Numerical Analyses of Piled Raft Foundation in Soft Soil Using 3D-FEM
ABSTRACT: In recent years, the piled raft foundation has been widely accepted as one of the most economical methods of foundation systems. To evaluate the possibility of implementing this system in a very soft ground condition, this research performed the numerical analyses of the piled raft and pile group foundation systems for low-rise (8-storey) and high-rise (25-storey) buildings with 1-2 basement levels in subsoil conditions of the central part of Thailand, using three-dimensional Finite Element Method. The soils are modelled with Hardening Soil model and Mohr-Coulomb model. Evaluations of the performances of piled raft foundation, i.e., the load sharing ratio of piles, settlement behaviors in both the foundation system and the raft are discussed in comparison with those of the pile group. With limited cases considered and assumptions in this study, the results suggest the potential of using the piled raft system for low-rise building having 2 levels of basement. With this condition, the raft can carry some bearing capacity from pile around 20%. However, the safety factor of piles in the foundation design seems to play a key role on the effectiveness of the piled raft foundation as well and should be further studied.
EXPERIMENTAL AND NUMERICAL STUDIES ON PUSH-UP LOAD TESTS FOR SAND PLUGS IN A STEEL PIPE PILE
This paper focuses on the bearing capacity of soil plugs (internal shaft resistance) though fundamental research on the bearing mechanism of dry silica sand plugs. Push-up load tests on the dry silica sand plugs inside a model pipe pile and DEM simulations were carried out to investigate the plugging behavior. The influences of the packing state of the soil plugs (the relative density), and the height of the plugs on the bearing capacity were investigated. Prior to the push-up load tests, element tests on the silica sand and DEM analyses were performed to characterize the silica sand and to determine suitable DEM analysis parameters. The experimental and DEM results clearly show that the push-up force increases sigmificantly with the increase in the aspect ration of the soil plug, H/D, and with the relative density of the soil plug. The DEM analyses show a good agreement with the experimental results when the push-up force is small. Furthermore, the DEM results reveal that only density of the soil plug in the lower portion, adjacent to the pile tip, increases gradually with the increase in the push-up displacement as well as the increase in H/D. Hence, it is the lower portion of the soil plug that mainly controls the capacity of the soil plug.
APPROXIMATE NUMBERICAL ANALYSIS OF A LARGE PILED RAFT FOUNDATION
An approximate method of analysis has been developed to estimate the settlement and load distribution of large piled raft foundations. In the method the raft is modelled as a thin plate, and the piles and the soil are treated as inter-active springs. Both the resistances of the piles as well as the raft base are incorporated into the model. Pile-soil-pile interaction, pile-soil-raft interaction and raft-soil-raft interaction are taken into account based on Mindlin’s solutions. The proposed method makes it possible to solve problems of large non-uniformly arranged piled rafts in a time-saving way using a PC. The method can also be used for cialis en france the deformation analysis of pile groups be setting the soil resistance at the raft base equal to zero. The validity of the proposed method is verified through comparisons with existing solutions. Two case studies on settlement analyses of a free-standing pile group and a large piled raft are presented. In the analyses, applicability of the equivalent pier concept is also examined and discussed. The computed settlements compare favorably with the field measurements
Geotechnical Instrumentation for tunnel and underground excavation: MRT Blue Line Extension Project
“The MRT Blue Line Extension is a 27 kilometers underground and elevated heavy rail transit system with 4 underground stations and 17 elevated stations situated along the route, 3 intervention shafts, a depot with operation control center and 1 park and ride.” อ่าน “Geotechnical Instrumentation for tunnel and underground excavation: MRT Blue Line Extension Project” โดย คุณสุวัฒน์ ศรีวงษ์ และ ดร.อรรถกิจ อาสาฬห์ประกิต (GFE) ในเอกสารประกอบงานแสดงเทคโนโลยีและการประชุมวิศวกรรมปฐพีแห่งชาติ ครั้งที่ 1 วันที่ 16-17 ตุลาคม 2557 ณ โรงแรมสุโกศล หน้า 36-46
Design and construction of flood protection system for Bangpa-in industrial estate
“Design and construction of flood protection system for Bangpa-in industrial estate” โดยดร.ธีระวุฒิ เจือณรงค์ฤทธิ์ คุณอำนาจ ยานุวิริยะกุล, คุณวีรยุทธ โกมลวิลาศ ทีมกรุ๊ป เอกสารประกอบงานสัมมนา 2013 TCDPAP & FIDIC/ASPAC Conference Bangkok หน้า 69-80.
Comparisons of rapid load test, dynamic load test and static load test on driven piles
ABSTRACT: Static load test (SLT) is usually used to obtain the bearing characteristics of a pile. However, it requires relatively high cost and testing period. In contrast, rapid load testing requires less cost and testing period. As one of rapid load test methods, Spring Hammer (SH, hereafter) rapid load test method has been developed in Japan. In this paper, validity of the SH test method with a simplified signal interpretation to estimate the static behaviour of a pile is discussed and demonstrated through comparison of the results from SLT and the SH test, as well as the results from dynamic load test (DLT).
Diversion Tunnel Concrete Plug Implementation Aspects Associated with Reservoir Impounding of NN2 Hydro Electric Project, Laos
Nam Ngum 2 Hydroelectric Power Project with 181 m high concrete faced rock fill dam (CFRD) and 615 MW installed capacity located about 90 km from the Vientiane has been fully commissioned since March 2011(see the general site layout of the project in Figure1).