On method of bearing capacity of soft rock ground based on in-situ load test

2010 ◽  
pp. 1115-1122
Author(s):  
Wenhua Gao ◽  
Jianqun Zhu ◽  
Ziyong Huang ◽  
Dong Liu
Keyword(s):  
Bearing Capacity ◽  
Soft Rock ◽  
Load Test

scholarly journals Predicting the bearing capacity of pile installed into cohesive soil concerning the spatial variability of SPT data (A case study)

2021 ◽  
Vol 11 (1) ◽  
pp. 45-64
Author(s):  
Duong Hong Tham ◽  
Truong Nhu Manh
Keyword(s):  
Bearing Capacity ◽  
Static Load ◽  
Physical And Mechanical Properties ◽  
Cohesive Soil ◽  
Load Test ◽  
Penetration Test ◽  
Static Load Test ◽  
In Situ Tests ◽  
Spt Data

Nowadays, in situ tests have played a viable role in geotechnical engineering and construction technology. Besides lab tests conducted on undisturbed soil samples, many different kinds of in-situ tests were used and proved to be more efficient in foundation design such as pressuremeter PMT, cone penetration test CPT, standard SPT, etc. Among them, a standard penetration test (SPT for short) is easy to carry out at the site. For decades, it has proved reliable to sandy soil, but many viewpoints and opinions argued that the test was not appropriately applicable to cohesive soil because of scattered and dispersed data of SPT blow counts through different layers. This paper firstly studies how reliable the SPT data can predict the physical and mechanical properties; secondly, the soil strength is determined in terms of corrected N-SPT values, and finally the bearing capacity of a pile penetrating cohesion soil. By analyzing data from 40 boreholes located in 18 projects in Ho Chi Minh City, South VietNam, coefficients of determination between SPT numbers and physical and mechanical properties of different soil kinds are not the same: R2 = 0.623 for sand, =0.363 for sandy clay and =0.189 for clay. The spatial variability of soil properties is taken into account by calculating the scale of fluctuation θ=4.65m beside the statistically-based data in horizontal directions. Finally, the results from two theoretical approaches of predicting pile bearing capacity were compared to those of finite element program Plaxis 3D and static load test at site. Correlation between the capacity computed by using corrected N-values instead of soil strength and results of static load test has proved to be well suitable in evaluating the bearing capacity of driven and jack-in piles, particularly installing in the cohesive soil using the SPT blows.

scholarly journals A Novel Numerical Method for Calculating Vertical Bearing Capacity of Prestressed Pipe Piles

2020 ◽  
Vol 2020 ◽  
pp. 1-20
Author(s):  
Rongbao Chen ◽  
Jichao Zhang ◽  
Zeyu Chen ◽  
Meixiang Gu
Keyword(s):  
Bearing Capacity ◽  
Static Load ◽  
Hard Rock ◽  
Soft Rock ◽  
Load Test ◽  
Static Load Test ◽  
Soil Layers ◽  
Vertical Bearing ◽  
Vertical Bearing Capacity ◽  
Rock And Soil

A novel method for calculating the vertical bearing capacity of prestressed pipe piles with the acceptable error was proposed and verified. Soils at the pile side and end were, respectively, simulated by an elastic-plastic model and a new double-line (at soft rock and soil layers) or triple-line model (at hard rock and soil layers); then, a mechanical model was established for simulating vertical bearing capacity of prestressed pipe piles, and the corresponding calculation process was carried out. The values of pile side resistance, pile end resistance, and pile end elastic displacement were first obtained from the results of high-strain dynamic testing (HSDT) and then were imported into the proposed numerical model for calculating the vertical bearing capacity of prestressed concrete pipe piles. The static load test was carried out to verify the numerical results. Besides, 20 piles were tested at two typical test sites (soft and hard rock bearing strata), of which 8 piles were arranged at the soft rock bearing stratum site and 12 piles were arranged at the hard rock bearing stratum site. The numerical results achieved from an empirical formula were also used for making a comparison. The values obtained by the proposed method were highly close to those achieved from the static load test with an error of within 10%. The outcomes indicated that the proposed numerical method can be potentially applied to predict the bearing capacity of prestressed pipe piles.

Experiment Study on Bearing Capacity of Muddy Siltstone Foundation and its Application

2013 ◽  
Vol 838-841 ◽  
pp. 101-106
Author(s):  
Dong Sheng Yang
Keyword(s):  
Theoretical Analysis ◽  
Bearing Capacity ◽  
Skin Friction ◽  
Static Loading ◽  
Soft Rock ◽  
Single Pile ◽  
Experiment Study ◽  
Loading Test ◽  
Static Loading Test

Rock-socket cast-in-situ piles is a commonly used style of foundation, but theoretical analysis, experiments and test research of bearing capacity behavior about rock-socket piles in soft rock have not adapted to the requirement of engineering. The static loading test of single pile on a project in argillaceous and silt laminate, through which the skin friction and point bearing capacity were measured, the bearing capacity behavior of rock-socket cast-in-situ piles in soft rock was analyzed.

Evaluation on Bearing Capacity Improvement of Cast-In Situ Bored Piles Using Post-Grouting Technology

2012 ◽  
Vol 204-208 ◽  
pp. 168-172
Author(s):  
Jing Cai ◽  
Yong Yu Wang ◽  
Xin Hua Wang ◽  
Hua Wei Yan
Keyword(s):  
Bearing Capacity ◽  
Load Test ◽  
Static Load Test ◽  
Bored Pile ◽  
Mud Cake ◽  
Side Resistance ◽  
Tip Resistance ◽  
Bored Piles ◽  
Post Grouting

Post-grouting technology is an effective method of improving mud cake in the pile tip and debris in the pile side. What’s more, it is also considered as a great method to improve the bearing capacity of the cast-in-situ bored pile. The post-grouting technology is used in the foundation of a tall office building in Shan Dong province. For this project, comparing results of the static load test and the theoretical calculation, some conclusions can be made that the bearing capacity of post-grouting pile is 126.5% more than that of unpost-grouting one, the ratio between the tip resistance and the side resistance of the post-grouting pile are 39.8% and 60.2% respectively, and the ratio between the tip resistance and the side resistance of the unpost-grouting pile are 28.9% and 71.1% respectively. It is estimated that the cost of cast-in-situ bored piles using post-grouting technology is 45%~50% cheaper than the unpost-grouting piles.

scholarly journals Prediction of Effects of Geogrid Reinforced Granular Fill on the Behaviour of Static Liquefaction

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
A. Hemalatha ◽  
N. Mahendran ◽  
G. Ganesh Prabhu
Keyword(s):  
Bearing Capacity ◽  
Load Test ◽  
Test Results ◽  
Plate Load Test ◽  
Large Size ◽  
Static Liquefaction ◽  
Granular Fill ◽  
Size Dimension ◽  
Subgrade Modulus ◽  
Different Thickness

The experimental investigation on the effects of granular fill and geogrid reinforced granular fill on the behaviour of the static liquefaction potential of the subsoil is reported in this study. A series of plate load test were carried out with different thickness of the granular fill, number of geogrid layers, and size/dimension of the footing. The test results were presented in terms of bearing capacity and subgrade modulus for the settlement ofδ10,δ15, andδ20. The experimental results revealed that the introduction of granular fill significantly increases the bearing capacity and effectively control the settlement behaviour of the footing. The introduction of geogrid in granular fill enhanced the Percentage of Control in Settlement and Bearing Capacity Ratio by a maximum of 328.54% and 203.41%, respectively. The introduction of geogrid in granular fill interrupts the failure zone of the granular fill and enhances the subgrade modulus of the footing by a maximum of 255.55%; in addition subgrade modulus of the footing was increased with an increase in the number of geogrid layers. Based on the test results it is suggested that the footing with large size has beneficial improvement on the reinforced granular fill.

scholarly journals Evaluation of Stiffness and Dynamic Properties of a Mine Shaft Steelwork Structure through In Situ Tests and Numerical Simulations

Energies ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 664
Author(s):  
Jacek Jakubowski ◽  
Przemysław Fiołek
Keyword(s):  
Numerical Simulations ◽  
Dynamic Properties ◽  
Vertical Motion ◽  
Load Test ◽  
Mode Shapes ◽  
Dynamic Amplification Factor ◽  
In Situ Tests ◽  
Mine Shaft ◽  
Numerical Investigations

A mine shaft steelwork is a three-dimensional frame that directs the vertical motion of conveyances in mine shafts. Here, we conduct field and numerical investigations on the stiffness and dynamic properties of these structures. Based on the design documentation of the shaft, materials data, and site inspection, the steelwork’s finite element model, featuring material and geometric non-linearities, was developed in Abaqus. Static load tests of steelwork were carried out in an underground mine shaft. Numerical simulations reflecting the load test conditions showed strong agreement with the in situ measurements. The validated numerical model was used to assess the dynamic characteristics of the structure. Dynamic linear and non-linear analyses delivered the natural frequencies, mode shapes, and structural response to dynamic loads. The current practices and regulations regarding shaft steelwork design and maintenance do not account for the stiffness of guide-to-bunton connections and disregard dynamic factors. Our experimental and numerical investigations show that these connections provide considerable stiffness, which leads to the redistribution and reduction in bending moments and increased stiffness of the construction. The results also show a high dynamic amplification factor. The omission of these features implicates an incorrect assessment of the design loads and can lead to over- or under-sized structures and ultimately to shortened design working life or failure.

CHARACTERIZING ANOMALIES IN DISTRIBUTED STRAIN MEASUREMENTS OF CAST-IN-SITU BORED PILES

2016 ◽  
Vol 78 (8-5) ◽  
Author(s):  
Hisham Mohamad ◽  
Bun Pin Tee ◽  
Koh An Ang ◽  
Mun Fai Chong
Keyword(s):  
Load Transfer ◽  
Load Test ◽  
Strain Sensing ◽  
Strain Profile ◽  
A New Technique ◽  
Optical Time ◽  
Distributed Optical Fiber ◽  
Non Destructive ◽  
Distributed Strain

This paper describes the method of identifying typical defects of bored cast-in-situ piles when instrumenting using Distributed Optical Fiber Strain Sensing (DOFSS). The DOFSS technology is based on Brillouin Optical Time Domain Analyses (BOTDA), which has the advantage of recording continuous strain profile as opposed to the conventional discrete based sensors such as Vibrating Wire strain gauges. In pile instrumentation particularly, obtaining distributed strain profile is important when analysing the load-transfer and shaft friction of a pile, as well as detecting any anomalies in the strain regime. Features such as defective pile shaft necking, discontinuity of concrete, intrusion of foreign matter and improper toe formation due to contamination of concrete at base with soil particles, among others, may cause the pile to fail. In this study, a new technique of detecting such defects is proposed using DOFSS technology which can potentially supplement the existing non-destructive test (NDT) methods. Discussion on the performance of instrumented piles by means of maintained load test are also presented

Judgement Method for Surrounding Rock Stability of Guanjiao Tunnel Based on Catastrophe Theory

2011 ◽  
Vol 90-93 ◽  
pp. 2307-2312 ◽  
Author(s):  
Wen Jiang Li ◽  
Su Min Zhang ◽  
Xian Min Han
Keyword(s):  
Plastic Strain ◽  
Catastrophe Theory ◽  
Soft Rock ◽  
Surrounding Rock ◽  
In Situ Monitoring ◽  
Engineering Practice ◽  
Stability Of Surrounding Rock ◽  
The Stability ◽  
Rock Tunnel

The stability judgement of surrounding rock is one of the key jobs in tunnel engineering. Taking the Erlongdong fault bundle section of Guanjiao Tunnel as the background, the stability of surrounding rock during construction of soft rock tunnel was discussed preliminarily. Based on plastic strain catastrophe theory, and combining numerical results and in-situ data, the limit displacements for stability of surrounding rock were analyzed and obtained corresponding to the in-situ monitoring technology. It shows that the limit displacements obtained corresponds to engineering practice primarily. The plastic strain catastrophe theory under unloading condition provides new thought for ground stability of deep soft rock tunnel and can be good guidance and valuable reference to construction decision making and deformation managing of similar tunnels.

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