4.1 Experimental results evaluations
4.1.1 Results of the Temperature and Weight
From Fig. 2, it is very easy to see humidity decrease gradually after 1 hour as temperature increases gradually. The water content contained in the sample boreholes was lost by volatilization, and the soil structure was rearranged, so soil particles moved the nearest distances together. When the temperature increased strongly, the volatilization process occurred fast, this resulted in just a puss - fast particles movement process, which was done continuously until water wasn’t contained in the boreholes and the soil surface was dry completely after 48 hours. At this completely dried state, the sample weight decreased clearly compared with the initial state. The recording results of the weight decreasing (Wg) with temperature shew particularly from C4, C6, C8, C9, to C10. At 340C temperature of 66.36g on the first day, compared with 44.48g on the second day; the temperature increased the maximum value at 350C with 44.22g. Then the temperature decreased gradually from 350C to 260C. However, the decreased weight values varied lowly after 48 hours.
On the other hand, the maximum weight decreasing value of 66.44g at 330C after 24 hours, and và 48.71g at 260C temperature on the first day; compared with 48.32g at 340C, and 48.69g at 260C (see Fig. 5).
The Weight variations with Temperatures of the Samples C2, C3, C5, and C7 after 2 hours.
However, Thy Truc Doan, 2023 determined the relationship between the Dry Unit Weight variations and different Depths of the Clay and Sand soil. The results presented the minimum Dry unit weight value is 0.74 gram/cm3 at 4.3m depth; which is compared with the maximum value of 1.626 gram/cm3 at 17.8m depth. The medium value at the center of the layer is 1.44 gram/cm3 (from 0.0m to 27.0m depth); whereas this value increased gradually to 1.57 gram/cm3 of the layer 1 “Clay layer” (from 27.0m to 40.0m depth). The biggest value of dry density obtained of 1.597 g/cm3; 1.582 g/cm3; and 1.580 g/cm3 at 18.3m depth of boreholes “HK1, 2, and 3”). The biggest value of dry density was obtained of 1.582 g/cm3 at 18.3m depth of boreholes “HK1, 2, and 3”); whereas the lowest dry density was obtained at 0.74 g/cm3 at 4.3m depth.
4.1.2 Results of the Sample, Outside Humidity Deviation, and Temperature
Recording of the Sample and Outside Humidity Deviations was determined carefully by the FJ3365 machine (see Table 1). The results presented in the sample humidity decreased as outside humidity is low, which means temperature increased. This shows an inverse ratio between the Sample and outside Humidity. The outside highest humidity presented in H0 = 76% with the maximum humidity samples C4: 30.6%; C6: 17.2%; C8: 16.3%; C9: 13.9% và C10: 16.2%. On the other hand, the minimum outside humidity obtained H0 = 53% of the sample humidity 0.03%; 0.01%; 0.06%; 0.05% và 0.1%. Moreover, the outside average humidity was shown H0 = 69.40%, whereas the sample average humidity obtained C4: 2.71%; C6: 2.69%; C8: 3.35%; C9: 3.27% and C10: 1.83% (see Fig. 8).
However, Thy Truc Doan (2022) presented the Field Test method with the Standard Penetration Test (SPT) with 3 boreholes and an Experimental Test in the laboratory of the Clay Soil which included 6 layers. The results showed the maximum moisture (water content) of 70.36% at -6.0m depth of the Clay layer; whereas at -28.0m depth of the Mixed Clay layer obtained 22.79%.
However, An experiment test measured the effects of different types of sand and a combination of Carbon fiber-reinforced polymer (CFRP) by Direct Shear Test. The results presented the differences between soils including poorly graded sand (SP), silty sand (SM), and Ottawa sand (OTS), which resulted in different moisture conditions (dry and saturated); whereas the decreasing of moisture content which caused the increasing of the interface friction angle; and that the dissipated energy with the dry state was higher than the saturated state (Amir Mostafa Namjoo et al., 2021).
An inverse ratio between the decreasing of the sample humidity and the increasing of temperature variations. The maximum temperature outside obtained T = 350C according to the sample humidity C4: 5.7%; C6: 9.2%; C8: 12.91%; C9: 19.45%; and C10: 3.1%. Comparison between the minimum outside temperature obtained T = 260C and the minimum sample humidity presented 0.03%; 0.01%; 0.06%; 0.05% và 0.1%. Moreover, the average value of temperature was shown T = 31.210C, the average sample humidity obtained C1: 0.72%; C6: 1.65%; C3: 2.43%; C5: 2.52%; and C7: 0.81%. However, the temperature-dependent model was used to investigate the tensile strength characteristic curves of unsaturated soils. Temperature variations of Clay soils of 200C, 400C, and 600C. The results presented the effection of suction stress by temperature capillary suction stress components at the maximum temperature of 600C, and this can contribute to the improvement of the analysis of desiccation cracking in unsaturated soils (Kwestan Salimi et al., 2021).
Moreover, the maximum samples humidity C1: 16.9%; C2: 13.99%; C3: 14.78%; C5: 16.36%; and C7: 22.98% with the maximum outside humidity presented H0 = 79%; compared with the lowest values of C1: 0.03%; C2: 0.08%; C3: 0.13%; C5: 0.03%; and C7: 0.07% whereas the minimum outside humidity obtained H0 = 64%. Moreover, the outside average humidity obtained H0 = 71.7%, the sample average humidity obtained C1: 2.2%; C6: 2.5%; C3: 3.1%; C5: 4.4%; and C7: 5.8%. On the other hand, the maximum sample humidities of C1: 16.9%; C2: 13.99%; C3: 14.78%; C5: 16.36%; and C7: 22.98% obtained at temperature T = 340C; compared with the lowest values of C1: 0.03%; C2: 0.08%; C3: 0.13%; C5: 0.08%; and C7: 0.07% at temperature T = 260C. Moreover, the average temperature obtained at T = 310C as the sample average humidity was described as C1: 2.25%; C6: 2.51%; C3: 3.06%; C5: 4.38%; and C7: 5.8% (see Fig. 9).
On the other hand, Thy Truc Doan (2022) presented the Field Test method with the Standard Penetration Test (SPT) with 99 boreholes and simulation of the Geo-statistical software (SGeMS), Ilwis software, and Kiring interpolation method to calculate the layer thickness variations with depths. The results show the ground structure was divided into two layers which included Clay and Sand. At a depth of 1.5m, Clay with pale brown colors; Mud mixed clay with dark gray color at a depth of 2.5m; Fill soil with yellow-brown color at 4.0m depth and light gray color at 5.5m; 12.0m grown-gray color. 17.0m red brow mixed white yellow color; 67.0m mixed clay with white mixed yellow color. However, crack width changed at temperatures 200C to 400C when cracks width from 0.76mm (0.03 in) to 6.71 mm (0.264 in) with fine materials; whereas the other cracks obtained 1.22 mm (0.048 in) to 2.18 mm (0.086 in) for coarse materials (Jingan Wang et al., 2022). Consideration of environment effection to crack deformation. The results presented the influences of daily day/night of the air temperature which created cracks shapes at the maximum temperature of 250C (Josbel A. Cordero et al., 2021).
However, J. Sima et al., 2014 measured the weather conditions during the test period with the Daily rainfall, potential evaporation, and highest temperature to credit cracks deformation on the slope surface. The results presented the maximum value of the daily rainfall obtained at 70mm on September 20, 2007; whereas the maximum value of the daily evaporation shew 4mm on October 15, 200; compared with the daily highest temperature described at 340C on September 25, 2007.
On the other hand, Thy Truc Doan (2023) An experimental test of the Clay and sand samples with 12 samples for each borehole. The soil was sieved through sieve diameters of 0.005 mm; 0.1 mm; 0.25 mm; 0.5 mm for the Clay soil; compared with the Sand of 0.14 mm; 0.315 mm; 0.63 mm; 1.25 mm; and 2.5 mm. The temperature in the laboratory was obtained at 26°C during the experimental time. On the other hand, the initial water contents were used with 2%; 5%; 8%; 10%; 15%; 20%; 25%; 30%; 40%; 50%; 60%; 70%; 80%; 90% and 100%. The water content variation coefficient “ψ” shows clearly according to the type of soil (Clay and Sand) at the different depths. The results presented the maximum water content of 94.35% (borehole “HK 2”) at 4.8 m depth; whereas the minimum value is 18.22% at 39.3 m depth (borehole “HK3”). The mean values are at the center of the layers at depths from 4.3 m to 15.3 m, and approximately 36.2%. On the contrary, the end of the layer is up to 19.95% at 18.3 m depth and up to 39.3 m depth.
However, the dual-probe heat-pulse (DPHP) technique was used to analyze soil mass where a narrow cylindrical sample combined with a heater and temperature probes multi-point heat-pulse (MPHP) sensor. There are three temperature probes were used to measure a volume of 840 mm3. The results were three times that of the DPHP sensor recorded in the maximum difference between the measured percentage of moisture where the standard oven-dried instrument obtained a value of more than 10%, compared with the MPHP sensor presented a discrepancy of 3%. On the other hand, cracks appeared in the soil mass according to the discrepancy of the DPHP sensor of 16% compared with the value of 3%. (Vinay S. Palaparthy et al., 2022).
4.1.3 Results of the Sample Humidity, Dewpoint, and Wind Speed
The Sample Humidity and Wind Speed deviations are measured carefully by the WSO machine (see Table 1). The sample humidity decreased gradually when the outside wind speed increased remarkably, this resulted in water volatility on the surface occurring which was faster than the low wind speed. That means the proportionality between the sample humidity and outside wind speed. The maximum wind speed was shown at 17km/h, which is according to the sample humidities obtained C4: 30.6%; C6: 17.2%; C8: 6.3%; C9: 19.45%, and C10: 16.2%. Compared with the minimum values of wind speed at 9km/h with the minimum sample humidities at 0.03%; 0.01%; 0.06%; 0.05% và 0.1%. Moreover, the average wind speed presented 12.87km/h, the sample average humidity described in C1: 2.71%; C6: 2.69%; C3: 3.35%; C5: 3.27%; and C7: 1.83% (see Fig. 10).
However, the sample maximum humidities obtained C1: 16.9%; C2: 13.99%; C3: 14.78%; C5: 16.36%; and C7: 22.98% with the maximum wind speed 22km/h; whereas the lowest values of the sample humidities shew C1: 0.03%; C2: 0.08%; C3: 0.13%; C5: 0.08%; and C7: 0.07% with the values of 11km/h. Moreover, the average wind speed was obtained at 16.4km/h when the average sample humidities presented C1: 27%; C6: 30.1%; C3: 36.7%; C5: 52.6%; and C7: 69.6%. However, the wind speed variations and high intensity presented such as days 24, 27, and 30 of evaporation (negative volume influx). The results show low humidity as wind speed removes from a wet to dry state. At this time, temperature gradients close to the soil surface (Josbel A. Cordero et al., 2021). Because the void ratio of the soil is affected by humidity changes, when the void ratio increases, in the big borehole, water into the borehole is easier than to escape outside of the sample surface, so the wind speed is strong which will make fast evaporation. So the sample humidity results will change clearly.
However, Thy Truc Doan (2023) An experimental test of the Clay to determine the Void Ratio “Pore Coefficient” (ε) With the Different Depths (D, m) by the “Confined Compression Test” at a slow speed within 24 hours to obtain the best results. The results present a value of 0.881 at 7.5m depth of the borehole “BH1”, whereas the maximum value of 2.558 at 4.5m depth of the borehole “BH2”, and the final value of 0.737 at 11.3m depth of the borehole “BH3”. In general, the pore coefficient variations decreased gradually as the depths. The minimum value obtained was 0.685 at 27.3m depth.
On the other hand, the sample maximum humidity of C1: 16.9%; C2: 13.99%; C3: 14.78%; C5: 16.36%; and C7: 22.98% whereas the outside maximum dewpoint obtained 270C; compared with the lowest values of C1: 0.03%; C2: 0.08%; C3: 0.13%; C5: 0.08%; and C7: 0.07% with the dewpoint at 250C. Moreover, the average values reported at 260C with C1: 27%; C6: 30.1%; C3: 36.7%; C5: 52.6%; and C7: 69.6% (see Fig. 11).
The sample humidity and Dewpoint deviations were determined carefully by “CEMDT-8321” (see Table 1). The results recorded in the sample humidity changing (increase or decrease) which is according to the dewpoint at 24 hours (the first day). Then dewpoint values decreased with two values of 250C and 240C, then these values increased in the constant values at 260C. On the other hand, the maximum dewpoint values shew at 260C, which is according to the sample humidity at C4: 5.7%; C6: 12.91%; C8: 19.45%; C9: 19.45%; and C10: 0.1%. Whereas the lowest values of dewpoint determined at 240C, the lowest humidity of the samples were accounted for 0.03%; 0.01%; 0.06%; 0.05% và 0.1%. Moreover, the average values of dewpoint recorded at 25.790C as the sample humidity obtained at C1: 0.72%; C6: 1.65%; C3: 2.43%; C5: 2.52%; and C7: 0.81%. Specially, the lowest dewpoint value at 240C accounted for C1: 0.14%; C6: 0.07%; C3: 0.61%; C5: 0.05%; and C7: 0.27%.
However, (Y. Lu et al., 2016) Clay with a specific gravity (Gs) of 2.59; Liquid limit (LL) of 62%; Plastic limit (LP) of 39%; a Shrinkage limit (LS) of 13.8%; Plasticity index (PI) of 23. The cyclic freezing–thawing was done within 12 hours at a temperature of -20°C; whereas the Clay sample thawed within 12 hours at a temperature of 25°C. The results presented that the water content decreased at the initial stage and then increased gradually up to a constant state. The numbers of freeze – thaw cycles obtained the residual water content of 11, 21, and 50 for the 5 mm, 10 mm, and 20 mm thick samples; and the residual water contents obtained approximately value of 14.0%, which was close to the shrinkage limit (13.8%).
4.1.4 Results of the Sample Humidity and Cloud Consistency
Differences between the sample humidity and cloud consistency were recorded carefully by the “CEMDT-8321” machine (see Table 1). Results shew the maximum cloud consistency of Cc = 73%, with C4: 5.7%; C6: 12.91%; C8: 19.45%; C9: 19.45%; and C10: 0.1%. Compared with the cloud consistency of Cc = 21% of the sample humidity accounted for 0.03%; 0.01%; 0.06%; 0.05%, and 0.1%. Moreover, the average cloud consistence obtained at Cc = 41.07% as the average sample humidity of C1: 2.71%; C6: 2.69%; C3: 3.35%; C5: 3.37%; and C7: 1.83% (see Fig. 12).
On the other hand, the maximum sample humidity presented C1: 16.9%; C2: 13.99%; C3: 14.78%; C5: 16.36%; and C7: 22.98% whereas the maximum cloud consistence obtained at Cc = 96%; compared with the lowest values of C1: 0.03%; C2: 0.08%; C3: 0.13%; C5: 0.08%; and C7: 0.07%; whereas the lowest cloud consistence values shew Cc = 22%. Moreover, the average value of Cc = 59.42% with C1: 27%; C6: 30.1%; C3: 36.7%; C5: 52.6%; and C7: 69.6%.
However, Thy Truc Doan, 2023 described the experiment text in the laboratory to measure the percentage of the fine clay particle variations of the Water Content with the depths, and consideration of saturation, and porosity. The results presented the maximum value of the percentage of the fine clay particle obtained was 38% at 25.3m, whereas the water content (W%) of 25.6%; saturation (S) of 85.05%, and porosity of 44.49%.; compared with the minimum value of 21% at 7.8m depth, which compared with the water content (W%) of 22.23%; saturation (S%) of 87.82%, and porosity (P%) of 40.55%. On the other hand, the percentage of the fine clay particle shew the values which is according to water content, saturation and porosity W%; S%;, and P% evenly; which is 14.5%; 13.5%; 18%; 14%; 21%; 13%; 26.5%; 16%; 15.5%; 20%; 17%;12%; 35%; and 37% at 1.8m; 2.8m; 4.3m; 5.3m; 6.3m; 9.3m; 9.8m; 11.8m; 12.8m; 14.5m; 15.3m; 16.8m; 17.8m; 19.3m; 21.8m; and 22.8m; whereas compared with the W% of 23.22%; 22.25%; 23.962%; 22.89%; 21.89%; 22.23%; 21.4%; 23.1%; 21.38%; 22.46%; 22.93%; 21.12%; 21.8%; 21.46%; 20.82%; 22.79%; 23.9%; 24.32%; and P% of 42.63%; 40.62%; 4294%; 41.64%; 41.55%; 40.55%; 40.78%; 41.69%; 40.4%; 41.22%; 41.9%; 40.94%; 40.93%; 41.2%; 39.87%; 41.73%; 42.7%; and 43.72%.
Moreover, Deviations in the sample humidity and foresight were determined carefully by data from ‘National Hydrometeorological Forecasting Center’. The results present the maximum value of foresight Fs = 16km with C4: 5.7%; C6: 12.91%; C8: 19.45%; C9: 19.45%; and C10: 0.1%. Compared with the minimum value of foresight Fs = 11km, which is according to 0.03%; 0.01%; 0.06%; 0.05%; and 0.1%. Moreover, the average value of foresight Fs = 14.36km according to C1: 0.72%; C6: 1.65%; C3: 2.43%; C5: 2.52%; and C7: 0.81% (see Fig. 13).
On the other hand, the sample humidity obtained at C1: 16.9%; C2: 13.99%; C3: 14.78%; C5: 16.36%; and C7: 22.98%, whereas the maximum value of foresight Fcs = 16km; compared with the lowest value of the samples C1: 0.03%; C2: 0.08%; C3: 0.13%; C5: 0.08%; and C7: 0.07% with foresight Fcs = 16km. Moreover, the average foresight shows Fcs = 14.75km with C1: 2.25%; C6: 2.51%; C3: 3.06%; C5: 4.38%; and C7: 5.80% (see Fig. 13).
4.1.5 Results of the Sample Humidity and Cloud Ceiling
Differences between the sample humidity and cloud ceiling were determined by data from ‘National Hydrometeorological Forecasting Center’. Results presented the maximum cloud ceiling Cclc = 9100m according to C4: 5.7%; C6: 12.91%; C8: 19.45%; C9: 19.45%; and C10: 0.1%. On the contrary, the minimum values of cloud ceiling Cclc = 1000m as the minimum sample values were 0.03%; 0.01%; 0.06%; 0.05%; and 0.1%. Moreover, the average cloud ceiling Cclc = 8087m with C4: 2.71%; C6: 2.69%; C8: 3.53%; C9: 3.27%; and C10: 1.83% (see Fig. 14).
On the other hand, the samples humidity obtained at C1: 16.9%; C2: 13.99%; C3: 14.78%; C5: 16.36%; and C7: 22.98% with the constant values of Cloud Ceiling Cclc = 9100m; Compared with the lowest values of C1: 0.03%; C2: 0.08%; C3: 0.13%; C5: 0.08%; and C7: 0.07%; whereas the average sample humidity of C1: 2.25%; C2: 2.51%; C3: 3.06%; C5: 4.38%; and C7: 5.80% (see Fig. 15).
However, an experiment test was done to determine water content in soil –geosynthetic interaction. The behavior of the soil-geogrid interfaces was done by the direct shear and pullout tests. The results presented that water content (humidity) decreased gradually as the increasing of internal friction interface and adhesion (Amir Mostafa Namjoo et al., 2021).
4.1.6 Results of the Sample Humidity and Phenomenol Deviation
In the Fig. 16, the relationship between the sample humidity and the phenomenon was recorded carefully by data from ‘National Hydrometeorological Forecasting Center’. The results presented the sample humidity changing C4: 1.37%; C6: 1.16%; C8: 1.84%; C9: 0.8%; and C10: 2.39% with Dense sunshine; whereas the Discrete Cloud showed the maximum sample humidity obtained at 5.7%; 9.2%; 8.9%; 7.1%; and 3.1%. Moreover, Light sunshine, the sample humidity presented at C4: 0.8%; C6: 3.6%; C8: 3.6%; C9: 2.2%; and C10: 1.55%; Moreover, with Clear Cloud presented C4: 0.31%; C6: 0.82%; C8: 12.91%; C9: 19.45%; and C10: 0.69% (see Fig. 16).
On the other hand, the lowest values of the sample humidity obtained C4: 0.14%; C6: 0.01%; C8: 0.06%; C9: 0.05%; and C10: 0.1% with Discrete Cloud; compared with C4: 0.03%; C6: 0.07%; C8: 0.26%; C9: 0.2% và C10: 0.1% with Light sunshine. On the other hand, Clear Cloud obtained at C4: 0.07%; C6: 0.33%; C8: 0.33%; C9: 0.05%; and C10: 0.45% (see Fig. 16).
Moreover, Discrete Cloud is according to the average values of the samples C4: 1.50%; C6: 3.21%; C8: 2.43%; C9: 1.95%; and C10: 0.9%; whereas with Light sunshine, the sample humidity obtained C4: 0.34%; C6: 1.21%; C8: 1.39%; C9: 1.11%; and C10: 0.58%; or Clear Cloud presented C4: 0.2%; C6: 0.62%; C8: 4.7%; C9: 6.65%; and C10: 0.6% (see Fig. 16).
However, sand shape characteristics was measured carefully by the Direct Shear Test. The particle shapes varied clearly from well-rounded (GB), well-angular (GP) to sub-rounded and sub-angular (natural sands). The results recorded two relative densities of 50% and 80%, which made changing shape of sand on the roughness interface surface (Amir Mostafa Namjoo et al., 2021).
Moreover, the differences between the maxium sample humidity and Phenomena were recomaximumred particularly by data from ‘National Hydrometeorological Forecasting Center’. The results were described carefully at Dense sunshine with C1: 1.51%; C2: 1.09%; C3: 0.72%; C5: 0.62%; and C7: 2.04%. On the other hand, Discrete Cloud obtained at the maximum sample humidity of 2.59%; 1.29%; 0.6%; 0.11%; and 0.37%; compared with C1: 16.9%; C3: 13.99%; C5: 14.78%; C7: 13.92% và C10: 21.5% at Light sunshine. Moreover, Clear Cloud shew C1: 0.33%; C2: 0.25%; C3: 0.91%; C5: 1.62%; and C7: 0.68%; whereas Dense Cloud presented at C1: 0.33%; C2: 0.08%; C3: 0.13%; C5: 0.23%; and C7: 0.13% (see Fig. 17).
Moreover, the lowest values of sample humidity of C1: 0.33%; C2: 0.08%; C3: 0.13%; C5: 0.23%; and C7: 0.13% at Dense Cloud; compared with C1: 3.05%; C2: 9.5%; C3: 11.83%; C5: 13.84%; and C7: 14.59% at Light sunshine; whereas with Clear Cloud presented at C1: 0.33%; C2: 0.25%; C3: 0.91%; C5: 1.62% và C7: 0.68% (see Fig. 17).
Moreover, Dense Cloud recorded shew the average values of the sample humidity of C1: 0.52%; C2: 0.51%; C3: 1.02%; C5: 4.51%; and C7: 6.06%; whereas Light sunshine obtained at C1: 9.98%; C2: 11.75%; C3: 13.31%; C5: 13.88% và C7: 18.05%; compared with C1: 0.33%; C2: 0.65%; C3: 1.95%; C5: 2.79%; and C7: 3.21% at Clear Cloud (see Fig. 17).
4.1.7 Results of the Shrinkage and Cracks
After 48 hours, sample C10 obtained a completely dried state. The shrinkage and cracks occurred on the surface. The results shew 3mm of the maximum shrinkage width whereas shrinkage length occurred along a quarter of the sample's curve. The crack length presented 40mm, 1mm of width, and 1mm of depth; whereas the shrinkage and cracks of the other samples are negligible.
However, (L. Jing et l., 2017) a new experiment test used for the determination of a new type of grout material composed of gypsum, quicklime, soil, and admixtures. A combination of soil 60%, 32% gypsum, and 8% quicklime was obtained particularly as the shrinkage ratios and cracks decreased. The results presented 0.63–0.6% at the age of 3–28 days of the shrinkage and cracks decreased gradually with the gypsum-quicklime-soil grout material with 40% binding materials and 60% soil. Moreover, (Qing Cheng et al., 2020) researched five soil samples that were mixed with different water contents including 12.5%, 14.5%, 16.5% (optimum water content), 18.5%, and 20.5% and dry-wet process of the soil. The results presented a decrease in the water content, crack geometrical parameters such as surface crack ratio, and crack density increased almost linearly. In comparison with the 20 mm thick layer, the first crack was obtained within 26 days according to the average water content of 48.4%; whereas compared to 61% for the 50 mm layer within 37 days (R.N. Tollenaar et al., 2017). On the other hand, ultrafine slag varying from 2.5–40% resulted in cracks after 7 days of cured conditions (Ram Wanare et al., 2022).
4.2 Numerical Simulation for the Mobilized Shear Stress, Strains, and Vertical Displacements under the Groundwater Levels Variations at the Different Depths
4.2.1 Theory and Boundary Conditions of the modal (Numerical modal)
a) Boundary conditions
Boundary conditions are used for dimensions along the lines of symmetry and the model is extended in both horizontal directions to a total width of 75m. In this case, the building is considered to be very stiff and the foundation bottom is at − 0.6m.
a) Project properties (Model properties)
The numerical model shows in the Units that include “Length = m”; Force = kN; Time = day; the vertical direction downward (-z). The unit weight of the water can be determined in 10 kN/m3. The limited soil contour included Xmin = 0, Xmax = 75, ymin = 0, and ymax = 75. A borehole will be located at (x, y) = (0,0) and the top boundary of the soil layer at z = 0; whereas the bottom boundary to z = -30m. On the other hand, the head value in the borehole is at -0.6m.
c) Material properties
The PLAXIS 3D software calculates the vertical displacement (or settlement) of the ground and the calculation theory depends on the Mohr-Coulomb model. The model has been designed in size 18m length, 18m wide, 2m height, and 2m thickness. The loading put on the ground is assumed as the building loading with the parameters in Table 6 (see Table 2).
Table 2
Material properties (Thy Truc Doan, 2022).
Parameter
|
Signs
|
Building loading
|
Unit
|
Thickness
|
d
|
2
|
m
|
Weight
|
γm
|
50
|
kN/m3
|
Type of behavior
|
Type
|
Linear, isotropic
|
-
|
Young’s modulus
|
E1
|
3.107
|
kN/m3
|
Posson’s ratio
|
ν
|
0.15
|
-
|
The soil properties of ‘Soft Sand ‘RHACLSMC’ are assumed as of the ‘Soft Clay layer’ and shown in Table 3 (see Table 3).
Table 3
Soil properties (Thy Truc Doan, 2022).
Parameter
|
Name
|
Sand
|
Unit
|
General
|
|
|
|
Material model
|
Model
|
0.7
|
-
|
Drainage type
|
Type
|
Drained
|
-
|
Unit weight above the phreatic level
|
γw
|
9.6
|
kN/m3
|
Unit weight below the phreatic level
|
γđn
|
19.6
|
kN/m3
|
Water unit weight
|
γn
|
10.0
|
kN/m3
|
Parameter
|
|
|
|
Young’s modulus (constant)
|
E’
|
1.104
|
kN/m2
|
Poisson’s ratio
|
ν’
|
0.3
|
-
|
Cohesion (constant)
|
c’ref
|
16
|
kN/m2
|
Friction angle
|
φ’
|
14
|
0
|
Dilatancy angle
|
Ψ’
|
0.0
|
0
|
Initial
|
|
|
|
K0 determination
|
-
|
Automatic
|
-
|
Lateral earth pressure coefficient
|
K0
|
0.5
|
-
|
d) Mesh generation
The mesh setting is generated and divided on the total of the model to ensure every point can be calculated carefully and exactly by the element finite method.
e) Performing calculation
When the created mesh process is finished, the three (3D) dimension models will be run. There are two stages to calculate the results. On the other hand, the value of K0 value has always defaulted. In the first stage, soil properties are created, and then geometry configuration, initial stress, and other properties are done. In the second stage, the calculated displacement is done by clicking the section of “plate” to install, this is considered as building loading is activated.
The groundwater levels were set up at the different depths of -0.6m; -1.5m, -3.0m, -5.0m, -7.0m, -11.0m, -13.0m, -15.0m, -17.0m, -21.0m, -23.0m, and − 25.0m, -27.0m, -30.0m.
4.2.2 Numerical Simulation for the Mobilized Shear Strength (Mss, kN/m2)
The maximum value of the Mobilized Shear Strength (Mss, kN/m2) at the groundwater level − 30m depth is 50.58 kN/m2. On the other hand, the Mobilized Shear Strength at depths 0.6m; 1.5m; 3.0m; 5.0m; 7.0m; 11.0m; 13.0m; 15.0m; 17.0m; 21.0m; 23.0m; 25.0m; 27.0m, and 30.0m according to 51.19 kN/m2; 51.31 kN/m2; 51.31 kN/m2; 50.94 kN/m2; 50.53 kN/m2; 50.85 kN/m2; 50.18 kN/m2; 50.62 kN/m2; 50.26 kN/m2; 50.20 kN/m2; 49.65 kN/m2; 50.71 kN/m2; 50.12 kN/m2; 50.58 kN/m2 (see Figs. 21 and 22).
The minimum value of the Mobilized Shear Strength (Mss, kN/m2) at the groundwater level − 30m depth is 0.01057 kN/m2. On the other hand, the Mobilized Shear Strength at depths 0.6m; 1.5m; 3.0m; 5.0m; 7.0m; 11.0m; 13.0m; 15.0m; 17.0m; 21.0m; 23.0m; 25.0m; 27.0m, and 30.0m according to 0.1389kN/m2; 0.1797kN/m2; 0.12kN/m2; 0.1567kN/m2; 0.1401kN/m2; 0.04083kN/m2; 0.03947 kN/m2; 0.04658 kN/m2; 0.01141 kN/m2; 0.0134 kN/m2; 0.01536 kN/m2; 0.003488 kN/m2; 0.009792 kN/m2; 0.01057 kN/m2 (see Fig. 23).
4.2.3 Numerical Simulation for the Total Volumetric Strains, εV
The maximum total Volumetric Strains (εV) of the ground at the groundwater level − 0.6m at depth is 0.000114m. On the other hand, the total Volumetric Strains (εV) at depths 0.6m; 1.5m; 3.0m; 5.0m; 7.0m; 11.0m; 13.0m; 15.0m; 17.0m; 21.0m; 23.0m; 25.0m; 27.0m, and 30.0m according to 0.000114; 0.0001317; 0.0001543; 0.0002135; 0.0001154; 0.0001425; 0.00009761; 0.0001053; 0.00009794; 0.00009097; 0.00009569; 0.00009246; 0.00009182, and 0.00009478 (see Fig. 24).
4.2.4 Numerical Simulation for the Vertical Displacements
The results present the maximum vertical displacement of the ground at the groundwater level − 0.6m depth that shows 0.00494m in Fig. 25 (see Fig. 25). On the other hand, the relationship between the Vertical Displacements (Sv, m) at the different Depths (Dgwl, m) such as: 0.6m; 1.5m; 3.0m; 5.0m; 7.0m; 11.0m; 13.0m; 15.0m; 17.0m; 21.0m; 23.0m; 25.0m; 27.0m, and 30.0m according to 0.00494; 0.005148; 0.005234; 0.004995; 0.004904; 0.005152; 0.005045; 0.005248; 0.005227; 0.005324; 0.005356; 0.005455; 0.005507, and 0.005613.
The results of the relationship between the Vertical Displacement (Sv, m), Strains at Depths (Dgwl, m) are shown in Fig. 26 (see Fig. 26).
Thy Truc Doan, 2022 described the research on the ground (Soft Clay) vertical displacement (settlement) under Rigid Foundation by the groundwater level variations. The research used the Plaxis 3D to analyze, calculate, and simulate. The results presented the comparison between vertical displacement with TERZAGHI and PLAXIS 3D simulation is a little different. In the TERZAGHI method, the value presented of 0.63m but with PLAXIS 3D was 0.15m and the variations of the groundwater levels at 1.5m, 2.0m, 3.0m, 4.0m, 5.0m, 6.0m, 7.0m, 8.0m, 9.0m, 10.0m, 12.0m, 15.0m, and 20.0m is 0.09083m, 0.09088m, 0.09089m, 0.09878m, 0.09856m, 0.1033m, 0.09871m, 0.1032m, 0.09988m 0.09914m, 0.09839m, 0.1076 and 0.1076m. At 6.0m, 8.0m, 15.0m, and 20.0m whereas other locations near similarity and the maximum value are at 15m and 20.0m depth. From there, the result of the vertical displacement of the rigid foundation by the groundwater variations results in reliability as respectively (see Fig. 27).
Thy Truc Doan, 2023 presented the research for the Finite element method of the internal friction angle and saturation degree with the groundwater levels variations to evaluate the vertical displacement of the soft ground (soft Clay) under the Groundwater Levels Variations at the Different Depths. The results presented the small value of the vertical displacement of the soft ground. However, this research results show a quite difference between the Sample Humidity deviation and the vertical displacement as the groundwater levels vary at the different depths. The maximum value accounted for 0.01975 m (z = -36.9m) depth according to friction angle ϕ0 = 290); whereas the minimum value obtained of 0.002844 m (z = 0m) depth with ϕ0 = 20. The mean value at the center of the Clay layer (from 0.0m to 27.0m) depths was shown at 0.0577m depth and compared with 0.0156 m depth at the Sand layer (from 27.0 to 39.6m) depths.