粉煤灰垫层与夯扩灌注桩联合处理高层建筑地基     

孙倡书谭佳良  周旭荣 《探矿工程》2006,33(9):4-6,8

利用夯扩灌注桩对桩端持力层的加密作用，可解决水下填筑问题，利用粉煤灰的可压密性和夯扩灌注桩承载力高的特点，可大幅提高复合地基承载力，减少工程投资。以河南洛阳某高层建筑为例，介绍了粉煤灰垫层和夯扩灌注桩组成的刚性桩复合地基在高层建筑地基中的应用。  相似文献   

CFG桩复合地基褥垫层的合理厚度确定方法研究          下载免费PDF全文

贾瑞杰  隆威  於法明 《探矿工程》2006,33(4):5-7

在CFG桩复合地基设计中，褥垫层的厚度设计是一个重点，它是复合地基承载力能否全部发挥的关键因素之一。但其设计上基本是靠经验取值，缺少理论根据。从理论方面入手，推导了褥垫层厚度的理论计算方法，给出了最佳垫层厚度、桩土应力比的解析表达式。  相似文献   

自重湿陷性黄土地区桩基设计探讨          下载免费PDF全文

徐建红 《探矿工程》2006,33(9):7-8

根据自重湿陷性黄土的特点、《湿陷性黄土地区建筑规范》（GB50025—2004）和《建筑桩基技术规范》（JGJ94—94）中关于桩基设计的对比分析，通过自重湿陷性黄土场地工程实例分析计算，依据负摩擦产生的机理——中性点理论，论述了自重湿陷性黄土场地中桩基设计应考虑中性点，而不应全部计入负摩阻的观点。  相似文献   

土钉墙与预应力锚杆联合支护技术          下载免费PDF全文

杨生彬 《探矿工程》2006,33(8):8-10,16

北京市深基坑工程中土钉墙支护技术应用比较广泛，对于边坡变形要求严格的基坑，采用土钉墙与预应力锚杆联合支护技术可有效控制变形，结合工程实例，介绍了该技术的设计思路及应用过程，说明了该技术的适用性，并就施工中遇到的问题进行分析，给出相应的处理措施。  相似文献   

复合土钉墙支护技术在某大型软土基坑围护中的应用          下载免费PDF全文

杜常春  章泽军  李飞  周喜锋 《探矿工程》2006,33(2):26-29

根据拟建建筑基坑的工程地质条件、周边环境条件、基坑开挖深度等特点综合考虑，对基坑分段采用超前微型桩支护加土钉墙、放坡加土钉墙2种复合支护方案。实践证明，该工程所采用的多种复合式支护实施方案，技术安全可靠，经济合理。  相似文献   

The simultaneous use of piles and prestressed anchors in foundation design     

F.A.B. Danziger  B.R. Danziger  M.P. Pacheco   《Engineering Geology》2006,87(3-4):163-177

The paper presents a simplified design procedure to evaluate the loads in piles and prestressed anchors when simultaneously used in foundations under tension loads and high overturning moments. Although involving some necessary simplifications for the sake of design, the procedure keeps the main features of load transfer from piles and anchors to the surrounding soil. The approximate method has been adopted by the authors in relevant projects in Brazil, whose long term satisfactory performance indicates its appropriate performance. Two practical examples have been selected to illustrate the application of the proposed method. It is shown that anchor prestressing plays an important role in limiting tension loads on the piles and controlling foundation eccentricity. The importance of monitoring for replacement of occasional prestress losses to prevent long-term pile overstressing is illustrated.  相似文献   

Modeling of Beams on Reinforced Granular Beds     

Priti Maheshwari  P. K. Basudhar  S. Chandra 《Geotechnical and Geological Engineering》2006,24(2):313-324

The paper describes a mechanical model for estimating the flexural response of a strip footing, supporting a column (imposing a concentrated load), resting on a compacted granular bed overlying a reinforcement layer for example, geogrids, geomats etc. below which lies a loose soil deposit. The footing is idealized as a beam and the reinforcing element is assumed to have finite bending stiffness and negligible frictional resistance. The upper and lower soil layers are idealized by a series of linear and discrete springs (Winkler springs) of different stiffness values. To find the response of such a model the governing differential equations have been derived and expressed in a nondimensional form. A closed form analytical solution of the same has been obtained subjected to appropriate boundary conditions. Using the present approach the resulting solution for a degenerated case of a long beam is found to be identical to the same of Hetenyi (1946, Beams on elastic foundations, University of Michigan press, Ann Arbor, MI). Parametric studies reveal that the ratio of flexural rigidity of upper and lower beam and the ratio of stiffness of the upper and lower soil layers affect significantly the response of the foundation.  相似文献   

The effect of thermal treatment on the 57Fe Mössbauer spectrum of beryl     

Geraldo Magela da Costa  Gabriel de Oliveira Polli  Márcio A. Kahwage  Eddy de Grave  Antônio Claret Soares Sabioni  Júlio Cesar Mendes 《Physics and Chemistry of Minerals》2006,33(3):161-166

Mössbauer spectra (MS) of blue, green and yellow beryl (ideally Be₃Al₂Si₆O₁₈) containing approximately 1% of iron were obtained at 295 and 500 K. Room temperature (RT) spectra of both blue and green samples showed the presence of an asymmetric Fe²⁺ doublet (ΔE _Q~2.7 mm/s, δ~1.1 mm/s), with a very broad low-velocity peak. There is no clear evidence for the presence of a ferric component. The MS of the yellow sample at RT consists of an intense central absorption with parameters typical for Fe³⁺ (ΔE _Q~0.4 mm/s, δ~0.29 mm/s), plus an apparently symmetrical Fe²⁺ doublet. This sample acquires a light-blue shade upon heating in air at about 620 K. Thermal treatments at high temperatures caused no significant changes in the MS, but the green and yellow beryl acquire a blue colour. All these results are interpreted in relation to the existence of channel water and the distribution of iron among the available crystallographic sites.  相似文献   

Construction Problems on the Karstified Limestone Tuffs of Condeixa, Central Portugal: A Case Study     

M. Quinta Ferreira  J. L. Velho 《Geotechnical and Geological Engineering》2006,24(1):101-116

During the excavations for the foundations of a three storey building on the limestone tuffs of Condeixa, Central Portugal, a large dissolution fissure and smaller dissolution voids were found. Since the area has never been the subject of engineering geology investigation, it was decided to evaluate the risk associated with the construction of the building. These limestone tuffs were formed in a continental environment by the precipitation of calcite carried by the water coming from the large limestone body in the east. The precipitated calcite mixed with the terrigenous materials and around trunks and leaves of plants, originating a very heterogeneous and porous ground, which is characteristic of limestone tuffs. The study started with a detailed geological survey followed by a large number of destructive drillings, located essentially under the pad foundations. The results revealed several karstic cavities with serious problems for the building foundations and the structure, and many smaller dissolution cavities, often filled with clayey soils. The ground treatment solutions used included, dental cleaning, filling with concrete or granular material the dissolution structures accessible at the level of the foundation, reinforcement of the footing and the structure of the building and adding a continuous foundation beam to hold the foundations together. The cost of the engineering geology study, site investigation, ground treatment, and the reinforcement of the foundation and building, increased the total construction cost from 2%, at the design stage, to 4.8%.  相似文献   

大吨位基桩抗压载荷试验中的锚桩预应力保护技术     

陈雅琴  张宏光  冯忠居  谢永利 《工程地质学报》2006,14(4):531-536

竖轴向承载力是桩基础设计的重要参数,现场静载试验是目前确定桩基承载力的主要手段之一。本文依托黄陵延安段高速公路洛河特大桥试桩工程,通过对原有工程桩施加预应力,形成了以工程桩为锚桩的锚拔体系。加载过程中试桩应力、锚桩应力及桩顶位移测试,结果表明,结合预应力技术,以工程桩作为锚桩构成桩基础静载试验的锚拔体系是可行的,同时提出了施加预应力大小的原则、方法以及确保后期曾作为锚桩的工程桩有足够承载能力应采取的必要措施。  相似文献