Questions:
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Scenario You have recently joined a medium sized general construction company who have acquired a brown field site which they intend to use for housing development. A site survey has revealed a number of areas where it is possible for problems to arise from the intended development. The director has asked you to provide some information on engineering geology and soil mechanics to help them deciding what course of action to pursue |
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Task 1: 1. Understand the common rock types, their mode of formation and uses within construction 1.1Classification of common rocks: engineering description of rocks to current codes of practice Question 1.1 (i) Examine the three main classes of rock and give a general description of their use in construction. (ii) Using current codes of practice describe slate oolitic limestone and granite 1.2 Mode of formation: petrographic classification of igneous rocks; common stable and unstable minerals; diverse nature of sedimentary rocks; grades of metamorphism Question 1.2 i) Briefly describe the mode of formation of the three main types of rock . ii) What is meant by an “unstable mineral” when used in describing rocks iii) The use in construction of extrusive igneous rocks 1.3 Rock and un-cemented sediments for construction use: common usage of geological materials for construction; characteristics of the main rock and soil deposits which make them suitable/unsuitable for construction use; differences between rock mass and rock material in construction; type and nature of rock discontinuities; characteristics of discontinuities which influence the engineering performance of rock materials Question 1.3 i) Using published methods of classifying aggregates, suggest suitable aggregates for foundation work, and for use in a road surface. ii) Briefly outline the factors that have to be taken into consideration when looking at rock mass rather than individual stones. iii) Describe one system of classification of rock mass which is widely used |
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Task 2: 2. Be able to classify soil types from the determination of their basic soil properties 2.1 Soil description and classification: differences between description and classification; classification tests to current codes of practice; liquidity and consistency indices for fine grained soils Question 2.1 i) The following table gives the sieve results from a soil. · Complete the table and draw a graph showing the cumulative distribution of particle size · suggest how this soil would be described and · explain briefly how you have come to your conclusion.
ii) Briefly outline what is meant by the following: · Made ground · Organic soil · Coarse soil · Fine soil · Dilatancy · Explain the difference in clay and silt · Bedding planes 2.2 Fundamental soil properties: particulate nature of soils; three-phase and two-phase states, calculations for soil density, moisture content, void ratio and degree of saturation; characteristics of fine grained soil responsible for development of apparent cohesion Question 2.2 i) A cone penetration test is carried out on a sample of clay and gives the following results:
Draw a graph of the results and estimate the liquid limit of this clay. ii) Another sample of the clay used in b) above is tested to find the plastic limit. The following results were obtained from five different estimates: 15.6%, 14.1%, 17.1%, 18.0%, 16.1%. Estimate the plastic limit and the plasticity index of the clay 2.3 Principles of effective stress: influence on the strength and deformation of soil, drained and undrained behaviour; influence of seepage on effective stress Question 2.3 i) Outline the difference between a drained and un-drained compressive strength test stating the difference between the shear strength values obtained. ii) A set of drained triaxial tests were carried out on sample of soil from a site. The results for the test are given in the table below:
Each sample was 76mm long and had a diameter of 38mm and had vertical deformation of 5.1mm · Draw the Mohr circles, determine the strength envelope of the soil with respect to effective stress. · Determine the Coulomb equation for the shear strength of the soil in terms of total stresses. 2.4 Calculations and graphs: total stress, pore water pressure and effective stress for soil sequence under hydrostatic conditions Question 2.4 i) A 4m thick layer of saturated soil with high clay content lies underneath a 1m covering of sand. An additional layer of sand 2m thick is laid on top. The density of the sand is 1,900kgm-3 · What is the effective stress on the clay immediately after the new sand layer has been put down, · the effective stress after many years. · Briefly outline what has caused this change. ii) A 4m layer of sand of saturated unit weight 18kNm-3 lies on top of a 5m thick layer of clay saturated density 20kNm-3 The ground water level occurs at 2m below the surface of the sand. Determine the total and effective stresses acting at the base of the clay layer. |
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Task 3: 3: Be able to establish the primary design parameters for soils 3.1Geotechnical design parameters: common methods for the determination of shear strength, compressibility and permeability to current codes of practice; potential limitations associated with the methods Question 3.1 i) Outline the shear box method of determining the shear strength of soil ii) Outline the triaxial shear strength test iii) Compare the results of these two kinds of strength tests and the use of each test in practice. 3.2 Ground investigation and in-situ sampling: current techniques for the acquisition of soil samples for laboratory testing; impact of sample quality on measured parameters; common methods of in-situ testing Question 3.2 i) Compare the use of laboratory testing with in-situ testing when trying to get information about the soil conditions on a construction site. ii) Examine the problems associated with obtaining undisturbed soil samples iii) What tests can be carried out on a disturbed soil sample? 3.3 Laboratory measurements: e.g. density, moisture content, void ratio, degree of saturation, permeability, porosity, shear strength, liquid limit, chemical nature Question 3.3 i) Briefly describe how the organic content of the sample would be measured ii) Outline how you would estimate plastic index of a sample of soil with a high clay content. iii) A sample of soil was tested on a falling head permeability tester and the head fell from 350mm to 250mm in 12 minutes. Assume that the diameter of the pressure tube is 8mm, how long would it take for the head to fall a further 50mm? |
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Task 4: 4: Be able to analyse the results from common soil tests 4.1 Laboratory data: shear box tests; volumetric response to shear; unconsolidated undrained and consolidated undrained with pore pressure measurement triaxial tests; triaxial shear strength parameters by Mohr’s Stress Circles and stress path meth Question 4.1 i) An un-drained shear box test was carried out on a series of soil samples with the following results:
Determine using graphical methods the cohesion and angle of friction of this sample. ii)
Plot the strength envelope of the soil a) with respect to total stress and b) with respect to effective stress. 4.2 Permeability tests: constant head and falling head permeameters; process results from field pumping tests (in terms of coefficient of permeability and radius of the cone of depression) Question 4.2 i)
Calculate the mean permeability. The diameter of the standpipe 3mm Diameter and length of the sample 100mm each. ii) Explain how an in situ measure of soil permeability many meters below the normal soil level on the site may be obtained 4.3 One-dimensional consolidation test: oedometer tests for coefficient of volume compressibility Question 4.3 i) Outline the method of test using the odometer to measure the consolidation of soil. ii) A specimen of fully saturated clay has been consolidated under a vertical pressure of 50kPa and is at equilibrium. The pressure is now doubled. Determine the pore water pressure and the effective stress after the pressure increase. |
i. Igneous Rocks
Molten Rocks are framed by the freezing and crystallization of a silicate melt (ruled by oxygen and silicon, with a mixture of different substances or metals). The event as well as circulation of molten rocks and volcanic rocks sorts can be identified with the process of plate tectonics. The liquid rock material from which volcanic rocks structure is called magma. Magma is liquid silicate material and may incorporate officially shaped precious stones and broke up gasses. The name magma applies to silicate dissolves inside the Earth’s outside, when magmas achieve the surface they are alluded to as magma. The key constituents of magma are O, Si, Al, Ca, Na, K, Fe and Mg. The properties of a magma (consistency, liquefying point) are to a great extent controlled by the SiO2 (thickness) and the H2O substance (dissolving point). SiO2 is the most plentiful part and ranges in plenitude from 35% in mafic rocks to 75% in felsic rocks. Two Dissolved gasses, CO2 and H2O, are imperative despite the fact that they are not the richest parts. The different sorts of molten rocks can be recognized by mineral arrangement, synthetic structure (connected to minerals), and composition. Surface portrays the way the minerals in the rock look like and identify with one another (substantial versus little; perfect precious stone shapes or spasmodic grains; and so forth.), and is in extensive parts impacted by the cooling history of the magma.
The purported Extrusive Rocks are those that make it to the surface of the Earth in a liquid express, have a tendency to cool rapidly, and have subsequently ordinarily have little gems (quick cooling does not permit expansive precious stones to develop). The ensuing surfaces are called aphanites (fine grained), polished and porphyritic (if a few gems framed before expulsion). In this manner these surfaces are normal for volcanic rocks..
The gathered Intrusive Rocks are those that don’t make it to the surface and chill off slowly inside the outside. Therefore we see basically phaneritic pieces with minerals of coarse to center grain size. If these rocks structure at particularly shallow profundities they may be called hypabyssal or subvolcanic rocks, and we may similarly see porphyritic surfaces (e.g. dykes and ledges).
Sedimentary Rocks are a result of the surface techniques of the earth (weathering, disintegration, downpour, stream, wind, wave activity, sea flow). The beginning materials for sedimentary rocks are the rocks outcropping on the landmasses. Techniques of physical and synthetic weathering separate these source materials into the accompanying parts:
Little parts of the source (rock, sand, or sediment measure) that may be identifiable rock sections or individual minerals
New minerals delivered by weathering courses of action (principally muds)
Disintegrated allotments of the source rock (broke up salts in stream and sea water)
From aggregations of these materials (fragmental material, muds, and broke up salts) all residue on the earth’s surface structure. Dregs may structure by:
Negligible mechanical collection (wind, water, for example, rock and sand stores in a stream or sand hills in a desert
Concoction precipitation, for example, salt and calcite precipitation in shallow oceans and lakes
Action of life forms, for example, carbonate gathering in coral reefs (natural precipitation), or aggregation of natural matter in bogs (coal forerunner)
Sandstones (molecule measure between 2 mm and 0.0625 mm) contain around 30% of all sedimentary rocks. Since in numerous molten and changeable source shakes the grain size of segment minerals is bigger than or equivalent to that of sandstones, it is substantially more hard to focus the source rock of a sandstone (as contrasted with a combination).
The richest mineral in sandstone is generally quartz, on the grounds that it is the hardest one of the rock shaping minerals and hence the most impervious to scraped area amid transport. The second most plentiful mineral is feldspar (potassium feldspar), took after by micas. These minerals are additionally the synthetically most steady (under states of the Earth’s surface) among the rock shaping minerals (Brooks and Brooks, 1941).
Dolostones comprise of the carbonate mineral dolomite [camg(co3)2], and happen in pretty much the same settings as limestones. Despite the fact that dolomite can accelerate hypothetically from seawater, it just once in a while does, and presumably a large portion of the dolostones in the sedimentary record are because of post-depositional substitution of calcite by dolomite (Mg for Ca trade by Mg-rich pore waters).
Evaporites are genuine compound silt. They comprise basically of salt (table salt [nacl] and different others) and/or gypsum (Caso4). They normally structure from vanishing of seawater. They oblige high vanishing rates (high temperatures) for their arrangement, and generally the sedimentation bowl must be incompletely or completely shut off (overall supersaturation not arrived at in view of flood of new water). They normally show parched (dry) atmosphere at their site of affidavit.
Carbonaceous Sedimentary Rocks are those that contain boundless common matter in diverse structures. Regardless of the way that they make simply a little division of sedimentary rocks, they are key essentialness resources. Coal, for example is a carbonaceous shakes that involves the changed (as a result of extended weight and temperature) stays of trees and other plant material. It has used subsequent to the latest century for essentialness creation and manufactured industry. Oil shales are dim mudstones that contain bounteous regular matter that has been balanced into solid (kerogen) or amazingly thick hydrocarbons (bitumen) that can be removed from the rock through warming. Tar sands are sandstones whose pore spaces are stacked with significant crude petroleum and bitumen. The hydrocarbons are by and large evacuated with steam (Chamberlin and Salisbury, 1904). At current oil costs (2004-2005) oil shale and tar sands are pulling in interest in light of the way that a couple of occasions are landing at the point where misuse becomes monetarily sensible. It is likely that these more capricious essentialness sources become more basic as oil supplies diminish over the nearing decades (Davson and Danielli, 1970).
Transformative rocks are those whose special structure, sythesis and mineralogy have been changed by conditions of high weight and temperature (higher than conditions of improvement of starting material). The materials from which alterable rocks structure are volcanic rocks, sedimentary rocks, and at one time existing transformative rocks. Mineralogical and textural changes in the midst of transformative nature happen fundamentally in the strong state. Alterable rocks structure when the precursor materials (volcanic, residue, etc.) are secured significantly and are accordingly brought into an environment of high weight and temperature. They are as needs be most by and large experienced in the middle zones of mountain cinchs (hoisted root zone), in old terrain shields, and as the storm subterrain room shake underneath the buildup veneer of stable territory stages (Dixon, 1982). Variably shakes and related volcanic interferences (from rock secured so significant that it broke up) make up around 85% of the territory outside.
Variably shakes may contain relic structures, for instance, stratification, sheets, and even such idiosyncrasies as sedimentary structures or volcanic arrangements.
Minerals: The minerals that structure in the midst of transformative nature are in parts the same as those that we know from volcanic rocks (we have to remember that the early divides structure deeper in the earth under conditions of high weight and temperature themselves). Thus quartz, biotite, muscovite, pyroxene, amphiboles and feldspars all structure in the midst of variably approaches.
Slates are the finest grained combination of foliated rocks and are made by useless transformative nature of shales and mudstones. The most trademark trick is the claimed slaty cleavage (from as of late confined micas). Slaty cleavage ordinarily is masterminded at a high indicate the first dozing material of the shales (Flanagan, 2001). In the picture on the left the bedclothes of the first shake dips at around 40 degrees to the benefit (sandy layers in tan), and the slaty cleavage dips at around 80 degrees to the benefit. Slates tend to part differentiated at this cleavage, and go into decay in platy parts (used as a piece of past times as a creation surface that could without a doubt be wiped off a clean Slate). The change of slaty cleavage depends on upon the measure of soil and detrital micas open in a rock (starting material for variably mica advancement).
Schists are medium to coarse grained foliated rocks, in which the parallel balanced micas and the foliation are quickly unmistakable to the eye. They are conveyed by mid-extent grade transformative nature, and contain despite micas other unmistakable minerals, for instance, quartz, feldspar, garnet and amphibole (BASIS FOR SUBDIVISION). They don’t simply structure from shales, also from other watchman shakes, for instance, basalt, rock, sandstones and tuffs. They are by volume the most ample alterable rock sort.
Gneisses are extraordinarily coarse grained transformative shakes that structure in the midst of high audit variability. They are especially united (segregation of as of late organized minerals into gatherings), and their principal minerals are quartz, potassium feldspar, and biotite or hornblende (ferromagnesian minerals). It is of practically identical association than stone, and if gneiss is warmed just a little bit further, a granitic melt will move from it (Foster, 1966). The picture at the left exhibits a garnet-biotite gneiss (garnet are the rosy detects, the dim mineral is the biotite) with quartz-feldspar groundmass (white-light dark).
Hornfels (a rock [from German “Fels”] that is as hard as a horn), is an interchange nonfoliated, fine grained alterable rock. Regularly it is dull shaded, fine grained and hard. It happens consistently in transformative aureolas around interferences (contact variability).
(ii) Slates are shaped from fine-grained dregs, for example, mudstone and shale. At the point when these are packed and warmed somewhat, minor new chips of mica develop, and have a tendency to line themselves up at right points to the heading of pressure. In spite of the fact that the individual mica gems can’t be seen, the rock breaks along a specific bearing, or cleavage plane. Here you can see the cleavage, and you can likewise see that it is not parallel to the first sheets stamped by dull and light groups (Fullagar and West, 2011).
Oolitic limestone is made up generally of sand-sized, adjusted pellets of calcium carbonate. In this closer see we can see that a percentage of the pellets have become by including layers of calcium carbonate onto a little sedimentary grain of quartz. Isle of Skye, Scotland.
Rocks are coarse-grained meddlesome molten rocks made of two various types of feldspar (potassium- and sodium-rich), together with quartz and a little extent of dim minerals.
Taking a gander at rock between crossed polarisers makes it less demanding to recognize the individual precious stones (Gallant, 2001). The rock is comprised of interlocking rectangular feldspars and sporadic clear quartz, all in shades of dim light black through to white.
Sedimentary rocks are shaped through the progressive aggregation of silt: for instance, sand on a shoreline or mud on a stream bunk. As the residue is covered it is compacted as more material is kept on top. In the end the dregs will get to be dense to the point that it is basically shaken. This procedure is known as lithification (Geikie, 1906).
1.2
i) Igneous rocks or volcanic rocks will be shakes which have solidified from a melt or magma. The melt is comprised of different parts of prior rocks which have been subjected to dissolving either at subduction zones or inside the Earth’s mantle. The melt is hot thus passes upward through cooler nation rock. As it moves it cools and different rock sorts will structure through a methodology known as fragmentary crystallization. Molten rocks can be seen at mid sea edges, regions of island circular segment volcanism or in intra-plate hotspots.
Metamorphic Rocks or transformative rocks will be shakes which once existed as molten or sedimentary shakes however have been subjected to shifting degrees of weight and high temperature inside the Earth’s outside (Lyell and Rudwick, 1990). The procedures included will change the synthesis and fabric of the rock and their unique nature is regularly difficult to recognize. Changeable rocks are ordinarily found in ranges of mountain building.
ii) A zone found close to the world’s surface that structures as an aftereffect of substance disintegration of unsteady minerals under the activity of surface waters and groundwater, and additionally the oxygen and carbon dioxide display circulating everywhere and disintegrated in these waters. The change is created mostly by the methodology of oxidative change. Metal sulfide metals and stores of sulfur, salts, and coal experience the most vivacious change. The metal sulfides are supplanted by oxides, hydroxides, carbonates, and sulfates of the same metals. Collections of alunite and gypsum structure where sulfur is available. Gypsum likewise collects in stores of rock salt. The deterioration of coal creases builds the substance of dampness, fiery remains, and oxygen in the coal, with a synchronous reduction in the measure of carbon and hydrogen (Pellant and Pellant, 2009). The blankets of oxidation items that structure under such circumstances at mineral stores are called mineral tops. Purported gossan, which is saved basically by lowland iron mineral, is recognized on account of sulfide metal stores; for salt and sulfur stores, the “gypsum top” is recognized. The oxidation zone stretches out down to the level of the groundwater and is generally a couple of meters to a couple of dozen meters thick, yet some of the time at specific parts it is dependent upon a couple of hundred meters thick (measuring from the world’s surface). In the oxidation process piece of the mineral material of a store may be broken down by the groundwater, permeate descending, and be redeposit underneath the groundwater level, structuring a zone of auxiliary mineral enhancement. An auxiliary advancement zone is unconventionally normal for some copper, uranium, gold, and silver stores.
iii) Extrusive igneous or molten rocks, volcanic, structure when magma goes’ to Earth’s surface. The liquid rock ejects or streams over the surface as magma, and after that cools structuring rock. The magma originates from the upper mantle layer, between 50 km and 150 km underneath the World’s surface.
At the point when magma emits onto the World’s surface, it cools rapidly. On the off chance that the magma cools in under a day or two, there is no time for components to structure minerals. Rather, components are solidified set up inside volcanic glass. Regularly, magma cools over a couple of days to weeks and minerals have enough time to structure however not time to develop into vast precious stones.
Basalt is the most widely recognized kind of extrusive igneous or molten rock and the most well-known rock sort at the World’s surface.
Total qualities or Aggregate characteristics have a huge impact on the conduct of new and solidified solid. In spite of the fact that these impacts of total attributes change consistently as a capacity of molecule size, the accompanying order will be made as per normal practice: material held in the N4 strainer will be considered coarse total, material passing No. 4 strainer and held in the No. 200 strainer (75 µm) will be viewed as fine total, and material passing No. 200 strainer will be called hereinafter micro fines.
Construction aggregate, or essentially “total”, is a general classification of coarse particulate material utilized as a part of construction, including sand, rock, smashed stone, slag, reused solid and geo-synthetic totals. Totals are the most mined materials on the planet. Totals are a part of composite materials, for example, solid and black-top solid; the total serves as fortification to add quality to the general composite material (Reeves, 1973). Because of the generally high water driven conductivity esteem as contrasted with most soils, totals are broadly utilized as a part of waste applications, for example, establishment and French channels, septic channel fields, holding divider channels, and street side edge channels. Totals are additionally utilized as base material under establishments, streets, and railroads. At the end of the day, totals are utilized as a stable establishment or street/rail base with unsurprising, uniform properties (e.g. to help avert differential settling under the street or building), or as a minimal effort extender that ties with more costly bond or black-top to structure cement.
Favored bituminous aggregate sizes for road advancement are given in EN 13043 as d/D (where the range shows the tiniest and greatest square work granulating that the particles can pass). The same gathering measuring is used for greater defensive layer stone sizes in EN 13383, EN 12620 for bond downright, EN 13242 for base layers of road advancement and EN 13450 for course balance (Rhodes, 1972).
Dependable appraisals of the quality and disfigurement attributes of rock masses are needed for very nearly any type of examination utilized for the configuration of slants, establishments and underground unearthing.
1.3
i) Rock mass characterization plans have been creating in excess of 100 years since Ritter (1879) endeavored to formalize an observational methodology to shaft outline, specifically for deciding help prerequisites. While the order plans are suitable for their unique application, particularly if utilized inside the limits of the case histories from which they were produced, significant alert must be practiced in applying rock mass characterizations to other rock designing issues.
Laubscher created the Mining Rock Mass Rating (Mrmr) framework by adjusting the Rock Mass Rating (RMR) arrangement of Bieniawski. In the MRMR framework the solidness and backing are dead set with the accompanying mathematical statements:
RMR = IRS + RQD + dividing + condition in which:
RMR = Laubschers Rock Mass Rating
IRS = Intact Rock Strength
RQD = Rock Quality Designation
Dividing = representation for the scattering of discontinuities
Condition = condition of discontinuities (parameter similarly subject to groundwater region, weight, or measure of groundwater inflow in the underground evacuation)
MRMR = RMR * conformity variables in which:
Conformity variables = components to make up for: the technique for unearthing, introduction of discontinuities and exhuming, impelled anxieties and in the days to come weathering.
The parameters to figure the RMR quality are similar to those used as a piece of the RMR game plan of Bieniawski. This may be dumbfounding, as a part of the parameters in the MRMR structure are adjusted, for instance, the condition parameter that consolidates groundwater region and weight in the MRMR system while groundwater is an alternate parameter in the RMR game plan of Bieniawski. The amount of classes for the parameters and the purpose of enthusiasm of the depiction of the parameters are in like manner more broad than in the RMR course of action of Bieniawski.
The change components depend on upon future (powerlessness to) weathering, uneasiness environment, presentation,
ii) The mix of estimations of RMR and MRMR chooses the gathered help potential. A rock mass with a high RMR before the change components are associated has a high help potential, and can be reinforced by, for example, rock jars, whatever the MRMR worth may be in the wake of uncovering. Contrariwise, shake shocks are not a suitable backing for a rock mass with a low RMR (i.e. has a low stronghold potential).
Laubscher uses a graph for the isolating parameter. The parameter is liable to a most amazing of three eccentricity sets that center the size and the kind of the rock pieces. The condition parameter is directed by the brokenness set with the most opposing effect on the constancy.
iii) The thought of alteration variables for the rock mass after a while later evacuation is uncommonly appealing (Richardson, 2002). This considers reward of adjacent mixtures, which may be present at the territory of the rock mass viewed, however may not be show at the range of the proposed uncovering or the other path around. Likewise, this thinks seriously about assessment of the effect of uncovering and revealing induced bothers, unearthing procedures, and the effect of past and future weathering of the rock mass.
2 (i).
|
Sieve size in 10-6m |
Mass retained in gram (g) |
Mass passed in gram (g) |
% Passing |
Log10 sieve size (particle size) |
|
6.3 |
0 |
172.6 |
20 |
20 |
|
2000 |
6.4 |
166.2 |
16 |
0.425 |
|
1.18 |
3.3 |
162.9 |
12 |
2 |
|
600 |
9 |
153.9 |
13 |
3 |
|
425 |
28.1 |
176.5 |
5 |
4.5 |
|
300 |
31.1 |
165.2 |
9 |
80 |
|
212 |
34 |
183.4 |
10 |
266 |
|
150 |
22.5 |
156.8 |
11 |
336 |
|
63 |
25.5 |
159.3 |
22 |
400 |
|
Pass through all to tray. |
12.7 |
155.3 |
20 |
2 |
According to the above data set of soil we can easily measure or calculate the cumulative distribution of soli particles by the help of graphical representation, which is shown in below (Comyn, 1985).
Soils having molecule bigger than 0.075mm size are termed as coarse grained soils. In these soils more than half of the aggregate material by mass is bigger 75 micron (Schoffeniels, 1967). Coarse grained soil may have stone, cobble, rock and sand. The accompanying molecule characterization names are given relying upon the span of the molecule:
Stone: atom size is more than 300mm.
Cobble: atom measure in range 80mm to 300mm.
Grave: particle assess in range 4.75mm to 80mm.
Sand: particle assess in range 0.075mm to 4.75mm.
The rate of diverse size of soil particles coarser than 75 micron is dead set. Coarse soils are primarily ordered by strainer investigation. The grain size dissemination bend gives an thought with respect to the degree of the soil, that is, it is conceivable to recognize whether the soil is decently reviewed or inadequately evaluated. In mechanical soil adjustment, the principle rule is to blend a few chose soils in such an extent, to the point that a wanted grain size circulation is gotten for the configuration blend (Stiles, 1924). Henceforth for proportioning the chose soils, the grain size circulation of soil is to be first known.
(ii).
Made ground
The Land or ground area, which is made by filling in a low zone with trash or other fill material. Regularly, such made area is not suitable for building without the utilization of a heap establishment, is known as made ground.
Organic soil
Organic or Natural soil has been regularly altered by the decay of plants and creatures and shockingly, today, the majority of the soil on the planet has been drained by agribusiness. Farmers who produce ensured natural produce should first create soil that meets with the criteria of the USDA. This obliges them to alter long ago drained soil with crucial natural mixes with the plan of restoring soil with the first abundance our planet at one time appreciated preceding the harm created by current industrialization.
Coarse soil
Soil composition may be appraised from fine to coarse. A fine surface demonstrates a high extent of better particles, for example, residue and earth. A coarse surface demonstrates a high extent of sand. The mean diameter of each coarse rock is in range of 20 mm to 80 mm.
Fine soil
Fine grained soils are distinguished on the premise of its versatility. Singular particles are not noticeable by stripped eye. Fine grained soils are likewise isolated in two gatherings, Silt and Clay or Mud. Particles having measurement in the middle of 75 micron to 2 micron are called Silt and particles having breadth littler than 2 micron is called Mud or Clay.
Dilatancy
The increment is in volume of a granular substance or soil when its shape is changed, due to more noteworthy separation between its part particles. The marvel whereby a thick substance or soil hardens under weight is known as dilatancy of soil.
In spite of the fact that clay and silt are named fine soils, they have some contrast between them are following in below.
1. Clay or Mud particles are much lesser in size than sediment particles, despite the fact that all silts with particles estimate short of what 0.075mm are named either silt.
2. Clay contains clay minerals, while silt doesn’t contain mud minerals.
3. Plasticity of clay is substantially more than that of silt.
4. Surface composition of silt is smooth and tricky to touch when wet, while mud or clay is sticky and plastic-like when wet.
5. In the greater part of the cases, dry quality of clay or mud is more prominent than that of silt.
6. Mud’s or Clays are vitality delicate to dry thickness, while silt is dampness touchy to dry thickness.
7. Expansion of silt is more prominent than that of clay.
8. Sturdiness of mud or clay is higher than silt.
In geography a bed is the littlest division of a geologic development or stratigraphic rock arrangement stamped by decently characterized divisional planes (bedding planes) dividing it from layers above and underneath (Troshin, 1966). A bed is the littlest lithostratigraphic unit, generally going in thickness from a centimetre to a few meters and discernable from cots above and underneath it. Couches can be separated in different ways, including rock or mineral sort and molecule size. The term is by and large connected to sedimentary strata, however might likewise be utilized for volcanic streams or fiery remains layers.
2.2 (i).
|
Penetration of cone mm |
12 |
16.3 |
18.7 |
19.7 |
20.3 |
|
Moisture content % |
31 |
33.6 |
35 |
35.7 |
40 |
According to the above data set the graphical representation of liquid limit of this clay is shown in below.
Soils having molecule bigger than 0.075mm size are termed as coarse grained soils. In these soils more than half of the aggregate material by mass is bigger 75 micron (Schoffeniels, 1967). Coarse grained soil may have stone, cobble, rock and sand. The accompanying molecule characterization names are given relying upon the span of the molecule:
Stone: atom size is more than 300mm.
Cobble: atom measure in range 80mm to 300mm.
Grave: particle assess in range 4.75mm to 80mm.
Sand: particle assess in range 0.075mm to 4.75mm.
The rate of diverse size of soil particles coarser than 75 micron is dead set. Coarse soils are primarily ordered by strainer investigation. The grain size dissemination bend gives an thought with respect to the degree of the soil, that is, it is conceivable to recognize whether the soil is decently reviewed or inadequately evaluated. In mechanical soil adjustment, the principle rule is to blend a few chose soils in such an extent, to the point that a wanted grain size circulation is gotten for the configuration blend (Stiles, 1924). Henceforth for proportioning the chose soils, the grain size circulation of soil is to be first known.
(ii).
Made ground
The Land or ground area, which is made by filling in a low zone with trash or other fill material. Regularly, such made area is not suitable for building without the utilization of a heap establishment, is known as made ground.
Organic soil
Organic or Natural soil has been regularly altered by the decay of plants and creatures and shockingly, today, the majority of the soil on the planet has been drained by agribusiness. Farmers who produce ensured natural produce should first create soil that meets with the criteria of the USDA. This obliges them to alter long ago drained soil with crucial natural mixes with the plan of restoring soil with the first abundance our planet at one time appreciated preceding the harm created by current industrialization.
Coarse soil
Soil composition may be appraised from fine to coarse. A fine surface demonstrates a high extent of better particles, for example, residue and earth. A coarse surface demonstrates a high extent of sand. The mean diameter of each coarse rock is in range of 20 mm to 80 mm.
Fine soil
Fine grained soils are distinguished on the premise of its versatility. Singular particles are not noticeable by stripped eye. Fine grained soils are likewise isolated in two gatherings, Silt and Clay or Mud. Particles having measurement in the middle of 75 micron to 2 micron are called Silt and particles having breadth littler than 2 micron is called Mud or Clay.
Dilatancy
The increment is in volume of a granular substance or soil when its shape is changed, due to more noteworthy separation between its part particles. The marvel whereby a thick substance or soil hardens under weight is known as dilatancy of soil.
In spite of the fact that clay and silt are named fine soils, they have some contrast between them are following in below.
1. Clay or Mud particles are much lesser in size than sediment particles, despite the fact that all silts with particles estimate short of what 0.075mm are named either silt.
2. Clay contains clay minerals, while silt doesn’t contain mud minerals.
3. Plasticity of clay is substantially more than that of silt.
4. Surface composition of silt is smooth and tricky to touch when wet, while mud or clay is sticky and plastic-like when wet.
5. In the greater part of the cases, dry quality of clay or mud is more prominent than that of silt.
6. Mud’s or Clays are vitality delicate to dry thickness, while silt is dampness touchy to dry thickness.
7. Expansion of silt is more prominent than that of clay.
8. Sturdiness of mud or clay is higher than silt.
In geography a bed is the littlest division of a geologic development or stratigraphic rock arrangement stamped by decently characterized divisional planes (bedding planes) dividing it from layers above and underneath (Troshin, 1966). A bed is the littlest lithostratigraphic unit, generally going in thickness from a centimetre to a few meters and discernable from cots above and underneath it. Couches can be separated in different ways, including rock or mineral sort and molecule size. The term is by and large connected to sedimentary strata, however might likewise be utilized for volcanic streams or fiery remains layers.
2.2 (i).
|
Penetration of cone mm |
12 |
16.3 |
18.7 |
19.7 |
20.3 |
|
Moisture content % |
31 |
33.6 |
35 |
35.7 |
40 |
According to the above data set the graphical representation of liquid limit of this clay is shown in below.
Mohr–coulomb hypothesis is a numerical model (see yield surface) depicting the reaction of fragile materials, for example, solid, or rubble heaps, to shear push and ordinary stress. The vast majority of the traditional is building materials some way or another take after this principle in any event a parcel of their shear disappointment envelope. For the most part the hypothesis applies to materials for which the compressive quality far surpasses the malleable strength. In geotechnical designing it is utilized to characterize shear quality of soils and rocks at distinctive compelling stresses.
The thickness of the soil layer is (4 + 1 + 2) m = 7 m
As well as the density of the sand is 1900 kg/m^3
Therefore, weight of the sand or soil is 1.9 kg
As well as effective stress σT = γh
Where, σ is total effective stress
γ is weight of soil or sand in kgh is the height of the soil column
Therefore, the total effective stress = 1.9*7
= 13.3
(ii)
We know that the kg/m³ * 0.00980665 = kN/m³
Therefore, 18kN/m3 = 1835.489 kg/m3 at thickness of soil column is 4m as well as 20kN/m3 = 2039.432 kg/m3 at thickness of soil column is 5m
Therefore, the total effective stress σT = γh
= (1835.489*4) + (2039.432*5)
= 7341.956 + 10197.16
= 17539.116
3.1
(i). An immediate shear test is a lab or field test used by geotechnical originators to measure the shear quality properties of soil or rock material, or of discontinuities in soil or rock masses.
The test is performed on three or four illustrations from a by and large undisturbed soil sample. A case is situated in a shear box which has two stacked rings to hold the example; the contact between the two rings is at pretty about the mid-tallness of the example. A keeping uneasiness is joined vertically to the case, and the upper ring is pulled along the side until the example misses the mark, or through a pointed out strain. The store joined and the strain influenced is recorded at standard intervals to centre a stress–strain curve for coupling uneasiness. A couple of illustrations are attempted at distinctive confining bothers to centre the shear quality parameters, the dirt union (c) and the edge of inside erosion, by and large known as rubbing plot (Φ).
(ii). A triaxial shear test is a normal framework to measure the mechanical resources of various deformable solids, especially soil (e.g. sand, dirt) and rock, and other granular materials or powders. Regardless of the way that the name triaxial test prescribes that the bothers would be different in three orientations; this is not legitimate in the test as is by and large done. In this test with oil or water as keeping medium, the restricting weights are equal in all headings (i.e. the extent that boss troubles: for a weight test: σ1 ≠ σ2 = σ3 and for versatile: σ1 = σ2 ≠ σ3). Just in a certified triaxial test the bothers in each of the three direction can be various (i.e.
(iii). Some praiseworthy elements that impact the quality are demonstrated. Each of these impact elements can change the quality parameter. On the off chance that a non-complete perspective is considered sensible results we can’t be normal. To plan the realities there are distinctive stages, authorization, arrangement, characterization, translation and confirmation. Evaluating the shake and rock mass conduct will dependably be a test; suitable testing methods and examinations are the first venture for a more sensible assessment (Walker, 2007). Consequently, testing and the testing results ought not to be regardless of the whole venture.
By excellence of the variability of unsaturated soil properties and the undeveloped condition of unsaturated soil mechanics previously, specialists managing structural designing works including unsaturated soil have been confronted with expanding issues. Jennings abridged the building issues connected with unsaturated soils into four principle bunches, to be specific:
a) Immediate settlement because of the untrained compressibility. This was because of the compressibility of the pore air or the fast stream of pore air to the environment or solvency of air in the pore water.
b) Heave because of swelling on wetting. Wetting can happen because of the entrance of water from the surface (from precipitation or run-off) or it can happen if the dirt is secured at the top surface, so forestalling dissipation of ground water to the environment. Numerous unsaturated soils, especially mud, are known to swell (increment in volume) on wetting.
c) Additional settlement because of breakdown of the dirt on wetting. Some unsaturated soils are known to fall (decrease in volume) on wetting.
d) Loss of shear quality because of suction lessening (wetting).
3.2
(i). Laboratory element testing of the soil sample or rock sample is a most important method of measuring the soil type in Geotechnical method or research program as well as in-situ soil or rock sample testing is a testing method for gaining soil. Both of the testing methods are provided the information or data about the moisture of the soil or rack sample, groundwater measurement as well as its pressure (Gallant, 2001). Both of the data set is provided the useful data as well as information about the soil or rock sample.
(ii). Some basic problems are shown in below.
(iii). The Standard penetration test is most useful test or method for the rock or soil samples. The standard penetration test (SPT) is an in-situ test or method to provide data or information for each and every sample of the rock or soil. The standard penetration test (SPT) process or method, which is describe in ISO 22476-3, ASTM D1586 as well as in Australian Standards it is AS 1289.6.3.1.
3.3
(i) The organic content of the soil or sample soil will be measure by the help of the semi quantitative system. There are two essential systems for the semi-quantitative estimation of natural matter in soils furthermore silt. Natural matter substance can be utilized as an unpleasant assessment of the aggregate natural carbon or organic content. Semi-quantitative strategies are based upon the indiscriminate evacuation of all natural matter took after by gravimetric determination of example weight reduction. The two essential semi quantitative strategies are: (1) misfortune on-ignition and (2) hydrogen peroxide absorption.
(ii) The plasticity index of soil is the numerical contrast between its fluid point of confinement and its plastic utmost, and is a dimensionless number. Both the fluid and plastic cut-off points are dampness substance (Woodhead, 1999). The plasticity index gives an evidence of, in addition to everything else, the decrease in dampness substance needed to change over soil from a fluid to a semisolid state. It gives the extent in dampness at which soil is in a plastic state. The plasticity index may be considered as a measure of the attachment controlled by soil.
(iii). Original statics of the soil – 350 mm
Fall measure of the soil – 250 mm
Net fall of the soil from the primary level – (350-250) = 100 mm
Net time taken to complete the head fall – 12 minutes
Diameter of the pressure tube: 8mm
Required fall in the soil – 50mm
Time taken to fall from 250 mm to 200 mm – x
Time taken to fall 100 mm – 12 minutes
Hence, the time taken by the pressure tube to fall 50 mm with the diameter being 8 mm is 3.42 minutes
4.1
|
Cell Pressure kPa |
Deviator Stress at Failure kPa |
Pore water pressure at failure kPa |
|
200 |
116 |
110 |
|
400 |
240 |
220 |
|
600 |
352 |
320 |
According to the above data set the graphical representation is shown in below.
|
Cell Pressure kPa |
Deviator Stress at Failure kPa |
Pore water pressure at failure kPa |
|
200 |
116 |
110 |
|
400 |
240 |
220 |
|
600 |
352 |
320 |
According to the above data set the graphical representation is shown in below.
4.2
|
Time in minutes |
Height of water in stand pipe mm |
Permeability |
|
0 |
1000 |
23.5 |
|
30 |
800 |
17.6 |
|
50 |
698 |
14.32 |
|
96 |
500 |
11.9 |
ii) Testing routines can be partitioned into two bunches, in-situ and research facility tests, depending on where the tests are performed. Run of the mill in-situ tests, performed without expelling specimens from their characteristic position, are geophysical tests, pie-zometer tests, extensive scale tests (e.g. in-situ shear test, bank test), tilt test, torque vane test, penetrometer or dilatometer tests. The standard research centre tests are immediate shear tests, unconfined what’s more limited pressure tests, determination of water content, thickness, versatility, mineral creation, permeability tests, (molecule) grain size investigation, dainty areas, swelling tests, and so forth. The traditional mechanical parameters for incline security examination are attachment, grating, dilatancy, shear firmness (solidifying and softening), (joint) compressive quality, joint harshness geometry (unpleasantness coefficient). Since the disappointment instruments are an exceptionally perplexing procedure and affected by the limit attributes, as specified in the recent past, it is regularly important to clear out institutionalized systems (Waterbeemd, Lennernäs and Artursson, 2003).
4.3
(i). The above test is used to determine the volume and the magnitude that decreases laterally and the other soil specimen that undergoes different changes when it undergoes different vertical pressures from the measured data that is stated above and can also be plotted against the curve that is plotted along with the data. These data are quite useful to determine the compression index and to understand the pre consolidation pressure that is found in the soil. The method is also obtained to determine the consolidation coefficient of the secondary soil that is compressed.
(ii). The saturated clay is under consolidation with a vertical pressure of 50 kPa
The state under which the pressure is exerted – Equilibrium
The pressure is now doubled at the equilibrium state
Hence the pore water pressure is – 12.5 Pa
The effective stress is 0.25 K when the pressure is doubled
50/2*0.5
12.5 Pa
50/12.5
0.25 k
References
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Brooks, S. and Brooks, M. (1941). The permeability of living cells. Berlin-Zehlendorf: Gebrüder Borntraeger.
Chamberlin, T. and Salisbury, R. (1904). Geology. New York: H. Holt and Co.
Comyn, J. (1985). Polymer permeability. London: Elsevier Applied Science Publishers.
Davson, H. and Danielli, J. (1970). The permeability of natural membranes. Darien, Conn.: Hafner Pub. Co.
Dixon, D. (1982). Geology. London: F. Watts.
Flanagan, A. (2001). Rocks. Minneapolis, Minn.: Compass Point Books.
Foster, R. (1966). Geology. Columbus, Ohio: C.E. Merrill Books.
Fullagar, P. and West, N. (2011). Geology. Arlington, Va.: National Science Teachers Association.
Gallant, R. (2001). Rocks. Tarrytown, NY: Benchmark Books.
Geikie, A. (1906). Geology. New York: J.A. Hill.
Lyell, C. and Rudwick, M. (1990). Principles of geology. Chicago: University of Chicago Press.
Pellant, C. and Pellant, H. (2009). Rocks. Pleasantville, NY: Gareth Stevens Pub.
Putnam, W. (1964). Geology. New York: Oxford University Press.
Reeves, J. (1973). Microbial permeability. Stroudsburg, Pa.: Dowden, Hutchinson & Ross.
Rhodes, F. (1972). Geology. New York: Golden Press.
Richardson, A. (2002). Rocks. Mankato, Minn.: Capstone Press.
Schoffeniels, E. (1967). Cellular aspects of membrane permeability. Oxford: Pergamon Press.
Stiles, W. (1924). Permeability. London: Wheldon & Wesley.
Troshin, A. (1966). Problems of cell permeability. Oxford, New York: Pergamon Press.
Walker, S. (2007). Rocks. Minneapolis: Lerner Publications.
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