In order to research the geogrid technology to improve the tailings dam stability,the paper introduces the mechanism of the geogrid reinforcing tailings dam and the simulation principle of the geogrids unit.It also introduces a calculation example.It uses the FLAC3D software to make a comparative study for the dam stability when geogrids reinforcing dam or no reinforcement. The result shows that: The X displacement value is reduced after reinforcement,but far from reinforced area X displacement is not change.It shows that the reinforcement effection appears at the reinforcement surrounding area.There is a little change about the landslide face after reinforced，which is more closer near early dam from the beach top. The safety coefficient rise from 1.69 to 2.37.The reinforcement effection is in good working order. The paper can provide some reference and instruction to the tailings dam safety.

For the study of soft subgrade pavement cracking process, it establishes the pavement structure tension crack model by elastic layered theory. Based on the finite element method, it studies the tension crack evolution process. It establishes the tension crack stress criterion to the roadbed. Analysis shows that the distresses of asphalt pavement of the real highway results from the damage by asymmetric sedimentation which is under excessively axle loading on pavement structure, rather than the fatigue damage by axle loading repetitions in the condition of asymmetric intensity in the same layer. The results show that the soft degree of the subgrade is proportional to the tensile stress, the more localized soft, the easier to crack the road. The soft roadbed does not have a homogeneous structure of the road surface, the tension stress rupture occurred in the discontinuous surface. The road structure has a set of tensile stress under the circulation wheel load, it formats a new fracture surface, and the structure form corresponding evolves, and causes stress state change. At last most of the road sub-base crack, and surface cracking occurres, so the pavement failure.

To study the stability of rock slope under dynamic load,the digital speckle correlation measurement (DSCM) is used for dynamic failure of rock slope containing two weak layers.It observes the displacement field, deformation field, and stress field during the process of crack formation, crack through the slope and slope collapse. Experimental results show that the initial deformation cracking on the surface around the structure of the weak layer, and then extended to top and the foot of the slope, and finally through the loose structure.The slope stability is controlled by the weak layer’s angle, the space form of the weak layer and the slope Mechanical Properties.It gives the failue model of the different positon in the slope.

In study of waste old plastic modified asphalt majority study staff generally cut and then directly the waste old plastic recycled into asphalt for shear cutting, mixing modifying. The modified asphalt made by this kind of method easily segregates, and makes a poor stability and uniformed property of modified asphalt. This obviously has become a difficult problem of waste old plastic modified asphalt. This article through DSC (Differential Scanning Calorimeter) test studies the property of domestic waste old plastic modifying agent and granular waste old plastic modifying agent made by special method. A study by comparison on the fundamental property and storage stability of this two types modifying agent modified asphalt is made. The result from study shows that the crystallization degree of specially made waste old plastic modifying agent decreases compared with decrease of molecule amount and molecule amount distribution becomes wide and inner cohesive energy becomes small and branching degree becomes great and flexibility is reduced. The waste old plastic modifying agent (PMB) can not only improve softening point of asphalt but also has sound storage stability without segregation and solve the segregation problem of modified asphalt. The mechanism of segregation of waste old plastic modified asphalt is analyzed. The study achievement has certain reference and applicable values in respects of recycling for use of waste old plastic and cost saving of modified asphalt and improving road pavement property