全尺寸隔水管在复杂应力状态下的力学特性试验研究

为对隔水管在复杂应力状态下的力学特性进行试验研究,研制了能够模拟高液压环境下管柱力学行为的特殊试验装置——深水管柱力学模拟试验系统,并借助该系统对全尺寸隔水管在受内外压条件下进行了力学特性模拟试验。结果表明:试验系统运行良好,能够有效地按照要求进行加载、卸载。试验中通过对隔水管试件进行内外压加载,同时对系统两端的轴向活塞加压,消除了由于内外压产生的轴向力,实现了在内外压条件下的隔水管力学特性模拟试验。通过在管柱外壁粘贴电阻应变片,得到了其真实径向应变与环向应变随内外压变化的关系曲线,并通过分析计算得到了试件的真实应力状态。由于隔水管加工制造等方面的误差,真实的应变数据、应力状态与理论推导结果并不重合。为了提高深水作业的安全性与经济性,可以借用试验结果对理论推导值进行修正,也说明了用试验方法进行隔水管力学特性研究的重要性。该试验系统为深水作业管柱等的模拟试验提供了一个良好的平台,能够有效降低深水钻采作业的风险,提高深水钻采作业的经济性与安全性,具有较高的推广应用价值。

Experimental Study of Mechanical Properties of Full Size Marine Riser in Complex Stress State

In order to conduct experimental study of mechanical properties of marine riser in complex stress state, special experimental equipment called deepwater pipe string mechanics simulation experimental system was developed to simulate pipe string mechanical behavior in high hydraulic environment. Based on this experimental system, simulation experiment of mechanical properties of full size marine riser subjected to both internal and external pressure was carried out. Results show that the experimental system is running well and can effectively load and unload in accordance with requirements. During experiment, the simulation condition was realized through simultaneous loading of internal pressure, external pressure and axial pressure. The purpose of axial pressure from the axial piston is to eliminate the axial tension force due to internal and external pressure. The relations among the actual radial strain, hoop strain and variation of internal and external pressure were obtained through sticking resistance strain gauges on the outer wall of pipe string. Actual strain data and stress state are not consistent with the theoretical derivation results due to the manufacture error of marine riser. In order to improve the safety and economy for deepwater operation, the theoretical results must be corrected by experimental data, which indicates the importance of experimental method in mechanical property study for pipe riser. This experimental system provides a good platform for simulation experiment of deepwater pipe string operation and can effectively reduce the risk and improve the security and economy of deep water drilling. So it has the value of promotion and application.