Applied Mechanics and Materials Vols. 353-356

Abstract: In order to comparative study the force characteristics of vertical and inclined cantilever retaining pile in foundation pit engineering, a practical excavation engineering was considered. Based on the engineering geological conditions of this foundation pit, two three-dimensional simulation models for computing the force characteristics of vertical and inclined cantilever retaining pile were built. Then the horizontal displacement of pile top, the lateral displacement and the bending moment of pile body were illustrated and contrasted in detail. It was shown that the horizontal displacement of inclined pile top is significantly less than that of vertical retaining pile. Moreover, the deformation and bending moment of inclined pile body are more reasonable than that of vertical retaining pile. Therefore, the stability of foundation pit was guaranteed through inclined pile support.

Abstract: In order to study sandstone rock strength and deformation parameters under pore water pressure conditions, triaxial compression tests of different hydraulic pressure were executed. Fitting equations of fine sandstone confining pressure and hydraulic pressure coupling effects were established. This research show that fine sandstone rock strength increases with confining pressure increases. Rock mass strength and cohesion have negative exponential relationship with hydraulic pressure. When the hydraulic pressure is 3MPa, elasticity and confining pressure fit to logarithmic relationship. Fine sandstone Elasticity modulus decreases with hydraulic pressure increases. Poisson’s ration and hydraulic pressure fit to linear relationship.

Abstract: In order to avoid the frost damage to subgrade, an objective method that using fly ash as the anti-frost heave is proposed in this paper. The effects of the frost heave rate on the thickness of replacement layer, the depth of replacement layer and the depth of groundwater were investigated through the uniform design method. The mathematical model of the relationship between the frost heave rate and three influencing factors also was indicated by indoor simulated tests and regression analysis. The results show that the thickness and the depth of replacement layer respectively are 16 cm and 55 cm below subgrade, which provides the specific anti-freeze measurement to the guidance of design and construction.

Abstract: We conducted the model test of unloading rock mass under compression-shear stress .Based on analysis and fitting to test data, we proposed the unloading rock mass three-dimension constitutive model.

Abstract: The dynamic parameters of silty clay in Dujiangyan under dynamic loading are studied with RCA resonant column apparatus made in GDS Company of British with different confining pressures. The results show that: The test process can be reproducible; the maximum dynamic shear modulus and damping ratio are increasing, and the shear strain amplitude is decreasing with increasing confining pressures. The empirical formula of the dynamic parameters of silty clay in Dujiangyan vs. confining pressures is formed. The study can provide basic data for seismic dynamic response analysis of soil.

Abstract: Geogrids reinforced soil retaining walls are widely used in various fields, such as highway, railway, architectural engineering, hydraulic engineering and so on because of its remarkable economical benefits, constructing convenience, adaption to the foundation simplicity of foundation treatment good vibration resistance shapely configuration and environmental pollution-free etc. Combined with a real engineering, the applied effects of geogrids reinforced earth retaining was tested. Based on the field test results and finite element method numerical analysis, the engineering characteristics of blocking reinforced earth retaining wall that used lime soil as filled material in construction period and after completion were opened out. The distributing characteristics and rules of wall back lateral soil pressure, tensile bar pull were put forward. Thus, technical references were provided for the similar structures.

Abstract: In order to study the mechanical properties of Crushed Stone-Loess (CSL), a mixture of loess and crushed stone, and Geogrid-reinforced CSL (GCSL), a series of unconfined compression tests were conducted using samples prepared respectively with CSL, GCSL, Pure Loess (PL) or Geogrid-reinforced PL (GPL). Samples varied either in the number of geogrid-reinforcement layers or in the relative compaction / in the content of crushed stone. Based on the analysis of the test results, the following conclusions are given: (1) The pattern of compressive stress-strain curves of GCSL changes gradually from obvious strain softening to strain hardening with the increase of the geogrid-reinforcement layers and the relative compaction. (2) While the compressive strain is greater than a certain value, the compressive strength of GCSL increases significantly with the increase of crushed stone content. (3) Under a larger compressive strain, the crushed stone inclusions improve apparently the compressive property of GCSL with closely spaced geogrid-reinforcement layers due to the interlocking between the crushed stone and the geogrid.

Abstract: Ground soil was looked as porous medium, a three-dimensional finite element model of shell-liquid-foundation-ground was built, and the influence of soil parameters, filling liquid mode, and liquid height on the tank ground deformation was discussed. The research shows that the subsidence range caused by additional stress is the 0.3D range of the tank bottom edge outer; the influence of soil constrained modulus on settlement is remarkable, with constrained modulus decreasing, the tank ground settlement increases; with soil permeability coefficient decreasing, the tank ground settlement decreases; the ground settlement curve shape is decided by soil constrained modulus and permeability coefficient; the influence of filling liquid mode on the ground final settlement is very small ,but on the pore water pressure peak is remarkable.

Abstract: This paper, based on dynamic triaxial apparatus of GDS, makes a consolidated undrained dynamic triaxial test of the saturated earth-rock aggregate of different earth-rock ratio, analyzes its processes and results, and preliminary discusses the influence of confining pressure, dynamic stress and earth-rock ratio on the dynamic strength of sandy pebble soil samples. Therefore, it providess some cognition of the study of earth-rock aggregate.

Abstract: In order to study the post-peak mechanics behavior of rock samples with a thick wall cylinder structure, damaged rock samples were precast with a new method. The uniaxial compression tests and tri-axial compression tests were conducted on the samples and the test results were compared with that of complete rock samples. The results show that strength attenuation value of the damaged samples increased with the confining pressure and the specific relationship was obtained by nonlinear fitting as (is the strength attenuation value and is the confining pressure); destructiveness of damaged samples was more serious than the complete ones; a new nearly horizontal failure phenomenon appeared under the tri-axial compression and it was more general with the increase of confining pressure. Structure effect of uniaxial strength attenuation was revealed based on the particle flow software system (PFC) and the corresponding theoretical model was found as (is the strength attenuation value under uniaxial compression of any damaged sample with a thick wall cylinder structure; is the strength attenuation value of standard damaged samples under uniaxial compression; is the structure ratio, and are the parameters of the material). Characteristic value of the strength attenuation value under uniaxial compression was obtained by calculation when the structure ratio was indefinitely large.