风化砂改性膨胀土干湿循环力学性质及裂隙演化规律研究

Research on the Mechanical Properties and Crack Evolution Law of Weathered Sand Modified Expansive Soil in Dry-Wet Cycle

为改善干湿循环条件下地基膨胀土工程力学性质,该研究对膨胀土(Es)、风化砂改性膨胀土(EsR1~6)、水泥改性膨胀土(EsC)、风化砂-水泥改性膨胀土(EsRC)共计9种土样开展膨胀特性、强度特性、干湿循环等试验。研究发现:风化砂掺量越大,EsR的最大干密度越大、膨胀率越小,呈现近似线性相关关系,且EsR的抗剪强度略低于原膨胀土,最佳风化砂掺量为30%;干湿循环中,风化砂与水泥均可抑制膨胀土的裂隙开展,且水泥抑制作用更强,二者同时加入时抑制效果最佳;干湿循环导致土的强度衰减主要表现在凝聚力上,含水泥试样的强度稳定性不如不含水泥试样。

To improve the swelling and instability failure of expansive soil under rainfall condition,expansion characteristics,strength characteristics,dry and wet cycles test were carried out on expansive soil(Es),modified expansive soil by weathered sandstone(EsR1~6),modified expansive soil by cement(EsC),modified expansive soil by weathered sandstone and cement(EsRC).It is found that:With the increase of sand content,the maximum dry density of EsR increases and the expansion rate decreases,showing an approximate linear correlation.The shear strength of EsR is slightly lower than that of Es,and the optimal content of weathered sandstone is 30%.In the dry-wet cycle,both weathered sandstone and cement can inhibit the crack development of expansive soil,and cement has a stronger inhibition effect.The inhibition effect is the best when both are added simultaneously.The strength attenuation caused by the dry-wet cycle is mainly manifested in the cohesion,and the strength stability of the sample containing cement is not as good as that of the sample without cement.