Applied Mechanics and Materials Vols. 90-93

Abstract: Abstract. The content of clay particles in powder sand is low, with small cohesion. Embankment erosion by water will lead to instability, to make a cover layer with clay. In order to resolve the erosion of powder sand embankment slopes affected by the rain, tested the powder sand and the cover layer soil, and conducted a survey of slope erosion situation in the embankment, divided the types of erosion. On this basis, base on the energy method, analysis the slope erosion by the impact of slope gradient, slope shape, the density and width of cover layer soil, rainfall intensity, conclude some applicable scouring protective measures for conditions of slope. The results provide a reference for the design of powder sand slope protective technology.

Abstract: The geological setting of Sichuan-Tibet Railway is complicated, while magmatic and metamorphic rocks are widely distributed. Reference to the other engineering experience of underground works under similar geological conditions at home and abroad, the analysis shows that it exists the hazardous possibility that the inorganic gas are toxic and harmful in the tunnels of Sichuan-Tibet Railway. Combining the conditions that inorganic gas produced and the geological conditions along the Sichuan-Tibet Railway, it analyzes and predicates that CH4, CO2, H2S, SO2, CO, NO2, NH3 and H2 are the main types of poisonous gas along the Sichuan-Tibet Railway. The poisonous gas is mainly distributed in the three suture zones, three crustal fault zones and more than three basement fault zones and mafic and ultrabasic rock zone, granites zone, volcanic zone and contact metamorphic zone. All these zones are the favorable migration point to area and gathering area to the toxic and harmful gas. It should be highly mentioned on the construction of the tunnels.

Abstract: The factors affecting the TBM tunnel behavior in jointed rock mass is investigated. In the numerical models the concrete segment lining of TBM tunnel is concerned, which is simulated as a tube neglecting the segment joint. And the TBM tunnel construction process is simulate considering the excavation and installing of the segment linings. Some cases are analyzed with different joint orientation, joint spacing, joint strength and tunnel depth. The results show that the shape and areas of loosing zones of the tunnel are influenced by the parameters of joint sets and in-situ stress significantly, such as dip angle, spacing, strength, and the in-situ stress statement. And the stress and deformation of the tunnel lining are influenced by the parameters of joint sets and in-situ stress, too.

Abstract: In order to extract the mineral resources existing at great depths, the mining industry is facing new serious challenges to safe and productive mine operation, and such challenges arise largely as a result of the high pressures imposed on deep mine excavations. In order to investigate the effect of confinement on rock fracturing under dynamic loads, blasting experiments by using cement mortar plates, which are square with a single centralized borehole, have been carried out. Two kinds of confinement, i.e. uniaxial and biaxial, are applied to the square plates. In the study of defect effect, circular cement mortar plates with randomly distributed defects are employed, the results show that confinement and defects affect rock fracturing significantly.

Abstract: Based on the structural characters of roof in fully mechanized top coal caving, mechanical analysis, mechanical calculation and simulation experiment were used to explore the particularity of roof structure in fully mechanized top coal caving. The simplified model of roof structure was built in final. The results shown that, during the mining by fully mechanized top coal caving, dynamic balance arch structure was formed by the roof and surrounding rock in working face. In the same time, multi span beam structure was formed in the tendency direction. The results of this paper would provide the theory basis for exploring the strata behavior regularity in further, and promote the safety in production of coal mining enterprises.

Abstract: The optimum model for blasting parameters of anchoring rock beam is established and its blasting parameters are optimized by making use of a strong mapped function of the neural networks technology with the typical samples of other practical smooth blasting parameters. The explosive types, the extent of joint development of rock mass, the diameter of bore-hole, the depth of bore-hole, the linear charge density, the burden line of least resistance and the spacing of bore-hole are considered as the primary effective factors in the excavation of anchoring rock beam. In the meantime, the experimental blasting parameters for anchoring rock beam are determined by the in-site blasting experiments of the protective layer and platform of rock mass in similar conditions. The results show that the in-site experimental blasting parameters are preferably identical to those of the optimum design. The acoustic wave examination for the blasting of the protective layer and platform of rock mass indicates that the blasting effect is satisfied and its smaller loose ring of surrounding rock mass is obtained.

Abstract: Pile grouting technology is widely used in engineering to effectively improve the vertical bearing capacity, in this paper; we made a comparative study on the bearing capacity of grouting pile and General pile in Wuqing district Tianjin City. And proving this method can improve the pile bearing capacity, with good effect, and significant economic benefits.

Abstract: In high seismic intensity area, strong seismic motion may cause the ruin of highway tunnel, especially the tunnel portal which is the weak links for anti-seismic fortifying. Based on soil-structure interaction model, 3D seismic responses of tunnel portal, in combination with the Menglian tunnel engineering on the Bao-Teng Highway in Yunnan, were performed by using viscous-spring artificial boundary and time history analysis method. The anti-seismic fortified length of tunnel portal to the effects of dynamic and crack property was studied. The results show that the acceleration of lining gradually decreases with the lining extends to the tunnel body under the high-intensity seismic load. Along the axial direction of the tunnel, the crack from the portal 50m is not obvious. The results provide references for the tunnel anti-seismic design．

Abstract: The vibration loads will be produced between wheel and rail on the running of the high-speed Train. The vibration energy will be transferred to the ground formation through the rail, guiding bed and tunnel lining structure, thereby causing vibration between the formation and surface and environmental interference effect problems. Thus the research of related issues caused by the high-speed train vibration has the vital great significance. The train design speed of the Shiziyang shield tunnel for Guangzhou-Shenzhen-Hong Kong passenger dedicated line is up to 350km/h. In this paper the research object is located in the segment of the homogeneous formation of the Shiziyang shield tunnel. The analysis of this paper includes the dynamic response rules of the shield tunnel and formation under the single high-speed train loads and the law of the pore water pressure accumulation and dispersion under train cyclic loading.

Abstract: As for stabilizing piles used to reinforce landslides, landslide thrust acts on their upslope sides but slope resistance acts on their downslope sides at the same time. In fact, the results that the former subtracts the latter are effective loads on piles, which can be called residual thrust on piles. The interaction between pile and rock or soil mass is simulated by elastoplastic finite element method in the paper. And the effect of slide mass and pile stiffness on residual thrust on stabilizing piles is analyzed. The results show that residual thrust on a stabilizing pile become more and more with elastic modulus of slide mass or the pile being increased. Meanwhile, action point of the resultant of residual thrust on the pile is lower and lower with elastic modulus of slide mass being increased but it is higher and higher to some extent with elastic modulus of the pile being increased. These results can be of theoretical reference for comparison and selection of various design plans of stabilizing piles.