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针对离石地区超高填方下深厚湿陷性黄土地基强夯加固参数及效果开展了系列试验研究,分析了强夯前、后各试验区平均夯沉量和土体主要物理力学指标的变化规律,并给出2 000、3 000、6 000 kN.m能级条件下强夯加固的夯点中心距、最佳击数、停夯标准及有效加固深度等主要参数,在此基础上确定了强夯有效加固深度的估算方法。试验结果表明,离石地区深厚湿陷性黄土地基强夯处理后加固效果显著,有效加固深度范围内黄土湿陷性基本消除;离石或类似地区湿陷性黄土地基采用2 000 kN.m及其以上能级进行强夯处理后,地基承载力特征值均可达到300 kPa以上,土体变形模量大于25 MPa,强夯有效加固深度可采用修正Menard公式进行估算,修正系数可取0.35～0.37;2 000、3 000、6 000 kN.m能级强夯最佳击数分别为11、10、10击,有效加固深度分别为5、6、9 m,夯点中心距分别为4、4、5 m,且分别可将点夯最后两击的平均夯沉量不大于5、5、10 cm作为停夯标准。试验研究成果可为同类工程的设计与施工提供参考。
A series of experimental studies have been conducted on the parameters and effects of dynamic compaction of deep collapsible loess foundations under ultra-high fill in the Lishi area. The average amount of sedimentation and major physical and mechanical parameters of the soil before and after the intensive excavation have been analyzed. The law, and gives the main parameters such as the center distance of the defect, the best number of hits, the stop criterion and the effective reinforcement depth under the conditions of 2 000, 3 000 and 6 000 kN.m energy levels, and it is determined on this basis. A method for estimating the effective reinforcement depth of a strong concrete. The test results show that the consolidation effect of the deep pluton in the deep collapsible loess ground in the Lishi area is significant, and the collapsibility of the loess is effectively eliminated within the effective reinforcement depth range; the collapsible loess foundation in limestone or similar areas is 2 000 kN.m. After the above energy levels are subjected to intensive treatment, the characteristic values of the foundation bearing capacity can reach more than 300 kPa, the deformation modulus of the soil is more than 25 MPa, and the effective reinforced depth of dynamic compaction can be estimated by using the modified Menard formula, and the correction coefficient can take 0.35 to 0.37. The best number of 2 000, 3 000 and 6 000 kN.m energy levels were 11, 10, and 10, respectively, and the effective reinforcement depths were 5, 6, and 9 m, respectively. The center distances of the flaws were 4, 4 respectively. , 5 m, and the average weight of the last two strikes can be no more than 5, 5, and 10 cm as the stopping criteria. The experimental research results can provide reference for the design and construction of similar projects.