**4. Results and cases**

This section introduces some examples of the results achieved with the application of the presented method. The two cases discussed are deeply detailed in [19, 20].

#### **4.1. Soil type map**

Soil type maps were developed in [20] using the kriging technique exclusively from the data of SPT reports, starting at 1-m depth and ending at 25-m depth. **Figure 7** shows a compilation of all generated maps, in order to simultaneously visualize the variation of the soil composition along the layers.

Visually, it was verified that the subsoil of the head campus of UFSC has an increase of soil granulometry from northwest to southeast and along the depth. By calculating areas according Geological-Geotechnical Database from Standard Penetration Test Investigations Using… http://dx.doi.org/10.5772/intechopen.74208 257

**Figure 7.** Soil types maps [20].

of the visual analysis, [19] exemplifies the comparison between the elevation surface modeled from SPT reports (**Figure 6b**, developed with limited dataset) and from one modeled from

The data validation is an essential step because it helps to improve the results and prevent the elaboration of maps with unreal results. This stage can provide a better comprehension of the

**Figure 6.** 3D Digital Elevation Model. Surfaces modeled from contour lines (a) and from SPT borehole coordinates (b) [19].

This section introduces some examples of the results achieved with the application of the

Soil type maps were developed in [20] using the kriging technique exclusively from the data of SPT reports, starting at 1-m depth and ending at 25-m depth. **Figure 7** shows a compilation of all generated maps, in order to simultaneously visualize the variation of the soil composi-

Visually, it was verified that the subsoil of the head campus of UFSC has an increase of soil granulometry from northwest to southeast and along the depth. By calculating areas according

solution developed, and clarify the strengths and limitations of the study.

presented method. The two cases discussed are deeply detailed in [19, 20].

**4. Results and cases**

**4.1. Soil type map**

tion along the layers.

contour lines (**Figure 6a**, developed with a rich dataset).

256 Management of Information Systems

to the type of soil, quantitatively, up to the depth of 11 m, there are 50% or more of the area covered by clay, silt and sand, while in the following layers, there is a predominance of pebble and rock.

#### **4.2. Impenetrable surface**

The surface of the impenetrable to the SPT percussion was generated by interpolating the values in each SPT borehole. As one of the results, the impenetrable map available in [20] is displayed in **Figure 8**.

It is verified that the regions with fewer SPT boreholes (map boundaries) present a contour for the impenetrable depth zones with fewer details, covering larger areas and having a shallower impenetrable when compared to regions with more SPT boreholes.

**Figure 8.** Impenetrable to SPT map [20].

#### **4.3. Groundwater surface**

The maps generated by the interpolation of the groundwater elevation in each SPT borehole allow to understand the behavior of the water table and can be used to verify the groundwater flow. A **Figure 9** shows the groundwater surface generated [19].

In this case, it is observed that groundwater flows from the higher elevations to the lower elevations, tending to flow to the main river of the city. The shorter the color shade transition in **Figure 10**, the greater the hydraulic gradient is.

Geological-Geotechnical Database from Standard Penetration Test Investigations Using… http://dx.doi.org/10.5772/intechopen.74208 259

**Figure 9.** Groundwater map [19].

**4.3. Groundwater surface**

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**Figure 8.** Impenetrable to SPT map [20].

The maps generated by the interpolation of the groundwater elevation in each SPT borehole allow to understand the behavior of the water table and can be used to verify the groundwater

In this case, it is observed that groundwater flows from the higher elevations to the lower elevations, tending to flow to the main river of the city. The shorter the color shade transition

flow. A **Figure 9** shows the groundwater surface generated [19].

in **Figure 10**, the greater the hydraulic gradient is.

For an analysis of seasonality, the groundwater data can be separated according to the rainy and dry periods of the year. [20] performed a historical series analysis of daily precipitation data to obtain the rainy and dry seasons, and based on it the SPT boreholes were classified as belonging to the rainy season (**Figure 10a**) and dry season (**Figure 10b**).

The comparison between the two maps makes it possible to evaluate the temporal variation of the water table. In the case presented, it is possible to understand the difference between the

**Figure 10.** Groundwater seasonality map. Rainy season (a). Dry season (b) [20].

water table level in each period, with higher groundwater level during the rainy season and smaller one in the dry season, as expected. These maps are a valuable tool to plan schedules for foundation execution, for example.

#### **4.4. Admissible stress map**

The maps developed by means of the admissible stress values of each borehole, at the required depths, guide the design of direct foundations. Based on Eq. (1), the regions where the admissible stress (σa) is smaller than 100 kN/m<sup>2</sup> are not valid, because they correspond to areas where the N-value is smaller than 5 (lower limit of the Eq. (1)). Likewise, the N-value greater than 20 (higher limit of the Eq. (1)) corresponds to 400 kN/m<sup>2</sup> of admissible stress, also a limit range to create the map for safety reasons. **Figure 11** displays an example of a map generated for three different soil depths in [20].

In this case, there is a tendency to increase the stress supported by the soil along the depths, growing from west and southeastern regions to north-central areas.

#### **4.5. Orientation of the foundation type map**

The orientation of the foundation type maps indicates the propensity to execution shallow or deep foundations. They are generated by means of the interpolation of the values assigned to the SPT boreholes according to the established criteria. It is recommended to include information about water table, considering that the presence of groundwater can guide the decisionmaking regarding the foundation type to be adopted.

An example developed in [19] of these maps is showed in **Figure 12**, for the Blumenau urban area.

The maps developed to one and two meters of depth divides the Blumenau urban area into two large regions, the southwest, orientated to shallow foundations, and the northwest, tending to deep foundation mostly. Due to the higher resistance of the deeper soil layers, the susceptibility to shallow foundation covers 39.1, 45.9 and 79.0% of the total area, to the depths of 1 (**Figure 12a**), 2 (**Figure 12b**), 3 m (**Figure 12a**), respectively.

#### **4.6. N-value contours map**

water table level in each period, with higher groundwater level during the rainy season and smaller one in the dry season, as expected. These maps are a valuable tool to plan schedules

The maps developed by means of the admissible stress values of each borehole, at the required depths, guide the design of direct foundations. Based on Eq. (1), the regions where the admis-

where the N-value is smaller than 5 (lower limit of the Eq. (1)). Likewise, the N-value greater

range to create the map for safety reasons. **Figure 11** displays an example of a map generated

In this case, there is a tendency to increase the stress supported by the soil along the depths,

The orientation of the foundation type maps indicates the propensity to execution shallow or deep foundations. They are generated by means of the interpolation of the values assigned to the SPT boreholes according to the established criteria. It is recommended to include information about water table, considering that the presence of groundwater can guide the decision-

are not valid, because they correspond to areas

of admissible stress, also a limit

for foundation execution, for example.

sible stress (σa) is smaller than 100 kN/m<sup>2</sup>

**4.5. Orientation of the foundation type map**

making regarding the foundation type to be adopted.

for three different soil depths in [20].

than 20 (higher limit of the Eq. (1)) corresponds to 400 kN/m<sup>2</sup>

**Figure 10.** Groundwater seasonality map. Rainy season (a). Dry season (b) [20].

growing from west and southeastern regions to north-central areas.

**4.4. Admissible stress map**

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N-value contours maps can be elaborated through the established database in order to allow an orientation according to the type of deep foundation to be used. Through the interpolation of

**Figure 11.** Admissible stress for depths equal 1 m (a), 2 m (b) and 3 m (c) [20].

**Figure 12.** Foundation type orientation for depths equal 1 m (a), 2 m (b) and 3 m (c) [19].

the N-value in each analyzed depth, curves of the soil resistance for the study area are obtained. This kind of maps, for instance, enable to evaluate the geotechnical soil profiles in various sectors of the study area, in order to observe the occurrence of layers with lower resistance index and the evolution of the soil resistance with increasing depth.

**Figure 13** shows a compilation of all generated N-value maps presented in [20], in order to simultaneously visualize the variation of the soil resistance along the depths.

It is verified in **Figure 13** that there is a growing tendency of the areas containing high N-values (darker color) with the increase of the analyzed depth. The analysis was performed until 25 m deep, where the impenetrable to percussion layer is completely achieved. The UFSC subsoil shows that the N-values decrease from the east, west and south regions to the central-north portion, which contains soft soils and, consequently, with lower resistance.

**Figure 13.** N-value map—matrix of comparisons [20].
