Advanced Materials Research Vols. 671-674

Abstract: At present, in-situ stress was not considered in Limit Equilibrium Method (LEM) of slopes, the influence of in-situ stress is very small on the stability of conventional slopes, but in deep-depressed open-pit mines, the influence should not be neglected. Formula for calculating the Factor of Safety (FOS) under the effect of horizontal in-situ stress was deduced using General Slice Method (GSM) of two-dimensional (2D) limit equilibrium method in this paper，a corresponding program SSLOPE was built, and the software was used in a deep- depressed open-pit iron mine. The results show that the FOS of the slope decreased by 20% when horizontal in-situ stress is considered, some reinforcements must be taken. Therefore, the influence of in-situ stress on slope stability should be taken into account in deep open –pit mines.

Abstract: The double-row piles retaining structure (DRPRS) is widely applied in the excavation engineering, but its calculation theory is immature and in appropriate. Based on the theory of earth pressure distribution, the distribution characteristics of earth pressure is analyzed to different layout form, and the general formula of earth pressure is derived. From the perspectives of the morphology of slip surface, linear slip surface morphology and broken-line slip surface morphology are proposed based on the feature of the DRPRS. A new calculation model is proposed combining the earth pressure and slip surface morphology. On this basis, one example is used to analyze the force and deformation mechanism of the DRPRS in detail. The research results can guide the engineering practices and promote the development of calculation theory for the DRPRS.

Abstract: Creep curves at different temperatures and stress-strain isochrones were abtained by using uniaxial creep test for frozen soft rocks of Cretaceous formation. The test results showed that the creep process was nonlinear,and the viscoelastic creep compliance was related to time and stress. On the basis of generalized Kelvin model,the nonlinear viscoelastic creep expression was proposed by nonlinear improvement on creep compliance and the parameters were also identified. Through the comparison between the theoretical curves and the test results,the correctness and rationality of the model are verified.

Abstract: Suitable anti-sliding spacing is one of the most important parameters in the design of anti-sliding piles. It is closely related to whether the soil arch effect can be completely played. Based on analyzing the stress model of soli arch effect on the adjacent soil, the relationship between the piles spacing and the cohesive force c as well as the internal friction angle of the soil behind piles is proposed. The reasonable pile spacing formula which based on the limiting equilibrium equation of state was deduced and verified the method with engineering practice.

Abstract: The bedding high rock slope is most likely to failure in the rock slopes. It is the sliding and bending deformation model (buckling failure) according to deformation characteristic of the north wing slope at the open-pit mine. Considering the influence of rocky self-weight, seismic force and groundwater, the failure mechanism of bedding high rock slope by energy method is researched on the basis of stability theory for elastic plane. And the critical length is obtained. Finally, the influences of model geometry on the critical length, such as the rock stratum dip angle, thickness and width length ratio, is analyzed.

Abstract: The microstructure and composition of carbonaceous shale are analyzed by using the scanning electron microscope and x-ray diffract meter, the dynamic characteristics of the disintegrating mechanism and microstructure are also studied. The results show: the connection between mineral particles of carbonaceous shale are destroyed under the action of water, the mineral particles will expand rapidly under the forces of sunlight and temperature change, generating uneven stress and micro-pores. The micro-pores will destroy the structure of rock and make the phenomenon of softening and disintegration. The results could provide a theoretical basis for the filling of carbonaceous shale embankment and the protection of slope.

Abstract: Acoustic emission technique based on sampling and disposing of the elastic wave caused by rock mass deformation, can comprehend the internal force, damaged degree of target component or material. Acoustic emission system as a dynamic non-destructive testing program, has now been widely used in various fields of engineering. Research on rock mass acoustic emission technology is to identify the stable status of the rock mass by using acoustic emission instrument to receive the elastic wave. Rock mass acoustic emission instrument requires high precision and high sampling frequency. The research status of the acoustic emission instrument and the problems appears in developing the device introduced in this article could be the reference for the future study.

Abstract: The number of test times and test effectiveness are dependent on the test approaches in sensitivity analysis of the slope stability. In the paper, considering the mechanical parameters and groundwater of rock and soil, the sensitivity analysis of the slope is researched by the uniform experimental design. Its results are analyzed through grey correlation analysis. It is shown that the change of groundwater level in the open-pit slope is the most sensitive in the open-pit slope.

Abstract: Sensitivity analysis of double-row piles is often obtained by changing the value of single influencing factor and doesn’t considering the interaction of influencing factors. So, a new sensitivity analysis method is proposed which can consider the interaction of influencing factors. In this method, uniform design (UD) and alternating conditional expectations regression (ACE) are used. The embedded depth of the forward pile, row space, length of the back pile, equivalent thickness of forward pile, equivalent thickness of coupling beam, and equivalent thickness of back pile are six input parameters called influencing factors. The maximum horizontal displacement of the pile head (MDP), maximum bending moment of forward pile (MMF), maximum ground settlement (GS), and coefficient of global stabilization (CGS) are four outputs as target parameters. The sensitivity can be obtained in this geological condition, excavation depth and surrounding environment. It is showed that the stiffness of back pile is the critical influence factor to MDP, the stiffness of forward pile is the critical influence factor to MMF and GS, and the length of back pile is the critical influence factor to CGS.

Abstract: A model is founded to simulate the process of artificial island construction by numerical analysis method. The displacement and deformation of the steel cylinder are analyzed. From the results, the settlement of steel cylinder is great, and the maximum is 28.5cm. At the same time, the steel cylinder has lateral displacement in the process of the island construction. The maximum lateral displacement is 12cm. The major influencing factor to the deformation of steel cylinder is the construction of filling sand inside and outside of island and flinging stone. Therefore, the settlement and displacement of steel cylinder should be monitored nearly during this construction step.