Industry Posts

Soil Consistency

The consistency of soil type should be seriously observed during the dumping of filling materials in the area of construction or rehabilitation. The ground compaction process and ground stability will be affected based on type of soil.

Use of organic soil for base course:

Organic soils have a different criteria compare to common mineral soils. Organic soil is difficult to deal with due to its high compressibility and poor strength. Looking at the case study of an actual area, proper soil mixing method was not applied as there are areas where organic soil was concentrated, and areas that have only common mineral soil present (Figure 1). The consistency of soil type is crucial to establish soil strength and ground resistance as opposed to what was already done in the actual site (Figure 2).

Use of broken concrete for top soil:

During construction of building foundations, a run-in with substantial large rocks embedded in the top soil will pose as a physical obstacle and possible damage to pile drivers when boring/ excavating the depth requirement for building foundation (Figure 4). The levelling of ground will also be affected due to the different reactions of soil to compaction/compression as there are areas where soil is mixed with broken concrete, and areas that don’t have broken concrete at all (Figure 5­­­), thus resulting to uneven plane (excessive ground differential deformation) when ground settlement occurs. Uniform vertical ground settlement can be achieved through consistency in the soil type/material being used for filling.

Note: The following actual case study was conducted by BPMJ Group when it was asked to assess the ground improvement operation in preparation for a construction project in Valenzuela City.

Surface Water and Groundwater

Ground settlement is a major challenge in infrastructure development due to the safety and damage it causes to the environment as well as to the project itself. Excessive levels of groundwater during a construction project may require a process called dewatering.

The surface water in the given case below (actual site photos) was only filled up with subbase composed of soil and rocks (Figure 6). This particular area was subjected to frequent inundation of surface water for a long time, and when there is surface water, groundwater is usually deposited underneath the native soil. Removal of surface water and groundwater should be conducted prior to any significant soil filling operations by way of excavation—in order to reach the groundwater below the surface. Once groundwater is exposed, dewatering can be done through drainage and/or pumping.

Groundwater (Figure 7) should be seriously dealt with as it has the tendency to influence soil settlement. Possible vertical movement (downward and upward movement of the ground surface)will occur during lowering and rising of groundwater, thus affecting, and possibly damaging the buildings and infrastructures above it.

Note: The following actual case study was conducted by BPMJ Group when it was asked to assess the ground improvement operation in preparation for a construction project in Valenzuela City.