CONCEPTS OF MECHANICAL PARAMETERS TRANSFER IN SOLID MEDIUM AND ITS APPLICATION IN ENGINEERINGS

Based on investigation into four aspects of qualitative mechanical analysis, principle model experiments, engineering dynamic load tests and numerical calculation, it was discussed that the transfer of stresses and accelerations in stratum medium have a close relation with its relative rigidity. The concepts of stresses and accelerations transfer in solid medium and its corresponding generalized, composite structure system are presented. The survivability of underground engineerings and protective engineering will be greatly increased if these concepts are correctly used in construction.

Development of cooperative system bridges

Cooperative system bridges comprise several basic structures that act jointly to improve structural characteristics. We delved into the historical development of cooperative system bridges. Cooperative systems are classified as different-load cooperative systems and same-load cooperative systems by distinguishing the modes of load distribution. For different-load cooperation,individual basic structures are at different positions in the direction along bridge axis and carry the loads separately. While for same-load cooperation,all basic structures overlap in geometrical locations and support the entire loads conjointly. The choosing of span ratios between basic structures,the design of connections of different-load cooperative systems were discussed as well as optimizations of relative rigidity for same-load cooperative systems which greatly influence structural characteristics. The general situation and several structural measurements of several cooperative bridges were demonstrated. This information can assist engineers in developing their concepts in cooperative systems and can lead to more efficient and economical cooperative bridges.

FACTORS INFLUENCING BENDING RIGIDITY OF SUBMERGED VEGETATION

The bending rigidity of submerged vegetation is closely related with vegetative drag force. This work aims at determining the effects of flow conditions and characteristics of vegetation on the bending rigidity of submerged vegetation. Based on the dimensional analysis method, the factors influencing the bending rigidity of individual submerged vegetation were analyzed. The relationship between the relative bending rigidity and its influencing factors was investigated by experimental observation, and a relative bending rigidity expression for submerged vegetation was obtained by means of multiple linear regression method. The results show that the submerged vegetation has three states under different inflow conditions, and the each critical relative bending rigidity of individual submerged vegetation was determined for the different states of submerged vegetation.

Influence of bending rigidity of submerged vegetation on local flow resistance

The different state of the submerged vegetation has different influences on the flow resistance. This paper explores the relationship between the state and the resistance of an individual submerged vegetation, and the relative bending rigidity of the submerged vegetation is determined by the state of the submerged vegetation. Based on the experimental observations, the state and the resistance of an individual submerged vegetation are analyzed under different inflow conditions. At the same time, the influences of the various submerged vegetations on the flow resistance are discussed under the same inflow conditions. Some interesting relationships are obtained between the flow resistance and the relative bending rigidity of the submerged vegetation, and it is shown that the flow resistance increases with the increase of the relative bending rigidity of the submerged vegetation, and they are positively correlated.