山区公路高填方涵洞加筋桥减载方法及其设计理论研究

STUDY ON THE METHOD AND THEORY OF LOAD REDUCTION BY REINFORCEMENT BRIDGE FOR THE CULVERT BENEATH HIGH FILLING

提出了高填方涵洞加筋桥减载方法及加筋桥减载原理,通过模型试验证明了高填方涵洞加筋桥减载的有效性及影响加筋桥减载效果的因素。根据加筋桥减载原理和模型试验结果,建立了加筋桥减载的结构力学模型,推导了加筋桥减载结构设计的计算公式,包括加筋桥的加筋设计荷载计算公式、加筋桥的数量(层数)计算公式、加筋桥的锚固长度计算公式以及加筋桥的加筋长度(跨径)计算公式等,为加筋桥减载结构设计提供了较全面的理论计算依据,并通过现场涵洞测试证明了加筋桥减载的良好效果。模型试验和现场测试表明,加筋桥减载具有减载效果好、施工工艺简单和结构性能安全可靠等优点,不但适用于高填方涵洞减载,而且适用于其他各种填埋式地下洞室的减载。

A new method of load reduction by reinforcement bridge for highway culvert beneath high filling is presented in the paper. According to this method and the principal of load reduction by reinforcement bridge, a reinforcement bridge which is consist of reinforcements and a load reduction ditch filled with unpacked soil is built above the culvert to reduce the earth pressure on it. Because the density of soil in the ditch is lower compared to the earth filled on the culvert, the reinforcements on the ditch will deflect down, and in the course of reinforcements deflecting, the vertical earth pressures are transported to the packed soil around the ditch by the reinforcements, as a result, the earth pressures on the top of culvert are reduced. The results of model test show that the vertical earth pressures on the top of culvert with reinforcement bridge are greatly reduced. The results also indicate that the distribution and numbers of reinforcement and load reduction ditch are important factors which affect on the effect of load reduction. Based on the mechanics mechanism of load reduction by reinforcement bridge and the results of model test, a mechanics model of load reduction by reinforcement bridge is presented and three important formulas, including the formula of load calculation, the formula of the numbers and length of reinforcements calculation, are derived from the mechanics model, and an example is given. To prove the effect of load reduction by reinforcement bridge in practice, the stresses of a concrete slab culvert are tested in field and the good load reduction effect is confirmed by the field test results. The results of model and field culvert testing demonstrate that the method of load reduction by reinforcement bridge can be used to highway culverts and other pipes beneath high filling.