Estimating in-situ soil permeability from CPT & CPTu
Estimating in-situ soil permeability from CPT & CPTu
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发表时间：
2009
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通讯作者：
P. Robertson
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作者：
P. Robertson
工程师通常希望估计土壤渗透性（导水率）的剖面，作为场地表征过程的一部分。已经提出了几种方法来估计渗透系数（k）使用CPT结果。这些方法通常基于两种方法：（1）估计的土壤类型和（2）CPTu耗散测试期间的耗散率。本文提出了更新的相关性，估计渗透系数的CPT和CPTu耗散测试结果。建议的相关性进行了简要评价与可用的已发表的结果。2基于土壤类型的渗透性估计Lunne等人（1997）建议，可以使用Robertson等人（1986）或Robertson（1990）提出的土壤行为类型（SBT）图表来估计土壤渗透性（k）。建议每个SBT的k值范围。表1显示了基于Robertson（1990）标准化SBTn图表的更新建议范围。表1根据Robertson（1990）的标准化CPT土壤行为类型（SBTn）估算的土壤渗透性（k）（根据Lunne等人，1997年）SBTn区SBTn k范围（米/秒）SBTn Ic 1敏感细粒3x 10至3x 10 NA 2有机土壤粘土1x 10至1x 10 Ic > 3.60 3粘土1x 10至1x 10 2.95 < Ic < 3.60 4淤泥混合物3x 10至1x 10 2.60 < Ic <2.95 5砂混合物1x 10至1x 10 2.05 < Ic < 2.60 6砂1x 10至1x 10 1.31 < Ic < 2.05 7密砂至砾砂1x 10至1 Ic < 1.31 8 * 极密/硬土1x 10至1x 10 NA 9 * 极硬细砂-* 超固结和/或胶结Manassero（1994年）报告了使用表1估计泥浆墙质量控制目的的k值的良好结果。Jefferies和Davies（1993年）发现，土壤行为类型指数Ic可以代表标准化CPT SBTn图中的SBT区，其中Ic基本上是定义土壤类型边界的同心圆半径。Robertson和Wride（1998年）以及Robertson（2009年）更新的Ic定义修改如下：Ic = [（3.47 log Qtn）+（log Fr + 1.22）]（1）
Engineers often want to estimate profiles of soil permeability (hydraulic conductivity) as part of the site characterization process. Several methods have been proposed to estimate the coefficient of permeability (k) using CPT results. These methods are generally based on two approaches: (1) estimated soil type and (2) rate of dissipation during a CPTu dissipation test. This paper presents updated correlations to estimate the coefficient of permeability from CPT and CPTu dissipation test results. The proposed correlations are briefly evaluated with available published results. 2 PERMEABILITY ESTIMATES BASED ON SOIL TYPE Lunne et al (1997) suggested that soil permeability (k) could be estimated using the Soil Behaviour Type (SBT) charts proposed by either Robertson et al (1986) or Robertson (1990). A range of k values was suggested for each SBT. Table 1 shows the updated recommended range based on the Robertson (1990) normalized SBTn chart. Table 1 Estimated soil permeability (k) based on normalized CPT soil behavior type (SBTn) by Robertson (1990) (Modified from Lunne et al., 1997) SBTn Zone SBTn Range of k (m/s) SBTn Ic 1 Sensitive fine-grained 3x10 to 3x10 NA 2 Organic soils clay 1x10 to 1x10 Ic > 3.60 3 Clay 1x10 to 1x10 2.95 < Ic < 3.60 4 Silt mixture 3x10 to 1x10 2.60 < Ic < 2.95 5 Sand mixture 1x10 to 1x10 2.05 < Ic < 2.60 6 Sand 1x10 to 1x10 1.31 < Ic < 2.05 7 Dense sand to gravelly sand 1x10 to 1 Ic < 1.31 8 *Very dense/ stiff soil 1x10 to 1x10 NA 9 *Very stiff fine-grained soil 1x10 to 1x10 NA *Overconsolidated and/or cemented Manassero (1994) reported good results using Table 1 to estimate k values for quality control purposes in a slurry wall. Jefferies and Davies (1993) identified that a Soil Behavior Type Index, Ic, could represent the SBT zones in the normalized CPT SBTn chart where, Ic is essentially the radius of concentric circles that define the boundaries of soil type. Robertson and Wride, (1998) and updated by Robertson (2009), modified the definition of Ic, as follows: Ic = [(3.47 log Qtn) + (log Fr + 1.22)] (1)