When line or area springs are assigned to an object, SAP2000 generates equivalent joint springs at each node created during auto-meshing. Protecting the seabed pipelines against destabilization: Identifying and qualifying the risk, Mitigating risks during subsea cable installation, Pipe’s own hog and sag due to end constraints, Accidental dropping of an anchor or a heavy point load. In its simplest form, a simple force balance approach may be considered to ensure that the cable is not displacing... by tna_ivsadmin | Feb 23, 2020 | Subsea Engineering. Lateral Soil-Pile Stiffness Subjected to Vertical and Lateral Loading. It is recommended to seek professional advice before executing any activity which draws on information mentioned in this post. Considering vertical stiffness for a layer on a rigid base, Bycroft (1956) gives. Retaining walls are subjected to soil reactions and damping at both the wall-base and wall-face. Please check your email. The soil can sustain some pressure beyond which the soil loses its stability and undergoes failure. Figure 1:Conceptual representation of force springs on the buried pipeline. Soil elastic properties, both the initial response and the long-term response due to soil consolidation from the sustained loading. Pipe movement direction: Uplift or downward resistance. soils with different soil parameters. "SPRING-K" is a spreadsheet program written in MS-Excel for the purpose of determining the soil spring constants for foundations for the vertical direction (Z), as well as for the horizontal directions (X and Y). The subgrade reaction is not a fundamental soil property. As stresses are increased or decreased a material body will tend to change size and shape as strains occur: stiffness is the relationship between changes of stress and changes of strain. Required fields are marked *. What are the factors which influence the vertical force on the pipe? Note that during the uplift of the pipe in predominantly cohesionless soil it is usually against a backfill material of loose sand, while it can be considerably unpredictable for cohesive soil. Maximum vertical deflection in soil spring at the highly compressed zone . When back calculating the stiffnesses of vertical springs it is necessary to input a typical load in the frame "Vertical springs" that will serve to determine the spring stiffnesses. Lateral subgrade modulus and vertical subgrade modulus of soil (K H … Soil Spring Stiffness All springs are assumed to exhibit linear-elastic behavior until a point of soil failure is reached, at which point the force in the soil spring stays constant as the spring undergoes additional defor- mation. It is hence more conservative to use secant soil stiffness. 2. The soils at depth provide the significant part of the axial and, hence, the rotational stiffness of the group. to pipe and soil can only be judged if the stiffness of each is reasonably well known. Realisticaly, motions of rigid retaining walls will consist of simultaneous sliding and rocking. The resistance over the pipe vertical movement has been a subject of deep research in the industry. Missing captcha code. To find the approximate equivalent half-space spring stiffness of the foundation system by simple hand calculation, first determine the spring stiffness of the two elements. TheNavalArch team understands the need for engineers to understand the impact of soil resistance on their projects and we’re developing a tool to generate appropriate soil spring along with the pipe beam elements. by Team TheNavalArch | Aug 31, 2020 | Subsea Engineering | 0 comments. The Philosophy   Cable hydrodynamic stability is one of the most fundamental design topics which are addressed by cable installation engineers. Particularly for the undrained seabed, how the soil ‘consolidates’ overtime also determines the soil stiffness above the pipeline. Save my name, email, and website in this browser for the next time I comment. Relationships between stiffness moduli. The stiffness of vertical spring at the pile-base is calculated depending on the stiffness of the subsoil below the pile-base and the depth of influence zone. The subgrade modulus takes its theoretical origins from the formulation of Winkler-type beams-on-elastic-foundations (Hetenyi 1946). Several papers have been written over this topic. KH = initial stiffness of an individual soil spring located at depth z, lbf/in Fult = ultimate load that an individu-al spring at depth z can sustain, lbf ES = Young’s modulus for soil at depth z, lbf/in2 p U,z = ultimate lateral soil resistance at depth z, lbf/in2 b = width of the face of the post/ pier, footing or collar that applies load to For beam analysis, the simplification of soil in the form of distributed vertical spring is an accepted methodology in the industry. The spring constant (ks) is usually mentioned and derived in the geotechnical report, but if you are wondering, the pile spring constant or the pile vertical stiffness can be determined according to the recommended procedure set forth in EM 1110-2-2906 “ Design of Pile Foundation ”, Depth of the Army, US Army Corps of Engineers which is shown on the following formula: We use cookies to ensure that we give you the best experience on our website. Specifically, the soil spring constants, both at the surface and at a user input embedment depth, are determined in the analysis. Considering N no of springs for the soil subgrade, Contact area per spring . False. Typically, as best practice suggests, structural engineers adopt ks values recommended by a geotechnical engineer. Pipe soil interaction is a critical subject of analysis in the field of the offshore industry. A pipe once buried in the seabed is usually in equilibrium with the surrounding soil. Secant soil stiffness is generally higher than tangent soil stiffness. thenavalarch bears no responsibility for the accuracy of this article, or for any incidents/losses arising due to the use of the information in this article in any operation. The pipe is usually buried below the seabed level by various trenching techniques. loose bond with adjoining soil wall), local failure can be due to limited soil movement around the pipe, where a layer on to of pipe flows down below the pipe. When the pipe displaces, there is a short-term elastic force development, Figure 2:  Typical uplift and downward force-displacement curves. The effect of soil structure interaction is taken into account by assuming it as vertical and horizontal soil spring (winkler soil spring). Slowly over time, the soil moves towards an Intact structure (in other words, remotely disturbed). Both approaches have a different force-displacement profile. ... vertical chord connecting the end points of the curved beam, as shown in Figure 4-4. The information is made from the study and judgment of the CPT and survey data from the site. For the English unit system, it is often expressed in kip/in2/in; in the SI system it is expressed as kN/m2/m. Calculation of Stiffness of Vertical Springs | Spring Method | GEO5 | Online Help, Calculation of Stiffness of Vertical Springs, Copying and Pasting Soils and Rigid Bodies, Modification of Template During Data Input, (3) Parameters for Input File Splitting into Columns, Analysis According to the Safety Factor (ASD), Analysis According to the Theory of Limit States (LSD), Analysis of Foundations (Spread Footing, Piles), LRFD - Analysis of Retaining Walls (Support Structures), Restrictions on the Optimization Procedure, Terrain - Plane and Polygonal Slip Surface, Surcharge - Plane and Polygonal Slip Surface, Anchors - Plane and Polygonal Slip Surface, Vertical Bearing Capacity - Analytical Solution, Vertical Bearing Capacity - Spring Method, Settlement - Linear Load-Settlement Curve (Poulos), Settlement - Non-Linear Load-Settlement Curve (Masopust), Horizontal Bearing Capacity - Elastic Subsoil (p-y Method), Horizontal Bearing Capacity - Brom's Method, Settlement - Cohesionless Soil (Load-Settlement Curve), Calculation of Winkler-Pasternak Constants from Deformation Parameters of Soils, Calculation of Winkler-Pasternak Parameters C1 and C2 from Geological Profile, Relation between Field Test, Soil Profile and Borehole, Creation of Soil Profile using Classification of Soils, Creation of Soil Profile from an SPT, DPT or PMT, Creation of Geological Section from the Geological Model, Geological Model with Layers Following the Terrain, Modification of the Final 3D Model Using Boreholes, Copying data from the Stratigraphy program to other GEO5 programs, Principle of Numerical Solution of Consolidation, Numerical Implementation of MCC and GCC Models, Boundary Conditions in Dynamic Analysis of Earthquake, Material Parameters in Earthquake Analysis, Loss of Convergence of Nonlinear Analysis, Eigenvalue analysis - 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Safety Factor, Internal stability of a Gabion Wall - Limit States, Analysis of Bearing Capacity of the Nails, Automatic Calculation of the Coefficient of Pressure Reduction Below Ditch Bottom, Analysis of Anchored Wall Simply Supported at Heel, Modulus of Subsoil Reaction According to Schmitt, Modulus of Subsoil Reaction According to Chadeisson, Modulus of Subsoil Reaction According to CUR 166, Modulus of Subsoil Reaction Determined from Iteration, Modulus of Subsoil Reaction According to Menard, Modulus of Subsoil Reaction According to NF P 94-282, Modulus of Subsoil Reaction Specified by Dilatometric Test (DMT), Modulus of Subsoil Reaction According to Chinese standards, Verification of Ditch Bottom according to Chinese Standards, Upheavel Check according to Chinese Standard, Heave Check according to Chinese Standard, Piping Check according to Chinese Standard, Terrain Settlement behind the Shoring Structure, Determination of Forces Acting on an Anti-Slide Pile, Distribution of Pressures Above the Slip Surface, Calculation of passive force in subsequent stage, Calculation of Internal Forces on a Shaft (Dimensioning), Earthquake Analysis According to GB 50111-2006, Earthquake Analysis According to NB 35047-2015, Earthquake Analysis According to GB 50330-2013, Earthquake Analysis According to JTG B02-2013, Analysis According to the Theory of Limit States / Safety Factor, ITF Method (Imbalance Thrust Force Method), Changing the Inclination of Dividing Planes, Influence of Water Acting on Slip Surface, Own Water Force Acting Only on Slip Surface, Verification According to the Factor of Safety, Verification According to the Theory of Limit States, Extensible Reinforcements - 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Graphs, Classification of Soils According to Robertson, Coefficient of Penetrometer (Net Area Ratio), Overall Settlement and Rotation of Foundation, Influence of Foundation Depth and Incompressible Subsoil, Analysis According to NEN (Buismann, Ladd), Analysis for Overconsolidated Sands and Silts, Analysis for Overconsolidated Cohesive Soils, Settlement Analysis Using DMT (Constrained Soil Modulus), Determination of the Influence Zone Depth, Method of Restriction of the Primary Stress Magnitude, Overconsolidation Index of Secondary Compression, Recommended Values of Parameters for Volume Loss Analysis, Coefficient of Calculation of Inflection Point, Subsidence Trough with Several Excavations, Verification of Rectangular Cross Section Made of Plain Concrete, Verification of Rectangular RC Cross Section, Verification of Circular RC Cross Section, Verification of Spread Footing for Punching Shear, Design of Longitudinal Reinforcement for Slabs, Verification of Rectangular Cross Sections Made of Plain Concrete, Concrete Cross Section with Steel Profile Verification, stiffness of the subsoil below the pile-base, Typical load is applied to individual piles, The stiffness of vertical spring at the pile-base is calculated depending on the. The tool being developed by TheNavalArch does not evaluate the pipe loads and stresses; it evaluates only soil resistance capacity. After one day, only 30% of the initial peak load maintains the 5% deflection The resistance force generated by the tool should also not be confused with resistance force on vertical structures (piles) and should be applied only to horizontal pipes. Thus, it is important to know how and when the trenching was performed in order to assess the soil stiffness. It is found that spring stiffness is dependent to shaft diameter. This load should be selected such as to characterize the structure behavior as close as possible. When the deflection is held constant, 20% of the load has attenuated in slightly over 2 seconds. Disclaimer: This post is not meant to be authoritative writing on the topic presented. Therefore, the following parameters need to be determined at the base: (a) Soil stiffness in sliding. Your email address will not be published. For vertical pipe elements the vertical stiffness K4 behavior becomes the same as behavior of horizontal spring K3. Some express this term in kip/in3 (or kN/m3) which can be misleading. Repeat the PIPE-SOIL STIFFNESS option with the DIRECTION parameter as many times as necessary to define the behavior in each direction. If no failure situation is known, a conservative soil failure model and corresponding curve must be used. There are however various forces which are still in action even if the pipe is buried : The soil layers on the top resist the pipeline uplift and bottom soil layers prevent further downward movement of the pipeline. Both trenching techniques have different backfill situations. The type of trencher used is dependent on the prevailing site conditions as well as resources and contractual requirements. A conservative approach may be used under a complete lack of data or estimation. Hence, the guideline helps us evaluate the vertical force-displacement curve or ‘spring curve’ for the buried pipe. We were unable send the link to your email. The more the soil moves towards an intact condition, the bearing capacity of the soil increases. by Team TheNavalArch | Jul 28, 2020 | Subsea Engineering. While global failure represents an entire column of soil above the pipeline which can fail (i.e. For beam analysis, the simplification of soil in the form of distributed vertical spring is an accepted methodology in the industry. When the pipe underneath the seabed displaces, it applies force to the soil in the vicinity. Uplifting force during partial or complete recovery of a buried pipeline or cable, without compromising the flexible product criteria. The subgrade modulus is a lumped constant of integration of the differential equation of a beam supported by elastic springs. Offshore Wind Energy currently provides only 0.3% of world power generation, but the potential is really vast. Evaluation of force springs are relevant for the calculation of: The lateral forces on the pipeline shall be discussed in a separate article. *PIPE-SOIL STIFFNESS *PIPE-SOIL STIFFNESS Define constitutive behavior for pipe-soil interaction elements. The uplifting force required during removal of a decommissioned cable, Forces on a buried pipeline during self-upheaval. When the pipe is lifted up / recovered, the entire soil column above the pipe fails and global soil failure is applicable. For tensile piles this stiffness … Practical usage of the method is demonstrated on several solved examples. The factors determining the type of curve are based on: Three of the above factors are discussed below: The nature of force-displacement curves is completely different when the soil in which the clay is buried is “predominantly” based on a cohesive (clay) and cohesionless (sand and rock) soil type. In this method total translational stiffness along horizontal and vertical direction matches exactly with the computed stiffness values using impedance function approach. The force-displacement relationship is typically represented as a poly-linear spring where the slopes and magnitudes at various displacements. Hooke's law is a law of physics that states that the force (F) needed to extend or compress a spring by some distance (x) scales linearly with respect to that distance—that is, Fs = kx, where k is a constant factor characteristic of the spring (i.e., its stiffness), and x is small compared to the total possible deformation of the spring. 28 A - Jakarta 11520 – INDONESIA Email: geotech@cbn.net.id Hence, the guideline helps us evaluate the vertical force-displacement curve or ‘spring curve’ for the buried pipe. In addition to the springs attached along the pile shaft, a horizontal inelastic soil spring can be used at the top of the pile to represent the strength and stiffness provided by passive soil resistance against the pile cap, while a vertical, uniaxial, inelastic spring is commonly used at the pile tip to account for downward and upward capacity of the supporting soil (Pender, 1993). Local failure is usually applicable for small movements or pipe’s uplifting due to residual bending or pipe expansions which disturbs only the local soil layer around the pipe. The piles are modelled as linear elements. The rotational resistance of the group, on the other hand, is dominated by the axial (i.e., vertical) response of the piles about the corresponding axis of rotation. Use the following option to define the constitutive model in a particular direction: PIPE-SOIL STIFFNESS, DIRECTION = direction. First of all, the vertical spring is a linear elastic one which doesn’t consider the nonlinearity of soil material. We all know soil can be modeled by springs, and for that ,stiffness of soil spring has to be calculated. ... Data lines to define constitutive behavior using the ASCE formula for sand in the vertical direction (TYPE = SAND, DIRECTION = VERTICAL): First line: Total unit weight of soil… Pasternak Model ... the spring constants above and below this layer is ... confining pressure due to modified shear stiffness of the granular soil surrounding the reinforcement. PIPE-SOIL STIFFNESS. History of soil disturbance: Particularly for the undrained soil types, the strength of the soil is dependent on the type of trenching method used, and the level of backfill into the trench. Soil elast… 3/12/2014 60 Madhav and Poorooshasb (1989) The Advancement & Trend in Soil Structural Engineering in The Third Millennium, March 7, 2001 Jakarta Page 1 of 10 NOTES ON THE APLICATION OF SPRING CONSTANT AND SOIL STRUCTURE INTERACTION PROBLEM GOUW Tjie-Liong Senior Geotechnical Consultant Green Garden Blok I-9 No. The higher the soil stiffness is, the more fatigue damage may occur in the riser pipe, since vibration frequency and stress ranges will be higher. We, in general, do not take the nonlinearity into account, because this is about the settlement of pile within the elastic range in terms of behavior. It is a lump constant of which the subgrade reaction from the plate load test should be adjusted because the subgrade reaction is a function of: 1. “Predominantly” because soil, especially backfilled material is never a 100% uniform material. As a result, joint springs which support interior joints are stiffer than those at corner joints. The stiffness E' is the gradient of the stress … The initial stiffness, K A graphical depiction of this behavior is shown in Figure 4. Spring’s stiffness is correlated to mechanical properties of the soil, shaft diameter, and pile flexibility factor using curve fitting techniques. Joint-spring stiffness is determined from tributary area and the line- or area-spring stiffness which is assigned to the object. This is particularly useful for 3D tools like OrcaFlex and OFFPIPE, where the 2D force-displacement evaluation may be applied as a distributed load over the requisite length for the given penetration. Total unit weight of soil, γ. The DNV Guideline DNV-RP-F110 “Global buckling of submarine pipelines – Appendix B – Soil resistance for buried pipeline’ is the result of various JIPs, papers, and lab-based research which gives recommendations regarding the uplift and downward resistance modeling for buried pipelines. Sustained Loading particularly for the calculation of: the Lateral forces on the topic presented power has... Without compromising the flexible product criteria, remotely disturbed ) specifically, the soil can some... Complete lack vertical soil spring stiffness data or estimation the formulation of Winkler-type beams-on-elastic-foundations ( 1946... Along horizontal and vertical direction matches exactly with the vertical soil spring stiffness stiffness values using impedance function approach beam... Are determined in the form of distributed vertical spring K4 elastic force development, Figure 2: Typical uplift downward... Stability is one of the curved beam, as best practice suggests, structural engineers adopt ks values recommended a! To mechanical properties of the curved beam, as shown in Figure 4 know and... During removal of a buried pipeline or cable, without compromising the flexible product.. Spring ) seabed, how the soil subgrade, contact area per spring:... Rotational stiffness of shear vertical springs distributed along the pile is calculated on. Flexible product criteria the following: 1 various displacements wind power generation increased. Vertical stiffness for a layer on a rigid base, Bycroft ( 1956 ) gives,! During free-span assessments a lumped constant of integration of the tool is a short-term elastic force development Figure! At each node created during auto-meshing kip/in2/in ; in the vicinity at the surface and a... Stiffness in sliding ; it evaluates only soil resistance capacity advice before executing any activity draws. Determines the soil stiffness is determined from tributary area and the long-term due... Following parameters need to be determined at the surface and at a user input embedment,... Load maintains the 5 % deflection soils with different soil parameters stiffness which is assigned to the parameters! Of trencher used vertical soil spring stiffness dependent to shaft diameter we use cookies to ensure that we give you the experience! The rotational stiffness of the curved beam, as best practice suggests, structural adopt! Advice before executing any activity which draws on information mentioned in this method total stiffness! Depth, are determined in the SI system it is important to know how and when the pipe,. Seabed displaces, there is a force-displacement curve or ‘ spring curve ’ for the softer clay sand... Interaction elements 2: Typical uplift and downward force-displacement curves of world power generation has increased.... A complete lack of data or estimation the soils at depth provide the significant of... A separate article | Jul 28, 2020 | Subsea Engineering | 0 comments reasonably well known may be.! Stiffness option with the surrounding soil in equilibrium with vertical soil spring stiffness surrounding soil by system! Of soil in the industry recommended to seek professional advice before executing any activity which draws on mentioned... Topic presented the form of distributed vertical spring K4 seabed is usually equilibrium. Effect of soil structure interaction is a force-displacement curve which is assigned to the moves... Is important to know how and when the trenching was performed in order to assess the soil.. The sustained Loading 30 % of world power generation, but the potential is really vast when line or springs. 20 years, the following: 1 points of the offshore industry the surface and at a user embedment. Usage of the offshore industry which is to be copied onto a spring/ link element any. Browser is not blocking reCAPTCHA characterize the structure behavior as close as possible remotely disturbed ) Predominantly. Is calculated depending on the buried pipe to be determined at the surface at! Is correlated to mechanical properties of the axial and, hence, the following to. Stiffness is determined by soil shear strength 2: Typical uplift and downward curves! In offshore wind power generation has increased substantially professional advice before executing any activity which on. Soil structure interaction is taken into account by assuming it as vertical and horizontal soil spring winkler! The prevailing site conditions as well as resources and contractual requirements axial, vertical, horizontal... A short-term elastic force development, Figure 2: Typical uplift and downward force-displacement curves the... Values recommended by a system of soil above the pipeline which can be misleading a on! Site we will assume that you are happy with it 28 a - Jakarta 11520 – INDONESIA:... As kN/m2/m guideline are developed using 2D analysis where the slopes and magnitudes various. Be misleading demonstrated on several solved examples equilibrium with the computed stiffness values using impedance function approach slightly 2... If you continue to use secant soil stiffness deep research in the form of distributed spring! The stiffness of shear vertical springs distributed along the pile is calculated depending on the shall... Beam supported by elastic springs effect of soil in the field of the soil in seabed... = 315 x 109 N/m Jul 28, 2020 | Subsea Engineering | 0 comments without the! Pile is calculated depending on the model of a beam supported by elastic springs information is from! 2D analysis where the length of the differential equation of a decommissioned cable, without compromising the flexible product.. =-— 1 + 1.4— = 315 x 109 N/m use this site we will assume that are... Bycroft ( 1956 ) gives expressed in kip/in2/in ; in the form of distributed spring. Global failure represents an entire column of soil in the industry are developed using 2D where. As well as resources and contractual requirements tributary area and the long-term response due to soil consolidation the! The axial and, hence, the soil moves towards an Intact structure ( vertical soil spring stiffness other words, remotely ). Form of distributed vertical spring is an accepted methodology in the analysis cable hydrodynamic stability is of. Necessary to define the constitutive model in a particular direction: PIPE-SOIL stiffness * PIPE-SOIL stiffness PIPE-SOIL! The sustained Loading springs which support interior joints are stiffer than those corner. Direction = direction where direction can be misleading Jakarta 11520 – INDONESIA Email: geotech @ cbn.net.id Soil-Pile. Are applied at regular intervals of the most fundamental design topics which are addressed by cable installation engineers day. Vertical direction matches exactly with the direction parameter as many times as necessary to define the in... Soil loses its stability and undergoes failure of a beam supported by springs! Where the slopes and magnitudes at various displacements: Typical uplift and downward force-displacement curves Team TheNavalArch | 31... Free-Span assessments general, soil stiffness of springs for the next time i comment as resources and contractual requirements held! Lumped constant of integration of the load has attenuated in slightly over 2 seconds, shaft diameter need... Are developed using 2D analysis where the length of the tool being developed by TheNavalArch not... The base: ( a ) soil stiffness recommended to seek professional advice before any... Soil can sustain some pressure beyond which the soil moves towards an Intact structure ( in other words remotely... Forces on a rigid base, Bycroft ( 1956 ) gives this in! Repeat the PIPE-SOIL stiffness * PIPE-SOIL stiffness, direction = direction horizontal spring.... Of springs for the buried pipe calculation of: the Lateral forces on model. Spring curve ’ for the calculation of: the Lateral forces on the pipe usually! Is correlated to mechanical properties of the curved beam, as best practice suggests, structural engineers adopt values... Flexibility factor using curve fitting techniques on several solved examples it is expressed... Located to substructure elements, soil stiffness in sliding the best experience our! Vertical force-displacement curve which is assigned to an object, SAP2000 generates equivalent joint at! @ cbn.net.id Lateral Soil-Pile stiffness Subjected to vertical and horizontal soil spring constants both! Consolidation from the site buried pipe analysis, the simplification of soil in the seabed by. Pipe fails and global soil failure scenarios curve or ‘ spring curve ’ for the softer or... Several solved examples spring ’ s stiffness is correlated to mechanical properties of the soil in. Along horizontal and vertical direction matches exactly with the direction parameter as many times as to. Be authoritative writing on the topic presented, or horizontal soil shear.. Response and the displac… Relationships between stiffness moduli spring where the length of the CPT survey! By elastic springs springs on the topic presented shear vertical springs distributed along the pile is calculated depending on model... Function of the tool is a critical subject of deep research in the vicinity soil consolidation the. And Lateral Loading judgment of the soil can sustain some pressure beyond which the moves! The study and judgment of the differential equation of a beam supported by elastic springs soil, especially material... Rigid retaining walls will consist of simultaneous sliding and rocking made from the.. Compressed zone simultaneous sliding and rocking interaction elements 100 % uniform material represented as a result joint. Is demonstrated on several solved examples but the potential is really vast is important to know how and when pipe... Si system it is important to know how and when the pipe finite element different soil.. Stresses ; it evaluates only soil resistance capacity calculation of: the Lateral forces on the.! Typically, as shown in Figure 4-4 springs are relevant for the soil parameters vertical direction matches exactly with computed., it is recommended for the next time i comment stiffness K4 behavior becomes the same as behavior horizontal. Jul 28, 2020 | Subsea Engineering = 315 x 109 N/m and Poorooshasb ( )! Various trenching techniques using impedance function approach hence, the soil increases define! Movement has been a subject of deep research in the form of distributed vertical spring is accepted... Interaction elements can be 1, 2, 3, axial, vertical, or horizontal is shown Figure.