Applied Mechanics and Materials Vols. 256-259

Abstract: A case of the long-short-pile composite foundation in liquefied soft soil under a 30-storey high-rise building is presented, in which the long and short piles are made of cement-flyash-gravel (CFG) and lime. A new design calculation method of bearing capacity and settlement of composite foundation is introduced, and the calculated value is compared with the actual measurement. The results show that the liquefaction of soft ground is eliminated and the demand of load and settlement for upper building is met. At the same time, it is proved that the design method is feasible.

Abstract: It is mining subsidence that causes the damage of ecological environment and the surface buildings. The basic method to relieve the damage is to controll surface subsidence effetely. For this problem, the thesis studied the characteristics of overlying rock failure through theoretical analysis, on the basis of the mechanism of surface subsidence. Then we obtained three main factors to subsidence which are sunken, compression, and lithological characters. According to the main factors influencing mining subsidence under cut and fill mining, then we reduce the impact from these factors successfully by taking appropriate measures to control it.

Abstract: In order to study the vertical bearing behavior of bored piles with breakage defects, a series of methods for simulation of normal piles and broken piles in laboratory was developed and used to investigate the vertical bearing behavior of these piles. The load-settlement curves of normal piles and broken piles were measured and analyzed. The tests revealed that the upper part of a broken pile works alone as a short pile before it contact with the lower part of the pile at the end of the first sudden drop stage.The analysis of the test results showed that the position of the breakage defect has a great influence on the lost in vertical bearing capacity of the pile.

Abstract: As mining process in the Mechanized mining face, making it easy come with flap top[1] along the the upward and downward entries. In this paper, through the use of carbon dioxide cannon, we do pre-split blasting experiment on triangular flap top in mechanized mining face, exploring an effective solution to a large area of goaf flap top suddenly breaking down, with the hurricane caused damage and fan-out of toxic and harmful gases, to achieve the purpose of production safety.

Abstract: The computational model based on the shallow mined-out areas was built by using FLAC3D, and the separation and dislocation characteristics of the layered roof in the mined-out areas were analyzed under different conditions. The results showed that the maximum value of the layered roof separation increased with the increase of the mining width, and that value decreased with the increase of lateral pressure and the cohesion between layers. The separation curves of the layered roof showed the shape variation from the symmetry flat arch to the asymmetric steeple arch and then to the linear form, the maximum separation value of the layered roof exhibited a three-stage tendency of a gradual increase, a steep reduction and a slight change, and the maximum dislocation value of the layered roof presented a two-stage tendency of firstly slow growth and then rapid growth with the increase of the dip angle of coal seam.

Abstract: The original algorithm holds that the weight and impact force of rockfall are large different. For easy calculation, the rockfall own weight can be almost neglected. But the impact force of rockfall has a slow increase of the process by the resisting effect of the soil during landfall and rockfall impacting soil over the pipe, which the rockfall own weight to the contribution of the impact force is great. Therefore, it is necessary to study on impact force of landfall and rockfall. We establish the mathematical model of impact force of landfall and rockfall by mathematics and mechanics knowledge, and put forward the wallop amplification coefficient method by the count, which results more close to the actual situation, comparing with the original algorithm. It shows that result, which is better than the original algorithm results, by the wallop amplification coefficient method can be widely used in practical projects.

Abstract: Tianluoshan relic sites is a typical earthen sites located at moisture circumstances. The potential application of silicone for strengthening Tianluoshan relic soils were evaluated by a series of laboratory drip injection tests. The main considered influence factors include: dry density, initial water content and degree of saturation. The results show that the drip injection effect of silicone for Tianluoshan relic soils greatly related with dry density and initial water content, the practical application guidance are also presented in the paper.

Abstract: Based on lots of previous studies, the unconformity structure characteristics were studied and the controlling effect of unconformity structure on hydrocarbon reservoir, migration path and oil-gas reservoir type were analyzed. The result shows that the unconformity structure is composed of upper basal conglomerate layer, lower weathering clay layer and semi-weathering rock; the interlocking pores in basal conglomerate layer and pore-cave-fracture system in semi-weathering rock are the main storage space of hydrocarbon reservoir; And hydrocarbon migrates laterally through capillary “channeling effect” in interlocking pores, and the pore-cave-fracture system in semi-weathering rock is an important path for hydrocarbon migration laterally and vertically; stratigraphic overlap hydrocarbon reservoir and stratigraphic unconformity reservoir are the two type of reservoirs related to unconformity, and buried hill reservoir is an important type of the latter.

Abstract: Transmission line foundation engineering inevitably encounters the special geological conditions in salt lake area, such as strong corrosion of saline soil, weakness of foundation soil and high water table of groundwater. In-situ tests on bearing characteristics of the selected pad and chimney foundation were conducted. Ultimate uplift bearing capacity and ultimate compressive bearing capacity of the pad and chimney foundation in salt lake are obtained, which can verify the rationality and reliability for its engineering popularization.

Abstract: This paper describes an experimental study on non-linearity critical strain energy release rate for frozen soil. Cracked single edge straight-through specimen and cracked chevron-notched specimen were used in test of three-point bending under mode I. The traditional equipment was reformed as the load applied direction was down-up, and dye penetration technique was also applied in. Measured technique and principle of non-linearity critical strain energy release rate are discussed. Some preliminary results are given out.