Published by the Japanese Geotechnical Society, Tokyo. Six issues per annum; circa 150 pages per issue. Current subscription: 9000 yen. ISSN 0038-0806.
Soils and Foundations is the international, English-language journal of the Japanese Geotechnical Society. In general, the journal tends to focus on the needs and interests of researchers rather than of practitioners. Most papers are concerned with soil properties and laboratory-based techniques, although dynamic problems, earthquakes and foundations are regular topics, and there is a steady interest in underground structures. Papers on site investigation appear relatively infrequently, and few papers deal with rock mechanics. The following brief selection from recent issues of Soils and Foundations summarises those papers that perhaps have an immediate practical relevance, rather than the more academically oriented papers.
Ground and pile-group responses due to tunnelling
N. Loganathan, H. G. Poulos and K. J. Xu
Soils and Foundations, 2001, 41, No. 1, 57–67
In urban areas, where many of the high-rise buildings are supported by pile foundations, the number of soft ground tunnels has increased rapidly during recent years. To minimise the risk of damage as a result of tunnel construction the engineer who designs a tunnel needs to be able to make reliable predictions of the ground deformations induced by tunnelling and their effects on any adjacent pile foundations. In this paper a closed-form solution, developed by the authors, is used to assess the displacement field around the tunnel. The displacements estimated are then imposed on single piles and pile groups in simplified boundary element analyses to compute pile and pile group responses. The analytical method presented in this paper was verified with a case history and with numerical results obtained using FLAC3D computer software. Comparisons are made to evaluate the group action for various pile group configurations. The influence of pile lengths and pile locations from the tunnel is also presented.
Estimating undrained shear strength of soft ground improved by pre-loading with PVD: case history in Bangkok
S. Shibuya and L. T. Hanh
Soils and Foundations, 2001, 41, No. 4, 95–101
The installation of prefabricated vertical drains (PVDs) combined with preloading is an efficient way to gain the prescribed strength and compressibility of very soft clay over a short period of time. This note describes case histories of such improvement performed in Bangkok. The change in undrained shear strength, su, before and after the ground improvement was investigated at two sites in the Bangkok area by means of field vane tests (FVT) and flat dilatometer tests (DMT). The FVT results showed that the su value of soft Bangkok clay increased over nearly the full depth down to the tip of the PVDs. It is also demonstrated that DMT may be a useful tool for promptly assessing the change of su in soft clay due to preloading. The applicability of the SHANSEP method in estimating the profile of su with depth in recently overconsolidated clay ground after preloading is also discussed.
Kinking deformation of PVD under consolidation settlement of surrounding clay
H. Aboshi, Y. Sutoh, T. Inoue and Y. Shimizu
Soils and Foundations, 2001, 41, No. 5, 25–32
Kinking deformation by buckling of a PVD (prefabricated vertical drain) due to consolidation settlement of the clay layer around it is discussed in this paper. A new testing device is manufactured for the purpose, and the deformation properties of two kinds of PVD during consolidation of the surrounding clay are compared. It is concluded that a fibre drain made only of natural fibres can sustain vertical permeability during a settlement strain of up to 24%, whereas a PVD made of plastic loses its permeability at 19% strain. The field performance of both materials is also referred to.
Back analysis of reclamation by pump-dredged marine clay: influence of groundwater lowering
M. Katagiri, M. Terashi and A. Kaneko
Soils and Foundations, 2001, 41, No. 5, 73–86
When pump-dredged clays are discharged into a pond, suspended soil particles settle loosely to create sediments, which subsequently consolidate owing to their own weight over a long period of time. In planning the capacity of such a disposal pond, it is important to estimate the time-dependent volume change of dredged clays during the reclamation process. As the land thus created is extremely soft, ground improvement work is necessary if there is a plan to utilise the land further. It is essential to predict the soil profile of reclaimed land for designing the ground improvement. In this paper the authors (a) outline the 18-year reclamation history of the Kanda Disposal Pond, (b) introduce a program to analyse the self-weight consolidation under fully submerged conditions, (c) modify the program to represent the suction effect due to groundwater lowering, and (d) verify the applicability of the modified program by comparing the calculated results with the measured data. A simple analysis under fully submerged conditions cannot explain the record of an 18-year reclamation, even if various combinations of consolidation parameters are used. The code modified to include the suction effect successfully simulates the actual behaviour when the appropriate parameters concerning the suction are chosen.
