INFLUENCE MECHANISM OF ORGANIC MATTER ON SECONDARY CONSOLIDATION CHARACTERISTICS OF SOFT SOIL
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摘要: 利用洞庭湖软土、高有机质含量泥炭土重塑有机质含量不同的试样,进行一维固结蠕变试验,测定其吸附结合水含量和有机质含量,确定吸附结合水含量与有机质含量的关系,研究有机质含量对软土次固结特性的影响机制。研究结果表明,土中的有机质含量越高,其吸附结合水含量越大,两者呈线性递增关系,并提出了相应的关系计算式;次固结系数与固结压力的关系曲线在结构强度附近有一个峰值点,在较大固结压力作用下,次固结系数可近似视为一不变的常数;随着土中有机质含量增加,次固结系数呈明显增加的趋势,在高应力水平下表现尤为明显,并探讨了其产生原因。研究成果对控制软土地区工后沉降有一定的指导意义。Abstract: This paper uses Dongting Lake soft soil and high organic matter content peat soil to reshape samples with different organic matter content. It conducts one-dimensional consolidation creep tests to detected the content of adsorbed bound water and organic matter. It then determines the relationship between adsorbed bound water and organic matter content. It analyzes the effect of organic matter content on the secondary consolidation characteristics of soft soil. The research results show that the organic matter in the soil and the adsorbed bound water are linearly increasing: the higher content of organic matter,the greater the content of adsorbed bound water. In view of this,we put forward the corresponding calculation formula. Moreover,the relationship curve between secondary consolidation coefficient and consolidation pressure has a peak point near the structural strength. The secondary consolidation coefficient can be approximately regarded as a constant under the action of large consolidation pressure. In addition,with the increase of organic matter content in soil,the secondary consolidation coefficient increases obviously,especially at high stress level. We discuss its causes in this paper. The research has certain guiding significance for controlling post construction settlement in soft soil area.
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Key words:
- Soft soil /
- Secondary consolidation /
- Organic matter /
- Bound water /
- Consolidation creep test
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表 1 土样基本物理力学性质指标
Table 1. Basic physical and mechanical properties of soil samples
密度
ρ/g·cm-3含水量
w/%土粒比重
Gs孔隙比
e压缩系数
a/MPa-1液限
wL/%塑限
wP/%塑性指数
IP液性指数
IL黏聚力
c/kPa内摩擦角
φ/(°)1.78 44.2 2.61 1.06 1.02 44.1 15.26 28.84 1.03 7.6 13.83 表 2 试验土样有机质含量
Table 2. Organic matter content of test soil samples
组编号 1# 2# 3# 4# 5# 6# 试样编号 1#-1 1#-2 2#-1 2#-2 3#-1 3#-2 4#-1 4#-2 5#-1 5#-2 6#-1 6#-2 γ/kN·m-3 17.32 17.28 17.23 17.21 17.24 17.31 17.26 17.29 17.25 17.21 17.19 17.25 w/% 43.84 43.75 44.38 44.32 44.36 44.30 44.01 44.10 44.36 44.20 44.31 44.25 OMC/% 2.89 3.01 6.45 6.37 9.40 8.90 12.80 13.12 16.59 16.51 19.11 18.79 表 3 试验土样的吸附结合水含量
Table 3. Adsorption bound water content of test soil samples
组编号 1# 2# 3# 4# 5# 6# 试样编号 1#-1 1#-2 2#-1 2#-2 3#-1 3#-2 4#-1 4#-2 5#-1 5#-2 6#-1 6#-2 Wg/% 12.83 13.72 14.40 13.75 14.62 14.26 16.02 15.25 16.11 16.70 17.56 16.49 -
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