚度解析模型,并采用Timoshenko梁单元构建齿轮-转子-轴承耦合动力学模型,系统揭示了不同修形量和修形曲线下齿轮LSTE与系统动力学响应之间的关系。在此基础上,采用遗传算法对齿轮LSTE相对峰峰值进行优化,获得最优修形参数组合。最后结合有限元/边界元法,分析了修形优化前后齿轮箱的噪声辐射特性。研究结果表明,经遗传算法优化后的修形参数可使主动轮位移幅频响应幅值与加速度幅频响应幅值相较其他修形参数均显著降低,齿轮箱辐射声功率级均方根值由未修形时的38.66 dB降至修形优化后25.32 dB,降幅达34.51%,降噪效果显著。研究成果为齿轮传动系统的低噪声设计提供了理论依据。展开更多
文摘The static drill rooted nodular pile is a new type of pile foundation consisting of precast nodular pile and the surrounding cemented soil.This composite pile has a relatively high bearing capacity and the mud pollution will be largely reduced during the construction process by using this type of pile.In order to investigate the bearing capacity and load transfer mechanism of this pile,a group of experiments were conducted to provide a comparison between this new pile and the bored pile.The axial force of a precast nodular pile was also measured by the strain gauges installed on the pile to analyze the distribution of the axial force of the nodular pile and the skin friction supported by the surrounding soil,then 3D models were built by using the ABAQUS finite element program to investigate the load transfer mechanism of this composite pile in detail.By combining the results of field tests and the finite element method,the outcome showed that the bearing capacity of a static drill rooted nodular pile is higher than the bored pile,and that this composite pile will form a double stress dispersion system which will not only confirm the strength of the pile,but also make the skin friction to be fully mobilized.The settlement of this composite pile is mainly controlled by the precast nodular pile;meanwhile,the nodular pile and the surrounding cemented soil can be considered as deformation compatibility during the loading process.The nodes on the nodular pile play an important role during the load transfer process,the shear strength of the interface between the cemented soil and the soil of the static drill rooted pile is larger than that of the bored pile.
