Papers by Author: Bo Li

Abstract: On the basis of the field measurement, the characteristics of advance strata behavior are analyzed in the past filling working face and the advance support method is optimized in the roadway. The practical measure researches show that, because the paste filling supports the overlying strata of the goaf availably, the strata behaviors of 2351 paste filling working face in Daizhuang coalmine are not obvious; And the protective pillar bears a little load, The strata behaviors in non-production side are smaller than that in production side. The overlying strata gravity mainly acts on the coal wall in front of the face and the paste filling in the goaf. The value and main influence range of advance stress in front of the face is quite small and the main influence range is less than 15m. According to the advance strata behavior characteristics of the paste filling working face, the advance support of the track roadway is changed from 3 rows to 2 rows. And the support length of each row reduces from 20m to 15m. The advance support after optimizing can reduce the labor intensity greatly and improve the working efficiency of backfill mining.

Abstract: The creep test of the No. 3 coal seam of Daizhuang Coal Mine is carried. Based on the experiment results, the creep support effect of deep pillar is analyzed with LS-DYNA. The results show that the circumferential initial creep stress of the tested coal is 3.061MPa and the circumferential initial creep stress is far below the axial initial creep stress which is 7.020MPa. In addition, the creep strength is 9.3266MPa and the creep coefficient is 0.6472. According to the test results, the creep support effect of deep strip pillar can be simulated excellently with LS-DYNA. Stress and deformation in simulated strip pillar show evident rheology. Many changes will take place in the stable situation of pillar after the working face mining. Under the effect of the overlying strata, this pillar turns into steady creep state after 15~16 months, then the pillar is able to maintain long-term stable state.

Abstract: 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.