Bearing Capacity Of Foundation Research Articles

Effect of Roughness on Seismic Bearing Capacity of Shallow Foundations near Slopes Using the Lower Bound Finite Element Method

Abstract A lower bound finite element analysis in conjunction with linear programming technique was used to evaluate the effect of soil–foundation interface roughness on the seismic limit load of s...

Research on settlement test and numerical calculation of west artificial island foundation of Hong Kong-Zhuhai-Macao Bridge

ABSTRACT The artificial island project of the Hong Kong-Zhuhai-Macao Bridge includes the island construction project, the island part at the junction of the island and the tunnel, and the transition section between the island and the tunnel. The bearing capacity and deformation characteristics of the compacted sand pile composite foundation are studied through the load test of underwater compacted sand pile composite foundation, and given the parameters such as pile-soil stress ratio of composite foundation. In addition, the numerical simulation analysis of the three-dimensional foundation model of the West artificial Island was carried out. The parameters were adjusted through back analysis of the calculated results and the measured data, and the adjusted parameters were used to calculate the post-construction settlement of the West artificial Island, which met the design requirements of no more than 50 cm.

An accessible calculation method of the bearing capacity of shallow foundations on anisotropic rock masses

Numerical modeling of the bearing capacity of foundations on rock masses having a high degree of anisotropy needs to represent, in most cases, a large number of discontinuities, thus making the numerical analysis difficult and, in most cases, unapproachable.In this research, a simplified numerical procedure by using the Discontinuity Layout Optimization method (DLO) which proves to be appropriate when studying the limit bearing capacity of foundations involving slip line formation and failure wedges is presented.A single discontinuity simplified procedure is proposed maintaining the accuracy of the full model. The isolated discontinuity is located in the proper position and has the correct slope to represent the whole family of discontinuities.DLO models using the proposed procedure can represent the different possible failure mechanisms that may occur in the rock mass. Besides, the ultimate bearing capacity of a particular case is checked against the available analytical solution.

Research on the Law of Bearing Capacity of the Bucket Foundation for Offshore Wind Turbines in Clay Soil

Xing, Z.; Fu, P., and Huang., L., 2020. Research on the law of bearing capacity of the bucket foundation for offshore wind turbines in clay soil. In: Liu, X. and Zhao, L. (eds.), Today's Modern Coastal Society: Technical and Sociological Aspects of Coastal Research. Journal of Coastal Research, Special Issue No. 111, pp. 43–48. Coconut Creek (Florida), ISSN 0749-0208.The bucket foundation can be used as the foundation of high-rise buildings. An in-depth understanding of the bearing capacity of the foundations is critical to ensure reliable design and safe operation of foundation. Based on the load characteristics of high-rise buildings and the parameters of soil, the authors explore the law of the bearing capacity of bucket foundations in clay soil and summarize the impacts of the ultimate horizontal load and the ultimate bending moment load on the failure of the bucket foundation. The research found that the failure mode of bucket foundations in clay soil was mainly caused by rotation, the optimal height-diameter ratio of the bucket foundation was about 0.57, and the envelope curve of horizontal load-bending moment failure was roughly an ellipse.

INCREASING THE STABILITY OF THE SAND CUSHION BY PRESTRESSING THE REINFORCING LAYERS OF GEOSYNTHETICS

The use of prestressing of geosynthetics allows accelerate their inclusion in work, reduce deformations and gaining bearing capacity of artificial foundation. The article presents results of research of two methods of construction reinforced sand cushions. In the first case, the effect of prestressing is achieved due to a certain order of layer-by-layer soil compaction of the cushion, in the second - by laying of the swellable material between the contours of the foundations. The experiments were carried out in a laboratory tank with a pneumatic loading device. There are three stamps united by a common frame on the surface of the cushion. To assess the stress-strain state of the soil foundation, the non-contact digital tracer imaging method was used. The experimental results are presented in the graphs form of the dependence of the stamp settlement on pressure and vector fields of particle movements. Modeling has confirmed the high efficiency of prestressing. The ultimate pressure on the soil foundation with two-layer horizontal reinforcement and prestressing of the reinforcing layers in the first method was 195 kPa, in the second method - 165 kPa, whereas in the absence of prestressing this value was 110 kPa. Foundation deformations also decreased significantly.

The effectiveness of the implementation of pile foundations on the example of the reactor building of a nuclear power plant with VVER-1000

Aims. The purpose of this work is to justify the reliability of the developed models of pile foundations on the data of field observers and to demonstrate the feasibility of using pile foundations to increase the stability and bearing capacity of the NPP structures foundation using the example of reactor building (RB). Methods. The data of field observers for the settlement of the RB are presented. The expressions for calculation of the static stiffness of the contact surface of the slab bottom and soil medium, as well as for pile foundations taking into account the effects of interaction of grillage and pile field with the soil media with a general character of displacement of a circular cross section pile are submitted. A spatial three-dimensional finite element static model of RB was developed together with the soil base. Isolines of vertical movements of RB fundamental slabs for natural foundations, as well as for pile foundations for normal operation are shown. A comparative analysis of the data of field observers with the calculation results allows us to justify the reliability of the developed model of the pile foundation. Results. The calculations of the foundation yield correspond to all the period of operation including construction, and the results of observations relate only to the period of operation that explain the difference. A comparative analysis of the data of field observers with the calculation results allows us to justify of the strong effectiveness of realization of pile foundation for the massive structures on soft soil bases.

Peningkatan Daya Dukung Pondasi pada Tanah Lempung dengan Perkuatan Kolom Tanah

One of the problematic soils for construction if the soil is used as a foundation for a construction is clay soil which has relatively low shear strength and bearing capacity. Therefore, it needs an improvement effort to increase the strength of the clay soil. The reinforcement soil column is an alternative effort to improve the soil. This paper presents the results of laboratory-scale experimental on the reinforcement modelling of clay soil columns mixed with 6% rice husk ash (RHA). Modelling was carried out with 6 variations of column groups with constant column length of 67cm. The first three variations are the variation in the distance between columns (s/d) with a fixed diameter of 8 cm. The other three variations are column diameter variations with a fixed s/d ratio. The results showed that the larger the distance between the columns, the smaller the bearing capacity of the soil foundation. If the s/d ratio is constant, it is found that the larger the column diameter, the greater the bearing capacity of the soil foundation. The maximum ultimate bearing capacity of the soil is achieved in variations with a column diameter of 12cm and a distance between columns of 30cm (s/d = 2.5) with a value of 39.56 kPa. This bearing capacity provides a BCR value of 3.75% or almost 4 times the bearing capacity of the unreinforced foundation.

Performance of loose sand with different waste materials in stone columns in North Cyprus

Stone columns are used to enhance the bearing capacity of poor ground and reduce the compressibility of soft clays. The aim of this study is to evaluate the effectiveness of stone columns with different waste materials on the performance of loose sand in North Cyprus. The study provides guidelines for the selection of the most effective and economical material for stone column construction. In this study, waste materials from different construction sites were selected: shredded bricks, crushed waste stone and crushed old concrete. The stone columns were constructed with these waste materials. Load–settlement responses of the unreinforced and reinforced soils with a single stone column and a group of stone columns constructed with these waste materials were determined under the same loading conditions. The obtained results showed a very good improvement in the settlement behaviour of the loose sand. As a conclusion, local waste building materials can be used effectively for stone column construction. The use of these waste materials will contribute to recycling and environmental sustainability.

Failure mode of monopile foundation for offshore wind turbine in soft clay under complex loads

Offshore wind turbines (OWT) subjected to long-term complex marine loads are prone to foundation damages, affecting their regular operation. However, the failure mode of the large-diameter monopile foundation under complex marine loads is not well understood. Hence, failure modes of monopile foundation for OWT in soft-soil seabed under unidirectional and multidirectional loads are investigated. Firstly, the mechanical characteristics of soft soil are tested indoors. Subsequently, the monopile foundation failure modes under unidirectional loads are examined, which indicates capacity failures of monopile foundation are progressive, and two distinct soil failure mechanisms are identified. Then, the failure modes and failure envelopes under multidirectional loads (horizontal load, vertical load, and bending moment）are explored. Results show that the failure envelopes in H–V and M–V load space are oval-shaped, and failure modes in H–V and M–V load space are characterized by wedge failure. More critically, the service performance of the monopile foundation in soft soil in a full lifecycle can be estimated by the location of the actual loads in the failure envelope. Finally, the effect of pile diameter on the bearing capacity of the monopile foundation for OWT under unidirectional and multidirectional loads is discussed.

KOMPARASI KINERJA ALAT PILE DRIVING ANALYZER DAN SOFTWARE CAPWAP DALAM MENGHASILKAN DAYA DUKUNG ULTIMIT PONDASI TIANG

Buildings that stand on soft soil usually use a pile foundation. Testing the ultimate bearing capacity of pile foundations in the field is a Pile Driving Analyzer (PDA) tool. Besides being inexpensive to test, the results can also be known quickly. This tool is supported by a software called CAPWAP (CAse Pile Wave Analysis Program).In this paper, a performance comparison of the Pile Driving Analyzer (PDA) and CAPWAP (CAse Pile Wave Analysis Program) software will be presented in producing the ultimate bearing capacity of pile foundations. The results of both will be analyzed in such a way that the causes of the differences in the performance of the Pile Driving Analyzer (PDA) and the CAPWAP software are known.The results obtained show that the performance of the Pile Driving Analyzer (PDA) tool will not be optimal if the energy transferred to the pile foundation is too small. The energy given by the hammer when struck must be in the range of 1% - 2%, if it is smaller then the performance of the tool in producing the ultimate bearing capacity will not be representative. The difference in the ultimate bearing capacity between the PDA device and the CAPWAP software for energy transferred to the pile foundation (EMX) under the specified energy standard is 10.71% - 33.23%. Meanwhile, energy that meets the specified standards has a value between 0.24% - 1.80%.

Reliability Analysis of Circular Footing by Using GP and MPMR

Circular footings are designed to bear a load of super structures. Studies have been done on the influence of soil properties on bearing capacity of shallow foundations. The use of circular foundation is practical in geotechnical engineering. During the design of circular footing, bearing capacity of soil is taken into consideration, and cohesion (c), unit weight (γ), and angle of internal friction (ϕ) are the most variable parameters. Reliability analysis is used frequently for the design of circular footing. Most of the authors have used first order second moment methods (FOSM). However, FOSM is a time-consuming method. Drawbacks of FOSM have been overcome by genetic programming (GP), minimax probability machine regression (MPMR). This article gives a distinct analysis between the developed MPMR based FOSM and GP-based FOSM.

Assessment of the Bearing Capacity of Foundations on Rock Masses Subjected to Seismic and Seepage Loads

It is usual to adopt the seismic force acting as an additional body force, employing the pseudo-static hypothesis, when considering earthquakes in the estimation of the bearing capacity of foundations. A similar approach in seepage studies can be applied for the pore pressure’s consideration as an external force. In the present study, the bearing capacity of shallow foundations on rock masses considering the presence of the pseudo-static load was developed by applying an analytical solution for the Modified Hoek and Brown failure criterion. Calculations were performed adopting various inclinations of the load and the slope on the edge of the foundation, as well as different values of the vertical and horizontal components of the pseudo-static load. The results are presented in the form of charts to allow an affordable and immediate practical application for footing problems in the event of seismic loads or seepages. Finally, and to validate the analytical solution presented, a numerical study was developed applying the finite difference method to estimate the bearing capacity of a shallow foundation on a rock mass considering the presence of an additional horizontal force that could be caused by an earthquake or a seepage.

Analisis Daya Dukung Tanah Pondasi Dalam Berdasarkan Data Lapangan Di Desa Baringin Kota Palangka Raya

Soil bearing capacity is the ability of the soil to support the foundation load acting on it. To produce an accurate bearing capacity, it is necessary to know the properties and characteristics of the soil. For this reason, a comparison of the carrying capacity of the soil is carried out based on the calculation of CPT / Sondir and SPT to be able to plan a safe and economical pile foundation. The purpose of this study was to determine the amount of soil bearing capacity of the deep foundation in the environment around the Ataqwa Mosque, Baringin Village, Palangkaraya City based on field tests, and based on laboratory tests, and to determine the value of the comparison between the Mayerhof Method and the Schmertmann-Nottingham Method. Based on the Sondir value, it is continued with the calculation of the carrying capacity of the soil, then the calculation results are analyzed and concluded. From the calculation of the value of the carrying capacity of the foundation pile implementation of point 1 (one), the highest value of 400 mm diameter piles in the Meyerhoff method is 75,319 kg, while the lowest bearing capacity value is also at 400 mm piles of 10,676 kg. For point 2 (two), the highest value is obtained at 400 mm diameter piles in the Shmertmann-Nottingham method of 65,853 kg, while the lowest bearing capacity value is also at 400 mm piles of 10,676 kg

Impact of Dismantled Sheet Pile Vibration on Cohesive Soil Parameters

The dynamic impact of geotechnical works can affect subsoil, as well as structures and technical devices. In order to prevent hazards resulting from vibration, the monitoring of geotechnical works execution is necessary. This paper presents an analysis of the relationship between the vibration caused by pulling out the sheet pile and the variability of cohesive soil parameters. The authors present the case study of a construction site in Wroclaw (Lower Silesian Province, Poland). The sheet pile profiles were used as a temporary protection of the foundation excavation. After the underground floors were constructed, the sheet piles were pulled out from the ground using vibrating techniques. This is a typical action to recover steel profiles that can be reused. While the sheet piles were being pulled out, the cohesive soil adhered to steel surfaces. In order to analyse the impact of dismantled sheet pile vibration on the variability of soil parameters, laboratory tests of basic soil physical and mechanical properties were carried out. The results were then compared with the primary parameters of soil as specified in the geotechnical documentation, which had been made at the initial stage to determine the geotechnical conditions for the foundation of the designed building. The comparison has shown a negative effect of vibrations on soil properties, including a decrease in the strength parameters, as well as an increase in the liquidity index and compressibility. In this case, an increase in the earth pressure on the existing underground structures and a reduction of the bearing capacity of shallow foundations may occur. Therefore, the vibration monitoring during sheet pile dismantling process is also very important.

Numerical study on bearing capacity of ring foundations for storage tanks on a rock mass

The bearing capacity of ring footings on a rock mass is investigated by employing finite element limit analysis (FELA). The rock mass obeys the modified Hoek-Brown failure criterion and an associated flow rule. Based on the FELA method, the bearing capacity factor Nσ is computed and presented in the form of design tables and charts that account for the variation of the geological strength index (GSI), the intact rock constant (mi), and the ratio of internal radius to external radius of the footing (Ri/R0). Typical failure modes associated with these parameters are compared and discussed. In general, the magnitude of Nσ increases with increasing GSI and mi, while the unit weight has negligible effect on the bearing capacity factor. As the value of Ri/R0 increases, the bearing capacity factor first increases, then decreases, and reaches the maximum value at Ri/R0 = 0.25, indicating that Ri/R0 = 0.25 may be the optimum ratio of the ring footing. In addition, computations of strip footings on rock masses are conducted for verification.

Solution for spherical cavity expansion in state-dependent soils

This work presents a spherical cavity expansion solution aimed at linking soil constitutive behavior with quantities that bear direct engineering meanings for practicing engineers (e.g., foundation bearing capacity). For this purpose, we derive the solution based on the state-dependent, critical state constitutive model proposed by Li and Dafalias (Geotechnique 50(4): 449–460, 2000), whose ability to realistically represent the actual mechanical behavior of sand has been extensively verified in the literature. To ensure the reliability of the solution, we verify it against an independent finite element analysis of spherical cavity expansion in solid governed by the same constitutive model. In this validation, we also highlight the dependence of cavity expansion response on the current state of granular materials relative to critical state. The application of the proposed solution in solving engineering problems is demonstrated in predicting the resistance of cone penetration and the ground movements associated with static pipe bursting in sand. We show that, based on the soil parameters determined from laboratory triaxial tests, the proposed solution can reasonably represent the dependence of cone penetration resistance on the density and pressure level of sand, as revealed from centrifuge testing. By comparing with finite element analysis, we demonstrate that the proposed solution can provide useful estimations for soil displacements caused by pipe bursting operation. These archetypal examples suggest that the proposed cavity expansion solution can form a theoretical basis for linking fundamental soil properties with quantities that have direct implications for geotechnical engineering practice.

Study on Wide-Deep Strip Foundations Resting on Unsaturated Soils

With the development of high-rise buildings, wide and deep foundations have been extensively applied to practical projects during the last several decades. This research aims to develop a solution that applies to wide and deep foundations with the necessary accuracy. Considering the influences of matric suction, adjusted soil parameters, wall friction, and stress strength nonlinearities from high matric suction, a solution for estimating the bearing capacity of strip foundations on unsaturated soils is presented based on the unified strength theory of unsaturated soils and the upper bound method of limit analysis. The validity and applicability of the solution are verified compared with Meyerhof's solution and Zhang's solution. The influences of the breadth, depth/breadth ratio, wall friction, matric suction, and adjustment factor of soil parameters upon the bearing capacity are discussed. Furthermore, a simplified chart-lookup method is presented for practical application. Because it includes the wall friction and assumes only a single failure pattern in derivation, the solution developed for the bearing capacity of strip foundations applies to both shallow and deep foundations.

Influence of the number of reinforcement layers on the bearing capacity of strip foundation resting on sandy soil

Reinforced soil technology is considered one of the most important methods of soil improvement due to its simplicity, easy implementation and saving cost. One of the known soil reinforcement methods is using geogrids to improve the bearing capacity of the soil and reduce the settlement of the soil beneath foundation. In this study, a strip foundation made of a rigid stainless steel with dimensions of 490 mm length, 135 mm width, and 40 mm thickness and reinforced with geogrid (called Tensar SS2) was tested in a laboratory model to investigate the effect of the number of reinforcement layers on the bearing capacity and settlement. The soil was reinforced with one, two, three, and four layers of geogrid (Tensar SS2). The obtained results showed that the reinforcement using geogrid system significantly improved the bearing capacity while reducing the settlement under the strip foundation compared with unreinforced soil. The test result also showed a good improvement in the bearing capacity when the number of reinforcement layers increased from one to four layers. The bearing capacity of the foundation increased when the soil reinforced by four layers of geogrid to about 2.5 times compared with the case of one layer of geogrid. In addition, the maximum settlement decreased to about 2.0 times compared with the case of one layer of geogrid.

Weakening Characteristics of Soft Clay Foundation under Earthquake

The dynamic triaxial test is carried out by the dynamic cyclic shear equipment GDS to determine the strength of soil after earthquake cyclic loading. The consolidation pressure is determined according to the in-situ stress state of soil samples. The samples are loaded with sinusoidal periodic loads of different amplitudes at a fixed frequency, with the failure standard of achieving the same final residual strain. Compared with the static triaxial test results, we can determine the strength weakening of soft clay foundation with different depths under earthquake load, which can provide a reliable reference for engineering problems such as the bearing capacity of pile foundation in soft clay.

Bearing Capacity of Square Footing Resting on Layered Soil

The bearing capacity of layered soil studies was carried out with various approaches such as experimental, theoretical, numerical, and combination of them. This work is focused on the settlement and bearing capacity of shallow foundations subjected to the vertical load placed on the surface of layered soils. The experimental part was performed by manufacturing soil cubic container (570 mm x 570 mm x 570 mm). A model square footing of width 60 mm was placed at the surface of the soil bed. The relative density of sand was constant at 60%, and the clay was prepared with a density of 19.2 (kN/m3) and water content of 14.6%. PLAXIS 3D FEM was used to simulate the experimental tests and performing a parametric study. The results showed that there was a good agreement between experimental work and corresponding numerical results. The value of the bearing capacity was obtained from load-settlement curve. The bearing capacity of layered soil showed higher value for footing resting on clay over sand soil. It was found that an increase in the ultimate bearing capacity regarding the clay over sand with increasing in first layer thickness ratio; while, a decrease has been indicated for the sand over clay. The critical depth was found at H = (2-3m), and the failure pattern was not unique for layered soil.