杭州地区海、湖相软土的工程特性评价

以杭州地区第4纪全新统海、湖相软土为研究对象,从土的成因分布、化学物理性质、应力应变关系等方面,通过室内常规物理试验、直剪试验、三轴固结排水剪切试验(CD)、压缩试验等进行系统研究.结果表明,杭州地区软土天然含水量高,压缩性高,承载力低；杭州地区存在2个明显的软土层,不同区域第1软土层埋深变化较大,第2软土层较稳定,分布于26.3～36.3 m埋深处,随着软土层深度的增加,有机质丰度逐渐增大.杭州软土在低围压下会出现剪缩现象,总体上呈应变硬化型,且具有很强的结构性.在研究成果的基础上,开发一种由室内压缩试验评估原状土压缩曲线的方法；研究杭州软土结构强度的损伤规律,推导结构强度损伤方程.所得结论对指导杭州地区的工程勘察和工程实践具有现实价值.

Assessment of engineering properties for marine and lacustrine soft soil in Hangzhou

The distribution, chemical physics properties and stress-strain relationship of the marine and lacustrine soft soil were researched by using regular physical test, direct shear test, three axis drainage consolidation shear test (CD), and compression test. The results show that the soft soil is easy to be compressed and possesses high natural water content and low bearing capacity. There are two obvious soft soil layers in Hangzhou, the depth of the first layer is various, but the second layer is stable with the depth of 26.3~36.3m. Organic matter abundance increases with the increase of soft soil depth; additionally shear shrink phenomenon of the soil is observed under low ambient pressure, and the stress-strain curve is of hardening of special pattern. The results also show that the soft soil has obvious structural effect. Based on the conclusions, a method of assessing field curve by knowing the indoor compression curve is to be established, which has taken the structural into account and introduced the destructuring index b. And then, damage rule of structural strength is stated and the structural strength damage equation is derived. The conclusions are meaningful to guide engineering construction in Hangzhou.