Effect Of Different Stiffness Ring Beam On Mechanics Properties Of Retaining And Protecting Structure Of Piles In Row

New challenges have constantly been turned up by the development of tall buildings in the field of civil engineering. One of them is the retaining and protecting engineering for deep excavation. Now people have laid stress on the quality of retaining and protecting engineering because it has influenced the cost of engineering and process of construction.It has many types of the retaining and protecting engineering for excavation. Piles in row are one of the most common retaining and protecting structures. The affect of top ring beam has not been thought highly at presenti which has been regarded as the safety measure. The whole retaining and protecting structure of piles in row and top ring beam is calculated by the method of cantilever beam, and the result is not reasonable obviously. It is the effect of ring beam in retaining and protecting mechanics properties for excavation that this paper focuses on.In this paper, there are eight groups tests. It is on condition of the retaining and protecting piles imitated by nylon sticks, the top ring beam imitated by steel board, the foundation wadded by sandy soil, and the sectional size and extra load changed. The test result makes known that ring beam and piles in row working as a whole is different from the state having no ring beam. It is best that the stiffness ratio of ring beam to pile is 2 to 3. We think over burying depth of piles is 30% of the whole length when ring beam existing. But it is necessary to decide according to the quality of soil layers and types of piles. The computer program of this paper has the important reference value on test analysis and engineering design. It resolves many complicated questions of calculating.Ring beam may control the top displacement of piles validly. It has affect on keeping buildings stabling around foundation pit. The stiffness ratio of ring beam to pile affects the maximum value of moment near the bottom of excavated pit. The earth pressure over the pit bottom calculated by the trapezoid mode, and the result is better according with the rectangle mode of sandy foundation.The author proposes making further research work in the followingrespects. It will has well-considered factors on the common affect of piles in row and ring beam whole retaining and protecting structure. We need the best results through enhancing imitating and researching the various situations. It should improve the methods of measure and analysis for enhancing the reliability. It will find the accurate calculating method on deflection of soil body so as to ensure the safety of buildings near the pit. Considering the space effect of retaining and protecting frame structure, it will has a space model fitting excavated pit.