Based on the basic characteristics of the landslide,its formation mechanism and the stability were studied and analyzed.The research showed that the topography and the material composition were geological conditions of the landslide,and the recent abundant rainfall was a primary induction factor of the traction-type landslide.Furthermore,the landslide was critically stable under the natural conditions.But if there were unstable conditions,the landslide would happen again.It was emergent to take measures of prevention to strengthen the drainages,and build retaining wall on foreland of the landslide so as to enhance monitoring.
Calcium sulfoaluminate cement (CSA) was used to stabilize a type of marine soft soil in Dalian China. Unconfined compressive strength (UCS) of CSA-stabilized soil was tested and compared to ordinary Portland cement (OPC); meanwhile the influence of amounts of gypsum in CSA and cement contents in stabilized soils on the strength of stabilized soils were investigated. X-ray diffraction (XRD) tests were employed to detect generated hydration products, and scanning electron microscopy (SEM) was conducted to analyze microstructures of CSA-stabilized soils. The results showed that UCS of CSA-stabilized soils at 1, 3, and 28 d firstly increased and then decreased with contents of gypsum increasing from 0 to 40 wt.%, and CSA-stabilized soils exhibited the highest UCS when the content of gypsum equaled 25 wt.%. When the mixing amounts of OPC and CSA were the same, CSA-stabilized soils had a significantly higher early strength (1 and 3 d) than OPC. For CSA-stabilized soil with 0 wt.% gypsum, monosulfate (AFm) was detected as a major hydration product. As for CSA-stabilized soil with certain amounts of gypsum, the intensity of ettringite (Aft) was significantly higher than that in the sample hydrating without gypsum, but a tiny peak of AFm also could be detected in the sample with 15 wt.% gypsum at 28 d. Additionally, the intensity of AFt increased with the contents of gypsum increasing from 0 to 25 wt.%. When contents of gypsum increased from 25 to 40 wt.%, the intensity of AFt tended to decrease slightly, and residual gypsum could be detected in the sample with 40 wt.% gypsum at 28 d. In the microstructure of OPC-stabilized soils, hexagonal plate-shaped calcium hydroxide (CH) constituted skeleton structures, and clusters of hydrated calcium silicates (C-S-H) gel adhered to particles of soils. In the microstructure of CSA-stabilized soils, AFt constituted skeleton structures, and the crystalline sizes of ettringite increased with contents of gypsum increasing; meanwhile, clusters of the aluminum hydroxide (AH3) phase could be observed to adhere to particles of soils and strengthen the interaction.
In this paper,commonly used methods for landslide prediction,especially the time prediction method,for landslides are discussed.The problems existing in the current slide prediction studies were pointed out and the development trends of landslide prediction research were forecasted.
The sea water intrusion has water-rock interactionprocess and spatial variability of geological parameters, which makes it difficult to calculate the intrusion process. The paper proposed a method combining GIS and 3D finite element method to simulate and analyze the sea water invasion process. The GIS is developed using database and component techniques, improving the data organization efficency. 3D finite element model adopts proper parameters from multi layers of GIS, decrease the error of the parameters selection. The dynamic seepage-diffusion coupling mechanism is also considered in the study. The seawater intrusion in NanGuanling region of Dalian City has been studied by the method. The calculation results of both flow and chlorine ion distribution field are all coincidence with actual observation well information. That stated the simulation method is feasible. The numerical simulation of next three years is also carried out and it showed that the seawater encroachment area will decrease. That means the amount of exploited groundwater in the past years is reasonable. The conclusion has active supervise meaning to prevention and cure of seawater encroachment in the area.
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