# Experimental Study of the Mechanical Properties of a Flexible Grid Filling Body
## 8 Discussion  
Using the flexible grid as the reinforcement material, we performed uniaxial compression, tensile, and shear tests of the flexible grid filling body. The following main conclusions were obtained from the experimental results:  
The uniaxial compressive strength of the flexible grid filling body gradually increased with the decrease in the grid spacing (the increase in the grid density), but the increase was not large. The uniaxial compressive strength of the flexible grid filling body was independent of the grid dimension, and the uniaxial compressive strength of the grid filling body in the different dimensions (one-dimensional, two-dimensional, and three-dimensional) was basically equal.  
The uniaxial tensile strength and shear strength of the flexible grid filling body first increased and then decreased with the decrease in the grid spacing (the increase in the grid density), and there was an optimal grid spacing. The uniaxial tensile strength and shear strength of the flexible grid filling body increased with the increase in the grid dimension; that is, the uniaxial tensile strength and shear strength of the one-dimensional grid < the two-dimensional grid < the three-dimensional grid.  
With the uniaxial compression test, the macroscopic failure mode of the specimen was conjugate shear failure, and finally, a \"dumbbell shape\" with two large ends and a small middle was formed. With the uniaxial tensile test, the macroscopic failure mode of the specimen was tensile failure. With the shear test, the macroscopic failure mode of the specimen was shear slip failure.  
From the analysis results, after adding flexible grids in the filling body, the tensile strength, shear strength, elastic modulus, cohesion, and internal friction angle of the filling body were increased to different degrees compared with the ordinary unreinforced filling body. Accordingly, the tensile strength, shear strength, cohesion, internal friction angle strengthening coefficient, and elastic modulus strengthening coefficient of the flexible grid filling body with different dimensions and spacings of the flexible grid fillings were proposed. The results showed that the tensile and shear strengths increased significantly after the addition of the flexible grid in the filling body, whereas the compressive strength increased relatively little.  
From the experimental process and the failure of the test block and the coupling effect between the flexible grid and the filling body in the test block, there is a friction passive resistance mechanism between the flexible grid with high tensile strength and the filling body, which makes up for the lack of tensile strength in the ordinary filling body, thereby improving the tensile strength of the flexible grid filling body. The flexible grid filling body is equivalent to improving the cohesion of the filling body without changing the friction angle of the original ordinary filling body, so that the filling body can obtain higher resistance to external loads (compressive strength).  
This material can meet the requirements of onsite use, when the compressive, tensile and shear strength of the ordinary filling body cannot meet the requirements of onsite use, such as the need for secondary digging in the filling body, the height of the filling body is too high, etc. One could consider adding a flexible grid to the filling body to meet the needs of use.  
Software, H.W.; resources, L.Z.; writing--original draft preparation, X.Z.; writing--review and editing, J.C.; project administration and funding acquisition, X.L. and W.W. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the National Natural Science Foundation of China, grant number 52074117.  
Not applicable.  
Data Availability Statement: Data are available on request due to privacy restrictions.  
We would like to thank [PERSON]. ([PERSON]) for his contribution of the Organizing experimental data.  
The authors declare no conflict of interest.