 Earlier we have discussed different techniques of monitoring this r-diam construction, now this is a typical figure, it shows this how this instrumentation has been made, if you look at SM means strong motion acylogram, SM is here strong motion acylogram graph, so for monitoring particularly earthquake tremors and T H is your temperature sensor, if you look at here this is your temperature sensor at the along the surface of this slope, E X is your extension meter, E X is your extension meter identify movement of your dam basement and P Z is your piezometers, P Z is your piezometers that means how much is your pore water pressure developed this is for P Z, P C is your pressure cell if you look at this P C these are all typical red color this is P C, P C and P C pressure cell along the width of this dam along the length direction it has been placed, so that how much pressure transferred from this dam to this foundation soil you can measure it, S C is your settlement cell, S C is your settlement cell and W L is your water level meter, this is your W L W L is your water level meter, these are all your water level meters, then similar kind of also there is another also earth field dam, one is your this is your rock field dam, second is your earth field dam in this case of earth field dam in the core if this is this is the core, this is your core part in this core you have your S M strong muscle nacellograph and you have also your you have your also S P, S P and as well as your pressure meters all virtual instrumentation has been placed in case of earth field dam in the core, then key components for design of instrumentations that means put in redundancy, that means instrumentation will get lost due to construction activities and equipment will stop working, so protect equipment from the contractors that means put in safe area mark equipment and protected during installation and post installation, then last is your spend money, so can remotely monitor and collect data and consider data analysis cost also this part also you have to taken into consider, then these are all your references taken from this geotechnical instrumentation for monitoring field performance by Duncliffe 1993, Will St. Sons publications, then US curves of engineers instrumentation of embankment and dams and lifts, so these are all these are all your key references. Now next slide we are going to start a new topic that is your design of your reinforced soil structure, design of your reinforced soil structure, this is also part of application of soil mechanics, reinforced soil structure that means soil structure whatever is there it has been reinforced by outside material, now reinforced earth structures it is particularly this why there is a reinforcement required particularly earth structures to exhibit a certain level of stability against your earthquake events, that means how important of this structure and particularly that area what is the seismicity of that area concerned that will also taken into consideration, how have earth structures performed during recent large earthquake that means that is your new seismic design procedures, in new seismic design procedures number one is your what are the physical mechanism working behind this seismic performance of earth structures, what is the physical, what is the physics behind it, how to design earth structure against high seismic load, how to design, then a comparative study of different design methods approaches, recent case history in Japan in 1993 to 2007 of earthquake magnitude varying from 7.6 to 6.6, now earthquake cause severe damage to highway embankments and on reinforced retaining wall is typically shown in this following slides, in the slides particularly where the earthquake cause a severe damage that means highway embankment particularly embankment and on reinforced retaining structures, if you look at here gravity type of retaining wall it happened in 1995 earthquake, Nanbu earthquake this is your gravity retaining wall this retaining wall is gravity retaining wall the damage has been made it has been taken from that side, how this damage is there because of earthquake, now second is one is your cantilever retaining wall if you look at here this is your cantilever retaining wall this damage because of your 1995 Nanbu earthquake, then this cantilever retaining wall is without any deep foundation, second is your collapse of retaining wall along national highway route 17 and adjacent embankment along Jetsu line it is a 2004 Niigata earthquake, if you look at here it is in this particularly this area is your 56 kilometer and 56 sorry 56 meter it has been damaged because of your earthquake, then collapse of retaining wall along national highway route 17, if you look at here reconstructed during particularly using GRS retaining wall, GRS retaining wall how the construction has been going on this is the first one is your means collapse of your retaining wall and this is by using your reinforced earth how this construction process is going on, then again 2004 Niigata earthquake one is your tunnel there is a damage of the tunnel also it lies nearby the river that is Sinano river nearby this river this is your damage failure of unreinforced embankment this is one is your retaining wall I have shown now unreinforced embankment it has never been reinforced it is just unreinforced embankment it is in case of it is 2004 Niigata earthquake, if you look at here this embankment how this there is a failure of unreinforced embankment, then same also unreinforced embankment then collapse of retaining wall at Kashiwajiki city because of 2007 Niigata earthquake if you look at here collapse of the retaining wall here this collapse of your complete retaining wall these are all examples involved in large scale landslide if you look at here large scale landslides also occurs because of landslides there is a gravity type of retaining wall it also collapse that means past earthquakes have provided numerous case studies of unreinforced soil wall performance under dynamic loading that means if I go to the previous study it gives numerous case studies these are all your case studies in Japan where your unreinforced soil wall performance under this dynamic loading or earthquake loading numerous cases have been reported where reinforced soil structure performance in major earthquake both means we have case study of reinforced as well as unreinforced soil wall performance under earthquake loading reinforced soil structure have performed well in earthquakes there means these are all reported people who have reported reinforced soil structures how it has been it performed particularly during your earthquake reconstruction of failed wall using geosynthetic reinforcement if you look at here reconstruction of failed wall using geosynthetic reinforcement these are all your geosynthetic by using geosynthetic reinforcement geosynthetic reinforcement if you look at here geosynthetic reinforcement there is a reconstruction of this failed wall, then reconstruction using combination of geo-synthetic reinforced retaining structures wall and anchoring, if you look at here these are all your anchoring, anchoring has been made here this point if you look at this is a point of your anchor, anchoring has been made this is a point of your anchoring along with your geo-synthetic stabilization using also soil nail these are all called anchoring by means of soil nailing. Now whatever we have discussed these are all your case studies discussion means basically one is your unreinforced earth unreinforced retaining wall as well as embankment there are case studies how it fails during earthquake then how it has been constructed to sustain your earthquake loading then what is the fundamental mechanics soil has an inherently low tensile strength as you know soil has a low tensile strength, but a high compressive strength which is only limited by the ability of soil to resist applied shear stresses soil has high compressive strength which is only limited by the ability of the soil to resist applied shear stresses. An objective of incorporating soil reinforcement is to observe tensile loads is to observe tensile loads or shear stresses thereby reducing the loads which might otherwise cause the soil to fail in shear or by excess deformation that means reducing load once you are reducing load what will happen to that load this load cause the soil to fail excessive load cause the soil to fail in terms of by shear or by means of excess deformation. If I by means if I reduce this load coming to the soil by applying by giving your soil reinforcement then also it satisfy this design criteria there is some similarity to the principle of reinforced concrete as the reinforced mass may be consider a composite material that means soil with reinforced wall if this is a soil then if I say it is soil with reinforcement soil this these are all your reinforcement reinforcement soil with reinforcement that means there is some similarity to the principle of reinforced concrete as the reinforced mass may be consider as a composite material soil with your reinforcing material may be consider as a composite material with improved properties particularly in tension shear and over the soil or concrete alone. Now range of applications this reinforced earth wall range of application if you look at number of application is your there some applications I have just numeraries one is your wall and abutments this is your wall and abutments second is your reinforced slope there is simple slope and this slope has been reinforced by means of geotextile or other materials if you look at these are all your reinforced slope you can reinforce the slope by also soil nailing then if you look at here reinforced slope is your reinforcement you can provide at the base at the base of your slope you can provide the reinforcement this is your reinforcement has been provided at the base of the slope or you can provide reinforcement along the slope that means a firm layer with a thin soft layer you can provide also you can provide reinforcement in pile embankment if this is your pile then you can at the top you can provide your reinforcement then embankment you can provide then reinforcement over area prone to subsidence that means potential weak zones or voids if there is a potential weak zone or voids then above this you can also provide reinforcement types of reinforcement geometry three types of reinforcement geometry can be considered first is your linear unidirectional that means strips including smooth or ribbed steel strip or coated geosynthetic strips over a load carrying fiber over a load carrying fiber second is your composite unidirectional one is your linear unidirectional second is your composite unidirectional that means for example grids or bars or mat characterized by grid spacing greater than 150 mm greater than 150 mm this comes under composite unidirectional then is your planner bidirectional that means continuous sheets of geosynthetics welded wire mesh and woven wire mesh the mesh is characterized by element spacing of less than 150 mm this is your planner bidirectional second is your first we have discussed about the mechanics then second part we have discussed types of reinforcement geometry what are the different types of geometry first one is linear unidirectional second is your composite unidirectional third is your planner bidirectional then third part is your reinforcing material what are the different materials used as a reinforcement distinction can be made between the characteristics of metallic and nonmetallic reinforcement that means metallic and nonmetallic reinforcement can be characterized metallic reinforcement typically we are using mild steel the steel is usually galvanized or may be epoxy coated look at here may be epoxy coated the steel is usually galvanized or may be epoxy coated these are called metallic reinforcement nonmetallic reinforcement generally in case of nonmetallic reinforcement we provide polymeric materials that means consisting of polypropene polythene or polyester that means nonmetallic reinforcement generally polymeric materials it consists of polypropylene polythene or polyester reinforcing materials are two types one is your metallic reinforcement generally we use mild steel with coated with epoxy epoxy and second one is your nonmetallic reinforcement this is a polymeric material it may be polypropylene polyethylene or polyester there are two classes reinforcing extensibility the next phase is your fourth part is your reinforcing extensibility there are two classes of extensibility in extensible and second is your extensible in case of in extensible the deformation of the reinforcement at failure is much less than the deformability of soil in extensible in extensible means if I compare with the soil mass that means the deformation in the soil mass will be more and the deformation of the reinforcing material or reinforcement is less second one is your extensible if I look at the extensible the deformation of the reinforcement at failure is comparable or even greater than deformability of soil that means if I compare with the soil this if it is extensible reinforcement that means the then reinforcement may be equal to the your deformation of your soil or the deformation of reinforcement is even more than your deformation of soil that means two classes of extensibility one is in extensible means every reinforcing material is extensible but we classify into in extensible and extensible the moment we say in extensible that means if I compare with the soil the deformation in reinforcement will be less as compared to soil but in case of extensible the deformation the deformation in reinforcement will be same to your deformation of soil or may be more than your deformation of soil so that is why it is called extensible now shear failure of soil soil generally fails in shear if you look at the basic mechanics there is a retaining wall retaining wall has been constructed to retain the soil mass so that a structure or man made structure can be made above this retain soil if you look at how this shear failure occurs soil try to soil try to push this retaining wall if I if you look at the animation soil try to push this retaining wall that means if retaining wall is away that means it acts active earth pressure look at this there will be mobilization of shear resistance and there will be a failure surface it does not mean that entire part of the retaining mass of the soil will fail there will be a mobilized shear resistance and failure surface this is your failure surface that means inside this failure surface mobilization of shear resistance occur at failure shear stress along the failure surface reaches the shear strength at failure shear stress along the failure surface reaches your shear strength shear stress along the failure surface reaches the shear strength of your soil shear failure mechanism if you look at the shear failure mechanism failure surface soil grains slide over with each other along the failure surface that means if I say this is my failure surface that means soil grains slide over each other along the failure surface no crossing in this case no crossing of individual grains crossing means no breaking of individual grains that means soil will soil grains will slide over each other if there is one soil grain if there is another soil grain what will happen the soil grain dotted line is slide over the soil grain is slide over another soil grain that means there is no crossing of individual grains that means if this is a soil grain if there is another soil grain it should not be it should not be it should not be like a crossing or breaking of soil particles no so this is the sear failure mechanism if I take a along the failure surface I can take small element what are they are acted now if you look at here at failure sear stress along the failure surface tau at failure this is my failure surface at failure sear stress along the failure surface this is sear stress along the failure surface this is called tau reaches your sear strength of soil reaches your shear strength of soil that is called tau f shear strength of your soil that is called tau f. Mohr–Coulomb failure criteria that means in terms of total stress if I draw the Mohr–Coulomb failure criteria that means tau f is equal to C plus sigma tan phi C is your cohesion and tau f is your failure envelope and phi is your frictional angle tau f is your maximum shear stress this soil can take without failure tau f is your maximum shear stress soil can take without failure under normal stress of under normal stress of sigma then Mohr–Coulomb failure criterion in terms of effective stresses effective stress angle is your phi prime and effective cohesion is your C prime and sigma prime is equal to sigma minus u is equal to pore water pressure. So this is a Mohr–Coulomb diagram versus stress versus shear stress versus your normal stress tau f is the maximum shear stress the soil can take without failure under normal effective stress sigma prime look at here total stress and effective stress it is your sigma prime if I go to the total stress if I go to the total stress it is only sigma in that means in total stress there is no generation of pore water pressure or may be the pore water pressure expulsion means complete pore water pressure has been generated. So has been built up so in case of effective stresses this will be your sigma prime. So Mohr–Coulomb failure criterion shear strength consist of two component cohesive and frictional this part is your intercept cohesion and angle is your friction. So tau f is equal to C prime C prime sigma prime f tan phi m. So as I said C prime is your cohesion component and sigma prime f tan phi is your this part is your sigma phi tan phi m this is your sigma phi tan phi m this is your frictional component and this part is your C C prime this is your cohesion component. A quick note C and phi are measures of shear strength higher the value means higher the value of C and phi higher the shear strength higher your shear strength Mohr circle of stresses if this is your soil element if you take it soil element in the soil mass then this will your sigma 1 prime and sigma 3 prime and with this a theta then you are getting tau and sigma prime reserving forces in sigma and tau direction you will get it tau is equal to sigma 1 prime minus sigma 3 prime by 2 sin 2 theta then sigma prime is equal to sigma 1 prime plus sigma 3 prime by 2 plus sigma 1 prime minus sigma 3 prime by 2 into cos 2 theta then you will get also another equation in terms of tau square plus sigma prime into sigma 1 prime plus sigma 3 prime by 2 whole square is equal to sigma 1 prime minus sigma 3 prime by 2 whole square. Now, if I draw a more circle between sigma 1 prime and sigma 3 prime, if you look at this is my more circle and this is your center sigma 1 prime plus sigma 3 prime by 2 and this will your sigma 1 prime radius will your sigma 3 prime by 2 this is your radius. Now, intersection of principle planes is your pole as I said intersection of principle stress is your pole. So, what will happen if you look at your sigma 1 is your major principle stress sigma 3 is your minor. So, sigma 1 is acting in this direction intersection that means this is your sigma 1 and sigma 3 is acting sigma 3 is acting if you the plane is like this if from sigma 3 if I am drawing a plane like this this is your sigma 1 plane then intersection of principle planes that in this point this is your pole with respect to pole if you draw a line of your failure plane at an angle theta where it touches that is giving your sigma and tau at failure plane I will stop it here. So, next class I will go in details of more circle of stresses.