摘要
本文细化了土骨架的新概念,并对黄土的微结构进行分析。总土骨架的一部分称为子土骨架,外包颗粒、外包颗粒的皮、集粒、凝块、点接触连接、面胶结连接都是子土骨架。黄土的粘粒之间分子键联接最弱,水稳性最差。点接触、面胶结连接归根结底也是土骨架的接触与联接,传递有效应力和提供大气张力库伦抗剪强度。当水侵入时,膜的真黏聚力及膜对颗粒的捆绑能力丧失,并且土的内摩擦角大大减小;水气不抵大气压强,自重应力变为自由水浮力,其他重力的有利作用丧失;土骨架失去接触而溃散,土骨架颗粒填充到架空孔隙中,并重新挤紧,表现为黄土的湿陷。一般来说,点接触结构的湿陷起始压力要比面胶结小很多,对应的是自重湿陷性黄土,面胶结结构对应的是非自重湿陷性黄土。本文提出外包粘粒皮颗粒群骨架的新概念。先由粘粒靠公共结合水膜和收缩膜联接形成大大小小的包皮,包皮之间点接触或面胶结联接在一起组成群;包皮内装有碎屑颗粒或集粒,两者之间有联接,地震时作群体振动。架空孔隙是黄土抗震的主要薄弱环节;骨架的连接方式和质点刚柔是黄土抗震的主要因素;点接触连接比面胶结容易破坏得多;质点的振动程度按砂粒、粉粒、集粒、凝块由高到低变化;一般来说,总的震陷程度按砂黄土、粉黄土、黏黄土由高到低变化。
This paper refines the new concept of soil skeleton and analyzes the microstructure of loess.A part of the total soil skeleton is called a sub-soil skeleton.The outsourcing particles,the skin of the outsourcing particles,aggregates,clots,point-contact connection and surface cementation connection are all sub-soil skeletons.Molecular bond is the weakest while water stability is the worst among the clay particles of loess.Point contact and surface cementation are ultimately the contact and connection of soil skeleton,transmitting effective stress and providing the coulomb shear strength of atmospheric tension.The true cohesion force of the membrane and the binding ability of the membrane to particles is lost and the internal friction angle of soil is greatly decreased when water invades.Hydrosphere does not match atmospheric pressure and gravity stress becomes free water buoyancy,thus other beneficial effects of gravity lost which leads to soil skeleton’s losing contact and collapsing.The skeleton particles were filled into the open void and recompacted,which is described as loess collapsibility.The initial pressure of the collapsibility of the point contact structure is much smaller than that of the surface cementation,which corresponds to sell-weight collapse loess,while the surface cementation structure corresponds to non-weight collapsible loess.A new concept of the particles framework of overlying skin made of clay particles was proposed in this paper.Firstly,the overlying skin is formed by connecting the clay particles with the public binding water film and contraction film and the overlying skin is connected with the point contact or the surface cementation together to form a group.The skin is equipped with clastic particles or aggregates.There's a connection between them which forms the group vibrates during an earthquake.Open void is the main weak link of loess seismic resistance.The connection mode of the skeleton,the stiffness and softness of the particle are the main factors for the seismic resistance of loess.The point contact connection is more easily broken than the surface cementation.The vibration degree of the particle varies from high to low according to sand,powder,aggregate and clot.Generally speaking,the overall seismic depression degree varies from high to low according to sandy loess,silty loess and clayey loess.
作者
蒙理明
张风
Meng Liming;Zhang Feng(Haikou Institute of Science and Technology,Haikou 571126,Hainan)
出处
《建设科技》
2018年第13期21-26,20,共7页
Construction Science and Technology
关键词
总土骨架
子土骨架
外包粘粒皮颗粒群骨架
湿陷
震陷
群体振动
大气张力库伦抗剪强度
Total soil skeleton
sub-soil skeleton
particles framework of overlying the skin made of clay particles
collapsibility
group vibration
atmospheric tension coulomb shear strength
