某桩基事故分析谈桩型的合理选择

文章通过对某工程实例的分析,说明建筑物桩基形式的合理选择,必须综合考虑设计要求、场地工程地质、水文地质的具体情况以及施工设备、工艺的适应性,才能确保桩基工程质量并最终节约建筑成本.     

Effects of separate and mutual application of Na and Si on drought resistance of Haloxylon ammodendron

We studied pot cultivated Haloxylon ammodendron’s growth, physiological changes and drought resistance under NaCl, H₂SiO₃, and NaCl+H₂SiO₃ treatments. Results show that 0.3 g/kg NaCl, 0.2 g/kg H₂SiO₃ or 0.3 g/kg NaCl+0.1 g/kg H₂SiO₃ treatments can effectively promote growth and improve the drought resistance of H. ammodendron. Compared with that without NaCl treatment, H. ammodendron’s height, crown diameter and fresh weight increased by 42%, 91% and 62% respectively under 0.3 g/kg NaCl treatment, and its main stem diameter, main root diameter and main root length increased by 40%, 39% and 23%, respectively. Compared with that without H₂SiO₃ treatments, H. ammodendron’s height, crown diameter and fresh weight increased by 36%, 45% and 27% respectively under 0.2 g/kg H₂SiO₃ treatment, and its main stem diameter, main root diameter and main root length increased by 23%, 23% and 20%, respectively. Compared with that under 0.3 g/kg NaCl treatment, H. ammodendron’s height, crown diameter and fresh weight and main root length increased by 9%, 10%, 17% and 12% respectively under 0.3 g/kg NaCl+0.1 g/kg H₂SiO₃ treatment. Compared with that under 0.1 g/kg H₂SiO₃ treatment, H. ammodendron’s height, crown diameter and fresh weight increased by 28%, 76% and 68% respectively under 0.3 g/kg NaCl+0.1 g/kg H₂SiO₃ treatment, and its main stem diameter, main root diameter and main root length increased by 30%, 32% and 27%, respectively. This suggests that moderate levels of NaCl+H₂SiO₃ interaction can effectively promote growth and improve drought resistance of H. ammodendron than separate applications of NaCl or H₂SiO₃.     

Effect of compressible parameters on vertical vibration of an elastic pile in multilayered poroelastic media

This paper mainly investigates the influences of compressible parameters on the vertical vibration of a pile embedded in layered poroelastic soil media. The pile is treated as a 1D elastic bar by the finite element method, and fundamental solutions for the layered poroelastic soils due to a vertical dynamic load are obtained by the analytical layer element method. Based on the compatibility conditions, the pile-soil dynamic interaction problem is solved. The numerical scheme has been compiled into a Fortran program for numerical calculation. Influences of the pile-soil stiffness ratio, compressible parameters, vibration frequency and the soil stratification are discussed.     

用置换法处理桩端沉碴

文章对超出规范规定范围内的桩端沉碴提出用置换法处理的技术方法 ,取得显著效果 ,克服了传统处理方法强度小等缺点 ,也避免了采用跨越处理工期长、造价高的不良后果。     

干振碎石桩复合地基处理及其效果

干振碎石桩是处理松软地基土的一种行之有效的方法，它是挤密桩的一种。新乡市地方铁路处仓库场地经干振碎石桩地基处理后，桩间土密实度有明显的提高，液化指数大幅度降低，复合地基承载力相应提高，满足了设计要求。     

Legacies of a Contested Campus: Urban Renewal,Community Resistance,and the Origins of Gentrification in Denver

The postwar urban renewal experience varied among US cities according to the result of local social contests pitting those imposing their power to transform urban space against those resisting it. In this paper, we examine the role of one such contest in shaping urban renewal outcomes in Denver, using the case of the late 1960s Auraria project. The project sought to remove a poor, Hispanic neighborhood in order to build a new downtown college campus, generating community opposition from the inner city neighborhood residents, leaders of the city’s Chicano Movement, and historic preservation activists. We demonstrate how resistance actively shaped the ultimate form and character of the project, and how the legacies of this urban renewal contest extended—in unforeseen ways—beyond the immediate struggles of the time. We argue that these legacies provide the essential context for understanding planning practice, redevelopment strategies, and gentrification dynamics in the city today.     

支盘桩抗压和抗拔特性的研究

在前期研究的基础上,分析了支盘桩高承载力和低沉降量的内涵。通过分析得出:在轴向压力作用下,支盘承受较大的荷载,支盘力占总荷载大约60 %以上,说明在承力上,支盘力控制着单桩承载力和沉降量的大小。在抗拔方面,由于支盘上方土阻力的作用,使支盘桩的抗拔力大幅度提升。     

桩土相互作用模型及模型实验

本文介绍了目前在桩基测量及计算中使用的一些桩土相互作用摸型,同时也介绍了在动载情况下研究桩土相互作用的模型实验,并将桩土模型的计算与实验结果进行了比较和分析。     

十字形振动翼共振法在处理可液化地基中的应用

目前国内外处理液化地基的方法很多,如换填法、强夯法、振冲碎石桩法、振冲砂桩法、振密法等,每种处理方法都有它的适用范围和局限性。共振法与其他液化地基处理方法相比,该方法无需用砂石骨料置换部分的地基土体,施工方便,加固效果显著,在国外得到了广泛的应用。本工程通过考虑场地工程概况、施工条件、经济技术条件等,采用十字翼共振法对该场地进行液化地基处理,用不同测试方法对处理后的地基进行抗液化评价。处理后通过静力触探测试和标准贯入试验测试,结果表明,十字形振动翼共振法可有效加固可液化地基,消除液化; 且设备简单,操作方便,施工效率高,造价相对其他加固方法低,对环境振动影响小,具有良好的应用前景。     

层状地基中群桩水平振动

在考虑地基土分层的基础上,采用动力Winkler地基模型模拟桩土相互作用并运用传递矩阵,求解层状地基中的单桩和群桩的阻抗函数.在计算动力相互作用因子时考虑了被动桩与土的相互作用.最后将相互作用因子和群桩阻抗的本文解与精确解进行对比,验证了本文方法的有效性.