How to overcome sample disturbance?
It is a well known fact that a good quality sample is necessary to get realistic soil parameters. Basically, preserving soil natural structure and stress condition in the laboratory sample determine the quality of soil parameters. However, many researchers pointed out that it is impossible to retain original soil condition even though we use so-called high quality sampler and same in-situ effective stress condition during the laboratory testing. On the other hand, many researchers have tried to overcome such problem of soil disturbance by introducing several methods of correcting soil parameters for poor quality sample. Moreover, recompression method and Stress History and Normalized Soil Engineering Properties (SHANSEP) method are two well known methods employed recently in geotechnical engineering practice.
1) Recompression method
Recompression method was developed by Bjerrum and Berre (1973) at the Norwagian Geotechnical Institute (NGI). In this method, soil specimens are reconsolidated to in-situ effective overburden pressure before sheared under undrained condition. Bjerrum mentioned that the principle behind this technique has been the swelling of sample that occurred before testing is so small and elastic in nature that the mechanical disturbance caused by such swelling can be eliminated by reconsolidating sample exactly as that it is in the in-situ stress condition before testing. Berre and Bjerrum (1973) highlighted that the volumetric strain during recompression should be less than 1.5 to 4%. This method should be used in the case of highly structured, brittle and sensitive clay with high quality sample. It is evident that the low plastic clay samples are found to be somewhat more disturbed than that of high plastic clay samples and reduced water content due to sample disturbance would cause gain in strength. On the contrary, increasing disturbance cause a reduction in strength and an increase in strain for the reconsolidated specimen at the verge of failure. Furthermore, there is some criticism on recompression method that the decrease in void ratio due to densification measure overestimating of strength even for bad quality sample.
2) SHANSEP Method
The SHANSEP method was first established by Ladd and Froott in 1974 at Massachusetts Institute of Technology (MIT). SHANSEP gives design procedure for clay showing normalized behaviour. It gives a way of taking into account the previous stress history of the soil, particularly overconsolidation. In this method, the sample is consolidated under several times greater stresses than its yield consolidation stress (normally, 1.5 to 4 times) and is then swell back to its field effective stress to minimize the adverse effect of soil disturbance.
This chapter discusses the result of experiment of soil properties at the Orthosiphon Stamineus plot, INSAT as describe in chapter three. The experimental were aimed to study the impact of compaction on soil properties at different depth for Orthosiphon Stamineus cultivation in order to determine the suitable soil classes, and propose best depth to plough the area to in order to have high yield with cost effective practice to manage the area.
Mississippi has a variety of different soils .The three general soils are 1) the river flood plain, known as the Delta, 2) a loess region, or bands of soils formed in windblown material that adjoins the Delta, and 3) Coastal Plain. The Mississippi Delta is better for growing row crop, while the loess and Coastal Plain region are better for animal production and forestry. The loess and Coastal Plain regions are divided based on similar soils, geology, climate, water resources, and land use called Major Land Resource Areas. The Mississippi Delta’s soil comes from sediments left by flooding various rivers in the region, rather than being a typical Delta formed by the mouth of a river. In the Delta most of the land is farmed, with three-fourths of the cropland to the north. Controlling surface water and drainage are major soil management issues. In the Delta soils are naturally diverse because of their alluvial origin. Particle sizes within the sediment decrease as distance from the originating stream increase. Another factor in Delta soil formation us surface water movement over time, because soils that formed under standing water have different properties than soils formed under moving water. Soils with large amounts of clay particles have unique features. When the soil is dry, small round aggregates form at the surface that look like shotgun buckshot, which is where the popular name for Delta clay soils “buckshot” came from. Soils with large clay content have very slow water filtration rates; this has led to significant aquaculture and rice production in the region. When floodwaters receded in the Delta, strong winds blew some of the dry sediment left by flooded river to the adjacent uplands to form the loess areas. Because of eas...
Yan, F., Feng, X., Chen, R., Xia K., Jin, C., Dynamic Tensile Failure of the Rock Interface
Davis, J. G., R. M. Waskom, and T. A. Bauder. Managing Sodic Soils. Colorado State
Bipolar due to Medical Condition is the second diagnosis being considered for the case of Fernando. Bipolar due to Medical Condition is being entertained due to Fernando’s goal-directed activity at work, apparent decreased need for sleep, as well as his excessive involvement in activities that have a high potential for painful consequences such as his diet, use of alcohol, and cigarette use that has lasted much more than a week’s duration. These considerations meet criteria A and B. However, criterion C does not fit as Fernando has not had disturbances in his social or occupational functioning or hospitalizations due to these behaviors. Due to the lack of fitting criteria Bipolar due to Medical Condition is being ruled out at this time ( American Psychiatric Association, 2013).
[4] Muni Budhu. Soil Mechanics and Foundations 3rd Edition and Foundations and Earth Retaining Structures (Combined book made for UBC). John Wiley & Sons, Inc. 2011.
As mental health services become more mainstream the individuals seeking those services become more diverse. The need for culturally competent counselors is on the rise. The following will highlight a scenario in which I am morally opposed to homosexuality and find myself working with a client who discloses he is homosexual and is having problems in his romantic relationship with another man. How I would handle this situation, ways in which my own moral standards in the context of this therapeutic relationship would be maintained, ways in which my moral stance might impact therapy, ways in which disclosure of my moral values may come into play, and considerations for how to address clashes between my own values and client values in the future will be the topics of discussion.
Soil liquefaction describes a phenomenon whereby a saturated or partially saturated soil substantially loses strength and stiffness in response to an applied stress, usually earthquake shaking or other sudden change in stress condition, causing it to behave like a liquid. The phenomenon is most often observed in saturated, loose (low density), sandy soils. This is because the loose sand has a tendency to compress when a load is applied; dense sands by contrast tend to expand in volume. If the soil is saturated by water, then water fills the gaps between soil grains. In response to the soil compressing, this water increases in pressure and attempts to flow out from the soil to zones of low pressure (usually upward towards the ground surface). However, if the loading is rapidly applied and large enough, or is repeated many times (e.g. earthquake shaking, storm wave loading) such that it does not flow out in time before the next cycle of load is applied, the water pressures may build to an extent where they exceed the contact stresses between the grains of soil that keep them in contact with each other. These contacts between grains are the means by which the weight from buildings and overlying soil layers are transferred from the ground surface to layers of soil or rock at greater depths. This loss of soil structure causes it to lose all of its strength. According to the
Several principles are implemented for successful rehabilitation. Of these principles includes the need for preventing disasters and anticipating problems before they arise, if this is taken to consideration then rehabilitation will be less costly and trouble free. When rehabilitating a site, all the components making up the ecosystem need to be looked at individually. They include soil, climate, vegetation, time and animals. These components need to interact at certain rates in order for the desired effect to be achieved and so might need to be altered.
The key to good research is preparation, preparation, and preparation. Hence, the key to making good sampling choices is preparation. Trochim (2008) defines sampling as the drawing of a sample (a subset) from a population (the full set). In our everyday lives we all draw samples without realising it. For instance, when one decides to taste some unfamiliar food or drink that is some form of sampling. Williams (2003 74) posits that “Sampling is a search for typicality). On the other hand, (Clark: 2006 87) defines sampling as “a process of drawing a number of individual cases from a larger population”. According to (Chiromo: 2006 16), “a sample is a smaller group or subset of the population”.
Regarding soil degradation in Nigeria, accurate information is needed to guide the government and the public on how and what to do. The government in Nigeria would not deny the fact that the country needs immediate actions to reclaim the quality and fertility of the soil. However, the people did not relax after seeing the developing problems. A lot of researching, teachers and professors, and government are trying so hard to encourage healthy agricultural practices and other measures that would reduce or eliminate soil degradation in the
The sampling design process includes five steps which are closely related and are important to all aspect of the marketing research project. The five steps are: defining the target population; determining the sample frame; selecting a sampling technique; determining the sample size; and executing the sampling process.
... although we may never be able to understand exactly what soil failures can occur when a natural disasters take place, as time goes on and testing instruments and materials advance we will hopefully have a better understanding of what we can do to avoid soil failures and come up with a better and more sufficient method of improving the soils structure and strength permanently. While researching the information for this report I feel I have a much better understanding for construction geo-technics and foundations especially regarding the deformation, liquefaction and pile information related to this specific event. I hope to carry the information I have learned from this event into the construction field and apply them towards an authentic project that’s taking place and know that the information, regarding soils, I have given input on will be precise and accurate.
There has also been lot of research in building systems that can monitor and investigate soil fertility and nutrition levels. Soil fertility data with dynamic, spatial and temporal characteristics of soil are fed to the systems which then use data mining techniques to come to analyze and diagnose soil problems. Such information can be very critical for success of crop.
Geotechnical Engineering covers the engineering properties of soils, the fundamentals of soil mechanics, and the application of geotechnical data and fundamentals to the design of foundation elements, earth-retaining structures, excavations, earth embankments and highway pavements.