影响水平旋喷桩质量的因素和事故处理

介绍了影响水平旋喷桩质量的几个因素，并指出水平旋喷桩在施工时发生的事故原因以及应采取的补救措施。     

DWX型单体液压支柱静力稳定性分析

简述了DWX型单体液压支柱的结构和工作原理,考虑了单体液压支柱油缸变形以及活柱体和油缸套接段的影响等因素,建立了DWX型单体液压支柱稳定性分析的计算模型,导出了相应的临界力计算公式。通过实例计算与现有方法进行比较,论证了其可行性。     

单片机在电磁振动给料机中的应用

由MCS-51单片机组成微控制器,实现全自动化给料闭环控制,作为控制对象的电磁振动给料机进行给料,固体流量计用于检测物料流量,通过A/D送进单片机,再经过PID控制处理使D/A产生控制电压,送给电振机,完成定量控制。     

复合地基设计理论的数值试验研究

该文通过“数值仿真”的思路与方法,对复合地基设计中的桩位、桩长、桩距等各因素影响下桩与桩间土中附加应力和桩侧摩阻力的分布特点进行了系统的数值试验研究,得到了一些传统研究方法无法得到的定量规律,对复合地基的设计理论具有一定的发展与深化。     

某钢厂轧机区PHC管桩基础单桩静载抽检不合格原因分析

该文介绍了某钢厂轧机区设备基础PHC管桩静载抽检单桩承载力偏低情况 ,经分析是由于饱和淤泥土中打入大面积群桩 ,引起桩基上浮所致 ,经采用复打后 ,静载试验结果均满足了设计要求 ,文中还总结了预防桩基上浮的一般作法。     

点荷载法检验挖孔桩岩基承载力的应用与分析

本文主要介绍了在三个挖孔桩工程中,用点荷载法检验岩基承载力以控制挖孔深度的情况,结果表明,与勘察报告建议的开挖深度基本一致。     

沉管灌注桩大面积断桩原因分析

通过2个工程实例分析了沉管灌注桩出现大面积断桩的原因是由于后期基坑开挖不当造成的,并提出了预防断桩出现的一些措施以及对断桩的处理补救措施.     

长春市轻轨工程大漂石地层灌注桩成孔钻进技术

结合长春市轻轨工程斜拉桥钻孔灌注桩施工实例，介绍了大漂石地层的筒钻法钻进原理、潜孔锤钻进工艺、岩心聚能爆破工艺及筒钻回转切石工艺等，为该类地层的顺利成孔成桩总结出了一套切实可行的施工方法。     

Electrical performance and ferroelectric phase transition characteristic in different oriented 0.73PMN-0.27PT single crystals

The electrical and optical properties of (001)- and (110)-oriented 0.73 Pb(Mg_1/3Nb_2/3)O₃-0.27PbTiO₃ single crystals are systematically investigated at various temperatures, both of which present a series of ferroelectric phase transition processes. Dielectric performance measurements reveal that the ferroelectric phase transition occurs over a temperature range, rather than at one temperature point. By testing the ferroelectric hysteresis P–E curves as well as bipolar and unipolar electric field-induced strain S–E curves, the values of remnant polarization, coercive field, maximum strain, and converse piezoelectric constant d₃₃^* change considerably near the phase transition temperatures. Simultaneously, the 0.73PMN-0.27PT single crystals with (001)- and (110)-orientations under a low electric field show ultrahigh d₃₃^* values of 3540 and 2817 pm/V, respectively, which can be attributed to the electric field-induced monoclinic and orthorhombic phases, respectively. The series of ferroelectric phase transitions upon heating, that is, from rhombohedral ferroelectric to monoclinic/orthorhombic, followed by from monoclinic/orthorhombic to tetragonal, and finally from tetragonal to cubic paraelectric, are further investigated via polarized light microscopy and Raman spectroscopy.     

Antiferroelectricity of NaNbO3: Single-crystal experimental study and first-principles calculation

Similar to the canonical antiferroelectric (AFE) compound PbZrO₃ in Pb(Zr,Ti)O₃ solid-solutions, the presence of double hysteresis loops and that of electric field–induced phase transitions are important characteristics of NaNbO₃ AFE materials; yet the phase transition behavior in the latter system is typically irreversible with the related mechanisms not fully understood. Here, we explore the phase transition mechanism of ferroelectric and AFE phases in NaNbO₃ based on measurements of single crystals with different directions in conjunction with density-functional theory (DFT) calculations. The tilting and distortion behaviors of the [NbO₆] octahedra are explained by DFT, and the ion displacement in the lattice is traced. The tilting and distortion behaviors of the [NbO₆] octahedra with different orientations are compared. We confirm that the tilt and distortion of the [NbO₆] octahedra along the [1 1 1] direction is the main reason to improve the stability of AFE phase. This conclusion is verified by the experimental characterizations of large-size NaNbO₃ single crystals successfully obtained in this study.