Advanced Materials Research Vols. 261-263

Abstract: A series of model tests were performed on dredged clay with high initial water contents for investigating the dewatering behavior by ventilating vacuum method (VVM). The results shows that the surface water separated from dredged clay can be quickly removed by VVM in which a new pattern PVD is used. In addition, the method also speeds up the deposition of dredged clay. The volume of dredged clay with an initial water content of 4.5 times liquid limit decreases by 50 percent within two months. This paper also investigated the spatial distribution law of water content by TDR method. It is found that the drainage distance of PVD is about 0.3-0.4m.

Abstract: The combined influence of the earthquakes and the widespread red-bed soft rock as fill material necessitates the increasing attention on the slope stability in the west region of Yunnan province. To determine the critical height of slope filled by such soft rock under seismic loading, this paper establishes a model simulating a fill slope based on the finite element method and the strength reduction theory. The influence of different slope configurations, including different slope ratios, heights, and side forms on the slope stability is analyzed, and with the stability factor equal or greater than 1.1 as designated in the specifications, the slope critical heights are back calculated. The results show: (1)seismic loading has a significant influence on the slope stability, although its decreasing magnitude slows down with the increase of the slope height.; (2)the fill slope 16m in height is most instable under seismic loading, so the slope at or greater than 16m high is not recommended; (3)whatever the loading forms on the slope, either under the gravity loading only or the combined gravity and seismic loadings, the linear slope is most instable, with increasing stability for concave and step slopes.

Abstract: The widespread red-bed soft rock, characterized by its poor engineering properties as road building materials, plus the frequent large intensity earthquakes necessitates growing attention on the seismic design of cut slope in the west region of Yunnan province, China. To calculate the critical heights of the slope under seismic loading, a slope model is established and its dynamic response under seismic loading is analyzed by using Fast Lagrangian Analysis of Continua (FLAC^3D)based on three-dimensional finite difference method .The reliability of the model is verified by comparing the analytical results with other relevant research results. The stability factors at different slope heights and ratios are gained; accordingly, back calculate the critical heights of the slope at different slope ratios under either the gravity loading only or combined with seismic loading, when the stability factor is equal or greater than 1.1. The above analysis helps provide seismic design guidance for the cut slopes of red soft rock in Yunnan province.

Abstract: In order to analysis the crack lengths of the different rocks which penetrated by the linear shaped charge jet with uneven thickness clad for cutting excavation, the ANSYS/LS-DYNA code was used to simulate the penetrating process which three kinds of rocks had been penetrated. The results show that: through simulating the penetrate process by eight kinds of linear shaped charge jet with uneven thickness clad, the longest crack was found in Gneiss, the shortest crack was found in Iron ore and the crack length of Granite in between. For the linear shaped charge in this record, the good effect was obtained through taking the uneven thickness clad which vary rate was 2%.The linear shaped charge jet with vary rate of less than 2% slightly was suitable for Gneiss, the linear shaped charge jet with vary rate of more than 2% slightly was suitable for Iron ore, and if Granite was penetrated by linear shaped charge jet with uneven thickness clad, the shaped charge which has 2% vary rate would be more appropriate. It is believe that through the features of penetrated rocks mentioned in the paper, new rock material can be applied easily for pre-splitting blasting engineering in cutting excavation.

Abstract: Beipan River Bridge is located on the Beipan River Grand Canyon in the middle of Yunnan-Guizhou Plateau. The bridge pile, diameter of 2.8m, subjects to the vertical load design value of 58000KN, the thickness embedded in the breeze rock more than 85% of pile, was almost a full rock-socket pile, its bearing load was large and embedded in rock deeply. Based on test method of self-balancing, the bearing characteristics of large-diameter rock-socket pile in argillaceous area have been analyzed, including the axial force of pile, side friction, the tip resistance and so on. The results indicated that the bearing characteristics of the part in sock was as same as the friction piles in muddy dolostone area; From the results of test the side friction of pile could be estimated higher in strong weathering argillaceous dolomite area while the friction in weak or puny weathering muddy dolostone was relatively close to the value of exploration reports. Pile tip resistance had a greater potential. Finally, analyzed the measured curve, it could be seen that the calculation of bearing capacity was less than the test result, and the pile foundation was safety enough.

Abstract: Through mathematical statistics analyses of basic PM indexes of Zhejiang soft soil samples, obtained are the statistics of soft soil PM parameters, and hence its engineering geological quality. Through linear regression analyses of the soft soil PM indexes by least square method, obtained is the formula of linear inter-index correlations, and tested is the significance between the linear correlation and parameters. The outcomes of the statistical regression analysis provide reference for a rough inter-calculation among soft soil PM indexes, and for engineering constructions.

Abstract: The choice of similar materials and the design of mix proportions is a key step in landslide model test. On the basis of experiment, we conduct a research for the similar materials which may sufficing volume weight, cohesive force, angle of internal friction, deformation modulus, and the infiltration coefficient on the same time. Then we put forward two kinds of schemes: one is the mixed material of high-strength glass micro beads and talcum powder; the other is the mixed material of lead beads, river sands, rubber powder and talcum powder. By analyzing the result of mix proportions test, We concluded the regularity that similar index varies along with different content of the similar material ingredients and found the notable influence factors , which provides important reference for the components of similar materials in the landslide model test.

Abstract: The different treatments, such as the sleeve valve grouting method and the high pressure grouting with sleeve valve grouting method is adopted according to the concealed cavity in Kunming new airport. Test results show that: (1) after treatment, the equivalent shearing wave velocity of whole soil layer of NO.GR1 is higher and the physical property of foundation is improved than before, meanwhile although a great deal of concrete are used in the engineering, there is only a little cement paste found between 2.2m~18.0m during the core-drilling test, which means the test is not successful. (2) The shearing velocity of improved layer is higher in NO.GR2, the shearing velocity of other layers is lower than before treatment, which means the high pressure grouting with sleeve valve grouting method is feasible method to treat the concealed karst cavity.

Abstract: The swelling rock slope reinforced by geogrid with wrapped face was one of reinforced methods in the swelling rock test region of main canal in South-to-North Water Division Project, the key step was the geogrid with wrapped face in layer by layer, which was not only the core step to make sure the reinforced swelling rock slope with geogrid as a integrality, but also the most complex, time consuming and cost in the whole process. From the in situ test, the construction technology and related construction parameters of geogrid of simplified face to reinforce the swelling rock slope was obtained, in which the construction of geogrid with wrapped face was optimized, the construction progress was improved and its cost was reduced, which contributed to the generalization and application of geogrid with simplified wrapped face to reinforce swelling rock slope in the middle-route of South-to-North Water Division Project, meanwhile, it was provided as a references for similar engineering.

Abstract: The bearing performance of composite foundation improved by flexible piles was influenced by changes of cushion’s modulus, the modulus ratio between soil on bottom of pile and soil surrounded pile, which was analyzed by the finite element method. Results showed that: 1.For single pile, by increasing of cushion’s modulus, the bearing performance nearby the top of flexible pile increased apparently, and the common tendency of settlement of pile and soil surrounded piles was affected negatively. For multi-piles, the increasing of cushion’s modulus resulted in the increasing of bearing performance and the common tendency of settlement of piles and soil surrounded piles was affected positively. 2.The change of modulus ratio between soil surrounded piles and soil on bottom of piles resulted positively in the change of frictional resistance and end-bearing performance nearby the bottom of single pile and reduced the settlement of composite foundation. But the multi-pile borne absolutely all loading due to the increasing of modulus ratio, and both of piles and soil surrounded piles had the same tendency of settlement.