Wetting-Induced Compression of Compacted Oklahoma Soils

The wetting-induced compression of compacted Oklahoma soils was investigated. One-dimensional oedometer tests were conducted on 22 Oklahoma soils that encompassed relative compaction and moisture contents within typical embankment specifications. Results show that factors directly related to the fines composition can be used for preliminary estimation of collapse potential. Statistical analysis of the oedometer test data indicates that variables having the most impact on collapse index were compaction moisture content, dry unit weight, plasticity index, and clay-size fraction. Charts were developed to facilitate the estimation of collapse settlement of fills for different conditions, including fill height, moisture content, and soil type. Three case histories involving embankments that experienced significant settlement are presented for comparison. The comparison shows a reasonable agreement between predictions and field estimates of collapse settlement at the embankment centerlines; the limited evidence suggests that predictions based on one-dimensional assumptions may underestimate actual settlements possibly due to the two-dimensional nature of embankments.     

In Situ Pore Pressure Responses of Native Peat and Soil under Train Load: A Case Study

Settlement and formation of piping holes on surfaces were observed along a rail embankment subject to normal traffic load. Piezometers were installed in the native peat and soil underneath the embankment inside and outside problematic area to measure the pore pressure responses during train traffic. Peculiar pore pressure responses were observed. Cyclic pore pressures were only measured during the first 60–80?s of the 6-min train passage, and thereafter the pressures decayed rapidly to the initial values. The pore pressure changes in the shallow peat layer were lower than those in the deep soil layer. Possible mechanisms causing such peculiar pore pressure responses, surface settlement, and piping holes were explored and identified. It was found that the stiffness contrast between the stiff, upper granular fill and the soft, native peat material could lead to a redistribution of tensile stress in the granular fill layer to the peat layer due to the moving train load. This stress redistribution promotes the propensity of vertical piping in the peat layer.     

机械式锯槽机成槽建墙施工技术在长江同马大堤加固工程中的应用

1998年“三江”大水过后,国家加大了对长江堤防治理的力度,我局利用自己研制的机械式锯槽机在堤防加固锯槽成墙方面的先进技术。成功地进入了长江市场。在施工过程中,我局以先进的技术,科学的管理,精心的施工,在第一期三个标段中首家保质保量完成了施工任务。工程竣工验收被评为“优质”工程。     

浅析城市特色空间对城市发展的积极作用——以苏州三条特色商业街为例

通过对苏州的平江路、山塘街及李公堤三条特色商业街的调研分析,认为城市特色空间能够完善城市功能、突出城市特色、延续城市历史、繁荣城市经济、弘扬城市文化以及塑造城市品牌。进而从三条街的规划、建设及管理经验出发,得出了针对城市特色空间塑造的相关启示。     

欧美国家近期溃坝研究及发展动向

在现代化的水利水电工程建设中,其水库和大坝安全以及溃坝是建设者、管理者和各级政府十分关心的重要方面,随着科学技术的进步、社会经济的发展以及人民生活水平的提高,对溃坝的研究以及安全管理对策也在不断地发生变化.在经过了20世纪60年代的溃坝研究高潮后,20世纪90年代末期,欧美国家又掀起了一轮新的溃坝研究高峰.介绍欧美国家近期溃坝研究的新动向,包括美国国家大坝安全计划以及美国土石坝溃坝洪水研究项目、欧共体历经二期6年的溃坝洪水研究项目、国际大坝委员会结合溃坝洪水研究的进展编写的技术公报,概括归纳目前国外在溃坝研究上的重点、研究方法和阶段成果,以及欧美国家关于溃坝研究的发展动向.     

Monitoring and analysis of settlement and stability of an embankment dam constructed in stages on soft ground

 This study is concerned with Karameh dam, an earth-fill dam constructed on soft ground. It is located on Wadi Mallaha adjacent to the Jordan River on the eastern side of the Jordan Rift Valley. The project involved 11.2 million m³ of zoned earth fill, about 6 million m³ of excavation, a spillway and draw-off structures. The total height of the dam is 45 m and the total capacity of the reservoir 55 million m³. The construction of the dam on soft ground generated positive excess pore-water pressures within the underlying foundation soils. The dam was constructed in stages to achieve the required level of safety and to monitor/control the settlement development. The study reported here involved analysis, assessment and interpretation of the geological, geotechnical and monitoring data obtained during the staged construction of the Karameh embankment dam. Available soil mechanics models related to 1-D, 2-D and 3-D consolidation theory, undrained settlement, stress history and normalised soil engineering properties were used in the study. The overall stability of the Karameh dam embankment and foundations was evaluated using effective stress analysis (ESA) and total stress analysis (TSA) methods. Received: 5 July 1999 · Accepted: 15 April 2000     

高填方地基沉降离心模型试验研究

以西南地区某机场为工程背景,用离心模型试验研究高填方地基的沉降变形特征。试验结果表明,高填方地基填筑体的沉降变形特征为＂沉降小,压实快＂,沉降主要发生在施工期,工后期的沉降约为总沉降的10%左右。     

Construction of an offshore dike using slurry filled geotextile mats

A study on the use of clay slurry filled geotextile mats to construct dikes for land reclamation at Tianjin Port, China, is presented in this paper. The dike so formed was covered by a thin layer of grouted geotextile mattress for protection. Through laboratory tests, a type of low plasticity clay was chosen to be the fill for the mats. A simple method for estimating the required tensile strength for the geotextile mat and the height of the mat was proposed. A preliminary design for the dike was made. Numerical analysis and centrifuge model tests were conducted to verify the design and assess the stability of the dike before construction. A field trial was also carried out in which a 100 m long and 4.8 m high dike was constructed on soft seabed. The dike has been stable and the settlement has been within the expected limit since the construction was completed in September 2001.     

库水位升降作用下填土岸坡稳定性的分析

库水位升降是诱发库岸滑坡的重要因素之一。将渗流场有限元计算与极限平衡分析结合起来,针对潘口库区水位升降对鳌鱼沟填土岸坡稳定性的影响进行分析。结果表明:该岸坡的安全系数随库水位的升降均呈现先减小后增大的变化规律,岸坡变形加剧主要可能发生在蓄水、泄水的初期,但水位升降过程中该岸坡仍将处于稳定状态。