Study On The Slope Stability Of Expansive Rock With Expansion Force

Expansive rock is widely distributed in China.With the development of national infrastructure construction,the engineering perplexity caused by expansive rock also increases.Expansive mudstone is a kind of special soft rock,which contains a lot of hydrophilic minerals and has the engineering characteristics of water swelling,water loss and shrinkage.When the water absorption of expansive rock is limited,it will produce expansive force,which will bring some puzzles and challenges to the construction of infrastructure.In this paper,the influence of expansion force on the stability of slope is systematically studied by means of indoor limit expansive test and numerical analysis.Based on the study of swelling characteristics of expansive rock,the failure mode of expansive rock slope and the numerical simulation method of stability analysis of expansive rock slope are discussed.The findings suggest:(1)On the basis of extensive collection of relevant engineering geology and design data,combined with site survey and investigation,the influence of factors such as moisture content and dry density of the strongly weathered swelling mudstone at Lushi Station on the expansion force was analyzed,and the expansion force was established.The relationship with the initial dry density and moisture content,research shows that the size of the expansion force has a power function relationship with the initial moisture content,and an exponential function relationship with the dry density;after data fitting,a calculation formula for the expansion force considering two factors is given;In actual engineering applications,the expansion force can be predicted to a certain extent;(2)Based on the humidity stress field theory,using the similarity between the temperature field and the humidity field,replacing the stress field generated by the expansion stress with the temperature field of the temperature stress,and establishing the relationship between the expansion force and the thermal expansion coefficient P=kth·?;Expansion force is applied to slope stability analysis to study the influence of expansion force on the stability of expansive rock slope.(3)Based on the study of temperature field instead of humidity field and the weakening characteristics of rainfall intensity of expansive rock at Lushi station,using the built-in strength reduction method of flac3D,the influence of two factors,expansion force and strength degradation,on the slope stability of expansive rock under different rainfall conditions is analyzed.The results show that the potential slip surface of expansive rock slope is circular arc after rainfall infiltration,and with the increase of rainfall intensity,the plastic area of the slope increases and tends to move to the lower part of the slope.(4)When the expansion force is only considered in the numerical simulation of the slope,the expansion force is 1.49,1.39,1.21 and 0.92,respectively,when the slope experiences no rain,moderate rain,heavy rain and rainstorm,and so on,and the expansion force is applied to the slope,the Factor of safety are 1.49,1.39,1.21 and 0.92,after the expansion force is applied,the potential sliding surface tends to go down,the plastic area increases slightly,and the shear failure is the main failure mode.(5)In the course of numerical simulation of expansive mudstone slope stability considering two factors,it is found that the Factor of safety of medium rain and heavy rain drop to 1.19 and 0.66 respectively;Compared with the slope without strength deterioration under the action of expansion force,the area of plastic zone decreases by about 25%,and the area of plastic zone still increases.The difference is that the area of plastic zone of tensile failure increases.Figure[41]Table[14]Reference[105]...