干湿循环对机制砂改良膨胀土力学与变形特性影响

Study on the Effect of Dry and Wet Cycles on the Mechanical and Deformation Characteristics of Mechanism Sand-amended Expansive Soil

在膨胀土中加入不同掺量的机制砂进行物理改良,对土样开展0~5次的干湿循环试验以分析土样的裂隙发育规律,并将干湿循环1、3、5次后的土样进行直接剪切试验及收缩和膨胀试验,探究经过干湿循环后土样的强度衰减和收缩膨胀特性。结果表明:机制砂可有效抑制膨胀土的裂隙发育,在机制砂掺量为10%时抑制效果最好,能较好抑制改良土裂隙集中发育,且在10%掺量下改良土的抗剪强度衰减幅度最小,收缩和膨胀特性方面也表现最佳。本试验验证了机制砂可延缓膨胀土在干湿循环过程中的裂隙发育和抗剪强度衰减,并且能改良土样的收缩膨胀变形特性,改良效果受机制砂掺量影响,综合考虑各项因素,机制砂掺量应控制在10%以内。

Different dosage(0%,10%,20%,30%)of mechanism sand is added into the expansive soil for physical improvement,and the above soil samples are subjected to 0-5 times of wet and dry cycle tests to analyze the crack development law of the soil samples,direct shear tests and shrinkage and expansion tests are conducted on the soil samples after 1,3 and 5 dry and wet cycles to explore the strength attenuation and shrinkage and expansion characteristics of the soil samples after the dry and wet cycles.The results show that the mechanism sand can effectively inhibit the crack development of expansive soil,and the best inhibition effect is achieved when the dosage of the mechanism sand is 10%,which can better inhibit the concentrated development of cracks in the improved soil,and the shear strength of the improved soil under the dosage of 10%has the smallest attenuation,and the contraction and expansion characteristics also have the best performance.This test verifies that the mechanism of sand can delay the development of cracks and shear strength attenuation of expansive soil in the process of dry and wet cycle,and can improve the contraction and expansion deformation characteristics of soil samples,the improvement effect is affected by the dosage of mechanism of sand,taking various factors into consideration,the dosage of mechanism of sand should be controlled within 10%.