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.

Under the action of tensile load obvious necking-down phenomena will accur in the metal test-piece. The tensile experiment about the metal test-piece has been studied, but the finite element simulation of the tensile necking-down phenomena has not been reported. The paper first studies the experiment of the mental test-piece, using the universal testing machine of WE-10A and WI-60T to load the mental test-piece and using IZ-910 infrared thermal imager to test the change process of infrared radiation temperature fields, then works out the finite element program to simulate the tensile necking-down phenomena of the metal test-piece with the elastic-plastic model. The experiment result shows that the infrared thermal effect of the metal test-piece in the process of loading is obvious, before the sample fracture will appear the omen of high temperature in the position where the future fracture will occur; in stress concentration the microcracks concentrate and the thermal figure is obvious; in the whole loading process the fracture starts from the local part, develops and evolutes gradually; with the stress change on the metal test-piece the infrared radiation tempreture of the test-piece surface changes, having the temperature-rising tendency in the total and the temperature rising trend in the local fracture position is obvious. This is because the metal test-piece material or the force is uneven and the stress concentration is formed, In the position of the stress concentration the deformation destruction firstly occurs. Because the energy is released in the process of deformation destruction, so the temperature change is obvious in the fracture position. After the experiment the obvious necking-down phenomena occurs in the test-piece. At the same time, in order to provide the theoretical basis for the experiment, with the finite element software of FEPG the finite element program is worked out, with the elastic-plastic model and the uneven material the fracture evolution process of the metal test-piece is simulated. Through the comparasion we can see that obvious necking-down phenomena appeared in the metal test-piece under the tensile load, the infrared information testing shows the temperature-rising is obvious in the position where necking-down phenomena occurs and the tensile necking-down phenomena of the metal test-piece is well simulated, which can provide helpful basis for the prediction and forecast of mental structure fracture.

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.