新老混凝土结合面对重力坝稳定性影响的研究

Study on influence of contact sliding along new-old concrete joint interfaces on gravity dam stability

在混凝土大坝工程建设中,对已建大坝进行适度加高是提高水库利用效率和防治安全的一种重要手段。然而在加高的同时,新老混凝土的结合面很容易受温度影响成为抗滑稳定的弱面,影响大坝安全稳定。针对这一问题,本文首次提出多条块组合滑动模式来对加高坝进行安全稳定分析。本文采用传统的刚体极限平衡方法,在考虑两种不同扬压力计算模式下,推导了三滑面计算公式,并针对南水北调中线丹江口大坝加高工程实例,成功复核其右联1坝段和右联7坝段沿指定滑裂面的安全系数,并在此基础上推导了N条块的计算公式。对同类大坝加高案例的稳定分析具有一定的借鉴意义。

In construction of concrete dams, raising the height of certain built dams appropriately is an important means of improving utilization efficiency and preventing disasters, but the joint interfaces of new-old concrete are prone to slide and become a weak plane that is sensitive to temperature. To solve this problem, we have developed a new contact sliding mode of multiple slices to analyze the slide stability of dam heightening. This paper uses a rigid limit equilibrium method to derive a calculation formula for three sliding interfaces, considering two calculation models of uplift water pressure. We applied this formula to the Danjiangkou dam heightening of the mid-route south-to-north water transfer project, and successfully rechecked the safety factors against sliding for the new-old concrete joints in the right dam blocks No. 1 and 7. For the recheck calculation, we also derived a corresponding formula for the case of N sliding interfaces. The results presented would help stability analysis for dam heightening in similar cases.