【摘要】 覆盖层地基土的动强度特性(参数)是进行地基土液化判别和结构-地基系统稳定分析的基础,是结构-地基系统动力响应特性的重要影响因素。厄瓜多尔CCS水电站取水枢纽的主体结构位于河谷深厚覆盖层地基之上,地基中的C2粉土为火山灰为主体成分的河流沉积土,表现出强吸水性和低天然干密度的特点。该类土的动强度特性鲜见有文献涉及,是本项目科研和设计人员关注的重点问题。本文,利用中型振动三轴仪进行厄瓜多尔CCS水电站深厚覆盖层地基C1细砂和C2粉土的动强度特性试验,重点考察以火山灰为主体成分的C2粉土的动强度特性和常规细粒土(以C1细砂为例)的异同。研究表明:和以往对常规细粒土动力特性的认识基本一致,火山灰沉积粉土的动强度特性受围压的影响;通过碎石桩等加固措施提高土的相对密度,可以显著提高地基的抗地震破坏能力;初始液化和5%轴向变形两种破坏控制标准下,等压固结土的振动破坏周次基本相同。更多还原

【Abstract】 The water intake structures of CCS water-power station are constructed on the deep overburden layer of valley in Ecuador. The dynamic strength characteristic parameters of foundation soils are the basic data of dynamic analysis of damfoundation system,and the dynamic strength characteristics of soil affects the dynamic response characteristics of the system greatly. Series of dynamic strength characteristics tests for soils of deep overburden layer foundation were done using the dynamic triaxial machine,and the dynamic strength characteristics of the soils were analyzed deeply. Especially,dynamic strength characteristics of the special soils(silt soil-C2) which deposited by volcanic ash mainly was studied seriously contrasting with the normal soils(take fine sand-C1 for example). The study shows that:dynamic strength characteristics of the deposited soils of volcanic ash is affected greatly by the confined pressure condition of soils,that is the same as the normal fine soils;the liquefaction resistance of soils can be increased though the increasing of soil density which can be realized using some engineering measures,such as the stone columns;the dynamic failure cyclic numbers(Nf) of soils in two different standards that are the failure standard of primary liquefaction and the failure standard of 5% axial deformation are closed basically.更多还原