中墩锚块底部接触方式和锚索优化研究

为了改善预应力闸墩受力状态,同时在节约成本的基础上,保证其结构的安全运行,从锚块与闸墩接触方式、锚索吨位和次锚索位置三个方面进行优化研究,对预应力闸墩进行优化分析,进而改善闸墩颈部、锚块和锚固洞的应力状态。结果表明:锚块底部与闸墩采用分离式接触方式,可以大大降低锚块下游面与闸墩交界处的拉应力。预应力锚索的拉锚系数的增大有利于减小闸墩颈部的拉应力,但同时锚块和锚固洞周围的拉应力会有所增大。次锚索靠近锚块下游面,可以更好地抵消主锚索对锚块产生的局部拉应力,但对闸墩颈部和锚固洞的影响很小。此算例推荐锚块底部与闸墩采用分离式接触方式;拉锚系数采用1.95,即主锚索永存吨位为3 200 k N,次锚索永存吨位为1 900 k N;水平次锚索尽量靠近锚块下游面布置。

Optimal study on contact mode of bottom anchor-block and anchor cable of central pier

In order to improve the stress status of the pre-stressed gate pier and ensure the safe operation of its structure on the basis of cost-saving at the same time，a deep study is made from three aspects，i.e. the contact mode between anchor-block and gate pier，the anchor cable tonnage and the position of the secondary anchor-cable，so as to make an optimal analysis on the pre-stressed gate pier，and then improve the stress status of the gate pier neck，anchor-block and anchoring-hole. The result shows that the tensile stress at the interface between the downstream face of the anchor-black and the gate pier can be largely decreased by adopting a separated mode for the contact between the bottom of the anchor-block and the gate pier. The increase of the anchorage coefficient of the pre-stressed anchor-cable is favorable for reducing the tensile stress at the gate pier neck，however，the tensile stress around both the anchor-block and the anchoring-hole can besimultaneouslyincreased to a certain extent. If the secondary anchor-cable is near the downstream face of the anchor-block，the local tensile stress caused by the main anchor-cable can be better offset，but it has little effect on the neck of the gate pier and the anchoring-hole. It is recommended from this calculation case to adopt the separated mode for the contact between the bottom of the anchor-block and the pier，1.95 for the anchorage coefficient，i.e. the permanent tonnage is to be 3 200 kN for the main anchor-cable and 1 900 kN for the secondary anchor-cable； while the horizontal secondary anchor-cable must be arranged near the downstream face of the anchor-block as close as possible.