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41.
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
42.
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
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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
45.
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
46.
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
47.
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通过对邯郸市某车间地基的勘察.分析和探讨了新近沉积粉细砂地层的勘察手段、其物理力学性质,及其利用载荷试验确定承载力的标准取得了较为满意的结果,提出的一些分析方法,对新近沉积的粉细砂地层的勘察具有一定的借鉴作用。 相似文献
49.
Ahmad Shlash Alawneh Osama K. Nusier Ahmed Abdul-Ezel Al-Mufty 《Geotechnical and Geological Engineering》2006,24(3):637-660
A reliability based method was used to design and analyse shallow foundations using first-order Taylor series approximation.
The computer program Mathcad was used to facilitate all mathematical and computional efforts. This method is an effective
tool to assist the foundation designers and analyists to investigate how reliable their designs or analyses are in relation
to the ultimate bearing capacity of the foundations. The approach presented in this paper provides a reliable alternative
for design and analysis of shallow foundations, rather than the conventional design methods, which employs the assumptions
of a specified saftey factor. Several examples were presented for design and analysis of strip footings embedded in sandy
soil, and rectangular and square footings analysis embedded in clayey soils. The program input and output of each example
are also presented and discussed. 相似文献
50.