Shrinkage strain of concrete specimen with different reinforcement configuration was measured at various depths from the exposed surface by using several pairs of displacement sensors. Only one surface of the concrete...Shrinkage strain of concrete specimen with different reinforcement configuration was measured at various depths from the exposed surface by using several pairs of displacement sensors. Only one surface of the concrete specimen was exposed to dry condition during the experiment. The results show that differential shrinkage strain occurs in both plain and steel reinforced concrete specimens according to depths from the exposed surface. A higher reinforcement ratio results in a greater restraint against shrinkage of concrete nearby reinforcement rebar and a worse differential shrinkage strain distribution in the concrete specimen. The restraint against shrinkage of concrete becomes lower with the increasing distance from reinforcement rebar. Under the same reinforcement arrangement, a higher free shrinkage of concrete leads to a stronger restraint against shrinkage and a higher shrinkage stress formation in local concrete. The relationship between shrinkage strain and reduction of relative humidity in reinforced concrete structure is far different from that in plain concrete.展开更多
This paper, based on the strain softening character of rock, and the de formation feature of roadway with badly damaged surrounding rock and adopting the ideal elastoplastic softening model, derives the formula for ca...This paper, based on the strain softening character of rock, and the de formation feature of roadway with badly damaged surrounding rock and adopting the ideal elastoplastic softening model, derives the formula for calculating the supporting resistance for the roadway. It is pointed out that controlling the rheid speed of the rock in the plastic softening area is critical and that the combined supporting, i. e. combining surrounding rock internal rein forcement with external supporting f is the reasonahle supporting to this kiud of roadways. The theory and practice introduced in this paper are of universal significance for harnessing the roadway with badly damaged surrounding rock.展开更多
基金Funded by the National Natural Science Foundation of China(No.50408016)the Fundamental Research Funds for the Central Universities (No. HIT. NSRIF.201198)
文摘Shrinkage strain of concrete specimen with different reinforcement configuration was measured at various depths from the exposed surface by using several pairs of displacement sensors. Only one surface of the concrete specimen was exposed to dry condition during the experiment. The results show that differential shrinkage strain occurs in both plain and steel reinforced concrete specimens according to depths from the exposed surface. A higher reinforcement ratio results in a greater restraint against shrinkage of concrete nearby reinforcement rebar and a worse differential shrinkage strain distribution in the concrete specimen. The restraint against shrinkage of concrete becomes lower with the increasing distance from reinforcement rebar. Under the same reinforcement arrangement, a higher free shrinkage of concrete leads to a stronger restraint against shrinkage and a higher shrinkage stress formation in local concrete. The relationship between shrinkage strain and reduction of relative humidity in reinforced concrete structure is far different from that in plain concrete.
文摘This paper, based on the strain softening character of rock, and the de formation feature of roadway with badly damaged surrounding rock and adopting the ideal elastoplastic softening model, derives the formula for calculating the supporting resistance for the roadway. It is pointed out that controlling the rheid speed of the rock in the plastic softening area is critical and that the combined supporting, i. e. combining surrounding rock internal rein forcement with external supporting f is the reasonahle supporting to this kiud of roadways. The theory and practice introduced in this paper are of universal significance for harnessing the roadway with badly damaged surrounding rock.
