Effects Of Active Earth Pressure On The Retaining Walls In Narrow Back Fill

Soil arching occurs when there is a difference in the stiffness of the soil and the structure bordering the soil. This happens depending on which of the two is harder. Is it the soil or the structure? If the structure is harder, then the soil load will arch into the structure, and if the soil is harder, it will arch away from the structure(Shahir 2018). The vertical composition of the soil is usually lower compared to that of the horizontal completion; this is what makes the soil adjacent to the structure harder, hence leading to soil arching. Most of the arching of soil is due to the difference in shear forces in the soil.

There are theories and formulas used in the calculation of the earth pressure coefficient “Which is always defined as the ratio of the horizontal stiffness of the soil to the ratio of the vertical stiffness of the soil. This, too, helps in geotechnical engineering, whereby the earth pressure coefficient is used to determine the type of materials to be used so that the built structure does not collapse or pause any threats to the users.

Geotechnical engineering plays a large role in the narrow backfills. Before the construction of a structure, several factors have to be taken into consideration. The mechanical and chemical properties of the surface materials have to be tested for their suitability to support the structure that is to be constructed (Adam Bezuijen 2018). This is usually done in order to find out the best kind of backfills to be constructed to neighbour the structure, which in most cases are always walls. Geotechnical engineering plays another role in balancing the materials that are used in making these structures, be it buildings, commercial houses, bridges, roads and even mini structures like concrete street lights.

Discrete element method analysis is also commonly used. This is common in the construction of roads, especially where more natural or artificial materials have been piled on top of the already existing surface materials (Ahmed 2018). A comparison of the results of the discrete element method and the theoretical results from ideal conditions obtained from the lab is made. The tests differ from place to place depending on the height of the soil arch, which, in turn, is crucial in determining the soil arching coefficient of the resultant soil in that particular place.

Soil arching effect undergoes the greatest pressure near the surface of the earth. This can, in turn, be summarized as soil arching pressure inversely proportional to the depth of the soil. This is applied in geotechnical engineering, more so in the contraction of underground tunnels running through soils with different chemical and mechanical properties.

Empirical and analytical methods are used to measure lateral earth pressure as they are relatively cheap compared to other direct methods, like the use of the dilatometer. Active pressures are obtained when retained soil is allowed to deform or just relax. The measures of both active and passive pressure play a major role in determining the minimum and maximum lateral pressure possible a soil will exert on the nearby structures. There are also other theories that predict active and passive earth pressure. For instance, the Rankine theory. A theory was also developed to find the active and passive earth pressure for rapture surfaces.

Narrow backfill has become a popular practice all around the globe. The most popular instance is the construction of retaining walls a few meters from the rock face cut, which is always carried out vertically. The space left between the rocks and the walls is used to work to enable the protruding breadth of the foundation. It also enables the construction of drains behind the walls.

Reference

Dehghani, Fariborz, Hadi Shahir, and Ali Ghanbari. “Seismic Active Earth Pressure of Narrow Geosynthetic-Reinforced Backfill on Rigid Facing.” Journal of Engineering Geology 11.3 (2018): 53-80.

c, Yang, et al. “Research on time–frequency analysis method of active earth pressure of rigid retaining wall subjected to earthquake.” Environmental Earth Sciences 77.6 (2018): 232.

Ahmadic, and Adam Bezuijen. “Full-scale mechanically stabilized earth (MSE) walls under strip footing load.” Geotextiles and Geomembranes 46.3 (2018): 297-311.