Application of Piezocone Penetration Test and Flat Dilatometer Test in Shanghai Soft Clay
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摘要: 依托上海轨道交通市域线机场联络线岩土工程勘察项目,开展了孔压静力触探试验与扁铲侧胀试验,并获取了高质量取样压缩试验结果,研究了不同试验、不同图表分类方法对土层分类效果的影响,分析了扁铲侧胀试验与超固结比、锥尖阻力与压缩模量的关系。研究表明:孔压静力触探图表法对上海软黏土的分类效果较好,而对于过渡型土体(粉土)和“混合土”则分类不理想,扁铲侧胀试验分类方法则能达到良好的分类效果;上海地区软黏土在埋深18.0 m以内具有明显的超固结性,超固结比随着深度的增加而减小,变化差异较大,埋深大于18.0 m的土则为正常固结土;不同类型的软黏土,锥尖阻力与压缩模量之间存在着明显的线性相关关系,并可用统一公式表达。Abstract: Based on the geotechnical engineering survey project of Shanghai Rail Transit Airport connecting line, the piezocone penetration test and flat dilatometer test were carried out, and the high-quality sampling compression test results were obtained. The effects of different tests and different chart classification methods on the classification effect were studied, and the relationship between flat dilatometer test and over consolidation ratio, cone tip resistance and compression modulus were analyzed. The results show that the chart method of pore pressure static cone penetration test has a good classification effect on Shanghai soft clay, but it is not ideal for transition soil (silt) and "mixed soil", and the classification method of flat dilatometer test can achieve a good classification effect. The soft clay is overconsolidation soil while the burial depth is less than 18.0 m in Shanghai area. Its overconsolidation ratio decreases with the depth increase, and the soft clay is normally consolidated soil while the burial depth is greater than 18.0 m. For different types of soft clay, there is an obvious linear correlation between cone tip resistance and compression modulus, which can be expressed by a unified formula.
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表 1 场区各地层物理力学参数
岩土名称 层厚
/m天然含水率
w/%密度
ρ/(g·cm−3)天然孔隙比
e0饱和度
sr/%液限
wL/%塑限
wp/%三轴UU试验 直接剪切Cq 黏聚力
c/kPa内摩擦角
φ/(°)黏聚力
c/kPa内摩擦角
φ/(°)①1填土 2.59 31.7 1.90 0.889 97 34.3 20.8 ③1淤泥质粉质黏土 4.08 43.6 1.74 1.218 98 36.7 21.6 23.0 0.7 10.0 10.4 ④1淤泥质黏土 7.51 41.7 1.74 1.183 94 38.2 21.7 27.9 1.4 10.1 11.8 ④2粉砂夹粉质黏土 4.77 28.0 1.89 0.768 95 33.6 20.8 3.1 29.8 ⑤1黏土 7.20 37.2 1.77 1.084 94 37.5 21.6 28.9 1.0 14.2 14.0 ⑤31粉质黏土 6.67 27.5 1.86 0.791 93 33.3 20.0 40.7 1.2 15.3 16.1 ⑤42砂质粉土 4.40 20.1 2.01 0.576 94 3.8 31.0 ⑦1T粉质黏土夹粉砂 4.00 24.7 1.96 0.707 95 35.2 19.5 44.2 14.3 ⑦2T粉质黏土夹粉土 2.23 28.4 1.92 0.787 98 32.3 19.2 94.0 1.7 26.0 20.9 ⑦2粉砂 33.18 22.2 1.98 0.632 95 3.6 31.2 表 2 场区各土层孔压静力触探试验成果统计
岩土名称 锥尖阻力
qc/MPa侧摩阻力
fs/kPa摩阻比
Rf/%超孔隙水应力
u2/MPa①1填土 1.064 42 3.95 0.025 ③1淤泥质粉质黏土 0.556 14 2.51 0.200 ④1淤泥质黏土 0.620 13 2.10 0.220 ④2粉砂夹粉质黏土 2.231 78 3.50 0.190 ⑤1黏土 0.889 18 2.02 0.337 ⑤31粉质黏土 1.957 51 2.60 0.350 ⑤42砂质粉土 3.494 68 1.95 0.359 ⑦1T粉质黏土夹粉砂 3.22 117 3.63 0.460 ⑦2T粉质黏土夹粉土 4.402 95 2.14 0.572 ⑦2粉砂 19.783 252 1.27 0.520 表 3 场区各地层物理力学参数
岩土名称 (p0-p1)
/kPa土性
指数ID水平应力
指数KD侧胀模量
ED/MPa侧胀孔压
指数UD①1填土 88.60 0.52 6.15 3.07 0.04 ③1淤泥质粉质黏土 37.00 0.22 2.14 1.28 0.11 ④1淤泥质黏土 71.90 0.26 2.06 2.47 0.31 ④2粉砂夹粉质黏土 86.70 0.15 4.66 3.01 0.37 ⑤1黏土 86.90 0.23 1.93 3.01 0.28 ⑤31粉质黏土 129.00 0.26 1.86 4.47 0.13 ⑤42砂质粉土 109.50 0.24 1.53 3.80 0.01 ⑦1T粉质黏土夹粉砂 569.2 0.25 2.33 15.80 0.15 ⑦2T粉质黏土夹粉土 476.3 0.22 2.07 13.39 0.17 ⑦2粉砂 803.70 1.52 1.42 27.89 表 4 依据土性指数划分土体类别
土类 土性指数Id 泥炭及灵敏性黏土 <0.10 黏土(含软黏土) 0.10~0.35 粉质黏土 0.35~0.60 黏质粉土 0.60~0.90 粉土 0.90~1.20 砂质粉土 1.20~1.80 粉质砂土 1.80~3.30 砂土 >3.30 -
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