Optimized LightGBM-Based Prediction of Foundation Bearing Capacity on Spatially Variable Bolton Sand

Aiming at the influence of water immersion in the loess stratum on the bearing capacity of the pipe gallery foundation, taking the prefabricated pipe gallery demonstration project in Xiongan New District as the research object, the static penetration test and indoor triaxial test of the foundation bearing layer of the pipe gallery before and after water immersion were carried out. In the experiment, the loss law of loess foundation bearing capacity before and after water immersion was analyzed by using the obtained soil physical index changes. The research results show that the foundation bearing capacity calculated using the static penetration test data before and after immersion are in good agreement with the field plate load test results, and the eigenvalues of the foundation bearing capacity calculated using the shear strength index are higher than the field measured results. According to the results of the static penetration test, the bearing capacity of the foundation after immersion will decrease, but the reduction range is within 4%, and there is a certain loss; the bearing capacity of the foundation before and after immersion calculated according to the shear strength index is reduced by 2.5%. It shows that the bearing capacity of the foundation will be lost to a certain extent after immersion in water, but the loss is small. It is recommended to strengthen drainage measures in the later stage to prevent the foundation from being soaked by rainwater.

The objective of the research paper is to develop a new model by which we can improve the bearing capacity of foundation by using geo fabrics. The primary design concerns for a foundation engineer are bearing capacity and settlement. The soil reinforcement technique of the geo synthetic has been taken into account for developing such a model that can be used to reduce excessive settlements on soft soils and prevent the foundation from failing. Hence, this paper summarizes the physical and numerical simulation to verify the results to enhance the performance of the foundation. Motivation: With the rapid increase in globalization, there has been a shortage of land. Deep foundations are required for poor soil conditions, sloping lands and where there is problems regarding site drainage. Besides with rising cost of materials and increased labor and time required for construction, it has become the need of the hour to develop a new model that will do away with the traditional materials, increase the bearing capacity, and reduce settlement to construct the foundations. The geo synthetics are the third revolution in civil engineering materials that has taken the world by surprise. Its increasing usage owing to its non biodegradable ness, durability, increasing the factor of safety and cost effectiveness can be used to develop a model that would increase the bearing capacity of foundations. Besides, in places where deep foundations are used for poor soil conditions and drainage problems, we can use this new cost effective model of shallow foundation with geofabrics that results in increased bearing capacity. I. Introduction: The primary design criteria for a foundation are bearing capacity and settlement. The use of geo synthetic material to improve the bearing capacity and the settlement performance of a shallow foundation has been of much interest to geotechnical engineers. Several research works has been carried out for soil improvement using several geosynthetic materials. Binquet and Lee used metallic strip under strip footing to improve its bearing capacity. Geogrids and geo cells were later on used for such work. From the finding of numerous researchers, it can be concluded that the bearing capacity of soil also changed with various factors like type of reinforcing materials, number of reinforcement layers, ratios of different parameters of reinforcing materials, and foundations such as footing width, location of the 1st layer of reinforcement to width of footing and vertical spacing between consecutive geogrid layer. However, not much appreciable work has been done with geofabrics to improve the bearing capacity of foundations. The ratio of improvement in the bearing capacity can be expressed in a non dimensional form as bearing capacity ratio (BCR) which is the ratio of bearing capacity of reinforced soil to bearing capacity of unreinforced soil. The present study investigates the improvement of bearing capacity of shallow foundations with the utilization of geofabrics. OBJECTIVE: 1. To improve the bearing capacity of foundations with the help of geo fabric 2. To determine the place where the geo fabric should be placed. 3. To determine the reason behind the increase in bearing capacity. 4. To validate the results using physical simulation.

Groundwater variation has a significant effect on the bearing capacity of sandy shallow foundations. Groundwater and capillary water in the shallow foundation would result in the various water distributions in the soil mass. Therefore, there are three types of water conditions in the shallow foundation. They are the total saturated, capillary-water-effect zone and dry soil. In this study, a physical mode experimental was developed to investigate the effect of groundwater variation on the deformation behavior under different loading conditions. The effect of water level and fluctuation times were examined by a novel setup with a water-pressure control system. A total of 10 group model tests were carried out. The results indicated that the relationship between water level height and foundation bearing capacity is negatively correlated. In addition, the numerical analysis was carried out to investigate the effect of water-level change on the bearing capacity of the foundation. The bearing capacity of the foundation decreases as the water-level cycles increase. The increase in the fluctuation range of the water level will decrease the bearing capacity of the foundation. The outcome of this study would be helpful to predict the bearing capacity of shallow foundations due to the change of the water level.

The wide-shallow bucket foundation proposed by Tianjin University of China is a new type of offshore wind turbine foundation. In this paper, the vertical bearing capacity of wide-shallow bucket foundation embedded in two layered sand that contains an underlying medium strength sand layer and a weaker or stronger overlaying sand layer is studied. A parametric study for bearing capacity is carried out with the ratio of unit weight γ1/γ2 (where γ1 and γ2 are the unit weight of the upper and lower sand layers respectively), the ratio of internal friction angle φ1/φ2 (where φ1 and φ2 are the internal friction angle of the upper and lower sand layers respectively) and relative thickness of the top sand layer H1/B (where H1 and B are the thickness of the top sand layer and the bucket foundation diameter). All of the presents were performed by the Finite Element Method and the results show that the thickness of the top layer has a great influence on the vertical bearing capacity of the foundation. Specifically, the upper sand layer is stronger, the bearing capacity ascends with the increase of the thickness of the top layer, and on the contrary, the upper layer is weaker, and the bearing capacity decreases with the increase of the top layer thickness. In addition, the bearing capacity of the foundation also increases with the ratios of the effective unit weight and the internal friction angle.

Bore Cast-in-place Piles broke the original water and heat balance state of the stratum in the bridge construction of Qinghai Tibet railway. The settlement of a bridge pile foundation was relatively large after more than ten years of operation. It was found that there is confined water in the foundation soil after investigation. Engineers planned to add auxiliary piles at the original pile side to reduce the settlement of the pile foundation.This paper studied the temperature change, bearing capacity formation rule and long-term bearing capacity change trend of the new pile-soil system after adding auxiliary piles on the original foundation, which provides certain theoretical basis and reference basis for engineering practice. A three-dimensional model of a bridge pile foundation was established by numerical method. Considering the influence of atmospheric temperature, hydrogeological conditions, concrete temperature into the mold, and the temperature of underground confined water, based on the heat transfer theory, the boundary conditions and initial conditions are given. The influence of the change of ground temperature field and the change of pile-soil interface temperature on the bearing capacity of the foundation was studied after the auxiliary pile was poured. The analysis shows that the measure to increase the bearing capacity by adding auxiliary piles is a double-edged sword. On the one hand, the auxiliary piles themselves constitute the bearing capacity together with the original pile foundation after thawing, on the other hand, the auxiliary piles are constructed by the method of pouring concrete in the field. The hydration heat of concrete makes the temperature of the original foundation soil rise, and reduces its bearing capacity. The whole bearing capacity will not be increased at the initial stage, but also will be temporarily reduced, and the whole bearing capacity will be formed after the frozen soil is frozen back in the later stage.

This study aims to investigate the impact of dimensional variations on the bearing capacity and settlement of filter buildings in the Benteng Kobema Bengkulu Regional Drinking Water Supply System (SPAM), which has a capacity of 380 L/second and plays a crucial role in providing clean water to the community. Given the potential risk of the Mentawai Pagai Megathrust subduction earthquake, it is necessary to evaluate the bearing capacity and settlement of building foundations. Based on the results of the Standard Penetration Test (SPT), the effect of variations on bearing capacity and settlement can be determined using two types of pile cross-sections, namely square and circular, accompanied by differences in pile cross-section dimensions, namely 300 mm, 400 mm, 500 mm, and depths of 7 m, 9 m, 11 m, and 13 m. The comparison is based on the bearing capacity of the foundation and the settlement of the pile foundation for the filter building of the SPAM Kobema Bengkulu project, using several methods: Poulos and Davis, Reese and Wright, Luciano Decourt, and the Finite Element Method. The smallest settlement is obtained by comparing the total settlement with the allowable settlement, which is 10% of the diameter. The test results show that the bearing capacity, deflection magnitude, and smallest settlement are below the permissible settlement limit, which is less than 10% of the foundation dimensions. The comparison between the static and numerical methods, or the Bearing Capacity Ratio (BCR), is closer to 1, indicating a more efficient and safer approach. In this analysis, a BCR value approaching one was obtained for a square-section foundation with a size of 500 mm, using the Reese and Wright method at a depth of 9 m. This yielded a bearing capacity of 312.04 tons for a single pile and 207.69 tons for a group of piles.

The influence of soil variability on the bearing capacity of a foundation has been simulated by various numerical methods. Due to the lack of repeatable tests in spatially variable soil, the effect of the spatial pattern on the failure mechanism of the foundation in a spatially variable soil is physically unclear. This study aims to investigate how the spatial pattern affects the failure mechanism and the bearing capacity of a shallow foundation by the laboratory tests conducted on spatially variable physical soil models. Four physical models were carefully prepared with accurately controlled shear strength according to the random fields of shear strength, which enable the comparison to classical bearing capacity theory. The failure mechanism and the bearing capacity were observed and compared to Terzaghi’s theory in homogeneous soils. Results show that the shear failure plane mainly developed in weak soils, which results in an asymmetric failure mechanism. This different failure mechanism leads to a very different bearing capacity of a foundation on variable soils compared to that on homogeneous soils of the same mean shear strength. This study paves a way towards a safe and economical foundation design by considering the effect of spatial variation in soils.

In this paper, based on Meyerhof’s theory of homogeneous foundation, the limit equilibrium analysis method and unified logarithmic spiral sliding surface assumption are used to derive the theoretical formula for the ultimate bearing capacity of a layered foundation when the foundation is completely rough. It should be noted that this formula is only applicable to strip foundations of upper soft clay and lower sandy soil. In addition, a comparative analysis is conducted between theoretical formulas and semiempirical formulas for layered foundations. On the basis of verifying the reliability of the theoretical formula results, numerical simulation is carried out to further explore and analyze the influence of the width to depth ratio of the foundation, the strength parameters of the double-layer soil, and the thickness of the upper soft soil on the bearing capacity of the foundation. Research has shown that the formula for the bearing capacity of a layered foundation derived in this paper has a certain degree of error compared to Meyerhof’s semiempirical formula, but it is in good agreement with numerical simulation results and Hansen’s weighted average method results. The ratio of the width to depth of the foundation, the ratio of the cohesive force of the double-layer soil, and the tangent ratio of the internal friction angle have a significant positive correlation with the ultimate bearing capacity of the foundation. The increase in thickness of the overlying cohesive soil has a negative impact on the ultimate bearing capacity of the foundation, and the thicker the soil, the smaller the foundation’s bearing capacity.

The bearing capacity of foundations is one of the interesting subjects in geotechnical engineering. In many cases, constructing foundations on natural or artificial soil slopes to develop the infrastructures is controversial. The construction of foundations on slopes can significantly affect the bearing capacity and slope stability. Soil stabilisation by polymer reinforcements is a modern method employed in various projects to prevent the failure of soil slopes and to improve the bearing capacity of foundations, subsequently. This paper aims to evaluate the bearing capacity of shallow strip foundations constructed on geosynthetic reinforced sand slope using a finite difference programme, FLAC. The effects of geometrical and resistivity parameters of reinforcements layers was investigated for determining the optimal values to achieve maximum bearing capacity. Furthermore, the effects of strength properties of sand embankment, foundation position and slope angle on the behaviour of strip foundation rested on reinforced soil slope were investigated. The results indicated that the bearing capacity of shallow foundations remarkably increased using geosynthetic reinforcement layers.


 
 
 
 TThe foundation is part of the structure that directly functions to transmit the load from the weight of the structure above it to the ground. In this study, a rectangular foundation is used which is placed on clay soil with 3 variations in dimensions and 7 variations in eccentricity loading. This data will be used in finding the ultimate bearing capacity value. The purpose of this study was to determine the effect of eccentricity loads on the bearing capacity of rectangular foundations on clay soil types. The method used is the Meyerhof method (1963). The results obtained are the magnitude of the value of the bearing capacity of the foundation in each variation of its dimensions which is influenced by the eccentricity of the load. The conclusion of this study is that the bearing capacity of the foundation can be viewed from the coordinates of the axis of the foundation which is affected by the eccentricity of the load. The greater the eccentricity of the load received by the y-axis, the greater the value of the ultimate bearing capacity of the foundation. Meanwhile, the greater the eccentricity load received by the x-axis, the smaller the ultimate bearing capacity value.
 
 
 

Prevailing state of the art in estimating bearing capacity of a foundation under earthquake load is to multiply the static bearing capacity by a factor of 1.25. This practice is in vogue in number of international codes including the IS code for design of such foundations, though it has been shown by Richard et al. (J Geotech Div ASCE 105(GT4):662–674, 1993) that the bearing capacity factors reduce significantly when the ground is subjected to earthquake loads. The analysis is essentially pseudostatic in nature. In this chapter, Budhu and Richards’ method has been modified to cater to fluctuating response of the ground due to passage of vertically propagating SV and P waves to estimate the free field time period of the site which in turn is used to estimate the design spectral acceleration (based on modal analysis) that affects the bearing capacity factors N c , N q , and N γ of the foundation. It is shown that bearing capacity factors fluctuate with modes and are also affected profoundly by the bedrock level prevailing at site. Finally, a comparison with static bearing capacity is made with various dynamic parameters that affect the bearing capacity of foundation.

The bearing capacity of a foundation is influenced by the diameter and straightness of the pile because the bearing capacity is highly dependent on the resistance of the pile tip and the resistance of the pile cover and the shape of the pile affects the strength of the foundation. Therefore, the purpose of this study was to determine the value of the bearing capacity of the pile foundation on the cross-sectional area and the effect of pile misalignment.The method used in this study is the descriptive analysis method. Data were collected from laboratory tests with a comparison of the field scale. The manufacture of pile test specimens with each variation was 10%, 25%, 50%, and 75%.From the test results, the variation in the cross-sectional area affected the bearing capacity value which increased as the variation in the cross-sectional area increased. As for the test results, the variation in the straightness of the pile affected the bearing capacity value which decreased as the variation in the pile misalignment increased.Keywords:bearing capacity, cross-sectional area, straightness, clay soil, laboratory tests, piles.

Skirts of sufficient stiffness may be used for improving the bearing capacity of an existing shallow concrete foundation or for obtaining enhanced bearing capacity of a new shallow foundation. The degree of improvement of bearing capacity for skirt foundations is likely to depend on several factors namely foundation base friction factor, skirt depth factor, skirt side roughness factor and soil compressibility factor. A series of small tank testing was carried out to study the effect of these factors on the bearing capacity of foundations with skirts. On the basis of these test results a modified bearing capacity equation for the centrally loaded foundation with skirts has been suggested. The results obtained from this proposed equation show that the use of structural skirts can produce enhanced bearing capacity ratios in the range of 1.4 to 3.5, depending on particular geometric and loading condition. INTRODUCTION BEARING CAPACITY EQUATIONS FOR SHALLOW STRIP FOUNDATIONS WITH STRUCTURAL SKIRTS RESTING ON DENSE SAND TEST APPARATUS, PROCEDURES AND MATERIALS RESULTS FROM TESTS USING SHALLOW STRIP FOUNDATIONS WITHOUT STRUCTURAL SKIRTS RESULTS FROM TESTS USING STRIP FOUNDATIONS WITH STRUCTURAL SKIRTS PREDICTED IMPROVEMENTS DERIVED FROM THE USE OF STRUCTURAL SKIRTS DISCUSSION AND CONCLUSIONS REFERENCES

The pile foundation is a deep foundation that is often used in the construction of high-rise buildings and small-scale buildings. The foundation is required to have a greater bearing capacity than the load on it. This study aims to determine the maximum bearing capacity of the foundation against the work load including the additional load from the 15-story Lamongan Muhammadiyah University building which was found to be cracked. Calculation of the bearing capacity of a single pile is carried out to determine the bearing capacity of a single pile using the Mayerhoff, Reese O'neil, and Reese and Wright method. Calculation of the bearing capacity of group piles is carried out to determine the bearing capacity of piles in one group using the Converse-Labarre, Los Angle Group, and Seiler-Keeney methods. Controlling the bearing capacity of single and group pile foundations, whether they are able to withstand the load on them using the axial loads and moments obtained. The results of the calculation of the bearing capacity of a single pile foundation at a depth of 30 m using the Meyerhoff calculation method obtained the carrying capacity of a single pile permit (Q_a) at point DB-1 of 916,80 tons and DB-2 of 916,80 tons, Reese and O' neil obtained Power single pile permit bearing (Q_a) at point DB-1 of 668,67 tons and DB-2 of 668,67 tons, Reese and Wright obtained single pile permit bearing capacity (Q_a) at point DB-1 of 1.070,08 tons and a DB-2 of 1.070,08 tons, while the shamanic strength of the largest pile group foundation was obtained using the Converse-Labarre method with ultimate bearing capacity using the Reese anad Wright method, bearing configuration from the pile group capacity (Q_g) (2 x 2) obtained at point DB -1 of 9.733,45 tons and DB-2 of 9.733,45 tons, configuration (2 x 3) at point DB-1 of 13.810,45 tons and DB-2 of 13.810,45 tons, configuration (3 x 2 ) at point DB-1 of 13.810,45 tons and DB-2 of 13.810,45 tons. The results of controlling the bearing capacity of the foundation by looking at the value of the allowable bearing capacity is greater than the value of the axial load (P ≤ Q_g). From the calculation of the bearing capacity of the piles it can be concluded that the pile foundations at points DB-1 and DB-2 are safe.

Discrete element method for bearing capacity analysis