**2. Sand composition and morphology parameters**

The investigated area is located in the southern part of Lithuanian continental coastal zone of Baltic Sea, the northern part of Klaipeda city [1]. To the north of the Klaipeda city, only the immediate near‐shore contains a sandy strip of Holocene marine sediments (m IV), which occurs in up to 4–5 m of the sea water depth. The material composing the near‐shore sediments in the continental coast zone mainly consists of different sand, where prevailing medium coarse and fine sand [2, 3] with admixture of gravel and organic matter [4, 5]. This sand was used for investigations (**Figure 1**). The coordinates of sampling location [1] are 55°46'4.07″, 21°4'39.06″ (WGS).

**Figure 1.** Location of sand sampling.

The average density of particles (*ρs*) value of marine sands is 2.67 Mg/m3 and varies from 2.65 to 2.71 Mg/m3 , respectively. The bulk density of the sand varies from 1.83 to 2.09 Mg/m3 , where average is 1.98 Mg/m<sup>3</sup> . Regardless to the genesis of marine sand and their grain size distribu‐ tion, the mineral composition consists mainly of quartz. The natural moisture content depends on the degree of saturation of water and ranges from 13.7 to 27.7%. The void ratio (*e*) in fine sand varies from 0.474 to 0.778, respectively [4–6]. The recent marine sediments (m IV) were formed in the coastal zone; therefore, a distinctive morphological feature of grain shape has high sphericity, where *P* = 0.84 [6]. Investigated sand mineralogical composition determined in reference [7], where basic consistency of the sand is ∼85% quarts, ∼6% feldspar with remaining contribution of carbonate, mica and some other minerals. The grading curve of investigated soil is given in **Figure 2**.

**Figure 2.** Grading curve of investigated soil sample.

Granulometric curve and separate particle shape discretization are one of the most relevant existing problems for numerical modelling via DEM. There are no direct recommendations for a single‐particle subscription with spheres (single‐particle subscription level based on spheres size and quantity). Subscribing soil particles with DEM, it is very important to choose size, shape, and physical properties of modelled particles. It is possible to model realistic size oedometer device without not scaled particles if quantity of modelled particles is small. Modelling of soil which is subscribed with a big quantity of particles is not possible because of the limitations of computer calculation capacity. All simplifications are accepted in order to decrees the calculation time. Another relevant problem, arising from all accepted simplifica‐ tions, is a very small quantity of the authors working on experimental and numerical testing validation. This fact only proves that there are still a lot of problems related to dispersive

The investigated area is located in the southern part of Lithuanian continental coastal zone of Baltic Sea, the northern part of Klaipeda city [1]. To the north of the Klaipeda city, only the immediate near‐shore contains a sandy strip of Holocene marine sediments (m IV), which occurs in up to 4–5 m of the sea water depth. The material composing the near‐shore sediments in the continental coast zone mainly consists of different sand, where prevailing medium coarse and fine sand [2, 3] with admixture of gravel and organic matter [4, 5]. This sand was used for investigations (**Figure 1**). The coordinates of sampling location [1] are 55°46'4.07″,

The average density of particles (*ρs*) value of marine sands is 2.67 Mg/m3 and varies from 2.65

, respectively. The bulk density of the sand varies from 1.83 to 2.09 Mg/m3

, where

systems, which are modelled with DEM.

246 Modeling and Simulation in Engineering Sciences

21°4'39.06″ (WGS).

**Figure 1.** Location of sand sampling.

to 2.71 Mg/m3

**2. Sand composition and morphology parameters**

Thirty‐three different sand grains corresponding nine sand fractions [8] have been examined, the total number of examined grains being 297. Investigation of grains morphology parameters provided with SEM and view analysis program. Example of investigation process is given in **Figure 3**. Smaller fractions within the 0.0063–0.15 mm are omitted in the panoramic view due to the lack of space in SEM camera. Rest of all fractions was investigated separately.

**Figure 3.** Soil 2D investigation with SEM [1]: pictures of panoramic view (left) and magnification of marked area (right).

The main morphological parameters of investigated sand fractions employed in 2D view analysis [9, 10] include these parameters, namely area (mm2 ), equivalent diameter (mm), sphericity, circularity, form coefficient, angularity. Final decision to investigate particles only in 2D was accepted according to literature analysis.

2D and 3D view analysis and determination of grain sphericity results accuracy 5–10% [11, 12]. Due to this fact, it is saved a lot of time which is spent for morphological parameters investigations with SEM and view analysis program. Small results differences between 2D and 3D analysis are due to particle landing on the investigation table with the biggest particle gravity centre (**Figure 4**). Particle stays on investigation table with the biggest stability surface in contact with investigation table [13]. In this case, particles maximum length is in a parallel line with investigation table surface and particles height which is perpendicular for investi‐ gation tables is the smallest. Results inaccuracy can be increased if it is investigated mainly flat grains [14].

**Figure 4.** Flat (on the left hand) and spherical (on the right hand) particle shape.

The analysis of the determined morphological parameters within each fraction shows that the shape of all grains is sufficiently similar—It tests the grains differ principally only in size. The obtained mean 2D morphological parameters of the particles are given in the **Table 1**.


**Table 1.** Mean 2D case morphological parameters of investigated sands [15].

The mean shape of investigated sand grain was determined using [16, 17] given solutions for sand shape characterization according to the particle sphericity and roundness. In this case, it is not necessary to use Fourier descriptors [18]. The analysis of the change of morphology parameters of investigated Baltic Sea soil‐type according to the equivalent diameter increment is shown in **Figure 5**.

**Figure 5.** Morphological parameters versus *dekv, 2D.*

The main morphological parameters of investigated sand fractions employed in 2D view

sphericity, circularity, form coefficient, angularity. Final decision to investigate particles only

2D and 3D view analysis and determination of grain sphericity results accuracy 5–10% [11, 12]. Due to this fact, it is saved a lot of time which is spent for morphological parameters investigations with SEM and view analysis program. Small results differences between 2D and 3D analysis are due to particle landing on the investigation table with the biggest particle gravity centre (**Figure 4**). Particle stays on investigation table with the biggest stability surface in contact with investigation table [13]. In this case, particles maximum length is in a parallel line with investigation table surface and particles height which is perpendicular for investi‐ gation tables is the smallest. Results inaccuracy can be increased if it is investigated mainly flat

The analysis of the determined morphological parameters within each fraction shows that the shape of all grains is sufficiently similar—It tests the grains differ principally only in size. The

obtained mean 2D morphological parameters of the particles are given in the **Table 1**.

**Morphological parameter Mean value**

Equivalent diameter (mm) 0.340 Sphericity 0.836 Circularity 0.515 Form coefficient 0.702 Angularity 0.410

) 0.112

The mean shape of investigated sand grain was determined using [16, 17] given solutions for sand shape characterization according to the particle sphericity and roundness. In this case, it is not necessary to use Fourier descriptors [18]. The analysis of the change of morphology

), equivalent diameter (mm),

analysis [9, 10] include these parameters, namely area (mm2

**Figure 4.** Flat (on the left hand) and spherical (on the right hand) particle shape.

**Table 1.** Mean 2D case morphological parameters of investigated sands [15].

in 2D was accepted according to literature analysis.

248 Modeling and Simulation in Engineering Sciences

grains [14].

Area (mm2

Particle shape
