Dynamic pile-soil-pile interaction. Part I: analysis of axial vibration

252A flexibility and slenderness. Dynamic stiffness and damping of several pile groups are assessed. Promising agreement is seen with rigorous solutions. Effects of soil inhomogeneity and pile group configuration are considered parametrically. 914418 Liquefaction and flow failure during seismic exploration Hryciw, R D: Vitton. S; Thomann. T G J Geotech Engng Div ASCE VII6, NI2. Dec 1990. P18811899 Failure of a road embankment in Michigan occurred by liquefaction triggered by seismic signals generated by vibratory tampers for a deep reflection study. Construction records were examined, laboratory and field tests carried out, and input ground motions simulated to calculate shearing stresses and cyclic stress ratios. The loose, cohesionless, hydraulic fill experienced maximum shear strain of 0.055%, in excess of known threshold value for generation of excess pore pressure. Estimated conditions of c~clic stress and shear strength indicate likelihood of liquefaction. Estimated residual strength of the soil mass was 8-12 kPa. 914419 Seismic risk analysis for earth dams Yegian, M K; Marciano, E A; Ghahraman, V G J Geotech Engng Die ASCE I"117. NI. Jan 1991, P18-34 A seismic risk analysis procedure in three steps is presented. Firstly, futurc occurrence of earthquakes is probabilistically described in terms ot" intensity and number of cycles and ground motion. A probabilistic assessment of permanent deformation of the dam is also carried out, characterising the seismic cvcnt in terms of acceleration, number of cycles, and predominant period of motion. The seismic hazard and seismic performance arc then combined to give the risk of seismic damage or fuilurc. A case study is illustrated. These risk based analyses arc useful at design and decision making stages, and l\~r avoiding compounding of conservatism. 91 44 20 Earthquake-induced permanent deformations: probabilistic approach Ycgian, M K: Marciano, E A: Ghahraman, V G J Geotech Engng Diz, ASCE Vl17. N1, Jan 1991, P35-50 A simple procedure is presented for estimating permanent deforn~ations of earth structures due to seismic events. It is based on computed permanent deformations obtained by Newmark's sliding block theory and recorded acceleration time histories. Earthquake magnitude is handled using equivalent uniform cycles of motion, uncertainties in model and parameters by modelling error theory. Normalised plots and a computer program (NIMPED) provide the probability that permanent deformation will exceed a specified value. Results are expressed in terms of damage probabilities in the form of a seismic performance analysis. 914421 Distinct element analysis of dry rock avalanches Uchida, Y: Hakuno, M Struct Engng Earthq Engng VT. N2, Oct 1990, P85-96 The DEM was designed to solve problems where continuity cannot by guaranteed. The method is outlined, then applied to study the type of dry rock avalanche which often accompanies strong earthquakes. First the effect of shaking on the size distribution in the cross section is modelled, then flow down ~

smooth and rough slopes. Results indicate that the largest pieces of rock will float to the surface of the flow and become concentrated at the front. 914422 Effect of spatial randomness of response characteristics on seismic stability of earth dams Hirata, K; Shinozuka, M Struct Engng Earthq Engng V7, N2. Oct 1990, P195-204 A method is presented for stochastic analysis of effects of spatial randomness of earth dams on their seismic stability. Spatial distribution of expected maximum shear strain in horizontal and transverse cross sections and distribution of local safety factors in both cross sections are determined. Spatial variations of dam material and geometry and randomness of the earthquake motion are taken into account. Effects are significant for the case examined of a triangular dam in a narrow, steep wailed valley. 914423 Method of estimating the seismicity of an artificial watersaturated soil base by finite element investigations llichev, V A; Likhovtsev, V M; Kurdryuk, A Y Soil Mech Found Engng 1/27, NI, Jan-Feb 1990, PI-5 In many urban areas of high seismicity, it is necessary to use foundations on man-made (stabilised) soil bases. These areas have different physicomechanical properties to the surrounding soil masses, and boundaries between the zones can act as viscous dampers to seismic wave propagation and partially isolate the surface structures. Finite element analysis of this situation is presented. Effects of groundwater level on the earthquake resistance of the artificial base are analysed. High water table has adverse effects on seismic response, and artificial drainage is suggested. 914424 Investigation of resistance of soil base to horizontal vibrations of piles Shaevich, V M Soil Mech Found Engng V27, N2, March-April 1990. P66-72 Piles at 3 sites in type 1 collapsible soils were subject to horizontal vibrations at the pile head. Amplitude frequency characteristics of the different pile types are presented and their non-correspondence is considered. A simplified analytical treatment of piles subject to horizontal dynamic loading is derived and results are discussed considering the potential of using results of the field tests in the determination of soil properties. 914425 Direct prediction technique for discontinuities in piles van Staalduinen, P C; Bielefeld, M W; Middendorp, P Proc 2nd International Conference on Foundations and

Tunnels, London, 19-21 September 1989 VI, P303-306. Publ Edinburgh." Engineering Technics Press. 1989 Sonic integrity testing, using reflections of waves from impact of a hand-held hammer on the pile head, is used to detect discontinuities in piles. The analytical technique for quantitative prediction of results, Signal Matching, is time consuming and unreliable for multiple discontinuities. An improved analytical technique, Direct Interpretation, based on the wave equation TNOWAVE, is under development to overcome these problems. First results are presented.

1991 Pergamon Press plc. Reproduction not permitted