| The expansive rock or soil owns the characteristics of "bulking, dehydrating shrinkage",which brings great harm to the building project, not only afects stability of the slope,roadbed,pavement of the road,railway,channels slope and so on, damages the base of buildings and leads to crack the superstructure, but also damages the stability of the country rock of tunnels,lining structure, even the supporting structure within the tunnel in the soft expansive rock area.At present,the studies of expansive geotechnical, both macro-deformation and micro-studying hand, has a considerable amount of reseaech results.However, the soil structure influnece the engineering properties of expansive geotechnical greatly, so the swelling characteristics of the expansive rock or soil of different regions and causes have great difference,even appear opposite conclusion, so it is necessary to study the expansive rock or soil in different areas.The expansive rock (soil) in Luwangfen test section of the misline of the North Water Transfer Project is in a semi-rock and semi-soil condition, which is not-complete decency but near to complete decency. It looks like rock in the drying condition,which is hard, but it becomes soil with water,so it is expansive rock(soil).As the channel slope excavating, the expansive rock(soil) in the certain depth of the surface of the channel is disturbed,and needs to be compacted,so the expansive rock(soil) of this part will have the swelling characteristics of remodeling. In this paper, combined with previous research results, this article studies importly the expansive-contractive characteristics of the remolded expansive rock(soil) from the expansion,contrantion and,expansion-contraction cycle, while present the modification for the proposed soil of this part,which has practical significance for the design and construction of the channel slope.This paper firstly analyses the basic physical and chemical properties of the expansive rock(soil), and obtains it's weak expansive viscous rock(soil), whose main mineral components are kaolinite,and has lesser amounts of montmorillonite,illite and so on, which provides the basic material base for the weak expansive properties.While this paper determinates the optimum moisture content and maximum dry density of the expansive rock(soil),which provides the basic controlling indicators for the following test. On the basis,this paper anlysis the dependency relation between the expansive deformation without loads and the initial state of the remolded expansive rock(soil), and draw the decreasing linear relation between the expansive deformation without loads and initial moisture conent,while the greater the initial dry bulk density, the greater the decreasing rate;the expansive deformation without loads decreases charging with the initial density and presents curve relation,and at the beginning of decreasing from the maximum dry density, the decreasing rate is veary great, when the degree of compaction lower than 96%, the trend rapidly slowing,and stabilizing.While,this paper analyzes how the expansive deformation without loads changes with having or no lateral confinement, because the sample generates large level deformation without lateral confinement,and particles loss in the deformation process, which provides a large amount of space for the following expansive deformation., so the unconfined expansive deformation is smaller than the confined expansive deformation, which is less than half of that in the confined conditions.In engineering pratice, most of the expansive rock or soil will bear the overlying loads.So this paper also anlysis the the dependency relation between the expansive deformation with loads and the initial state of the remolded expansive rock(soil),and get the following conclusion:when the initial density is smaller and overlying loads are larger than expansive stress,the remolded expansive rock(soil) doesn't occur expansion,but collapsible phenomenon after immering water, and with the overlying load increasing, the collapsible deformation first increases and then decreases, and there is the collapsible peak;when the initial dry density is more than the compaction degree 96%, the remolded ezpansive rock(soil) shows expansive deformation after immering in water with the overlying loads, and the swelling deformation with loads decreases with the overlying loads increasing, which tends to a constant value.Therefor, in engineering pratice, dealing with expansive rock or soil problems,particularly weak expansive rock or soil,we have to consider the size of the overlying loads,and then anlysis the expansive rock or soil swelling or not after immering,and the take a appropriate approach.As the initial water content greater, the sample particles have finished more swelling deformation in preparing sample process, so samples with the same volume has smaller pore size, which results hydrophobic sbstructing.So the swelling deformation with loads decreases with the initial water content increasing;and for the samples of smaller initial dry density, when the overlying loads is larger, the samples will occur collapsible deformation,which samely decreases with the initial water content increasing,showed a linear relationship.On this basis,this paper presents a formula describing common relationship between expansion rate with loads and the initial water content and the overlying loads for the remoded sample with larger dry density. This paper also find that the initial water content hardly affect the end water content,but the overlying loads affect greater, because the overlying loads larger,the affective stress greater, the water suction is samller, which leads the ending water content smaller.When the loads increase to a certain size,the suction is no longer affected,and the ending water content tends to a certain value.In addition, this paper analysis the relationship between the swelling rate with loads and processing water content, and presents that the expansive deformation increament is getting smaller and smaller even if absorpting same water content with water content of the sample increasing, and expansive deformation will cease when the water content achieves the inflation limit.Many studies have pointed out the swelling pressure decreases with the initial water content increasing,but this paper get the different conclusion through measuring the swelling pressure of the remodeled expansive rock(soil) in different initial states.Namely, the swelling pressure first increase then decrease with the initial water content increasing.This phenomenon presents that the size of the swelling pressure not only relate with the initial states,but also relate great with the pore structure changing in the test process.This paper also study the shrinkage deformation of the remodled expansive rock(soil), and presents that the shrinkage deformation increases with the initial water content increasing, and the shrinkage limit also increases and tends to be stable and not increasing when the initial water content closes to the liquid limit, which also verify the method of measuring shrinkage limit in geotechnical specification.In addition, we also study the cycle expansion-contraction deformation of the remolded expansive rock(soil), indicating that the expansion-contraction deformation decreases with the recurring series increasing, and the swelling characteristics resuce rapidly, and the expansion-contraction deformation tends to be stabilized when the cycle progression reaches to a certain level.Therefore, it is one of methods decresing the expansion-contraction characteristics that pre-making the expansive rock(soil) occurring multi-stage cycle expansion-contraction deformation.In the foundation of studying the expansive-shrinkage deformation of the remolded swelling rock(soil), we propose a new method of improving expansive rock or soil, which is ISS improving the expansive rock or soil.The study shows that the expansion-contraction characteristics of the remolded expansive rock(soil) get improvement and significantly reduce after improving by ISS, and the shear strengh also advance.This paper proposes the best solution ratio of 1:300 of improving the remolded expansive rock(soil) by ISS on the basis of test.
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