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为了评价土的结构性对黏性土地区CPTU测试结果的影响。对湛江地区黏土(层)进行室内固结试验和CPTU原位试验,获得孔压静力触探响应特征,对比分析室内试验与CPTU测试结果求取固结系数的差异性。结果表明:湛江黏土的触探指标较高,qc=(2.5~3.0)MPa,Rf平均值约为1%;在强结构性黏土地区利用CPTU测定结果划分土层具有较高的准确性;受强结构性影响,土的埋深越大,CPTU的孔压消散时间越短,土的固结系数越大;浅层土试验孔压消散初期土体出现剪胀现象;利用室内试验得到湛江黏土在结构破坏前的固结系数Cv是重塑土的固结系数Cv的10倍左右;贯入过程中由于结构的破损会使探头周围土体的渗透性迅速降低出现指标失真,导致基于CPTU测试得到原状土的固结系数远小于室内试验结果;最后,考虑结构性,根据CPTU资料提出一个可用于估算结构性黏土固结系数的方法,该研究为准确获得结构性黏土地基处理设计参数提供了合理的科学依据。
In order to evaluate the effect of soil structure on the CPTU test results in cohesive soil areas. The consolidation test and CPTU in-situ test for clay (layer) in Zhanjiang area were carried out to obtain the characteristics of pore pressure static cone penetration test. The difference between the indoor test and the CPTU test result was analyzed. The results show that the Zhanjiang clay has a higher detection index (qc = 2.5-3.0 MPa) and an average Rf of about 1%. It is highly accurate to classify soil layers based on the results of CPTU measurements in strongly structured clay areas. Strong structural impact, the greater the soil depth, the shorter the pore pressure dissipation time of CPTU, the greater the consolidation coefficient of soil; the dilatancy of soil appeared in the early stage of dissipation of shallow soil test pressure; the Zhanjiang clay The consolidation coefficient Cv before the structural failure is about 10 times of the consolidation coefficient Cv of the remolded soil. Due to the structural damage, the permeability of the soil around the probe rapidly decreases due to structural damage during the penetration process. The consolidation coefficient of undisturbed soil is far less than that of the laboratory test. Finally, considering the structure, a method that can be used to estimate the consolidation coefficient of structural clay is proposed based on the CPTU data. This study provides a basis for accurately obtaining the design parameters of structural clay foundation treatment Reasonable scientific basis.