水岩作用下裂隙岩体变形特性试验研究

为了解水岩作用对完整岩体及损伤裂隙岩体变形特性的影响,在一定应力状态下将岩样预压损伤后,分别在0 MPa、0.4 MPa、0.8 MPa的水压力缸中密封浸泡30 d再进行重复加载破坏试验。试验结果表明:经预压破坏后,未浸水的裂隙岩样在不同围压下再次加载至完全破坏时,极限应变变化幅度较小,低于7%,弹性模量降低12%~23%,变形模量降低3%~5%,极限应变、模量变化与围压之间没有明显关系;压力水浸泡对岩体软化作用明显,经预压破坏含有裂隙的岩体,浸泡后再次加载时,极限应变增加0%~37%,弹性模量降低28%~61%,变形模量降低32%~57%。相同围压下,含预压裂隙岩样在浸泡后的强度相比完整岩样未浸水时有较大幅度的下降。比较不同水压浸泡后裂隙岩样,随着浸泡水压的增大,岩样强度降低程度越大;随着围压的增大,岩样强度随水压增大降低的程度逐渐减小。含预压裂隙岩样若不考虑压力水浸泡作用,第二次加载强度与第一次加载相比亦有所降低,围压越大,降低程度越小,裂纹对岩体强度的影响越小。与"完整"岩体相比,裂隙岩体对水软化作用更加敏感,长期浸泡后岩体力学性质弱化明显,更易产生不稳定问题。

Experiment research on deformation characteristics of fissured rock mass under water-rock interaction

In order to find out the influence from water-rock interaction on the deformation characteristics of both the intact rock mass and the fissured rock mass，a repeated loading failure experiment is made on the rock samples after the preload-failure under a certain stress state，which are sealed and soaked into the water pressure cylinders of 0 MPa，0. 4 MPa and 0. 8 MPa respectively for 30 d. The experiment result shows that after preload-failure，the ultimate strain changing amplitude of the unsoaked fissured rock sample is less and lower than 7% when it is loaded once again to full failure，for which the elastic modulus is decreased by 12% ～ 23% and deformation modulus is decreased by 3% ～ 5% ，while there is no significant relationship among the ultimate strain，variation of modulus and the confining pressure. The water soaking effect is quite significant on rock softening. The ultimate stain is increased by 0% ～ 37% ，the elastic modulus is decreased by 28% ～ 61% and the deformation modulus is decreased by 32% ～ 57% for the preload-failured rock mass with fissures when it is loaded once again after soaking. Under the same confining pressure，the strength of the soaked rock mass with preload-fissures is to be decreased to a large extent if compared with that of the unsoaked intact rock mass. Comparing the fissured rock samples those are soaked under various water pressures，the decrease of the strengths of rock samples are to be larger and larger along with the increase of the soaking water pressure，while following with the increase of confining pressure，the rock strengths are to be gradually decreased along with the increase of water pressure. If the pressure water soaking effect is not considered，the strength of the preload-fissured rock sample after the secondary loading is to be decreased to a certain extent if compared with that after the primary loading，i. e. the larger the confining pressure is，the less the decrease is to be and the less influence from fissure on rock strength is to be. Compared with the intact rock mass，the fissured rock mass is more sensitive to the softening effect of water，thus the mechanical properties of the rock mass is to be significantly weakened and more prone to cause the problem of instability.