Applied Mechanics and Materials Vols. 353-356

Abstract: Uniform safety factors are normally assumed in slope stability analysis and this assumption can influence the rationality of the analysis. New analysis methods were obtained based on Fellenius, Bishop and multi sliding surface method to study a failed slope of a port in southern China. The calculation results show that the safety factors of soft soil layers will be overestimated and the safety factors of hard soil layers will be underestimated if soil mass of slope vary widely in the strength. For the failed slope in this paper, the factors obtained with normal methods will be overestimated because of the hard soil layer of this slope.

Abstract: Horizontal drainage cushion plays a key role in vacuum preloading projects. The traditional horizontal drainage cushion is sand blanket which consumes large amount of sand and is not enviromentally friendly. Several improvements or modifications of horizontal drainage cushion were developed in engineer practices in recent years. Drainage net was used as horizontal drainage cushion in ultra-soft soil improving projects in order to solve the laying problem of sand blanket. Sand ditch was used to deduce the consumption of sand. Direct vacuum preloading method linked the PVDs and filer tubes together in order to improving the transfer efficiency of pressure and canceled the sand blanket at the same time. Low position vacuum preloading method set horizontal drainage cushion below the surface of the ground in order to cancel the sealing membrane.

Abstract: Finite element software was employed to establish a model to simulate the compound soil nailing. The model simulates the process of constructing prestressed compound soil nailing. Compared the condition prestressed with no prestress, analyzed the Impact of prestress anchor on the deformation in the process of construction and the effect on axial force of soil nail. Applying prestress is able to control the horizontal displacement obviously, but has not obvious effect on vertical displacement, especially place the anchor bolt at the lower part of the slope. In the process of construction, prestress has an advance effect on the deformation of foundation pit and the axial force of soil nails near the anchor bolt.

Abstract: Soil-water characteristic curve is used to describe the matrix suction and water content of the curve of the relationship between volume, according to the soil-water characteristic curve can be deduced the unsaturated soil shear strength, permeability coefficient, etc., this paper gives the different initial water content and different types of soil, soil-water characteristic curve for practical engineering foundation reinforcement to provide reference.

Abstract: According to the problemsof serious deformation of soft rock roadways and lack of system andcomprehensive study on surrounding rock characteristics and failure mechanismin Shajihai mining area, this paper carried out a series of mechanicalexperiments on the characteristics of surrounding rock in this area includinguniaxial compression test, triaxial compression test and water absorption propertiestest. Mechanical test results show that the compressive strength of surroundingrock of roadway is generally low, and mudstone compressive strength is thelargest which is 19.23 MPa, and compressive strength of the minimum is coalwhich is 11.32 MPa under natural condition. However sandstone and mudstone’sability of water absorbing is strong, and coal saturation strength issignificantly greater than that of mudstone and sandstone. Therefore, we shouldmake full use of the strength of coal in roadway layout and support design.

Abstract: In order to find out themicroscopic structure and determine mineral composition and relative content ofroadway soft rock in Shajihai mining area, this paper carried out experimentsof scanning electron microscope (SEM) analysis and X-ray diffraction analysis.SEM test results show that the microstructure of the surrounding rock isgenerally poor and joint, crack, pore are developed. The crack is easy toexpand under the effect of surrounding rock pressure and water, which makesrock mass more broken and greatly reduces the stability of surrounding rock.X-ray diffraction analysis test shows that the component content of clayminerals in the surrounding rock is high. Clay mineral in mudstone containsmontmorillonite and content of illite/smectite mixed layer is relativelyhigher, up to 45%. In conclusion, soft rock roadway of Shajihai mine areabelongs to the typical swelling-jointed compound soft rock. The targeted andreasonable compound transformation technology and coupling support measuresmust be adopted when supporting.

Abstract: Abstract: Soil-rock mixture is one of the complex geological bodies, in which microstructure is critical to determine its mechanical property. So it is of great significance to establish a statistical model on the basis of statistical recognition of microstructure of this media. Digital images taken on-site and Autocad is used here to conduct recognition of soil and rock. Rock is equivalent to random polygon in this paper. Taking approximate ellipse as reference, the statistical characteristics of long axis,short axis ,flattening and boundary roughness can be obtained. A stochastic model is established on this basis. Biaxial compression test curves are attained by digital image model and rock stochastic model confirm the effectiveness of statistical model of long structure in soil-rock mixture and the method of stochastic media generation.

Abstract: This paper intends to solve the leakage of the surface waters on the proposed underground garage impact from a practical engineering, so we carry on the detailed analysis about the surrounding hydro geological conditions to provide scientific basis for underground garage waterproof design. On that basis, we establish the hydro geological conceptual model, using Visual MODFLOW4.1 software to simulate the seepage field in two kinds of working conditions, and get the result of the surface waters on the proposed garage impact. Thus in the underground garage of the soleplate waterproof design we adopt different block waterproof practices which may save a lot of fund, and have the important theoretical and practical significance to us.

Abstract: In this paper,the rule of direct proportion between anchor stress and creep strain of rock mass is taken as a starting point. After tunnel excavation,stress distribution of anchor in perfect circle tunnel is analyzed,then an important conclusion that the location is coincident between peak stress of anchor and plastic zone border of rock mass can be drawn in terms of theoretical derivation when rock mass is in plasticity.