The Evolution Mechanism of the Slope Toppling Deformation for Early-Warning Analysis

With massive engineering projects performed in high and steep mountain areas, the evidence of toppling deformation, which has been an important engineering geological problem in construction, has been exposed and observed in quantities. Three key issues in the early warning of toppling slopes are the boundary condition, evolution mechanism, and deformation stability analysis. This paper investigates an evolution mechanism for timely predicting the occurrence of toppling induced slope failure in rock masses, relates boundary formation and progressive development about toppling fracture planes. By describing an instantaneous toppling velocity field and identifying two possible fracture plane geometries (linear and parabolic), the optimal path of toppling fracture plane is searched via critical toppling heights (i.e., minimum loads) calculation using the upper bound theory of limit analysis. It is interesting to find that no matter what the slope structures and mechanical parameters are, the optimal path of toppling fracture plane is straight and most likely oriented perpendicular to the bedding planes. Hereby, considering structural damage will enable progressive toppling deformation instead of systemic failure, the toppling deformation evolution is probably taking place of a loop following the formation of the first fracture plane due to exceeding slope critical height. In the loop, deformation and column inclination updates due to fracture plane formation and fracture plane inclination increase to adjust the changed inclination of columns, as it may take degrees perpendicular to columns. And this progressive formation of ever more inclined fractures plane is what lead to sliding collapse. Altogether we divide the toppling evolution into 5 stages, and define the instability criterion for toppling deformation transform into sliding collapse as the fracture plane inclination being equal to its friction angle. In addition, a PFC2D simulation of the entire slope toppling process is performed to verify this speculative evolution mechanism, and a satisfactory result is acquired. Finally, a deformation calculation model of toppling slopes is proposed for stability analysis in accordance with the instability criterion, which is further applied in a typical toppling case. The findings of this study could lay a foundation for the deformation, stability and early-warning analysis of toppling slopes.

Shear Strength Deterioration Effect and Slope Reliability Analysis Under Extreme Ice-snow Melting Conditions

Extreme ice-snow melting in winter affects the infiltration process of snow water on the slope surface significantly, and plays an important role in the deformation stability of landslide. The fluctuation trend of slope stability under ice-snow melting is the same as that of soil volume water content. The deterioration effect of mechanical parameters will directly affect the deformation stability of bank slope. Based on this, the ice-snow melting cycle model test of slope soil was designed and carried out. The results are showed.(1) We were established an ice-snow melting model based on physical process. In the process of ice-snow melting, the soil cohesion and internal friction Angle have obvious deterioration effect .The deterioration of cohesion is obviously larger than that of internal friction Angle. In the early part of the ice-snow melting cycle, the deterioration of shear strength parameters is very obvious. Among them, the deterioration of shear strength parameters caused by the first four ice-snow melting cycles accounted for about 70% of the total deterioration. After the G2/T2 ice-snow melting cycle, the degree of phase deterioration gradually decreases. The deterioration trend of shear parameters of soil samples gradually tends to be gentle. (2) In the ice-snow melting cycle, the inside of the soil samples have micro-cracks, fissures repeatedly opened and closed, gradually developed and converged. The result is that the soil samples change from dense state to loose state where internal cracks develop. The internal damage of soil samples is the fundamental reason for the gradual deterioration of shear strength.（3）We are keep to the relative independence principle of creep model and unsaturated seepage equation. We are studied and improved the parameter solving method of creep model. The modified model is reasonable and effective. The creep trend and main characteristics of the unsaturated soil can be described well. Shear strength deterioration effect and slope reliability analysis under extreme ice-snow melting conditions .It has important reference significance to the protection of extreme snow and ice disaster on the bank slope.

Optimization and Application of Support Scheme for Tunnel with High In-situ Stress in Ningchan

Based on the national highway 569 Mandala Datong highway Ningchan tunnel, the study on the optimization design of high ground stress tunnel support parameters is carried out. The results show that the single-layer primary support with I20b as the main support framework cannot control the large deformation of high ground stress tunnel, mainly manifested as arch frame failure and concrete spalling; adopting “double-layer initial support” can control large deformation to a certain extent; increasing the stiffness of inner layer support can reduce the “double-layer” to a certain extent The results show that the cumulative deformation of “support”, but cannot significantly shorten the deformation stability period; appropriately increasing the reserved deformation between the inner and outer layers of the initial support has the best supporting effect, the cumulative deformation is small, and the deformation stability period is shortened. The research results provide a basis for similar high stress tunnel support measures.

Gas molding of structure parts at non-linear ductile deformation of anisotropic materials

There are offered correlations for the computation of gas shaping technological parameters of structure elements. A state of material non-linear viscosity (creep) is accepted. The energetic equilibrium equation, equations of damage capacity and a criterion of local deformation stability are used. There is computed gas pressure, operation duration (time), material damage capacity, critical deformation at the formation of volume casing. Product samples are presented.

Gabor Frames and Deep Scattering Networks in Audio Processing

This paper introduces Gabor scattering, a feature extractor based on Gabor frames andMallat’s scattering transform. By using a simple signal model for audio signals, specific propertiesof Gabor scattering are studied. It is shown that, for each layer, specific invariances to certainsignal characteristics occur. Furthermore, deformation stability of the coefficient vector generatedby the feature extractor is derived by using a decoupling technique which exploits the contractivityof general scattering networks. Deformations are introduced as changes in spectral shape andfrequency modulation. The theoretical results are illustrated by numerical examples and experiments.Numerical evidence is given by evaluation on a synthetic and a “real” dataset, that the invariancesencoded by the Gabor scattering transform lead to higher performance in comparison with just usingGabor transform, especially when few training samples are available.