Applied Mechanics and Materials Vols. 204-208

Abstract: The strength of massive jointed rock mass can be estimated based on Mohr-Coulomb criterion and Hoek-Brown criterion without making expensive experiment of massive jointed rock mass in site. Only using regression analysis, through transformation，Mohr-Coulomb criterion is compared with Hoek-Brown criterion, the strength of jointed rock mass can be economically obtained. In this paper, based on Geological Strength Index GSI and parameter Jv(Joint/m3), the strength of massive jointed rock mass can be obtained. As an example of GSI 24 for massive jointed rock mass is taken, generalized Hoek-Brown criterion is analyzed linearly and approximately using regression analysis, strength of jointed rock mass can be economically obtained That provide economical and effective method for practical engineering analysis

Abstract: Groundwater in pores and fractures of rock can result in destruction of a reservoir dam. Therefore, techniques of forecasting characteristics of groundwater flow have wide applications in areas of hydraulic engineering. A consecutive experiment was designed and combined with analyses of groundwater chemistry to solve a groundwater hydrology problem in multilayer pore-fissure media with weak permeability layer occurring in hydraulic engineering construction in China. Results show that changes of electrical conductivity of groundwater samples from wells, springs and drillings with time have a good relevance except a sample in local position with very weak permeability layer; and that a system and pathways of groundwater flow in multilayer pore-fissure rock with weak permeability media can be determined by the method of a consecutive test combined with groundwater chemistry analyses.

Abstract: The main compression layer of Xi’an is over-consolidated. Based on the property, the physical model is designed as a steel cylinder which is 2.5m diameter,3m high. The soil layers are inter-bedded with silty clay and medium-fine sand. The consolidation pressure and overburden pressure is 295KPa. The process of soil deformation was simulated as the water recovering by increasing the water pressure in the medium-fine sand layer. Data monitoring test reveal that the deformation of the medium-fine sand layer and the silty clay layer is piecewise consequent，the consolidation will stop when the water pressure surpass a certain threshold value; During this test, the deformation of sand have the consistency with the variation of stresses in the medium-fine sand, but the deformation of the silty clay layer lagged to the variation of stress. The increase of water pressure in medium-fine sand cause compression pressure of others soil layers to increase. Based on the study of this test, we could predict that the land subsidence of Xi’an will not stop unless the confined water pressure surpasses the threshold value. What is more, we can reduce the subsidence through spasmodic pumping without cutback of pumping.

Abstract: Phosphorous fractionation is a method developed to estimate sizes of readily soil available P pool, soil P sub-pools and their ability to replenish the available P. Three types of acid soils (1aterite red soil, yellow red soil and brown red soil) were used in pot experiment under a rain-shelter condition to investigate the effect of lime amendment on P fractions and their bioavailability by plant of broad bean. A novel phosphorus fractionation scheme was developed and used to study the phosphorus fractionation of the tested soils compared with the two typical soil phosphorus fractionation schemes, adopting a series of extractants such as 0.25mol L-1 NaHCO3, 1h (for Ca2-P), 0.5mol L-1 NH4F (pH8.5), 1h (for Al-P), 0.7mol L-1 NaClO, pH 8.05, 85°C water bath 30min (for Org-P), 0.1mol L-1 NaOH-0.1Na2CO3, 4h (for Fe-P), 1mol L-1 NaOH, 85°C water bath 1h (for O-Al-P), 0.3 mol L-1 Na-citrate-0.5 g Na2S2O4 -0.5 mol L-1 NaOH, 85°C water bath 15min (for O-Fe-P), 0.25mol L-1 H2SO4, 1h (for Ca10-P). Main results are obtained just as follows: besides Ca2-P, Al-P, Fe-P and O-Fe-P are potentially available phosphorus resource. Although O-P reflects the difference of P between lime and control treatment well, when it appears as a whole, it needs further subdivision to reflect soil phosphorus biologically availability difference better.

Abstract: On the foundation of the item that the residence flood controlled technique and standard tested and the analysis according to the formation of the sediment and the regulation of the sedimentation in the actual river. In the process of the studied item, design a kind of a new sedimentation basin in order to lower the sand carrying capacity of the down water in the limited distance and the biggest limit. Through the model experiment of this kind of the sedimentation basin and find out the result of the sink the sand under the different discharge, in order to guide the actual engineering application.

Abstract: Based on limit equilibrium method, the subgrade stability formula under rainfall infiltration is derived and the influence of matric suction on subgrade stability is analyzed using the safety coefficient formula. What’s more, the affection of rainfall intensity, duration and soil permeability on subgrade stability is studied and the influences is obtained. The presented research provides the theory basis to controlling of rainfall infiltration.

Abstract: In order to study the creep properties of coal or rock containing gas, the creep properties of coal or rock without gas were studied firstly. Through analyzing the previous creep experiment results of coal or rock, one nonlinear damage creep model of coal or rock was founded based on the general Kelvin model. In this model, assumed that the damage is a function of stress level and time, and introduced one nonlinear hardened function into the general Kelvin model, the nonlinear damage fading creep equation and the nonlinear damage creep whole process equation were obtained. Besides this model, considering the composite structure of coal or rock, gas and gas absorption layer, and assuming that this structure has the stick-slip property under the outside load, so a stick-slip module was added in the general Kelvin model and a new nonlinear damage creep model of coal or rock containing gas was founded. Given the value of the material parameters in the two equations, the creep curves varied with the time were drawn under different axial compression. Through the theoretical curves, the nonlinear damage creep model in this paper was proved to be rational.

Abstract: Low permeability, low abundance, water-bearing gas reservoirs are widely distributed in China, and their reserves constitute 85% of all kinds of reservoirs in current. It has important realistic meanings to develop them. Determining of reasonable gas well production is the prerequisite to achieving long-term high productivity and stable production. This paper takes Shanggu gas field at Sulige Gas Field for example, respectively from the dynamic data analogy methods, the pressure drop rate statistical methods, gas curve methods, production system nodal analysis methods, and studied the reasonable capacity of the low permeability gas reservoir. Through comprehensive analysis，the comprehensive technical indexes about single well reasonable production was determined.

Abstract: Soil-Structure Dynamic Interaction (SSDI) is an important content of earthquake engineering and earthquake resistance of engineering structures. However, very few researches have been done on Pile-Soil-Structure Interaction (PSSI) under blasting vibration so far. In this paper, large finite element software ANSYS/LS-DYNA is used to simulate PSSI under blasting vibration. Research shows that the top displacement, acceleration and shear stress of piles are larger than the tip of piles, and the distribution laws are inverted triangles. What’s more, PSSI system sustains its vibration after the impact of blasting seismic waves, but the effect of the vibration is smaller than the blasting seismic waves does, which roughly conform to the measured results. These conclusions could provide theory basis for earthquake resistance of engineering structures and design of pile foundation.

Abstract: As the population growth and land resources declining, high-rise building project is increasingly common in the construction work. Through in-depth thinking and active exploration, specific attention to matters of deep foundation pit and pile foundation construction technique, which is the key construction techniques in the high-rise building project, was summarized in this article. It suggests to make a careful and detailed geological survey, and then choose the right design program and develop a reliable construction plans. This scheme was proved to be a useful reference and guidance for the development of high-rise building construction technology.