再生混凝土压-剪应力下受力性能与破坏准则

为了研究再生混凝土在压剪复合受力下的力学性能，利用真三轴试验机对30组再生混凝土立方体试件分别进行了直接剪切和压剪性能试验，对比了试件破坏形态的差异，分析了再生粗骨料取代率、水灰比及压应力比对剪切强度的影响，选用不同破坏准则对压剪复合作用下的强度进行了分析。结果表明：再生混凝土直剪及压剪复合受力破坏形态与普通混凝土相似，直剪强度随再生粗骨料取代率增大而减小，随水灰比增大而减小；压剪复合受力状态下，再生混凝土的极限剪应力随着压应力比的增大呈增幅逐渐减小的增大趋势；通过方差计算，定量分析了压应力比和再生粗骨料取代率两个因素对压剪复合应力下再生混凝土立方体试件剪切强度的影响程度，发现压应力比对剪切强度的影响更明显。选用不同强度准则对试验数据进行分析，得出基于八面体应力空间的破坏准则与试验结果吻合程度最高，且随着再生粗骨料取代率的增加，该准则的精度也逐渐提高。

Mechanical properties and failure criterion of recycled aggregate concrete under compressive-shear stress state

In order to study the mechanical behavior of recycled aggregate concrete when subjected to compressive-shear stress states, experiments were conducted with 30 sets of specimens by using a triaxial testing machine. The failure modes of the specimens were obtained. The influence of replacement ratio of recycled coarse aggregate (RCA), water to cement ratio and compressive stress ratio on the shear strength was analyzed. Different failure criteria were selected to analyze the shear strength under compressive-shear stress state. The results show that the failure mode of recycled concrete under direct shear and compressive-shear states is similar to that of ordinary concrete. The shear strength decreases with the increase of replacement ratio of RCA, and decreases with the increase of water to cement ratio. Under compressive-shear state, the ultimate shear stress increases with the increase of compressive stress ratio, however, the increasing trend gradually slows down. Based on variance calculation, the influence of the compressive stress ratio and the RCA replacement ratio on shear strength under compressive-shear composite stress state was quantitatively analyzed. It is found that the influence of compressive stress ratio on shear strength is more obvious. Different strength criteria were selected to analyze the strength. The failure criterion based on octahedral stress space has the best agreement with the test results, and the accuracy of the criterion increases with the increase of the replacement ratio of RCA.