Similar Material Model Research Articles

New Viewpoint of Foundation Stability of Newly Building upon Goaf

Foundation deformation of new buildings upon old mined out area and the survival subsidence and deformation of old goaf had been studied by similar material model in the paper. When additional stress caused by building foundation reached a thick hard rock sandstone stratum, the vertical deformation was blocked while horizontal deformation expanded significantly. The actual influence depth of ground loading is obvious smaller than theoretical result. The spread depth of building load upon mined out area is related with the disturbed degree by mining, the ground loads spread depth is greater with the increase of disturbance degree. After passed through key strata and caused overburden stratum separation closed, the additional stress caused by ground foundation would quickly reach inside of goaf, caused movement and deformation on strata upon goaf. But the movement and deformation is relied to the situation of goaf, there would not significant activation in all mined out areas.

Study on Failure of Soft Overburden of Fully Mechanized Top Coal Caving

The similar material model experiment takes the NO.S2S9 coal face in DaPing coal mine as a prototype to research the characteristics of movement and failure of the soft overburden under fully mechanized top coal caving conditions. The abutment pressure distribution and periodic weighting, caving span are given by monitoring the stress and strain in the similar material model. The results show that rocks fracture extended from button with the advance of workface. The first caving step distance of main roof is 34m. The periodic caving step distance of main roof is 10m. The internal stress field is 10m and the peak abutment pressure point is 80m far away from the coal wall, while the disturbance range in anterior coal wall is 200m. Some cracks are closed in the later stage. The advance of around 300m is the distance that the water flowing fractured zone’s height reaches the highest value. The biggest height of water- flowing fractured zone is 140m. The soft overburden has strong plastic deformation capability. The synchronism of failure and movement of overburden is strong. The failured overburden is compacted and the cracks keep close with the advance of workface. The simulation experiment provides a reference bases for the application and promotion of thick seam mining technology.

Experimental Investigation of Simulating Similar Materials of Multi-Seam Mining in Steep

The similar material model method is used to simulate to the movement of cover rock and ground which is caused by mining underground coal, the substance of deformation and failure law of similar material model method is that artificial materials which are used in the experiment have similar physical and mechanical properties as archetype, affinity constants of geometry, movement and force are used as similarity index and criteria in the simulation experiment as the most important factors. The prototype model is made into a certain proportion model in reduction, and the initial state and boundary conditions of model must be similar as archetype. Then exploit the simulating model, the regular patterns of fault destruction, curve, movement and deformation of cover rock can be discovered in the process of exploiting the simulating model, and the movement and deformation of the surface and its sphere of influence can also be got. Finally the observations of model can be calculated and projections up to the prototype by the similarity index, so the most important regular pattern of the prototype can be got.

Application of Ordinary Digital Photography Technology in Data Collection of Similar Material Model Experiment

Application of Ordinary Digital Photography Technology in Data Collection of Similar Material Model Experiment

Experimental Study on Performance of Pressure Sensor and Similar Material Model

In this paper, in order to get the mechanical properties of the different ratio similar material models and resolve the matching problem of pressure sensor and measured similar material, according to the similarity theories, the repeated loading tests on different ratio similar models were performed by multi-stage loading. This paper got the stress-pressure curve and the failure strength of each model. Test results show that there are significant differences in the matching abilities between different ratio similar materials and pressure sensors, and the matching abilities between different models of the same ratio and pressure sensors also have some differences. The matching ability between similar material and pressure sensor should be detected, so as to correct the experimental data. Test results also show that different ratio similar materials have stable and different mechanical properties. The mechanical properties of the similar material can be adjusted appropriately by changing the ratio. The mechanical properties of different ratio similar materials should be tested before the similar material simulation test.

Deformation characteristics of surrounding rock of broken and soft rock roadway

A similar material model and a numerical simulation were constructed and are described herein. The deformation and failure of surrounding rock of broken and soft roadway are studied by using these models. The deformation of the roof and floor, the relative deformation of the two sides and the deformation of the deep surrounding rock are predicted using the model. Measurements in a working mine are compared to the results of the models. The results show that the surrounding rock shows clear rheological features under high stress conditions. Deformation is unequally distributed across the whole section. The surrounding rock exhibited three deformation stages: displacement caused by stress concentration, rheological displacement after the digging effects had stabilized and displacement caused by supporting pressure of the roadway. Floor heave was serious, accounting for 65% of the total deformation of the roof and floor. Floor heave is the main reason for failure of the surrounding rock. The reasons for deformation of the surrounding rock are discussed based on the similar material and numerical simulations.

Material modelling in the seismic response analysis for the design of RC framed structures

Two similar continuum plasticity material models are used to examine the influence of material modelling on the seismic response of reinforced concrete frame structures. In the first model reinforced concrete is modelled as a homogenised material using an isotropic Drucker–Prager yield criterion. In the second model, also based on the Drucker–Prager criterion, concrete and reinforcement are included separately. While the latter considers strain softening in tension the former does not. The seismic input is provided using the Eurocode 8 elastic spectrum and five compatible acceleration histories. The results show that the design response from response history analyses (RHAs) is significantly different for the two models. The influence of compression hardening and strength enhancement with strain rate is also examined for the two models. It is found that the effect of these parameters is relatively small. In recent years there has been considerable research in nonlinear static analysis (NSA) or pushover procedures for seismic design. The NSA response is frequently compared with that obtained using RHA, which also uses the same material models, to verify the accuracy of the static procedure. A number of features exhibited by reinforced concrete during dynamic or cyclic loading cannot be easily included in a static procedure. The design NSA and RHA responses for the two material models are compared. The NSA procedures considered are the Displacement Coefficient Method and the Capacity Spectrum Method. A comparison of RHA and NSA procedures shows that there can be a significant difference in local design response even though the target deformation values at the control node are close. Moreover, the difference between the mean peak RHA response and the pushover response is not independent of the material model.