混凝土重力坝水下爆炸荷载作用下的弯曲破坏

Bending failure of a concrete gravity dam subjected to underwater explosion

目的:探索混凝土重力坝在水下爆炸荷载作用下的破坏模式和破坏机理。方法:1.利用离心机试验和数值模拟对混凝土重力坝在水下爆炸荷载下的破坏模式进行对比研究;2.结合水下爆炸的物理过程,对大坝破坏模式的产生机理进行分析,并利用应变历史对其进行验证。结论:1.混凝土重力坝较薄的上部易受破坏,且在下游拐角位置可以观察到水平断裂。2.在大坝下部约1/3位置处,可观察到另一拉伸断裂;该断裂主要受上游面的弯曲拉应力控制,使该断裂向下游发展。3.一些在历史战争中产生的大坝破坏具有相似的破坏模式,即通常在大坝上部出现不同深度的溃口;这种失效模式与本研究的结果一致。4.坝体下部拉伸断裂的位置决定了溃口的深度。

Dam structures are prime targets during wars,and a tragedy is likely to happen in a populated area downstream of a dam exposed to explosions.However,experimental investigations of the failure of a concrete gravity dam subjected to underwater explosion(UNDEX)are extremely scarce.In this study,centrifuge tests and numerical simulations were performed to investigate the failure of a concrete gravity dam subjected to a near-field UNDEX.The results revealed the existence of two tensile fractures inside the dam,one in the upper part and the other in the lower part.Due to the narrowness of the upper part,there were coupled effects of bending tensile loads in the upstream face and a reflected tensile stress wave in the downstream face,resulting in severe tensile damage to the upper part in both the upstream and downstream faces.The fracture in the lower part was measured at around one third of the height of the dam.This fracture was produced mainly by the bending tensile loads in the upstream face.Driven by those loads,this fracture started from the upstream face and developed towards the downstream face,with a horizontal angle of about 15?.The underlying mechanisms behind the two tensile fractures were confirmed by recorded strain histories.The dam failures presented in this study are similar to those produced in historical wars,in which dams were under similar attack scenarios.