三峡堰基淤砂的流滑特性和抗剪强度指标的选用

Flow\|sliding property of sand deposit in the cofferdam of the Three Gorges Project\=and the determination of its shear strength parameters

本文通过应力控制式固结不排水剪切试验，研究三峡围堰基淤砂的流滑特性．整理出淤砂的稳定状态线和稳定状态强度曲线，在此基础上，把饱和松砂的抗剪强度指标区分为大应变有效应力摩擦角Φ′、峰值有效应力内摩擦角Φ′ｐ、峰值总应力内摩擦角Φｐ以及稳定状态内摩擦角Φｒ４种类型供不同工程条件选用．文中还提出进入流滑状态的３个条件及土体内流滑区分布范围的分析方法．

In this paper the flow\|sliding property of the fine\|silty sand in the Three Gorges Project cofferdam has been studied by CU test on thes tress\|controlled triaxial apparatus.From the experimantal results the steady state lines and the steady state strength lines of two kinds of the sands with different initial void ratio and differnet consolidation ratio are obtained.The main factors determining the loose sand to get into the steady state under dymanic loading are expounded.On this basis the shear strength parameters of saturated loose sand are classified as effective stress friction angle at large strain Φ′,effective stress friction angle at peak value Φ′p ,total stress friction angle at peak value Φp and friction angle at steady state Φr,provided for different working condition of soil mass.As an instance,the flow\|sliding region in an earth cofferdam during 7° seismic intensity is estimated and the friction angles at steady state Φr of each elements in flow\|sliding region are given.