Simulation-based Analysis of Surface Jobsite Logistics in Mechanized Tunneling

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1 Simulatio-based Aalysis of Surface Jobsite Logistics i Mechaized Tuelig Markus Scheffer 1,a, Tobias Rahm 1,b ad Markus Köig 1,c 1 Chair of Computig i Egieerig, Faculty of Civil ad Evirometal Egieerig, Ruhr-Uiversität Bochum, Uiversitätsstr. 150, Bochum, Germay a PH ; markus.scheffer@ruhr-ui-bochum.de b PH ; tobias.rahm@ruhr-ui-bochum.de c PH ; koeig@if.bi.rub.de ABSTRACT The costructio procedure i mechaized tuelig is affected by a complex iteractio of logistic processes. Due to restrictive factors, like limited space o costructio sites, a just i time delivery of material is required for productio purposes. Slight differeces of the productio rate of a Tuel Borig Machie (TBM) have huge impacts at the logistical chai. Therefore, the logistic maagemet is oe of the key factors resposible for the success ad profitability of tuelig projects. I this paper, a discrete evet simulatio model is preseted that supports tuelig experts i the plaig process ad that ca be applied i the costructio phase as a tool for decisio aalysis. Sice each TBM is uique, it has a uique demad for logistic solutios. Therefore, the simulatio model is implemeted i a modular maer such that it ca be applied for a vast umber of differet projects i mechaized tuelig. The properties of the costructio site ad the TBM are freely cofigurable. To show the fuctioality of the model a fictive demostratio model was coducted. It illustrates the ifluece of differet logistic processes o the productio rate of a TBM as well as the complex iteractios of sigle logistic processes i the supply chai of a costructio site. INTRODUCTION I mechaized tuelig each TBM features special equipmet accordig to the geotechical formatios. Additioally the boudary coditios of each project are also uique or ca chage cotiuously durig the costructio phase. Today the plaig of logistic cocepts for tuelig projects is based o past experiece of the project egieers o ucertai performace forecasts. However, the productivity of the logistical chai must match the excavatio rate to esure productivity durig the project phase. As a example a icrease i excavatio rate leads to a icreased demad of material for the TBM ad therefore ad provides additioal requiremets for the costructio equipmet o the jobsite.

2 Equally, chages i the jobsite setup or disturbaces of costructio equipmet ca reduce the productivity of the TBM. For these reasos a efficiet plaig of the logistic chai ad the eeded costructio equipmet for tuelig projects iscomplex ad hard to maage with stadard plaig tools. STATE OF THE ART Due to the various sources of ucertaity regardig the geotechical formatios, geomechaical behavior or groud water table, mechaized tuelig represets oe of the most difficult ad complex areas i egieerig. The lack of iformatio ad ucertaities affects the project plaig, project schedules ad project costs. To hadle these ucertaities is oe of the most challegig tasks for the project maagemet of tuelig projects. I the past two decades, the TBM techic was successfully established i the whole spectrum of soils, i hard rock ad all kids of geotechical boudary coditios (Maidl et al. 2012). A commo way to aalyze differet aspects of TMB ad tuelig projects i the plaig phase or durig the costructio phase is the use of simulatio models. To estimate the performace of TBM M. Alvarez Grima et al. (2000) ad Pham et al. (2011) combie fuzzy logic (FL) ad artificial eural etworks (ANN) methods. With the use of real TBM project data for traiig the ANN the authors make a forecast for the peetratio rate ad advacemet speed of TBM s. Rock mass properties, geometry ad machie characteristics are used as the mai factors ifluecig the peetratio rate. The limitatio of this approach with respect to the project plaig is the disregard of the rigbuildig process ad the whole supply chai maagemet as elemetary aspects for mechaized tuelig projects. Additioally the jobsite setup ad the layout of temporary facilities (TF) like warehouse, maiteace shops ore storage spaces ca have large impacts o the project performace (Zhou et al. 2009). Cheg ud O Coor (1996) ad Sebt et al. (2008) developed GIS techology based approaches to estimate the optimal layout of temporary facilities for costructio jobsites. All of these approaches are usig the geometry of the TF, facility relatioships ad the existig amout of space for the site layout plaig. Complete project plaig ad costructio process simulatio is ot cosidered withi these purely geometry based methods. To forecast ad aalyze the efficiecy, of the TBM ad of the whole tuelig project, combiatio of differet simulatio strategies with respect to the special characteristics of the TBM techique is required. Rahm et al. (2012) provide a multi method simulatio model combiig a discrete evet process simulatio (DES) of the TBM ad a system dyamic (SD) material flow model. The performace predictio of the project is idetified cosiderig techical disturbaces but with disregard to the jobsite layout ad the ifluece of the logistic chais. Some holistic simulatio models ad sesitivity aalysis of tuelig costructio projects were developed by AbouRizk et al. (1999) ad Ebrahimy et al. (2011). The mai disadvatage of these holistic approaches is the project-specificity of the simulatio template. Each TBM i mechaized tuelig is uique ad therefore eeds special uique templates.

3 All approaches for simulatio models i mechaized tuelig focuses o differet aspects of the tuelig project but disregard the couplig effects of the TBM advace process, jobsite layout plaig ad supply chai maagemet. Furthermore a free cofigurable simulatio template allows aalyzig the effects of the logistic processes o the project process for a large umber of tuelig projects. OBJECTIVE Logistic processes ad the uderstadig of the supply chai maagemet is a key factor for the success of tuelig costructio projects. To aalyze the iflueces of the logistic chai o the project performace a discrete evet logistic simulatio model ca be used. All ifluetial factors of the logistic chai o the advace rate of the TBM, ad therefore o the project performace, have to be idetified ad cosidered. The couplig of a process orietated simulatio model, the jobsite layout ad the logistic chai allows a accurate forecast of required resources ad materials o the jobsite. These iformatios ca be used to achieve a just i time delivery without losses of performace due to missig material. Additioally, the efficiecy of the costructio equipmet ca be improved. CONCEPT I order to implemet a logistic simulatio model, first step is to idetify ad abstract the elemets of a tuelig jobsite ifluecig the performace of the TBM from logistical poit of view. I this paper, the System Modellig Laguage (SysML (Object Maagemet Group 2010)) is used to describe the implemeted elemets ad their coupligs. Fehler! Verweisquelle kote icht gefude werde. shows the block defiitio diagram (bdd) of the model for the simulatio-based aalysis of surface jobsite logistics i mechaized tuelig. I the bdd the basic structure, hierarchy ad relatioships betwee the show elemets are described. Because of the combiatio of productio ad logistic processes i oe simulatio model, it is ecessary to defie boudary coditios ad a objective fuctio. I this case the TBM is modeled as the elemet that requests the overall requiremets ad defies the performace of the jobsite. The costructio time of the project is chose as objective fuctio which has to be miimized. Model boudaries are choose accordig to jobsite geometry ad defied storage places. The Costructio Equipmet elemets (Figure 1) ca be uderstood as the coectio betwee the exteral ad the iteral jobsite logistic system. All elemets show i Figure 1 are predefied ad freely cofigurable i techical specificatios. This cocept offers a easy ad efficiet way chage simulatio setup, to compare differet scearios ad therefore to aalyze the logistic processes ad to idetify bottleecks or spare productio capacity.

4 bdd Tuel Costructio Site Surface Jobsite Tuel Shaft TBM Storage Cargo Costructio Equipmet Segmet Storage Muck Pit Mortar Storage Job Shop Segmet Mortar Rails Pipes Barrel Grease Crae Trucks Tuelvehikel Excavator Figure 1. bdd-diagram for tuel costructio site i logistic simulatios I mechaized tuelig the costructio process does ot take place o the jobsite. All materials eeded for the costructio of oe segmet rig must be trasported from storage places ito the shaft ad through the excavated tuel sectios to the TBM. These logistic processes are coordiated by a itegrated, priority-based order system. Oce the TBM cosumed material, e.g. the segmets durig the rigbuildig process, a delivery order will be geerated. If the segmet storage cotais eough segmets, the order is set to the costructio equipmet e.g. surface crae to trasport the segmets ito the shaft. A importat goal is to prevet dowtime of the TBM. Therefore all available equipmet ad material is primary used to support the excavatio process. The exteral logistic, e.g. segmet delivery, has a lower priority ad is executed afterwards. IMPLEMENTATION Durig the last years the discrete-evet simulatio is a commo way to aalyze logistic chais or differet logistic scearios. The formal model is implemeted i the simulatio software AyLogic AyLogic is usig the statecharts paradigm for the simulatio of discrete evets. The described blocks of the SysML bdd are represeted by Active Object Classes (AOC) i the simulatio software.

5 Each block is implemeted i a ow AOC with freely cofigurable properties. Fehler! Verweisquelle kote icht gefude werde. shows the drag ad drop approach to create the simulatio model usig the preseted elemets. With this method it is possible to create a uique simulatio just by selectig the required elemets ad brig them together i the developmet eviromet. Secod step is to modify the elemet properties e.g. the techical specificatios of the TBM or the maximum load of the crae. Figure 2. Cofiguratio of the simulatio model Afterwards CAD drawigs are used to defie the jobsite layout. All embedded elemets are automatically idetified ad will be used for the simulatio of the logistic chai. The layout of the jobsite ad the available storage spaces costitute the maximum stock of material o the jobsite. Process times are calculated with respect to the elemet properties ad the jobsite layout. The implemeted approach is very versatile i use. All elemet iteractios ad depedecies are predefied. With the use of the SysML model ad the show hierarchy the extesio of the model is possible with miimum effort. Example To show the beefit of the simulatio for the plaig process of the logistic ad the success of tuelig projects, a demostratio model is preseted. The model shows the iflueces of three differet logistic scearios o the TBM performace ad thus the project duratio of a fictitious jobsite. A tuel of meter legth has to be drive with the use of a TBM (Ø 8.0 meter). The jobsite layout allows storig 32 rigs of segmets (7+1) ad 2400m³ of excavatio material ( 32 advaces). Table 1 shows the importat time parameter of the logistic simulatio. Three differet soil layers are visible with differet excavatio speed represeted by a trucated ormal distributio. The ormal distributios are stretched by the value of σ ad trucated to fit i [mi, max]. I all sectios the time to build oe rig is adopted with a ormal distributio with mea value 15 miutes. Maiteace work o the TBM is plaed every 200 rigs with a duratio of 24 hours.

6 Table 1. Time parameter setup of the simulatio model Parameter Value [mi] µ σ mi max Advacemet rate Sectio m Sectio m Sectio m Rigbuildig Durig the plaig phase three differet alterative jobsite setup alteratives were idetified. I the first setup oe gatry crae type 1 is istalled to trasport the segmets delivered by trucks to the segmet storage ad from the segmet storage ito the shaft. It is assumed that there will be o disturbace due to the exteral delivery logistic. As log as there is free storage space, there are trucks deliverig segmets to the jobsite. That meas that TBM dowtime is caused by problems i the jobsite logistic. a) b) c) Figure 3. Simulatio scearios The secod sceario simulates the use of a more powerful gatry crae type 2. This crae features twice the maximum load as type 1. That allows the crae to lift up two segmets at the same time. I the last setup two craes of type 1 are istalled. That leads to a split of the logistic processes. Oe crae executes the uloadig of the delivery trucks while the secod oe is resposible for segmet trasportatio ito the shaft. Both craes ca lift oe segmet at a time. The aim of the simulatio is to aalyze the performace of the jobsite setups ad idetify the best oe with respect to their ability to support the aticipated TBM performace ad thus reduce the project duratio. The simulatios experimets are executed with fixed seeds to get reproducible results. The results of the simulatio rus are show i Figure 4. Without ay disturbaces due to the jobsite logistic, the project duratio of this setup is the summatio of the maiteace, advace ad rigbuild time. I the first sceario severe dowtimes of the TBM occur ad the simulated project duratio icreases

7 from 357 days to 803 days. To aalyze the reasos for these dowtimes the utilizatio of the gatry crae is show. It is obvious that the gatry crae operates at full capacity. Therefore the bottleeck of the logistic system is detected ad the setup of the costructio equipmet must be chaged. Figure 4(a) ad (b) illustrate the compariso of the two alterative setups. The use of a gatry crae type 2 reduces the project duratio by over 468 days (42%). But the utilizatio of the crae is still close to the limit. Especially the compariso of the gatry crae s iactive time ad the maiteace duratios of the TBM idicate that this setup is still ot sufficiet for the performace of the TBM. A more efficiet alterative is the use of two gatry crae type 1 ad the divisio of the logistic workflow. The dowtime is reduced to 29 days. Compared to the iitial setup this etails a reductio of above 93%. The project duratio ca be shorteed to 386 days. I order to further reduce the dowtime of the project, icreasig the segmet storage might provide a possible strategy. However, this is ot coducted i this publicatio. a) b) c) Figure 4. Project duratio ad crae utilizatio CONCLUSION AND OUTLOOK I this paper a iovative ad freely cofigurable cocept for surface jobsite logistic simulatios i mechaized tuelig is preseted. The beefit of the described approach is that there are two aalyses possible. O the oe had, the simulatio ca be used to idetify the parts of the logistic system resposible for performace losses resultig i a icreased project duratio. Each elemet of the costructio equipmet ca be evaluated by aalyzig their utilizatio. Secodly, after idetificatio of the iefficiet elemets, additioal ressources ca be added or alteratives ca be defied. This supported by the flexible cofigurability of each elemet. Thus the best setup for the give jobsite boudary coditios ca be idetified.

8 Due to the formulatio of the model i SysML ad the modular implemetatio the extesio of the simulatio model is ot limited. I the ext step the preseted logistic simulatio will be coupled to other existig simulatio models i mechaized tuelig. This approach will exted the simulatio with a system dyamic material flow model ad a disturbace aalysis of the TBM. The show simulatio model ca be executed as a Mote Carlo experimet ad therefore aalyze the sesitivity of differet logistic processes o the performace of the TBM. Further research must address the sesitivity of logistical bottleecks ad validate the show approach with real data of tuelig projects. REFERENCES AbouRizk, S. M.; Ruwapura, J. Y.; Er, K. C.; Ferado, S. (1999): Special purpose simulatio template for utility tuel costructio. I: Simulatio Coferece Proceedigs, 1999 Witer, Bd. 2, S vol.2. Cheg, M.; O Coor, J. (1996): ArcSite: Ehaced GIS for Costructio Site Layout. I: Joural of Costructio Egieerig ad Maagemet 122 (4), S DOI: /(ASCE) (1996)122:4(329). Ebrahimy, Yasser; AbouRizk, Simaa M.; Ferado, Siri; Mohamed, Yasser (2011): Simulatio modelig ad sesitivity aalysis of a tuelig costructio project s supply chai. I: Egieerig, Costructio ad Architectural Maagemet 18 (5), S M. Alvarez Grima; P.A. Bruies; P.N.W. Verhoef (2000): Modelig tuel borig machie performace by euro-fuzzy methods. I: Tuellig ad Udergroud Space Techology 15 (3), S Maidl, Berhard; Herrekecht, Marti; Maidl, Ulrich; Wehrmeyer, Gerhard (2012): Mechaised shield tuellig. 2. Aufl. Berli: Erst W. + Soh Verlag. Object Maagemet Group (2010): OMG Systems Modelig Laguage (OMG SysML ): Versio 1.2. Pham, H. V.; Yuji, F.; Kamei, K. (2011): Hybrid Artificial Neural Networks for TBM performace predictio i complex udergroud coditios. I: System Itegratio (SII), 2011 IEEE/SICE Iteratioal Symposium o, S Rahm, T.; Sadri, K.; Koch, C.; Thewes, M.; Koig, M. (2012): Advacemet simulatio of tuel borig machies. I: Simulatio Coferece (WSC), Proceedigs of the 2012 Witer, S Sebt, M. H.; Parvaresh Kara, E.; Delavar, M. R.; AWT_TAG (2008): Potetial Applicatio of GIS to Layout of Costructio Temporary Facilitie. I: Iteratioal Joural of Civil Egieerig 6. Zhou, F.; AbouRizk, S. M.; AL-Battaieh, H. (2009): Optimisatio of costructio site layout usig a hybrid simulatio-based system. I: Simulatio Modellig Practice ad Theory 17 (2), S