The engineering background, including the geological and hydrogeological characteristics of Beijing’s six metrolines, the construction of which were all commenced in 2007, has been extensively studied. The possible geotechnical risks arisen from the construction phase and service stage of these metro lines were evaluated, i.e. ground subsidence along the lines, the occurrace of excessive uplift forces acting on the the structures because of unexpected changes in the groundwater level，seepage failure, earthquake impact from near-site faults, ground liquefaction and structure erosion by the groundwater and soil. Potential geoenvironmental influences from the construction of the new lines were also investigated, such as gound settlements induced by excavation and dewatering, he waste of water resources from dewatering, the damming effect of tunnels on the ground water flow, and water contamination. Based on the above studies, a geotechnical risk evaluation and management system has been developed for the new lines using GIS and 3D techniques.
The Batutegi reservoir was constructed on the Way Sekampung River in Lampung Province in southern Sumatra Island, Indonesia, it belongs to the Way Sekampung irrigation porject. The main purpose of the reservoir is to store water for irrigation and multi-purpose uses. The construction of dam was commenced in 1996, and the impounding of the reservoir was commenced in August 2001. The Batutegi Dam is a 122m high earth core rockfill dam. Instruments were installed in and on the dam body to monitor the performance of the dam during the construction and operation of the reservoir. The monitoring data collected show that the dam displayed typical behavior of a large scale embankment dam. Based on these data, it has been confirmed that the initial impoundment was carried out safely and the performance of the Batutegi Dam is satisfactory.
The Socialist Republic of Vietnam opened the door for renovation in 1986. Due to the cheap cost of labor, many foreign enterprises have invested in Vietnam, particularly, in HoChiMinh City and capital Hanoi. The engineering properties of soil in these two cities are basically similar and have been classified in marsh sedimentary formation which consists of rotten remnants and possesses the characteristics of high water content, sensitivity and compressibility. This paper gives soil improvements applied in road embankment and high embankment in abutment. To avoid the soil lateral movement pushing the abutment structure, the correct construction sequence in the vicinity of abutment is that the high embankment shall complete prior to abutment structure including piles installation. In general, the soil replacement method is suggested in the embankment of 3m or less in height and sand drain improvement is applied when the embankment height is more than 3m.
Based on the key technology analysis on the design and construction of SMW method in Nanjing Metro project, this paper points out that the SMW method may well be applied to deep and big foundation pit projects. The use of SMW method has universal significance on metro station built in soft and weak soil layers with high water content, especially for projects with excavation depth exceeding 15m.
The Application of PVDs on Bangkok Clay－Case Studies
曼谷黏土(Bangkok Clay)以其高塑性、高含水量及低強度的特性而聞名，也是在進行公共建設包括道路、機場、房屋建築等工程項目必須面對的難題。本文主要討論垂直排水帶(prefabricated vertical drains or PVDs)應用於泰國第一條跨省際的高速公路:曼谷-春武里高速公路(Bangkok-Chonburi New Motorway)及新近完工啟用的曼谷新國際機場(Suvarnabhumi Airport)中的地質改良工程設計及施工成效進行評估。在打設排水帶後進行的預壓荷重除了一般傳統的土堤外，在新機場第三跑道新建工程中並採用了真空預壓的方式進行地質改良，同時利用現場佈設之監測儀器量測紀錄改良後地盤沉陷狀況，以評估不同改良方式之成效。
Bangkok Clay is known for its high plasticity, high water content and low shear strength. It is also an inevitable issue which the engineers have to deal with for infrastructure construction projects such as roadway, airport and buildings built on Bangkok Clay. This paper introduces the application of prefabricated vertical drains (PVD) in the Bangkok-Chonburi New Motorway and the Suvarnabhumi Airport construction projects. In addition to the application of preloading followed by the installation of PVDs usually used in conventional embankment, the vacuum pumping preloading method was also used for the third runway construction of this new airport. The effectiveness of various ground improvement methods was evaluated based on the ground settlement records that had been measured carefully by the monitoring instruments in the field.
In this paper, the processes of tender preparation, planning, design and construction of the gas pipeline tunnel project beneath the Yangtze River for the West-to-East Gas Transmission Project are discussed. This project is the first tunnel cross the Yangtze River and is build under the Turn-Key contract by CTCI Corporation of Taiwan. Because the different consideration of engineers from two sides across the Taiwan Strait, different sorts of issues are brought out during the processes, including the bids procedure, the planning considerations, the design standards, the design review system and the construction process.
The compositive techniques on shallow imbedded tunnel in new line of Beijing subway constructed beneath existing subway are introduced. These techniques contain, the status investigation and evaluation of existing subway, the confirmation of deformation control standard of existing subway, the influence prediction of new subway construction on existing subway, the optimization of construction scheme and the selection of assistant construction, the decomposition of control standard and stage control, the long-distance real time monitoring of the dynamic change of existing subway, the handling of uncommon conditions, etc. After these techniques were studied and used, the new subway was successfully constructed with the existing subway in proper safe operation.
This study presents the surcharge preloading practice with prefabricated vertical drains on soft ground at a swamp area in Vietnam. On the high compressibility of soft soils, this paper addresses the design considerations and construction procedures of the preloading method. Meanwhile, through the long-term monitoring results, the field effectiveness including progressive settlements and slope stability is discussed. The changes of soil properties after preloading are also assessed. Based on the long-term monitoring results, the high groundwater level rising during raining season governs the preloading effectiveness on the soft ground in a swamp area. The settlement-induced problems and solutions in the field are summarized for reference.
For the development of coastal site in Fujian, the geotechnical engineering experiences on site investigation, consideration of pile foundation design, measurements of settlement of backfill , evaluation of preliminary ultimate pile load test, supervision and inspection of working pile construction are presented in this paper. The procedures and panel review on the results of site investigation and the change order of foundation design revised based on pile load tests and inspection are also discussed. Besides, the comparison on codes of geotechnical investigation between Taiwan and Mainland China are summarized.
The Wenchuan Earthquake of Ms 8.0 taken place in Sichuan, China is characterized by its extensive surface fault rupture, long duration time, shallow depth of hypocenter and more than 60000 casualties. Being one of these faults located within Longmen Shan thrust belt, the Beichuan fault gave rise to the Wenchuan Earthquake. Both Wenchuan Earthquake in China and Chichi Earthquake in Taiwan occurred in the leading deformation front of two active collisional plate boundaries. Similarities of the geological and geomorphological background between the Wenchuan Earthquake and the Chichi Earthquake promote the discussion of the geotechnical related issues by comparing these two cases in this article. Location of Beichuan fault in Longmen Shan thrust belt could be regarded as the Shuilikeng-Chenyulan Fault in central Taiwan, where might have the potential of reactivation. In the near future, the hazardous scenarios such as massive landslides, debris flows experienced in the Chenyulan stream area in Taiwan could also happen in Sichuan, China where had been heavily struck by Wenchuan Earthquake. The settlement ratio of Bi-kou Dam in China is similan to Li-yu-tan Dam in Taiwan, both are matching the calculation results by the Seed-Lee-Idriss method. The arising speed of water table in Tang-jia-shan dam-up lake estimated from CSRSR remote sensing images and SRTM data resemble that provided by the Ministry of Water Conservancy, China. Even though the earthquake prediction is still a challenge, based on the experience by analyzing Wenchuan Earthquake and Chichi Earthquake and their consequence on the humanity, the features of active faults and related seismic hazards can be properly evaluated. Once the active faults are found located near the urban area, it is important and urgent to establish appropriate emergency response and evacuation plans, as well as the mitigation design after disasters, in order to validly prevent damage and reduce loss.