振杆密实法加固粗粒混合土模型试验

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200kPa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时，加固效果优于k值为1/10的情况，前者的地基承载力和沉降率比后者分别高出50kPa和7%左右；粗粒混合土在14Hz振动频率下的地表振动速度较大，可达36mm/s，对采集到的振动数据进行Hilbert-Huang Transform（HHT），其HHT能谱图显示振动频率在14Hz附近时，地震响应较大；以正三角型布置加固点位，群点作用可以有效的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26.4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施工关键参数依据。

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

In the central and western regions of China, coarse-grained mixed soil is widely distributed, but its loose nature and unevenness make it challenging to use these unconsolidated materials as foundations for structures. With the primary objectives of enhancing the bearing capacity of coarse-grained mixed soil foundations and eliminating unevenness, this study proposes the application of the vibration probe compaction method to treat such foundations. Indoor model experiments were conducted as the primary research approach, encompassing vibratory compaction tests, lightweight dynamic probing tests, and density measurement tests. Throughout the experimentation, real-time monitoring of vibration and settlement indicators was implemented to investigate the consolidation effects of the vibration probe compaction method on coarse-grained soil. The study also analyzed the impact of parameters such as the k-value (d90/diameter of the probe) and vibration frequency on the consolidation effectiveness. The results indicate that, after vibrational treatment, the average number of lightweight dynamic probing blows can reach 13, an increase of 11 blows compared to pre-treatment. The average compaction degree at the bottom of the specimen can reach 81%, resulting in an increase in bearing capacity of over 200 kPa. The treated soil transforms into a low-compressibility foundation; When the k-value is 1/2, the reinforcement effect surpasses that of the k-value being 1/10, with the former exhibiting approximately 50 kPa higher bearing capacity and 7% higher settlement rate compared to the latter; For coarse-grained mixed soil under a 14 Hz vibration frequency, the ground vibration velocity reaches 36 mm/s. Utilizing Hilbert-Huang Transform (HHT) on the collected vibration data, the HHT spectrogram demonstrates significant seismic response around 14 Hz; Employing a triangular arrangement for reinforcement points effectively eliminates the unevenness in the foundation soil. The unevenness coefficient (K) decreases from 26.4 before the experiment to 1.39. The vibration probe compaction method provides a novel approach for treating coarse-grained mixed soil foundations and offers crucial parameters for on-site construction.