干湿循环对地裂缝带黄土抗剪强度影响研究

EXPERIMENTAL STUDY ON STRENGTH CHARACTERISTICS OF LOESS AT GROUND FISSURES IN XI'AN UNDER ACTION OF DRY AND WET CYCLE

为研究长期干湿循环作用对地裂缝带及其附近黄土强度的影响,以西安地裂缝场地典型黄土试样为研究对象,通过室内试验方法(主要为直接剪切实验),研究地裂缝带黄土试样在干湿循环作用下不同含水率的抗剪强度参数及其强度衰减特性,提出了地裂缝带黄土衰减强度的求取方法,研究表明:(1)干湿循环作用下,地裂缝带黄土抗剪强度随着干湿循环次数及含水率的增加而逐渐减小,1次干湿循环或大于18%含水率对抗剪强度参数影响明显;(2)1次干湿循环作用其强度衰减最为明显,随着干湿循环次数的增加而增加且增幅逐渐下降;(3)1次干湿循环作用下其强度随含水率衰减最为明显,随着含水率的增加其逐渐减小,且在12%以下含水率时其强度衰减较高,大于12%含水率时强度衰减较小。

This paper studies the effect of long-term dry and wet circulation on the strength of ground fissure zone and its nearby loess.It takes the typical loess samples of ground fracture site in Xi an as the research object.It studies the shear strength parameters and the strength attenuation characteristics of the loess specimens with different moisture content under dry and wet circulation with laboratory test method(mainly for direct shear test).It puts forward a ground fissured loess strength attenuation calculation method.Research results show the follows.(1)Shear strength of ground fissured loess is decreased gradually with the cycle number and water content.One dry-wet cycle or greater than 18%moisture content have affected on the shear strength parameters significantly.(2)The intensity attenuation of the 1 drying and wetting cycles is most obvious.It increases with the increase of dry and wet cycles.(3)Under the action of 1 dry and wet cycle,the attenuation of its strength is most obvious with the moisture content.It gradually decreases with the increase of water content.Its strength attenuates higher when the water content is below 12%,and the strength attenuation is smaller when the water content is greater than 12%.