scholarly journals Study on the Bearing Capacity and Engineering Performance of Aeolian Sand

2020 ◽  
Vol 2020 ◽  
pp. 1-11 ◽  
Author(s):  
Han Xia ◽  
Jingtao Zhang ◽  
Jun Cai ◽  
Huangsong Pan ◽  
Xuesen She
Keyword(s):  
Bearing Capacity ◽  
Soil Structure ◽  
Soil Layer ◽  
Aeolian Sand ◽  
Mu Us Desert ◽  
Large Numbers ◽  
Loose Soil ◽  
Load Tests ◽  
Physical And Mechanical Characteristics

The climate in the aeolian desert has great differences from that in other regions, generally showing large diurnal temperature differences and extremely dry and low groundwater level characteristics. Therefore, the physical and mechanical characteristics of the sand are different from those of other regions, and it has a loose soil structure, large pores, and a low bearing capacity. To ensure the security and applicability of engineering, it is necessary to study the engineering characteristics of aeolian sand. This paper focuses on the bearing capacity parameters of aeolian sand in the Mu Us Desert, and test sites in 6 weak foundation areas are selected. Large numbers of basic soil mechanical parameters have been collected through in situ static load tests (SLT) and laboratory confined compaction tests (CCT) to evaluate the effect of foundation treatments. The results show that the characteristics of aeolian sand in the Mu Us Desert include low moisture, poor cohesion, and easy compaction. The mud and water content affect the bearing capacity of aeolian sand. For weak foundations, adding a geogrid or replacing a weak soil layer with stone and aeolian sand can significantly improve the bearing capacity.

scholarly journals Examination of soils and crops after the inundations of 1st February, 1953. II. The influence of salt on the chief vegetable crops.

1955 ◽  
Vol 3 (1) ◽  
pp. 1-14
Author(s):  
J.G.C. Van Dam
Keyword(s):  
Seed Germination ◽  
Soil Structure ◽  
Salt Content ◽  
Leptosphaeria Maculans ◽  
Soil Layer ◽  
Index Number ◽  
Vegetable Crops ◽  
Brussels Sprouts ◽  
Poor Seed

Eleven trial fields were selected on the islands of South Holland in an investigation of the reactions of vegetables to the salt content of the soil. The C index (number of grams of NaCl per litre of soil moisture) was calculated for the 5-20 cm. soil layer, and varied from normal to 8. In fields with a high C index the following effects were observed: Before rain leaching, seed germination of leeks, spinach and carrots was poor. Seed germination of chicory was also poor where the soil structure had deteriorated; soil structure was improved by gypsum applications. The crops grew more slowly and were harvested at a later date than in normal soils. Bolting was stimulated in cabbage lettuce and spinach. Lettuce, endive and savoy cabbage showed marginal leaf scorch, and leeks showed tipburn. Phaseolus beans, peas and strawberries were very sensitive to even a low salt content. There were only slight differences in yields of brassicas sown in situ and transplanted; with leeks sowing in situ was inferior to transplanting. The forcing quality of chicory roots from salty soils was approximately the same as of those from normal soils. The cauliflower crop failed in the trial fields. Yields of leafy crops were better in soils with high than with low moisture contents. Brussels sprouts and red cabbage were more susceptible to attack by Phoma lingam [Leptosphaeria maculans] in the salt trial fields than in normal soils. (Abstract retrieved from CAB Abstracts by CABI’s permission)

scholarly journals Safety and quality assurance for geotechnical constructions in urban areas

2019 ◽  
Author(s):  
Steffen Leppla ◽  
Rolf Katzenbach
Keyword(s):  
Quality Assurance ◽  
Urban Areas ◽  
Construction Projects ◽  
Soil Structure ◽  
Engineering Practice ◽  
The Finite Element Method ◽  
Existing Structures ◽  
Geotechnical Structures ◽  
Load Tests

Safety and quality assurance are the most important aspects for the design and the construction of geotechnical structures. These aspects consider the optimisation by reducing the resources material, money and time. For construction projects with a distinctive soil-structure interaction in the vicinity of existing structures special methods have to be applied to guarantee safety and quality. Therefor numerical simulations using the Finite-Element-Method (FEM), in-situ load tests on the construction site, special foundation techniques like the Combined Pile-Raft Foundation (CPRF), the observational method and an independent peer review are necessary. The paper explains the application and the combination of these tools by examples from engineering practice.

Discharge-pulse Geotechnical Electro Discharge Technology of Bases Strengthening

2020 ◽  
Vol 787 (12) ◽  
pp. 63-65
Author(s):  
N.S. Sokolov
Keyword(s):  
Bearing Capacity ◽  
Mechanical Characteristics ◽  
Discharge Pulse ◽  
Zero Values ◽  
Traditional Technologies ◽  
Negative Friction ◽  
Geotechnical Problems ◽  
Physical And Mechanical Characteristics

The problem of increasing the bearing capacity of the base is an relevant problem in modern geotechnical construction. When significant loads are transmitted to the base, the use of traditional technologies is not always justified. Often there is an urgent need to use non-standard ways to strengthen the bases. In many cases, the geotechnical situation is aggravated by the presence of weak underlying layers with unstable physical and mechanical characteristics in engineering-geological sections. When strengthening such bases with the help of traditional piles, the latter can get negative friction, which significantly reduces their bearing capacity on the ground, sometimes reaching zero values. This may lead to additional precipitations of the objects being constructed and constructed in the zone of geotechnical influence. The use of ERT piles in most cases successfully solves many complex geotechnical problems.

Driven cast-in-situ pile capacity: insights from dynamic and static load testing

2021 ◽  
Author(s):  
Kevin N. Flynn ◽  
Bryan A. McCabe
Keyword(s):  
Dynamic Load ◽  
Shear Stresses ◽  
Load Testing ◽  
Pile Capacity ◽  
Compression Load ◽  
Shaft Resistance ◽  
Pile Installation ◽  
Cast Concrete ◽  
Load Tests

Driven cast-in-situ (DCIS) piles are classified as large displacement piles. However, the use of an oversized driving shoe introduces additional complexities influencing shaft resistance mobilisation, over and above those applicable to preformed displacement piles. Therefore, several design codes restrict the magnitude of shaft resistance in DCIS pile design. In this paper, a series of dynamic load tests was performed on the temporary steel driving tubes during DCIS pile installation at three UK sites. The instrumented piles were subsequently subjected to maintained compression load tests to failure. The mobilised shear stresses inferred from the dynamic tests during driving were two to five times smaller than those on the as-constructed piles during maintained load testing. This was attributed to soil loosening along the tube shaft arising from the oversized base shoe. Nevertheless, the radial stress reductions appear to be reversible by the freshly-cast concrete fluid pressures which provide lower-bound estimates of radial total stress inferred from the measured shear stresses during static loading. This recovery in shaft resistance is not recognised in some European design practices, resulting in conservative design lengths. Whilst the shaft resistance of DCIS piles was underpredicted by the dynamic load tests, reasonable estimates of base resistance were obtained.

scholarly journals Soil physico-chemical characterization in the different soil layers of National Maize Research Program, Rampur, Chitwan, Nepal

2018 ◽  
Vol 3 (1) ◽  
pp. 28-44
Author(s):  
Dinesh Khadka ◽  
Sushil Lamichhane ◽  
Amit P Timilsina ◽  
Bandhu R Baral ◽  
Kamal Sah ◽  
...  
Keyword(s):  
Research Program ◽  
Soil Structure ◽  
Sandy Loam ◽  
Chemical Properties ◽  
Single Layer ◽  
Chemical Characterization ◽  
Bottom Layer ◽  
Soil Parameters ◽  
Physico Chemical

Soil pit digging and their precise study is a decision making tool to assess history and future of soil management of a particular area. Thus, the present study was carried out to differentiate soil physico-chemical properties in the different layers of excavated pit of the National Maize Research Program, Rampur, Chitwan, Nepal. Eight pits were dug randomly from three blocks at a depth of 0 to 100 cm. The soil parameters were determined in-situ, and in laboratory for texture, pH, OM, N, P (as P2O5), K (as K2O), Ca, Mg, S, B, Fe, Zn, Cu and Mn of collected soils samples of different layers following standard analytical methods at Soil Science Division, Khumaltar. The result revealed that soil structure was sub-angular in majority of the layers, whereas bottom layer was single grained. The value and chrome of colour was increasing in order from surface to bottom in the majority pits. Similarly, the texture was sandy loam in majority layers of the pits. Moreover, four types of consistence (loose to firm) were observed. Furthermore, mottles and gravels were absent in the majority layers. Likewise, soil was very to moderately acidic in observed layers of majority pits, except bottom layer of agronomy block was slightly acidic. Regarding fertility parameters (OM, macro and micronutrients), some were increasing and vice-versa, while others were intermittent also. Therefore, a single layer is not dominant for particular soil physico-chemical parameters in the farm. In overall, surface layer is more fertile than rest of the layers in all the pits.     

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