Bearing Capacity Tests Research Articles

An analysis of the static load test on single square pile of 40x40 cm2, using finite element method in Rusunawa project, Jatinegara, Jakarta

Piling Foundation is one of the foundations which is used to penetrate its load through soil layer. The power carried by the piling is obtained from the end bearing capacity, that is, the compressive end piling and friction bearing capacity obtained from friction bearing and adhesive capacity between the piling and the soil around it. The investigation on the Standard Penetration Test is aimed to get the description of soil layer, based on the type and color of soil through visual observation, and soil characteristics. SPT data can be used to calculate bearing capacity. Besides investigating the SPT, this study is also been equipped by taking the samples in laboratory and loading test on the piling and Ducth Cone Penetrometer (DCP) data to confirm its bearing capacity.This study analyzed bearing capacity and settlement in the square pile of 40X40 cm in diameter in a single pile or grouped, using an empirical method, AllPile program, Plaxis program, and comparing the result with interpreting its loading test in the foundation of Rusunawa project, Jatinegara, Jakarta. The analysis was been done by using the data on soil investigation and laboratory by comparing them with Mohr-Coulomb soil model.Ultimate bearing capacity from the SPT data in the piling of 15.4 meters was 189.81 tons and the parameter of soil shear strength was 198.67 tons. The sander point, based on Aoki and De Alencar bearing capacity was 276.241 tons and based on Mayerhoff it was 305.49 tons. Based on the loading test of bearing capacity, unlimited bearing capacity for the three methods was Davisson (260 tons), Mazurkiewich (270 tons), and Chin (250 tons). The efficiency of grouped piles according to Converse-Library Equation method = 0.73, according to Los Angeles Group Action Equation method = 0.59, and according to Sheila-Keeny method = 0.94. Bearing capacity based on piling strength was 221.76 tons, bearing capacity based on calendaring data was 201.71 tons, and lateral bearing capacity of a single piling foundation was 129.6 kN (12.96 tons). When the maximum load (280 tons) was been given, more decrease occurred in the Maintained load test of 21.00 mm and Quick Load Test method of 20.67 mm, compared with the result of Load Test in the field of 18.74 mm. Based on ASTM D1143/81, the permitted value was 25.40 mm. Therefore, based on that decreasing, it could be concluded that foundation piles were safe in the construction. The pore water pressure is highly influenced by time so that in Maintained Load Test and Quick Load Test, there was the disparity in the level of pore water pressure. Based on the result of the calculation, Quick Load Test showed that in pore water pressure was dissipated in its acceleration.

An Accuracy Problem of the Fwd Time History with Regard to the Application of the Sasw Method

Abstract A Falling Weight Deflectometer (FWD) represents one group of the devices used for diagnostics of pavement bearing capacity. Usually, the FWD dynamic load is substituted by a static load in the evaluation process to determine the equivalent modulus of a pavement structure or modulus of pavement layers. However, the data recorded during a bearing capacity test by FWD can be used to reveal the propagation of a dynamic impulse generated by FWD. It gives a possibility to use them in an evaluation method based on the propagation of waves generated by dynamic impulse. Therefore, the FWD time history data was assessed with regard to possible using in the method of the Spectral Analysis of Surface Waves. Basically, the possibility to determine the velocity of a generated surface wave was evaluated. It was found out the same deflection values exist at consecutive time intervals in the relevant part of the time history data (the arrival of the front of the wave or the area of maximum deflection value). Two methods were used to determine the exact time of the wave occurrence at receivers. It was concluded the differences between the used methods exist. It means the calculated velocities of a wave and shear modulus are also different. Importance of the shear modulus differences were estimated using the Slovak bearing capacity classification based on elastic modulus values. Taking into account the range of modulus in one classification class it can be stated the differences in the shear modulus determined according to used two methods could be very significant if the values calculated for short distance of the receiver are used. In the case of longer distance of the receivers the differences are not so high and significant.

Geogrid for unsealed forest roads: installation considerations and bearing capacity testing in New Zealand

ABSTRACTThis study established 10 field trials on corporate forest roads in New Zealand to demonstrate geogrid installation procedures and test for differences in bearing capacity, hereafter referred to as road strength, for road segments with and without geogrid reinforcement. The primary objective of this research was to determine if thinner aggregate surface layers could be used in conjunction with geogrid reinforcement without significant reductions in road strength. Each trial consisted of three 25-m long road segments randomly configured with the following pavement designs: (1) Control section that consisted of a single aggregate layer overlying a compacted subgrade soil; (2) Geogrid reinforcement that used the same aggregate thickness as the Control; and (3) Geogrid + Reduced Aggregate treatment that used a thinner aggregate layer. Road strength was measured with a Clegg Hammer for the prepared subgrade, finished road surface (i.e. before traffic), and after one winter of log truck traffic. Overall, there were no clear differences in road strength among treatments before or after trafficking. Several factors related to studying operational forest roads are thought to have contributed to this finding, including relatively low traffic volumes (285–1220 loaded trucks) and variability in aggregate thickness within and among sites. Geogrid-reinforced roads may perform better over time and with more traffic. In terms of cost, this finding supports the common practice of simply using thicker aggregate layers to achieve a desired strength as long as aggregate is cheap, local, and readily available.

The influence of loading plate diameter on the results of trial load tests of dynamic replacement columns

The dynamic replacement method of soil strengthening consists in the constructing columns made of aggregate of various granularity. In order to form them, heavy pounders (weighing from 10 to 20 tonnes) are dropped from the height of 25 m. Considering the specificity of this technique, it is quite important to verify on site the assumptions of the project, such as diameter and length of columns, their compaction or stiffness. For that reason, a number of examinations are performed, including column excavations, various types of probing tests or trial loads. The latter consists in determining the “load-settlement” dependence - usually during initial and secondary loadings phase – and on their basis, indicating the value of deformation modulus. Therefore, a stiff plate is placed on the column head and the loading is realised using actuators leaning on the ballast. The diameter of the loading plate depends on diameter and length of column and on the predicted pressure under the plate. The diameter of the loading plate is often smaller than column's diameter. This paper tries to determine the influence of the diameter of the plate used in test loads on the result of the research presented as “load-settlement” dependence and on the values of deformation modulus determined on their basis. The calculations were performed using FEM on a spatial numerical model calibrated on the basis of column's bearing capacity tests. Two models were applied in calculations: elastic-ideally plastic and isotropic hardening elastoplastic.

A study on application of squeezed branch pile in clay soil foundation

Taking a Power Plant Project as an example, the experimental study on clay soil foundation treatment with squeezed branch pile is carried out. The experimental data before and after soil foundation treatment were compared, through the pile capacity test, pile composite foundation soil bearing capacity and static load test, etc.. The theoretical calculated value difference between carrying capacity and the actual test results were obtained to verify the feasibility of Squeezed branch pile in composite foundation program, and get the Squeezed branch pile bearing capacity and other design parameters, which provides a reference for the optimization of engineering piles and the treatment of the thick clay soil foundation.

Compression test and analysis of multi-limbs built-up cold-formed steel stub columns

Multi-limbs built-up cold-formed steel stub column is a main structural member consisting of a single C-shaped and U-shaped basic component connected by self-drilling screws. Axial compression bearing capacity tests and finite element analysis of nine multi-limbs built–up cold–formed steel stub columns with three different section forms were conducted in this paper. The results of finite element analysis are close to the test results, which verify the accuracy of the finite element analysis. In order to study the influence of width–thickness ratio and screw spacing on the bearing capacity of the build-up column, the parametric analysis was carried out on the maximum width–thickness ratio of the plates and the screw spacing. The results show that the failure modes of all specimens are local buckling and distortional buckling. Multi-limbs built–up cold–formed steel stub columns consisting of a few basic components can work in harmony, the integral behavior is desirable. The axial load bearing capacity of the multi-limbs built-up section stub column increases when the maximum width–thickness ratio of the plates decreases; the screw spacing has a little impact on the ultimate axial compressive capacity and the buckling capacity of the multi-limbs built-up cold-formed steel stub columns.

Research on bearing characteristics of socket-spigot template supporting system

The socket-spigot template supporting system is widely used in engineering applications in China. As a newer type of support structure, there has been growing research interest in its bearing capacity. In this paper, four vertical bearing capacity tests were carried out on the basic mechanical unit frame of a socket-spigot template supporting system. The first goal was to explore the influence of the node semi-rigid degree and the longitudinal spacing of the upright tube on the vertical bearing capacity. The second objective was to analyze the displacement trend and the failure mode during the loading process. This paper presents numerical analysis of the vertical bearing capacity of the unit frames using the finite element software ANSYS. It revealed the relationship between the node semi-rigid degree and the vertical bearing capacity, that the two-linear reinforcement model of elastic-plastic material can be used to analyze the socket-spigot template supporting system, and, through node entity model analysis, that the load transfer direction greatly influences the node bearing area. Finally, this paper indicates the results of on-site application performance experiments, shows that the supporting system has adequate bearing capacity and stability, and comments on the common work performance of a socket and fastener scaffold.

LOAD BEARING CAPACITY OF THE GLASS RAILING ELEMENT

In this paper some basic physical and mechanical properties of glass as structural material are presented. This research is about specifically manufactured glass railing element that will be a part of a pedestrian bridge construction in Zagreb, Croatia. Load bearing capacity test of the glass railing element is conducted within the Faculty of Civil Engineering in Zagreb and obtained experimental results are discussed and compared to the ones provided by the numerical model. Taking into account the behaviour of laminated glass and results of experimental and numerical testing, glass railing element can be regarded as safe.

Friction and wear reductions in fluorinated plain and fully formulated oils through enhanced heating time using moderate loading under boundary lubrication conditions

AbstractThe use of fluorinated mix catalyst (titanium fluoride: TiF3 + iron fluoride: FeF3) with polytetrafluoroethylene: PTFE in engine oil is increasingly a strategy to improve fuel economy and component durability to simultaneously provide low friction and excellent wear protection. The influence of these additives shows promising results during load bearing capacity testing and long‐term durability experiments. This paper addresses the enhancement of friction and wear performances of 0.1% and 0.05% phosphorus plain zinc dialkyl dithiophosphate (ZDDP) oil and fully formulated engine oil when heated to 100°C for specific time under thermal and tribological conditions for moderate pressure loading (1.9 GPa Hertzian pressure or 180 N) which simulate the cold start of a car under 700 rpm rotational speed or the valve trains loading where most of the ZDDP are applied.Tests were performed in a ball on cylinder tribometer under boundary lubrication conditions. Surface analyses were carried out using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Results showed that the anti‐wear additives (2 wt. % PTFE + 0.5 wt. % FeF3 + .5 wt. % TiF3) provided excellent wear protection to 0.1% phosphorus plain and fully formulated oil when cylinder is immersed in the desired lubricant and heated for a predetermined time but performed poorly in 0.05% phosphorus fully formulated oil under the same conditions. The transform of anti‐wear coated material to the worn surfaces, which was a function of the anti‐wear performance of additives, was shown to have an influence on friction performance. The wear reducing effect, which was observed in fluorinated additives tribological tests, indicated a positive contribution and good tribofilm formations. Copyright © 2016 John Wiley & Sons, Ltd.

Prestress Loss and Bending Capacity of Pre-cracked 40 Year-Old PC Beams Exposed to Marine Environment

Six prestressed concrete beams (PC beam) were used for evaluation, consist of four post-tension beams (PC-O) and two pre-tension beams (PC-R). In order to investigate the effect of crack on prestress loss and bending capacity after long-term exposed, prestressed concrete beams were pre-crack and then exposed to marine environment. Experimental work was carried out to evaluate PC beams performance after long-term exposed. In addition, visual observations and load bearing capacity test was carried out. Furthermore, evaluation of prestress loss conducted using three-point loading bending test and the remaining tendon forces in the beam were determined using Crack Re-opening Method. The experimental results revealed that prestress loss was increased due to corrosion of strand/wire which affected by the pre-crack on the prestressed beams. Approximately a prestress loss around 26% and 30% was recorded for post-tension and pre-tension beams respectively.

Experimental study on structural response of CFG energy piles

Energy piles have gradually emerged as a new application of ground source heat pump systems due to the heat exchange efficiency per unit length, excellent heat conductivity and low construction cost. Full-scale field tests are carried out to study the thermo-mechanical behavior of “Cement Fly-ash Gravel (CFG) piles”, a popular ground improvement technology in China. These piles are actually constructed by continuous flight auger (CFA) with the cement, fly ash, gravel, etc., being the constituents of the concrete used to form the pile shaft. The displacement of the pile head is measured, thermal stress due to temperature change of the pile is calculated and the changing laws of the stress/strain and temperature profiles along the depth of the pile under thermal loads and constant mechanical loads applied on pile head are analyzed. An ultimate bearing capacity test of a single CFG pile/soil composite foundation is carried out to investigate the effects of the heating–cooling exchange process on the bearing capacity of CFG energy piles. Systematic tests are implemented to study the mechanical responses of CFG energy piles and the effects of thermal stress on the mechanical behavior of the piles, which will benefit the design and application of CFG energy piles.

EXPERIMENTAL EVALUATION OF THE INFLUENCE OF THE LEVEL OF THE GROUND WATER TABLE ON THE BEARING CAPACITY OF CIRCULAR FOOTINGS

In this study, a bearing capacity device is designed and fabricated to determine the load-settlement behavior of three circular footing models resting above the ground water table. Capillary rise in the studied well graded sand is measured and the level of the water table is controlled at the desired heights during each bearing capacity test. Moreover, shear strength parameters and soil water retention curve of the soil are also determined. Experimental results show that using the conventional equations available in the literature of foundation engineering to determine the bearing capacity of footings built above the ground water table can be highly conservative. Moreover, despite the conventional theories, lowering of the ground water table can result in a decrease in the bearing capacity of shallow foundations. Therefore, utilizing the in situ experiments such as cone penetration test performed while the ground water table is at its highest level can lead to a quite non-conservative estimation of the bearing capacity of footings. In addition, an empirical relationship is proposed to simulate the bearing capacity factor, , of circular footings based on the experimental results.

Pile Model Tests Using Strain Gauge Technology

Abstract Ordinary pile bearing capacity tests are usually carried out to determine the relationship between load and displacement of pile head. The measurement system required in such tests consists of force transducer and three or four displacement gauges. The whole system is installed at the pile head above the ground level. This approach, however, does not give us complete information about the pile-soil interaction. We can only determine the total bearing capacity of the pile, without the knowledge of its distribution into the shaft and base resistances. Much more information can be obtained by carrying out a test of instrumented pile equipped with a system for measuring the distribution of axial force along its core. In the case of pile model tests the use of such measurement is difficult due to small scale of the model. To find a suitable solution for axial force measurement, which could be applied to small scale model piles, we had to take into account the following requirements: - a linear and stable relationship between measured and physical values, - the force measurement accuracy of about 0.1 kN, - the range of measured forces up to 30 kN, - resistance of measuring gauges against aggressive counteraction of concrete mortar and against moisture, - insensitivity to pile bending, - economical factor. These requirements can be fulfilled by strain gauge sensors if an appropriate methodology is used for test preparation (Hoffmann [1]). In this paper, we focus on some aspects of the application of strain gauge sensors for model pile tests. The efficiency of the method is proved on the examples of static load tests carried out on SDP model piles acting as single piles and in a group.

INNOVATIVE ASPHALT RESEARCH USING ACCELERATED PAVEMENT TESTING

Accelerated pavement testing is one key for innovations in the field of road pavement structures and materials due to its power of assessing mechanical performance in close to reality situations. This paper discusses two types of mobile load simulators for applying unidirectional wheel loads at comparatively high frequencies, the MMLS3, a one third scale device, and the MLS10, a full-scale device. Through examples it is demonstrated that these devices are suitable for testing complex systems, such as mechanical resistance of light reflectors on pavements, traffic resistance of bituminous plug expansion joints for bridges, performance of grid reinforced pavements as well as water resistance of porous asphalt against traffic induced pumping effects. Moreover, an example of MLS10 ultimate bearing capacity tests on a real test section is shown focusing on the discussion of strain gauge, acceleration, rut depth and falling weight deflectometer (FWD) measurement results.

The Behaviour of Confined Granular soil loaded by a square footing

This research involves the behaviour of confined granular soil supported by asquare footing. A series of bearing capacity tests were carried out on a small-scalelaboratory model, which filled with sand, placed in a dense state and confined withUPVC cell. The response of an unconfined state was measured in the beginning,and then compared with the confined sand. The studied variables included thecylinder height and diameter, the depth of the footing to the top of the cylinder andthe embedded depth of the footing.The test results indicated that the soil confinement resists lateral displacement ofsand underneath the footing, which is leading to a significant improvement for theresponse of the footing. The curves of load-settlement generally showed the sametrend in all the cases. Failure was considered as a settlement, which was equal to8% of the total footing width. Also, the recommended optimum cell height,diameter, footing depth to the top of the cylinder and the embedded depth offooting that give the maximum bearing capacity improvement were presented anddiscussed. According to the present research results, a conclusion based on the soilconfinement role and found to be notably increased the bearing capacity andstiffness. Furthermore, a modification of load–settlement behaviour of the subgrade sand was also gained.

Analytical Bearing Capacity of Strip Footings in Weightless Materials with Power-Law Failure Criteria

AbstractSokolovskii’s method of characteristics is extended to provide analytical solutions for the ultimate load at the moment of plastic failure under plane-strain conditions of shallow strip foundations on weightless rigid-plastic media with a noncohesive power-law failure envelope. The formulation is made parametrically in terms of the instantaneous friction angle, and the key idea to obtain the bearing capacity is that information can be transmitted from the free surface (where external loads are known) to the contact plane of the foundation. The methodology can consider foundations adjacent to a slope, external surcharges at the free surface, and inclined loads (both on the slope and on the foundation). Sensitivity analyses illustrate the influence on bearing capacity of changes in the different geometrical parameters involved. An application example is presented and design plots are provided, and model predictions are compared with results of bearing capacity tests under low gravity.

地下室锚杆抗拔试验与分析

总结了抗拔锚杆桩承载力的经验计算方法。蚌埠市某住宅项目工程设计采用768根抗浮锚杆，锚固段长度是16 m，锚固直径为150 mm，对其中8根锚杆进行了抗拔试验。测试结果表明，加载至300 kN时，上拔位移为10.35 mm~12.69 mm，且能达到稳定状态，卸载后残余位移约为最大位移的2/3，试验锚杆抗拔承载力均满足设计要求。通过试验结果数据拟合得到Q-S曲线，预测了锚杆的抗拔极限承载力，并与不同经验方法计算结果进行了对比，结果表明不同方法计算结果与预测值略有差异，但均大于实测最大加载值300 kN。 The experience calculation methods of the pullout capacity of anchor pile are summarized in this paper. An engineering design of 768 pieces of anti-floating anchor was adopted in Bengbu city, and all the anchoring depth is 16 m, anchorage diameter is 150 mm. 8 pieces of anchor were selected to perform the pull-out tests. The test results show that, the range of uplift displacement is from 10.35 mm to 12.69 mm when the load reaches up to 300 kN, and it can reach a stable state. The residual displacement is about 2/3 of the maximum displacement after unloading, and all the anchors meet the design requirements of uplift bearing capacity test. The Q-S fitting curve is obtained by approximate prediction of bearing capacity of anchor pullout from the test results. Meanwhile, the results were compared with different calculation methods, and it shows that there is a slight difference between different calculation methods and predictive value. Nevertheless, they are all larger than the measured maximum load value 300 kN.

Bridge Bearing Capacity Test and the Application Research Carbon Fiber Reinforcement Technology

First, conducting static load tests for a 5 span bridge, then carry on application research for the bridge based on the embedded carbon fiber (CFRP) reinforced flexural reinforcement aiming at the shortcomings of its flexural properties, At last, the effectiveness of strengthening reinforced concrete beam that reinforcement by embedded CFRP has been discussed. The results show that embedded CFRP reinforcement beam can make full use of the characteristics of high strength of CFRP, which can improved obviously the capacity of the reinforced beam and the maximum increased capacity can reach 13.2%. In addition, the application of the embedded CFRP reinforcement technology has been discussed, which provides a meaningful reference for the development of the technology.

Research for the Load Method of the Metro Lining Segment

Bearing capacity tests of three reinforced concrete lining segments were carried out. The effect of the loading method and ultimate bearing capacity of the reinforced concrete lining segments and the maximum displacement and reinforcement ratio on the failure mechanism was analyzed based on the simulation results. The simulation results show that the yield load and ultimate load of the lining segments can be effectively increased because of the axial force effect. the loading method on the full surface was proposed. The the ultimate load and yielding load increase as the reinforcement ratio increase is radial distribution in the state.

Load Bearing Capacity Tests of Mechanical Joining on Timber-Concrete Beam

Timber-concrete composite structures, which use advantages of both materials, are suitable for new works and reconstructions of civil and residential buildings. There are described many methods of joining between timber beam and concrete slab in technical literature. Joints are more and more sophisticated which brings higher demands on work control and technology. Main goal of the paper is in design technologically low demanding method of joining with steel plates and nails, to test its shear strength and to compare it with other similar joining .