Applied Mechanics and Materials Vols. 501-504

Abstract: This paper reports on part of an ongoing experimental program at the University of Adelaide on FRP-concrete-steel composite columns. The results from twenty specimens including 12 double skin tubular columns (DSTCs), two solid concrete-filled fiber reinforced polymer (FRP) tubes (CFFTs), and six CFFTs with inner voids (H-CFFTs) are presented. The specimens were manufactured using high-strength concrete (HSC) and their FRP tubes were fabricated using unidirectional S-glass fiber sheets. The results of the experimental study indicate that that H-CFFTs perform significantly worse than DSTCs and CFFTs and their performance further degrades with an increase in the diameter of inner void. Comparison of the results from DSTC and CFFT specimens indicate that both hollow and concrete-filled DSTCs exhibit improved compressive behavior compared to CFFTs.

Abstract: Rainfall is one of the most important factors of the slope stability. After the "5.12" earthquake, there are a large number of loose solid produced by earthquake on the mountain, which leads to the soils strength loss in the earthquake disaster zones. and induces landslides and collapses easily in the heavy rainfall condition. The soil parameters obtained from the tests, the scene investigation of the Erman mountain landslide of Han Yuan County, the new developed control of ArcGIS to obtain intuitive landslide warning graphs have been carried out. Results show that the picture of hazard grade is consistent with the actual situation of landslide on Erman mountain. It will provide a scientific way to analyze the influence of heavy rainfall on slope stability.

Abstract: This paper uses 2D DDA program to simulate the failure process of highly jointed rock slope with a fault. In addition, seismic forces, as a most common triggered factor of landslide, are also simplified simulated by applying an initial velocity to the slope. Based on the simulation results, the weakest discontinuity, fault, determines the slide path of rock blocks; the accumulation of blocks' displacements leads to the overall failure of slope; and the existence of highly developed joints provide the possibility of the accumulation of displacements.

Abstract: In this paper, the author simulates geological conditions of permafrost areas, establi-shes CFG group piles indoor model, observes the pile and frozen soil temperature field, then compares the calculated results of the group piles and frozen soil temperatures under concrete hydration heat effect by using ABAQUS with the measured temperature data, thus determines the applicability of ABAQUS for analysis of CFG group piles temperature in permafrost areas, in order to analyze temperature distribution regularities of group piles and frozen soil under concrete hydration heat effect, thermal perturbation range of CFG group piles in permafrost areas, and effects of different concrete molding temperature on model temperature field.

Abstract: Rockburst is a phenomenon of geological hazard due to excavation in brittle rockmass of high in-situ stress which endanger to the engineers and construction equipments with unexpectedly damaged. At present, researchers and engineers mainly concentrate to the requirement of rockburst and whether to arise. Although the delay characteristic of rockburst (DCR) has been realized and recorded, but the knowledge of the mechanism of this feature is insufficient. In the paper, the delay characteristic was researched from the stress release rate (SRR) of the excavation rock mass using the numerical simulation software. Firstly, using the core replacement technique, the relation of the SRR and core modulus reduction (CMR) was determined. Secondly, the mechanism of the DCR was analyzed from the elastic strain energy distribution and the plastic strain energy distribution in the different SRR. Finally, the plastic field shape and range under different SRR was contrasted and analyzed. Conclusions can be drawn as follows: with the increase of CMR value, the SRR shows increase trend in the form of exponent. In the process of excavation, the rockmass elastically deform under the low SRR value. When the SRR value equals certain degree, the portion of rockmass will be plastic field and behind the plastic region there will be arise a elastic strain energy centralized phenomenon. Under the different the SRR value, the field style change to the tension-shear field from the shear field in the rock mass and the rockburst rank obviously different.

Abstract: The upper-bound method of limit analysis combined with strength reduction technique is employed to analyze the stability of an earth slope reinforced with multi-directional anchors. A homogeneous and isotropic earth slope reinforced with two rows of anchors is considered. Attempts are made to obtain the optimal angles of anchors. Parametric studies show that, for homogeneous and isotropic slopes, the optimal angle of the first row of anchors is 0°; while the optimal angle of the second row of anchors varies with anchor positions, and generally is less than 15°.

Abstract: Seepage piping seriously threatens the safety of levee, but study on mechanism of regressive erosion is not in-depth. According to the characteristics of piping channel upstream movement, we designed a set of experiment equipment. In given experiment condition, we did the experiments with 2 kinds of overburden and 2 different position of piping channel, and measured the value of each piezometric tube. As the experiment results shows, the tip hydraulic gradient can better reflect the problems of regressive erosion, comparing with average hydraulic gradient between piping exit and outer river. The development of the regressive erosion is determined by the tip hydraulic gradient. It will stop expanding when the tip hydraulic gradient decreases after large-scale upstream movement. This paper lays a foundation for further theoretical study.

Abstract: To evaluate the influence factors of accumulative plastic strain of frozen silt clay, the dynamic cyclic triaxial tests with stress-controlled are conducted to investigate the behaviors of frozen soil induced by cyclic loading. The relationships between accumulative plastic strain and vibration numbers for frozen silt at different dynamic stress amplitudes under different temperature, vibration frequency and initial water content are obtained. The test results show that the accumulative plastic strains increase with rising tempeature, increasing the vibration numbers and dynamic stress amplitude. The accumulative plastic strain rate increases with increasing the vibration frequency. With increasing the initial water content, the accumulative plastic strain of frozen silt clay increases.

Abstract: Fiber reinforced polymer (FRP) materials have good performance such as high strength, high modulus, corrosive resistance, and so on. FRP materials can be used to reinforced reinforcement effects significantly and improve durability of traditional reinforcements. A series of model tests were conducted on foundations reinforced with horizontal FRP reinforcemens. The influence of reinforcement modes on bearing capacity, settlement, strain of FRP and earth pressure were analyzed. From the test results, it was shown that the FRP reinforcement can significantly increase the bearing capacity and reduce the settlement, especially for double-layer reinforcement. And the effects of the anchoring inclusions were little, as compared with the reinforcements.