| With the rapid development of China’s infrastructure,a large number of black or grayblack clay rocks containing carbonized organic matter are exposed in highways and engineering construction in Guangxi,Yunnan,Guizhou and other places.These rocks are collectively called carbonaceous rocks,and they have Weathering,easy to soften by water absorption,easy to disintegrate when disturbed by water,and other difficult engineering features,especially the engineering problems of carbonaceous rock slopes The stability is good.With the erosion of sunshine and rain,the carbonaceous rock disintegrates and softens,the strength decreases,the slope stability gradually decreases,and it is easy to cause safety accidents.The research on the anchoring measures of carbonaceous rock slopes is still immature,so this paper takes 5 rock samples collected in Liuzhou area(LZ1,LZ2),Hechi area(ND,ZL)and white area(BS)of Guangxi as the research object.Laboratory tests studied the disintegration differences of different types of carbonaceous rocks,designed and tested the shear characteristics of different types of carbonaceous rocks and different strength mortar anchorage sections,and achieved certain research results,which are important for related engineering projects.Theoretical support and guiding significance.Firstly,through consulting a large amount of data,the system summarizes the domestic and foreign related achievements on the physical and mechanical properties of carbonaceous rock and the treatment measures of carbonaceous mudstone slope engineering,which provides a basis for the research of this paper.Firstly,by referring to a large number of documents,the analysis and summary of the domestic and foreign relevant results of the physical and mechanical properties of carbonaceous rock and the treatment measures of carbonaceous mudstone slope engineering are provided to provide research ideas for this article.Then,the distribution characteristics of carbonaceous rocks in Guangxi area and the engineering geological characteristics of carbonaceous rocks in Liuzhou area,Hechi area and white area are analyzed,on-site integrity sampling is carried out,physical and mechanical properties tests and indoor disintegration tests are carried out.Finally,combined with the special properties of carbonaceous rock,the shear strength test of the anchoring section of carbonaceous rock and mortar was designed and carried out.The carbonaceous rock and different strength mortar,different carbonaceous rock and the same strength mortar and different curing time were analyzed.The shear displacement curve of the anchor section of rock and mortar,and explore the failure mechanism of different shear failure phenomena.The main conclusions are as follows:1)The density of carbonaceous rock samples is not high,the average value is 2.5 g/cm3,and the water content is between 0.29%-4.54%.The chemical element composition of five types of carbonaceous rock is analyzed.The main chemical elements contain Si and Al,Fe,Ca and K,among which the content of elemental Si is the highest,above 50%,followed by elemental Al,between 13%-31%.The rock sample contains a large amount of quartz minerals,followed by the clay mineral illite,with a content of 15%-30%,but the LZ1 rock sample does not contain illite,but contains 28% kaolinite.2)Different carbonaceous rocks exhibit different disintegration characteristics.After 6 indoor dry-wet cycles,the disintegration of carbonaceous rock samples tends to be completed.The highest resistance to disintegration is the carbonaceous materials with the numbers ZL and ND.Followed by carbonaceous rock samples with the numbers LZ1 and LZ2,and the weakest disintegration resistance is the carbonaceous rock sample of BS.By comparing and analyzing the disintegrability of rock samples No.BS and No.ND,it is found that the disintegration of carbonaceous rock is not only determined by the clay composition and content in the rock,but also closely related to the structural characteristics of the rock.3)The total organic carbon content of carbonaceous rock has a negative correlation with the density of carbonaceous rock,and has a positive correlation with its water content.From the trend,it can be judged that the disintegration resistance index of carbonaceous rock shows the total organic carbon content Certain negative correlation.4)The cohesion c value of the carbonaceous rock sample and the anchorage section of mortar with different strengths is less than 1 Mpa.Although the numerical dispersion of the internal friction angle is high,the values are low.When the roughness of the anchoring section is constant,most of the failure surfaces are at the cemented surface of carbonaceous rock and mortar,and some are in weaker carbonaceous rock.The shear strength of the anchoring section is close to that of carbonaceous rock.5)When different carbonaceous rocks and mortar are anchored,under the action of different normal stresses,M25 mortar and M35 mortar and the carbonaceous rock anchoring section numbered ZL have high shear strength,M30 mortar and the carbonaceous rock anchoring section numbered LZ2 High shear strength.Combined with its basic physical properties,it is found that the rock structure with high shear strength in the anchoring section is relatively compact,with few pores and cracks,of which the clay mineral content is not high,the strength of the rock sample body is higher than other rock samples,and it is not easy to shear.damage.6)The shearing characteristics of the anchoring section of mortar and carbonaceous rock at different curing times are different.In the test results,the strength of the anchoring section for 28 days of curing is greater than 7 days of curing,and the strength of 7 days of curing is greater than 28 days of curing.The phenomenon.This phenomenon does not happen accidentally due to test error.The reason for this phenomenon is that the hydration and hardening of cement is a long-term process.At different curing times,the degree of hydration cementing at the cemented surface of the mortar and carbonaceous rock is different,and the density of the network structure is different,resulting in cementing.The strength of the surface is different.The second is that during the production of the shear test sample,the cross section of the carbonaceous rock needs to be exposed to water for a long time,and the clay mineral illite on the surface of the carbonaceous rock interacts with water to produce uneven expansion and make its interior Gradual expansion and fracture occurred,and most of them eventually broke along the bedding structure.These two factors affect the shear strength of the anchoring section. |
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