MICP固化土遗址裂隙的剪切强度试验研究

Experimental study on shear strength of cracks in MICP solidified soil sites

土遗址作为文化遗产,具有重要的历史、文化及科学价值,而裂隙是影响其稳定性的主要病害,裂隙的发育和延伸甚至会损毁土遗址,因此须对土遗址裂隙进行合理的修复和固化。微生物诱导碳酸钙沉积技术(MICP)是一种绿色环保的土体固化技术,将其用于土遗址裂隙的固化,不仅环境友好,而且与遗址原材料具有更好的相容性。文章首先通过室内试验制备不同裂隙开度和裂隙结构面粗糙程度的遗址土裂隙试样,然后对其进行注浆固化,最后通过剪切试验获得裂隙开度和结构面粗糙度对固化效果的影响规律。结果表明:碳酸钙胶结物在裂隙处沉积并胶结裂隙两侧土体,增强了试样的整体性及力学性能;裂隙开度越小,结构面越粗糙,固化后试样的剪切强度越大,且裂隙开度较结构面粗糙度对剪切强度的影响大;在裂隙开度0.5mm、结构面粗糙的条件下,固化后试样的黏聚力最高可达到38.18kPa,内摩擦角可达33.42°。

As cultural heritages,earthen sites have important historical,cultural and scientific values.However,as the main diseases,cracks seriously affect the stability and even cause damage of the earthen sites.Therefore,reasonable restoration and solidification of cracks in earthen sites should be carried out.As a green and environmentally friendly soil solidification technology,Microbial-induced calcium carbonate deposition(MICP)is not only environmentally friendly,but also has better compatibility with the raw materials of the site.In this paper,the site soil crack samples with different crack widths and structural plane roughness were prepared,and then grouted and solidified.Finally,the influence rules of crack width and structural plane roughness on the solidification effect were obtained through shear tests.The results show that the calcium carbonate cement deposits at the crack and cements the soil on both sides of the crack,which enhances the integrity and mechanical properties of the samples.The smaller the crack opening is,the rougher the structural plane is,and the greater the shear strength of the cured specimen is.The effect of the crack opening on the shear strength is greater than the roughness of the structural plane.When the crack opening is 0.5 mm and the structural plane is rough,the cohesion of the cured specimen the internal friction angle can reach 38.18 kPa and 33.42°,respectively.