The Research On Damages And Distorts Of Rock-concrete

In the process of construction and operation of large-scale civil engineering, The interaction between engineering project and geologic body is a basic question in civil and geotechnical engineering stability , In this thesis, the deformation, damage and acoustic emission (AE) of the concrete, the sandstone, the bi-material ,the bi-body specimens due to uniaxial compression load and uniaxial cyclic compression load have been investigated with the method of a combination of experimental investigation, theoretical analysis and numerical simulation.The four models of uniaxial compression test were carried out. Meanwhile, the AE signal at the process of compression was monitored by AE instrument as well. Result show that the bi-material specimen is a continuous medium and two medium lateral deformations were cooperated there was damaged together. Meanwhile, surface of the specimen appear part-through and continuous macro-cracks which from concrete to rock. In the initial stages of the loading it has a few AE signs while at about 20% peak load appear lots of sonic emission Activity. Keep loading propagating of cracks is much slower and also has a low emission rate , at 70% of peak load AE become much active. While the bi-body specimen is discontinuous media, Propagation of the crack has been blocked by two medium's interface and under smooth interface circumferential strain of the two medium propagated respectively and have extreme disparity, In initial stages of the loading there was a few AE signs, keep loading, propagating of cracks was much slower and also has a low emission rate, at 75% of peak load AE increased more significantly.Because AE is the elastic wave that the crack development releases, the AE message can take the measure of the damage development. The article proposed for the first time use the "normalization" of the AE count as damage variable D. Based on the analysis of the experiments, through the concrete theoretical analysis confirms its rationality.In the article further analysis of the concrete, the sandstone, the bi-material model and the bi-body model specimens with the "normalization" of the AE count as damage variable, Obtains the corresponding damage evolution curve and the equation, find that three is the continual body, its damage evolution divides into three stages, but latter for discontinuous body, the damage evolution divides into four stages. Substitution damage unidimensional elasticity this construction obtains the theory stress - strain curve found to coincide with the experimental stress-strain curve was good, Verification that the "normalization" of the AE count can characterize damage variable. Thus the relation between the AE parameter and the damage variable is established.The experiment of four models were carried out under uniaxial cyclic compression load and at the mean time the AE signal at the process of compression was monitored by AE instrument as well. Result show that four samples of each loading and unloading curves do not coincide with the curve, forms a plastic-loop. With the number of cycles, the plastic-loop becomes increasingly close. Under the same loading environment, the elastic modulus, Poisson's ratio, the damage variable of bi-material specimen decreased slowly than the bi-body specimen. AE of the bi-material specimen after second circulation massively reduces, and after the sixth cycle hardly produce, until last cycle produce a small amount. AE of the bi-body specimen although after second circulation massively reduces, but every circle in the ceiling near the small stress have the few amount, Verification that under the same loading environment, the bi-body specimen damage accumulates is quicker.Obviously, the bi- material specimen and the bi-body specimen have the difference in the destruction process, the sound emission characteristic and this construction relation.