The role of geogrids in dealing with weak foundations is mainly reflected in two aspects: firstly, improving the bearing capacity of the foundation, reducing settlement, and increasing foundation stability; The second is to enhance the integrity and continuity of the soil, effectively controlling uneven settlement.
The mesh structure of geogrid has a reinforcing performance that is manifested by the interlocking force and embedding force between the geogrid mesh and the filling material. Under the action of vertical loads, geogrids produce tensile stress while also exerting a lateral restraining force on the soil, resulting in high shear strength and deformation modulus of the composite soil. At the same time, the highly elastic geogrid will generate vertical stress after being subjected to force, offsetting some of the load. In addition, the settlement of the ground under the action of vertical load causes the uplift and lateral displacement of the soil on both sides, resulting in tensile stress on the geogrid and preventing the uplift or lateral displacement of the soil.
When the foundation may experience shear failure, geogrids will prevent the appearance of the failure surface and thus improve the bearing capacity of the foundation. The bearing capacity of geogrid reinforced composite foundation can be expressed by a simplified formula:
Pu=CNC+2TSinθ/B+βTNɡ/R
The cohesion of C-soil in the formula;
NC Foundation bearing capacity
T-Tensile strength of geogrid
θ – inclination angle between the foundation edge and the geogrid
B – Bottom width of foundation
β – Shape coefficient of foundation;
N ɡ – Composite foundation bearing capacity
R-Equivalent deformation of foundation
The last two terms in the formula represent the increased bearing capacity of the foundation due to the installation of geogrids.
The composite composed of geogrid and filling material has different stiffness from the embankment and lower soft foundation, and has strong shear strength and integrity. The geogrid filling composite is equivalent to a load transfer platform, which transfers the load of the embankment itself to the lower soft foundation, making the deformation of the foundation uniform. Especially for the deep cement soil mixing pile treatment section, the bearing capacity between piles varies, and the setting of transition sections makes each pile group tend to operate independently, and there is also uneven settlement between villages. Under this treatment method, the load transfer platform composed of geogrids and fillers plays a more significant role in controlling uneven settlement.
Post time: Nov-08-2024