Advanced Materials Research Vols. 919-921

Abstract: The principles about soil formation and the difference between rock and soil are introduced. The general knowledge about stratigraphic classification is interpreted in detail. Based on several hundred geological survey report about construction and renovation, one new classification method based on difficult degree of construction is put forward, by which rocks are divided into three levels on the base of Protodyakonov's coefficient f, and soils are divided into three levels on the base of geological age. The classification method put forward is helpful for estimating the difficulty of the construction, construction amount and Construction time.

Abstract: Because the suction bucket foundation is construction period and low cost advantages,application of suction bucket foundation is more and more widely. In this paper, whether the suction bucket foundation can be used as the basis of transmission tower in river area were studied.According to the working mechanism of bucket foundation in soft clay ground and characteristics, through ABAQUS finite element simulation, bearing capacity under the pressure and uplift ultimate draw suction bucket foundation, and compare with the experimental results, verify the feasibility and accuracy of simulation.According to the transmission requirements of bearing capacity of the foundations,design the basic size,and verify whether the requirements of bearing capacity of foundation, confirmed the suction bucket foundation can be applied to the area of river network transmission tower.

Abstract: The traditional AHP in the judgment matrix is established by using 1-9 scale, this scale has transfer difference, consistency of judgment matrix and thinking is not equivalent shortcomings. The improved AHP scaling theory is used in deep foundation pit support index weight determination, the selection of foundation pit supporting is more comprehensive scientific reasonable accurate.

Abstract: In order to analyze the stability of surrounding rocks with two groups parallel joints under different angles, a new method, DDARF (discontinuous deformation analysis for rock failure) program was adopted to investigate three cases of uniaxial compression tests of two groups parallel joints sample with the angels 30, 45 and 60. The results show the sample with 30 is least prone to be destroyed and the sample with 60 are most likely to be destroyed. Then DDARF program was also applied to investigate the underground cavern excavation process of two groups parallel joints surrounding rocks with the angels 30, 45 and 60. The results show that the stability of underground cavern with joint angel of 60 is worst in the aspect of stability.

Abstract: When creating underground pipelines, tunnels and other long cylindrical holes often used drilling-and-blasting method of penetration. Depending on the type of rock in the array may be local induration or sintering which results in increase in the deformation properties of the ground, or cracking resulting in a decrease in deformation properties. Thus the array becomes inhomogeneous. The article provides a calculation of the stress-strain state of array considering its local inhomogeneity.

Abstract: In this paper, the stress and strain distribution in coal seam and fault edge under various fault dips is numerically simulated to study the stability of the barrier pillar and determine the reasonable length of coal seam mining using COMSOL Multiphysics package. Numerical simulations show that remarkable increase in stress around fault edge when coal seam is about 250 m away from the fault with a smaller fault angle and the stability of fault is seriously affected by the mining excavation. While the obvious increase in stress around fault edge can be observed until coal seam is about 200 m or 150 m away from the fault with a larger fault angle and the stability of fault is seriously affected by mining excavation. Numerical results indicate that the larger the fault dip is, the larger the reasonable mining length in coal seam where a fault near coal seam exists. Moreover, the fault with smaller dip is more easily activated to induce the failure of the fault and the occurrence of water inrush in coal mining. To prevent the occurrence of fault failure accident, we need to study the reasonable mining length of coal seam, to ensure the safety production and increase the recovery ratio of coal.

Abstract: The excavation of large area close to the top of the tunnel, is likely to lead to a big displacement and deformation of the tunnel, even endanger the safety of subways operation. Therefore, it has become a problem urgently to be solved that how to accurately predict and reduce the deformation of subway tunnel caused by excavation of sunken plaza. Build a numerical model in the finite difference software FLAC 3D, then according to the order of the construction organization, calculation and analysis four different reinforcement schemes in the process of the excavation of sunken plaza, the reinforcement schemes are Without reinforcement measures, adopt gantry soil-cement mixing pile reinforcement scheme, sinking square are at the bottom of the uplift pile reinforcement scheme and comprehensive use of soil-cement mixing pile of door and sinking square with uplift pile reinforcement scheme, then comparison and evaluation the effects of the four kinds of reinforcement schemes around the selected four indicators, they are the maximum vertical settlement of the tunnel, the maximum horizontal displacement value of the tunnel, the maximum convergence of a tunnel diameter and the minimum radius of curvature tunnel deformation curve .From the analysis, some conclusions can be drawn.

Abstract: According to the seam floor aquifer inhomogeneity,in order to analysis the coal deformation and failure law in pressurized water ,this paper established mechanical model of nonuniform pressure and fluidstructure interaction models,using numerical simulation software FLAC3D analysis fluidstructure interaction water inrush regularity .Analyzing the extent of damage from the coal seam floor, the stress and displacement when working face promote different distances, this paper carried out the basic rules of mining face water inrush. This study shows that by monitoring the position of bottom water inrush occurs easily, analyzing the influence of pore pressure by the mining ,it can be accurately analysis the risk of water inrush and play an important role in guiding prevention and control of water inrush.

Abstract: In order to control deformation of foundation pit effectively and guarantee safety of building around, utilizing the stress characteristics of arch, use the new spatial retaining structure of arc row piles with arc ring beam on the pile top. The arc ring beam can provide constraint to pile top, so internal force of pile body distribution is uniform, and improve the integrity stability of piles. The ring beam with compression mainly can give use of high compression capability of concrete. According to the high order statically indeterminate characteristics of the retaining structure, calculation model of ring beam and pile respectively is established by the redundant forces between beam and pile top. By using deformation compatibility to set up flexibility equation of the retaining structure, and solve the redundant forces, then calculate the internal force and displacement of ring beam and piles. Through calculating the practical engineering, research the effect of excavation depth on internal force and displacement of piles and the arc ring beam on the pile top.

Abstract: In order to study the expansion properties of slates, this paper tests multiple groups of data, including free expansion ratio, expansion force and expansion strain for the different stratification slates in Chongqing. We found that with the increase of time, the axial expansion ratio and swelling pressure of different stratification slates begin to increase rapidly in the initial period,until gradually moving to a maximum value.In addition, slates stratification in different directions has different expansion properties, the perpendicular to stratification direction has greater expansion ratio, is about 2.5 times more than the expansion ratio of parallel to the bedding. In the constrained conditions, axial expansion ratio of the slates is much larger than that without constraints. Different stratification of expansion pressure and the expansion strain of the slates is linear in the volume remains unchanged. This research project has certain reference value for the civil engineering on the different stratification slates expansion construction in Chongqing.