Advanced Materials Research Vols. 243-249

Abstract: In this study a resonant column apparatus was used to obtain the shear modulus and damping ratio of the waste granular rubber and cement soil mixtures. Specimens were tested for different rubber contents and confining pressures. Experiments show that with the rubber increased, the damping ratio of the rubber and cement soil mixtures increases, dynamic modulus decreases. When the confining pressure increases, the shear modulus of rubber and cement soil mixtures increase gradualy, damping ratio increase slightly.

Abstract: The auxiliary shaft ingate of Pengzhuang Coal Mine deformed greatly with large roof fallings. Through the analysis of destruction, the ingate reinforcement schema is put up according to the engineering consolidation experience and the advanced consolidation experience at home and abroad. On the completion of the ingate project, the surrounding rock mass is stable without apparent deformation. The two-side and roof deformations are 4mm and 5mm respectively according to the convergence deformation test, improving the integrity and bearing capacity of the shaft and pipelines effectively. Thus the deformation of the surrounding rock mass is under control, guaranteeing the long-term stability of the roadway.

Abstract: The traditional method of calculating soil arch effect was described Firstly, and the inadequacy of traditional methods was analyzed. On the basis of their predecessors, the rectangular cross section of a rational spacing between passive pile was mainly discussed. Based on the mechanical properties of soil between anti-slide piles analysis, a pile of soil conditions of static equilibrium, cross-section strength of the section of the conditions and strength condition of the arch to common control methods to determine the critical pile space were put forward.Relatively reasonable a spacing formula for calculating pile spacing has been obtained. Comparing with rational pile space formula obtained and the traditional formula for the actual project data, the results indicate that, for the cross-section 2.5mx2.5m the pile, formula by rational pile space the calculated results and the calculation method has been compared and analyzed the results, when the landslide thrust 47kN/m².According to rational pile space formula the results calculated by the situation more in line with the actual project, it is of significance to practical engineering design of anti-slide pile, and there is a greater using and reference value for the similar project via the methods used and the conclusion.

Abstract: There are many soft-clay sediment foundations in Yinchuan area, most of which are made of soft-clay silt from lakes. Its secondary consolidation deformation occupies a large proportion of its total deformation, and displays a greater volume of settlement after work completion, which seriously influence the normal use of buildings. The orthogonal experiments are designed to study the influence of factors such as current stress, dry density and OCR on the secondary consolidation behavior of soft-clay sediment of lake in Yinchuan. The regulation and mechanism of secondary consolidation is revealed. Some useful conclusions are reached to provide reference for projects design and construction.

Abstract: To understand features of bearing capacity of suction caisson foundation is one of the key issues in design and construction of deep-water marine structures. In this paper, the general-purpose finite element analysis package ABAQUS is employed to conduct three-dimensional numerical analyses on load-carrying features of suction caisson foundation under vertically uplift load, horizontal load and moment. Then the ultimate bearing capacity of suction caisson foundation for undrained condition of the soil is evaluated by displacing-controlling procedure. Moreover, three-dimensional failure envelope of suction caisson foundation under combine loading condition are established by the proposed numerical procedure.

Abstract: Based on the research of the conception of “deep stratum” and “deep engineering”, through collecting about 600 groups of the measured geostress data in deep rocks of China mainland, the features of the geostress in deep rocks are elementarily analysed referring the analysis method of Hoek and Brown. The distribution rules of the vertical stress, the maximum and the minimum horizontal principal stresses with depth in deep stratum are analysed, and trend of the lateral pressure coefficient with depth is also discussed.

Abstract: With Monte-Carlo theorem, inclusive of the uncertainty of double phase geo-material parameters as well as math model boundary condition, stochastic difference math model was carried out for bulk terrestrial underground water seepage on the basis of plain confined steady underground water flow math model. The key conclusions are: seepage field behavior has close relation with turbulence of random B.C.; distribution of stochastic head potential depends on the geo-born-variation of parameters and the methods introduced in this paper are applicable for this achievement.

Abstract: To explore the relationship among the erosion ability of high-pressure cavitating water jets, hydraulic parameters and rock nature with a series of experiments relating to the efficiency of rock-breaking with cavitating water jets for different porosity of rock under different confining pressures and pump pressures. The results show that the erosion efficiency (erosion mass and erosion depth) of cavitating water jets is fitted a conic curve with pump pressure and confining pressure. It increases with the pump pressure increases while decreases with the confining pressure increases; the length of the bubble cloud decreases with the confining pressure increase and the length increases with the pump pressure increase, which is accorded with cubic curve. The bubble cloud length influences the rock-breaking efficiency by deciding the valid stand-off distance directly. Under the experimental condition, the cavitation happens once the pump pressure reaches 7MPa, and the cavitating water jets can crushing the sandstones which the uniaxial compressive strength is 96MPa. On the other hand, the porosity of rock is another main factor of rock breakage with high pressure cavitating water jets. The higher the porosity of rock is, the easier the rock can be broken.

Abstract: In order to study influences of applied load on pile top on the negative skin friction behaviors of piles, field investigations of negative skin friction behaviors of three identical piles with different loads on pile top are made in the same site. Test results show that applied load on pile top affects negative skin friction behaviors evidently. Additional settlement of pile induced by negative skin friction becomes larger, negative skin friction induced by the settlement of soil surrounding the pile becomes smaller with the increase of load on pile top. Dragload induced by negative skin friction decreases and position of neutral point in pile moves up while applied load on pile top increases. While there is no applied load on pile top, additional settlement induced by negative skin friction is minimum, dragload induced by negative skin friction is maximum and the neutral point is the farthest from the top of piles. The field investigation results may be useful to the further research for negative skin friction behaviors of pile.

Abstract: The behavior of micropiles in soft clay, under vertical compression and tension loading, was examined by field tests at a site in Shanghai. The soil profile consists of topsoil, silty clay, sandy silt, muddy clay, and clay soil. Two compression and three tension loading tests were conducted on five single micropiles. The piles were instrumented with vibrating wire force sensors, and they were monitored during the process of loading to investigate the mechanisms of load transfer. Both the ultimate vertical load capacity and the deflection at applied loads were examined. The results indicate that the pile load–displacement response under vertical compression or tension loadings was nonlinear. Both the compression and the tension load carrying capacity basically increased with a linear trend. But, the ultimate load capacities under tension were about 50-60% of those under compression. Tip resistance was about 10-15% of the applied compression load, not existing in the micropiles under tension. The average skin friction for micropiles under compression loading was about 50% higher than that for piles under tension loading.