Nine groups of cement mortar with different mix proportion were designed to measure their fluidity 0h, 0.25h, 0.5h, 0.75h and 1h later, compressive strength and rupture strength of 3d, 7d and 28d were also tested to find out the relationship between compressive strength, rupture strength, water-cement ratio and sand-cement ratio by software Origin. Considered the three factors above, the optimum mixture ratio was determined finally to meet the requirements.
In this paper, the responses of cavern underground reinforced by external cross-anchoring under blast loading were simulated by three-dimensional computational model made in software FLAC3D. It compared and supplementary analyzed the calculated displacement curves, the nephograms of maximum principal stress and destruction of cavern with that of model test, and analyzed the effect and mechanism of reinforced cable in this way comprehensively from deformation and destruction of surrounding rock outside, dynamic strain of cavern, energy absorption by anchor and energy consumption transferred through stress etc.
The objective of this paper is exactly to assess the effect of anti-explosion for tunnels anchored outside under the condition of thin coating layer. To meet the similarity requirements, two groups of test models were made to simulate the responses of caverns under blast loading. It showed that: been anchored outside, displacements of the wall in caverns was decreased, so were the acceleration and compressive stresses with varying degrees, but the deformation stiffness and the overall stability were enhanced. This method does not take up space inside but it is beneficial to reduce the minimum thickness of protective layer and provides a new way to improve the anti-explosion performance for caverns under the conditions of thin coating layer.
It analyzed the reasons for the early cracks in high-performance concrete, and prepared overall program to improve the mechanical properties and the durability of the HPC. It studied on cracking control of HPC at early age and improvement of impermeability by mixing ratio test. The result showed that , it get better inhibition on the early cracks by reasonable adjustment to the water-binder ratio, fly ash and mineral fine powder dosage with saturated aggregates and the right amount of expansion agent, and it also provided high-performance concrete for different performance with a mixture ratio test methods.
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