振杆密实法加固粗粒混合土模型试验

Model Experimental Study on Coarse-grained Mixed Soil Reinforced by Vibration Probe Compaction

中国中西部地区粗粒混合土分布广泛,但其松散性和不均匀性导致这些散体材料难以作为构筑物的地基。以提高粗粒混合土地基的承载力和消除不均匀性为主要目标,提出使用振杆法处理粗粒混合土地基,以室内模型试验为主要研究手段,分别进行了振动加固试验、轻型动力触探试验和密度测量试验,并在试验过程中实时监测振动和沉降指标,探究了振杆密实法对粗粒土的加固效果,分析了k值(d90/振杆直径)和振动频率对加固效果的影响。结果表明:振动处理后,式样的轻型动力触探击数平均可达13击,较处理前提高了11击,试样底部的平均压实度可达81%,相应的承载力提高200 kPa以上,经振杆密实法处理后变为低压缩性地基土;当k值在1/2.0时,加固效果优于k值为1/10.0的情况,前者的地基承载力和沉降率比后者分别高出50 kPa和7%左右;粗粒混合土在14 Hz振动频率下的地表振动速度较大,可达36 mm/s,对采集到的振动数据进行了希尔伯特-黄变换(HHT),其HHT能谱图显示振动频率在14 Hz附近时,地震响应较大;以正三角型布置加固点位,群点作用可以有效地消除地基土的不均匀性,地基土的不均匀系数K从试验前的26.40减小到1.39。振杆密实法可为粗粒混合土地基处理提供新思路,也可为现场施工提供关键参数依据。

Coarse-grained mixed soil is widely distributed across China’s central and western regions.Its loose nature and unevenness present challenges when using these materials as foundations for structures.This study proposes using the vibration probe compaction method to enhance the bearing capacity of these foundations and eliminate unevenness.The primary research method involves conducting indoor model experiments,including vibratory compaction tests,lightweight dynamic probing tests,and density measurement tests.These experiments incorporate real-time monitoring of vibration and settlement indicators to assess the consolidation effects of the vibration probe compaction method on coarse-grained soil.Additionally,the study evaluates the impact of parameters such as the k-value(d90/diameter of the probe)and vibration frequency on the ef-fectiveness of the consolidation.The findings reveal that after vibratory treatment,the average number of lightweight dynamic probing blows in-creases to 13,an increase of 11 compared to before treatment.The average compaction degree at the bottom of the specimen reaches 81%,enhan-cing the bearing capacity by over 200 kPa.The treated soil becomes a low-compressibility foundation;when the k-value is 1/2.0,the reinforce-ment effect is superior to that when the k-value is 1/10.0,with the former exhibiting approximately 50 kPa higher bearing capacity and a 7%high-er settlement rate compared to the latter.When applying a 14 Hz vibration frequency to coarse-grained mixed soil,the ground vibration velocity reaches 36 mm/s.The HHT spectrogram showed a significant seismic response of around 14 Hz using the Hilbert-Huang Transform(HHT)on the collected vibration data.Employing a triangular arrangement for reinforcement points eliminates unevenness in the foundation soil.The uneven-ness coefficient(K)decreases from 26.4 before the experiment to 1.39 after.The vibration probe compaction method offers a novel technique for improving the foundations of coarse-grained mixed soil and provides essential parameters for on-site construction.