Shallow landslides in nearly saturated uncohesive to slightly cohesive soils are triggered by high intensity, short duration rainfall which infiltrates into soil and changes intergranular friction and effective stresses. For this, the especially developed Soil-Water Interaction Modelling System (SWIMS) was used with CL-ML type soils. For simplicity, rainfall intensity and duration were kept constant. Results showed that (1) All 35°slopes were failed by translational failure. For the other (15°, 25°) slopes, no failures were observed; (2) For all slopes, FOS increased with increasing compaction degree and decreased with increasing slope angle; (3) Other parameters, such as soil density, porosity, saturation degree, water contents, and water permeability may also affect shear strength/slope stability, especially for low degrees of saturation (S < 95%), compared to high degrees of saturation (S =, > 95%). (4) A correlation of SWIMS tests observed that average wetting band depths (h obser ), with the calculated wetting band depths from the Lump Equation (h LE ), were poor, as h obser values were much higher than h LE values. Differences increased for very low degrees of saturation (S), compared to S > 95%. This meant that the Lump equation underestimated wetting band depths. Further, if the Lump equation is still considered valid, this would imply either water-permeability increases, porosity decreases or both occur towards full saturation; a process where the last possibility is the most probable occurrence.

Soil suction is one of the most important parameters for describing the moisture condition and engineering behavior of unsaturated soils. Therefore, changes in suction behavior of soils in the presence of saline waters are important for engineered barriers. The aim of this study was to determine the change in suction and swelling behavior of soils, which were exposed to salt solutions (NaCl, CaCl 2 , natural seawater) with respect to distilled water. The three soil samples were gathered with different mineralogy and plasticity characteristics and tested for determining matric and total suction values and for obtaining free swelling characteristics in the presence of salt solutions. The bentonitic soil sample had the highest total suction value in the presence of seawater. Kaolinitic and zeolitic soil samples had the highest total suction values in the presence of NaCl solution. The highest modified free swell index value of the samples was obtained in the presence of NaCl solution for all the soil samples. No relationship was found between the total suction, matric suction and the modified free swell index value of the tested soils.

The increasing number of cut slopes in Hong Kong, its rugged topography, high population density and scarcity of land, in addition to the complex nature of the weathered rock masses and adverse climatic conditions, inevitably magnify the potential for cut slope failures. With the extension of residential and infrastructural development into the New Territories in Hong Kong, a large number of slopes are cut in weathered pro®les derived from metasedimentary rocks. This paper reviews the engineering properties of the saprolitic soils in these pro®les, presents case studies of the ®eld performance of cut slopes, analyses possible mechanisms of instability and provides recommendations on the current local practice of remedial measures.

Design and construction of high-speed train railway (HSTR) infrastructure is different from that for normal trains, since high geometric standards and material properties are involved. For example, HSTR embankments are designed to limit total-differential settlements to minute amounts. In this study, a typical 'slab-track' type HSTR embankment was used to investigate the replaceability of one fill strata known as 'uncemented-prepared-subgrade layer' (U-PSL), constructed by using a locally obtained medium sand, as opposed to various 'cemented-prepared-subgrade layers' (C-PSL), whose mixes were prepared at two waterto-cement (w/c) ratios and three cement contents (c). Three size cylindrical samples were cast, 7-28 days water cured and were tested to obtain the unconfined compressive stresses, strains, elasticity moduli and Poisson's ratios at failure. Test results were then fed into the Plaxis-FEM program to find the maximum total settlements of individual layers and compared with the requirements. Only three C-PSL mixes having cement contents (c) of 20, 25, 30 % and water-to-cement (w/c) ratios of 0.4 and 0.5 met the strict settlement criteria. The study showed that the original (h = 2 m) thick U-PSL can be replaced with 0.3h-m thick C-PSL at w/c = 0.5 (i.e. h = 0.6 m). Likewise, the original (h = 2 m) thick U-PSL can be replaced with 0.2h-m thick C-PSL at w/c = 0.4 (i.e. h = 0.4 m). Also, the extra effort of doing in situ soil compaction and testing in layers is reduced or eliminated. This would give not only alternative ways to HSTR embankment designers/constructors, but also substantial savings in construction time and costs.

The original design of the planned Izmir Bay Immersed Tube Tunnel, considered it to be a continuous subsea tunnel for the whole length of about 7.6 km. But this was later changed into having 2 shorter tubes of 2.7 km long each connected thru' a 2.2 km long artificial island created in the middle of the bay from the excess dredged material, a concept which also reduces costs and increases efficiency. This island will serve as a venue for the 2025 Expo Exhibition, which Izmir city will apply to organize in the future. Reason for the research study was to provide a preliminary design, using a dynamic analysis, during the current pre-feasibility stage, of the immersed tunnel to show whether it can be built across the Izmir Bay. This paper takes into account the new alignment and presents the results of a 2-D dynamic analysis conducted of the prefabricated 100m long tunnel elements, sitting within a backfilled dredged ditch, dug after the recommended ground improvement was carried out. Analyses considered staged construction and the results showed that: Tunnel units and its surrounding soils inside the dredged ditch act together to provide a better earthquake response with a damping effect of the earthquake force; Tunnel units do not float to the sea surface, but continued to stay inside the dredged ditch and applied positive stresses to the foundations during the design earthquakes. As there was no floating, there was no need for anchoring the tunnel to ditch bottom; Tunnel units and immersion joints (made of specified strong elastomer material) continued to stay in compression longitudinally and provided a superb water-tightness level; There were no risky (un-tolerable) ground deformations during, after striking of the design earthquakes. Total vertical and differential displacements of the tunnel units and in the surrounding soils were all at acceptable levels; Concrete surface crack widths occurring in the tunnel units, during striking of the design earthquakes were also found to be allowable. Study results show that the tunnel elements can withstand Mw=7 short duration (<10 sec) or Mw=6 long duration (>10 sec) earthquakes without major damages to their structure.