Soil-cement column wall with wall-strut to minimize ground movement for a road tunnel construction in Bangkok subsoils (original) (raw)
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Soil-Cement Wall without Bracing for Mat Foundation construction in Bangkok Sub-Soils
Construction of large mat foundations for a monumental building project in Bangkok sub-soils need to excavate for the depth of 5.7m. Because of the limited area of the site and relatively low shear strength of Bangkok soft clay, the earth retaining structure is needed to prevent failure of the soil around the mat foundation during the excavation. The selected retaining structure and supporting system must be stiff enough to prevent large soil movement which may cause damage to the unrestraint pile. The common practice in Bangkok area for earth retaining structure is steel sheet pile wall or cast in-situ reinforced concrete wall with steel temporary bracing. For this project, because the cost and time are limited; therefore, the soil-cement wall, SCW, without temporary bracing is used as a retaining structure instead of the conventional wall-bracing method. Due to limitation of well documented experience of the SCW construction in Bangkok sub-soils, the behavior of the wall is carefu...
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0.8m thick cast-in-situ diaphragm wall having toe depth of 28m with two level temporary bracing was used to construct the basements of a structure which is located near the river and surrounded by buildings, including a historical one in Bangkok, Thailand. Due to the site condition, unbalanced lateral loading on the wall was expected and an excavation down to -12.7m below the existing ground level was carried out with instrumentation, consisting of (8) inclinometer tubes installed in the wall panels, settlement plates around excavation zone and tiltmeters and beam sensors on the existing structures. This paper presents computer model analysis and performance of the wall including results of instrumentation. Behaviour and performance of the wall is compared with those of other projects in Bangkok area.
Journal of Structural Engineering and Geo-Techniques, 2012
With the growing population and density in metropolitan areas, higher tendency to live in high-rise buildings, and increasing demand for parking lots, it seems necessary to excavate soil to construct underground spaces. During excavation work, as the height of the wall increases, special care should be taken to the wall stabilization to avoid any consequent damage including extensive property damage or loss of life. Different methods such as performing steel or concrete pile, sheet piling, reciprocal anchorage, diaphragm wall, soil nailing, and soil anchorage can be utilized to stabilize excavation wall. As all of these methods have their own advantages and disadvantages, it is important to know the limitations and differences of each method. Besides providing more work space in the wall, using novel methods of stabilization may lead to considerable savings in cost and time. By examining the behavior of retaining structure and also predicting the value of wall displacement, resultin...
Construction of Diaphragm Wall Support Underground Car Park in Historical Area of Bangkok
Fifth International Conference on Case Histories in Geotechnical Engineering, New York, USA, 2004
Geotechnical aspects in construction of diaphragm-wall-support 2 level underground car park building, located in the historically and culturally significant area of Bangkok is presented in this paper. Results of the preliminary analyses showed that the deflection of the thin diaphragm wall of 0.60 m width would be large if it was to be fully cantilevered to fulfill the architectural and utility aspects of the car park structure. It was therefore decided to use buttress to minimize the diaphragm wall deflection. Performance of buttressed-support diaphragm wall is demonstrated based on the inclinometer monitoring results. Intensive modification of construction sequence in actual work execution with “value engineering options” different from tender stage design is demonstrated along with application of observational method.
Temporary support of excavation walls-case study
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Various methods of temporary stabilization of soil excavations are used to support the excavations wall. Soldier pile system and bored concrete piles are very versatile excavation retaining system for deep excavations in urban areas surrounded by major structures and infrastructures provided that limiting lateral displacements are not exceeded. In this study we have surveyed performance of various support systems that applied in excavations walls of entrance ramp of the Niayesh road tunnel project. These walls were supported by soldier pile system reinforced by soil nails and Bored Pile system reinforced by anchors and struts elements. The lateral deformations of walls were monitored parallel to the excavation progress from several target point on the surface of the wall. Some Finite Element models were developed to analyze performance of the walls. The analyses results were compared with monitored lateral deformations and performance and stability of each system were compared with other systems.
A Novel Approach to Use Soil-Cement Piles for Steel Sheet Pile Walls in Deep Excavations
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In recent years, owing to advances in technology, excavation pits have shown increased improvements. Taking advantage of advanced solutions combined with traditional ones has brought about considerable advantages for construction contractors and saves on expenses to carry out construction projects. Owing to their ability to analyze geotechnical problems, several calculation and simulation software, such as Plaxis, Bentley, along with many others, have grown in popularity. Among them, Midas is one such software, which is a set of solutions developed by the MIDAS IT company and is widely applied in many constructions. The authors evaluated the ability to use Midas software to calculate the stability of a wall in a deep excavation pit for the Ho Chi Minh City Water Environment Improvement Project. The results of these researches reveal that combining soil-cement piles and steel sheet piles decreases the internal forces in sheet steel pile walls. At the same time, this solution not only reduces horizontal displacement but also keeps the settlement of the soil around the excavation pit within the permissible range, which helps to ensure that the adjacent pavements are stable and will not crack. The results of this study can be applied to similar geological constructions.
Design of Anchored Diaphragm Wall for Deep Excavation
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High-rise buildings pose new challenges for engineers, especially in the field of calculations and design of above-ground structures, bases and foundations. Some consideration the anticipated responses to adjacent buildings during construction are presented. This will require the design professional to survey the condition of the adjacent properties to understand their present condition and fragility, establish acceptable limits, conduct soil-structure analyses of various support systems and develop limits on their respective movements, and develop a monitoring strategy. This paper shows the technology for support excavation structures as shoring system for 1000 mm thick diaphragm wall, which is supported with four layers of pre-stressed anchorages. The shoring system calculations had been designed by PLAXIS 2D, which can assess in very detail the deformations and settlements in the soil. The basement walls are a formed with reinforced concrete diaphragm wall panels, which are supported with ground anchors. The basement slab is to be a pile-supported raft, which is a made up of discrete sections to accommodate thermal and lateral movements. These numerical methods were a carried out within the investigation of the interaction of anchored diaphragm wall of high-rise buildings with soils in the problematic ground conditions of Astana. Recent advances in monitoring by using 3D laser-scanning technologies and acquiring quality information about built environments using embedded and other advanced sensors give to engineers a real picture of soilstructure interaction. This information is combined with the design model to create an integrated model, which is a dynamically updated during the construction period.
Stone Columns and Tensioned Anchors to Completely Eliminate Tunnels Trough Settlements
The complex tunnelling constructive environment in urban area in similar green field situations is faced through analytical evaluations in order to control the design calculation process and subsequently manage the interventions techniques with the aim of totally reducing the typical settlements trough above the tunnel either during the construction stage or during the serviceability stage. Recently, the author has proposed an operative and mathematical method by an opportune choice of tensioned anchors to control the tunnel lining settlements. In order to completely eliminate the remainder typical soft soil trough which is normal to the line of the tunnel, it is here proposed to use and properly calculate the interventions of stone columns by the SAVE (silent, advanced, vibration-erasing) Compozer method, in combination with the anchorages.