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**Industry**

**Oilfield Places**

**Technology**

The increasing demand for continuous risk assessment in civil engineering has led to the development of seismic exploration systems for tunnel excavation. On such system is the Integrated Seismic Imaging System (ISIS) that has been developed at the GFZ. In contrast to comparable systems, ISIS can be used on any type of tunnel excavation in soft rock as well as in hard rock tunneling. Based on ISIS, the OnSITE project focuses on new hardware for integrated measurements during underground excavation, modelling and processing of data measured under these specific circumstances and the interpretation of the seismic result with various data sets (geological mapping, TBM parameters). The hardware development has generated wireless data logger for underground work and new seismic sources for the exploration of the seismic results was combined with TBM parameters and geological mapping showing remarkably good results.

- Modeling and processing of data measured with ISIS for a better understanding of the seismic wave field
- Development of hardware for seismic acquisition in underground construction.
- Interpretation of seismic data collected with ISIS using a multivariate data set.

ISRM-SINOROCK-2009-048

ISRM International Symposium on Rock Mechanics - SINOROCK 2009

SPE Disciplines: Reservoir Description and Dynamics > Reservoir Characterization > Seismic processing and interpretation (1.00)

Christiansson, R. (Swedish Nuclear Fuel and Waste Management Co) | Ericsson, L.O. (Department of Civil and Environmental Engineering, Chalmers University of Technology) | Gustafson, G. (Department of Civil and Environmental Engineering, Chalmers University of Technology)

An in-depth conceptual understanding of the hydraulic conditions nearby and in the surroundings of an underground facility is a multi-disciplinary task. The Ã„spÃ¶ Hard Rock Laboratory (HRL), Sweden provides an opportunity to explore the parameters of importance for understanding the development and characteristics of the Excavation Damaged Zone (EDZ).

Detailed characterisation and modelling of the geometry of the blast induced fractures in crystalline rock that forms the flowing system indicate weakly connected flow paths. However, there may be special hydraulic effects in relation to the open boundary of the tunnel wall. Even though the focus of a repository for nuclear waste deals with long term saturated flow in the post-closure phase, there is a need to understand the physical and chemical evolution in the bedrock in a broad perspective. The hydraulic conditions in the vicinity of the tunnel are dependent on the excavation method, as well as the construction materials used during tunneling. Recently developed methodologies for designing grouting schemes regarding hydraulic testing, determination of fracture transmissivities and fracture connectivity provide guidance on how to model the hydraulic aspects of the EDZ.

The major horizontal stress is in the order of 28 – 30 MPa at the 450-m level, trending NW – SE, sub-parallel to the NW joint set and, consequently, perpendicular to the two tunnels. The minor horizontal stress and the vertical stress are both close to the gravitational stress, 12 – 13 MPa. (Andersson, 2007).

The mean uniaxial strength of the diorite is 211 MPa and the Young’s modulus is in the order of 76 GPa.

(Figure in full paper)

ISRM-SINOROCK-2009-177

ISRM International Symposium on Rock Mechanics - SINOROCK 2009

SPE Disciplines:

Presently the survey of absolute displacements of targets fixed at the tunnel wall is the state of the art in performance monitoring of tunnels. Monitoring data are used to assess the stabilization process of the tunnel, more recently also for the short term prediction of the ground conditions ahead of the face.

The displacements do not substantially vary in rock mass conditions with nearly constant properties and influencing factors. On the other hand, changes in the rock mass structure or properties result in changes in the displacement characteristics.

For nearly constant conditions, the displacement trends show minor fluctuations within a certain normal range, due to minor variations in the rock mass properties. Deviations from this range are clear indicators for changing conditions ahead of the face or outside of the tunnel. To identify such trend deviations the normal range of the trend lines becomes crucial. Geostatistical methods allow an automatic identification of trends along the tunnel. Using data from completed tunnel projects a “reference trend table” can be established. By comparing actual observed trend characteristics to this reference table changing ground conditions ahead of the face can be identified and hence, the change in the displacement characteristics and magnitudes can be predicted.

During construction the measurement results contain all influences of the ground structure, stresses, and interaction between ground and support. The previously established characteristic behaviors for certain conditions are compared to the monitoring results. In case of agreement it can be established that the observed behavior is “normal”. Deviations from the expected behavior can have various reasons. One may be that the behavior during design was not assessed correctly. In this case, a refinement of the model is required. Another reason for behavior deviating from the expected can be a change in the ground conditions ahead of the face. It is meanwhile well known that trends of displacement vector orientations can be used to predict changing ground conditions ahead of the face (Schubert & Budil 1995, Steindorfer 1997, Jeon et al. 2005).

ISRM-SINOROCK-2009-144

ISRM International Symposium on Rock Mechanics - SINOROCK 2009

Oilfield Places: North America > United States > Alaska > North Slope > Western North Slope > Alpine Oil Field (0.97)

SPE Disciplines:

Song, W.K. (Korea Institute of Geoscience and Mineral Resources) | Jung, Y.B. (Korea Institute of Geoscience and Mineral Resources) | Sunwoo, C. (Korea Institute of Geoscience and Mineral Resources) | Lee, B.Y. (Korea Institute of Geoscience and Mineral Resources)

To simplify SMR estimation GSI values were substituted for RMR parameters except rock strength and ground water condition. This new method is named KSMR(Korean Slope Mass Rating). The validation of this method was checked out through comparing the hazard ratings estimated using SMR method. In spite of a high correlation between two methods, SMR estimation show a little difference compared to the real stability of slopes. This is because slope height is not reflected in SMR. For the adjustment of this factor, the hazard classes estimated by KSMR and the subjective observation of experts were compared. The optimal adjustment rating for slope height was induced using a genetic algorithm. When using the adjusted KSMR, the final hazard classes came to a little more close to those obtained from the experts.

In Korea, the stability assessment method for the individual slopes through physical stability analysis has been applied. Song and Lee (2005) have performed stability assessment and research on ways to prevent rock failure for several railway open-cut slopes. Lee (2003) has prepared a stability determination table with a somewhat low coefficient of correlation.

In this study, a new method based on SMR has been developed to allow the site engineer to perform the assessment for rock slopes comprehensively with simplicity and reliability. This method named KSMR (Korean Slope Mass Rating) was referred to three experts for its feasibility verification.

In addition, a statistical evaluation for the adjustment of KSMR related to the slope height was carried out under the support of the experts.

GSI has been used to determine the value based on the range by selecting the sphere diagrammatically considering the structure and the surface conditions of the rock mass. However, in this case, if the original data are not conserved, it is difficult to figure out the selected sphere on which the corresponding GSI value was determined. For example, two different geological conditions such as very blocky rock with very good surface and massive rock with good surface can give the same GSI value.

The new method suggested in this study gives the average GSI value by selecting one of 6 grades for rock structure and one of 5 grades for surface condition, respectively. In order to obtain this correlation formula, optimized method was applied. Additionally, the maximum value of the modified GSI was adjusted to 70 which is the maximum value of RMR excluding rock strength and underground water conditions.

2.2 KSMR sheet

The assessment method of KSMR applying the modified GSI, rock base strength, underground water condition.

ISRM-SINOROCK-2009-025

ISRM International Symposium on Rock Mechanics - SINOROCK 2009

SPE Disciplines:

A new commuter train tunnel under Stockholm City is currently being designed. The main portion of the tunnel is to be constructed in crystalline bedrock using drill and blast methods together with conventional support elements in the form of shotcrete and rock bolts. Standard rock reinforcement classes, which are dependent on excavation span and rock mass quality, will be used to determine the required reinforcement for the majority of the tunnel system. The rock mass was divided into four rock classes (A-D) and the tunnel into four categories for excavation span. Potential failure mechanisms were identified for the different combinations of rock mass quality and excavation span and appropriate analysis methods were selected for the various combinations. For all analyses, a range of material properties and initial stress conditions were used to account for natural variation in the input data. Preliminary standard reinforcement classes were determined by evaluating the results from all analyses and using the application of engineering judgment. Numerical analyses, including the preliminary reinforcement were then carried out for chosen combinations of rock types and tunnel sizes.

This paper presents the methodology used to design the standard rock reinforcement classes for the City Line. The standard reinforcement classes are to be used for the majority of the planned tunnel system. Standard reinforcement classes will not be used in areas with low rock cover (less than half of the tunnel width), crossing points with existing tunnels, tunnels with a span greater than 20 m, and poor rock quality.

The City Line is, with respect to civil works, divided into 5 different contracts: a) Odenplan/Vasa, including single- and double-track train tunnels, service tunnels and an underground station, b) Norrmalm, including single- and double-track train tunnels and service tunnel, c) NorrstrÃ¶m, including single- and double-track train tunnels, service tunnels and an underground station d) SÃ¶derstrÃ¶m, including a submerged concrete tunnel (not included in these analyses), and finally e) SÃ¶dermalm, including single- and double-track train tunnels and service tunnels. The same design methodology was used for all contracts.

(Figure in full paper)

ISRM-SINOROCK-2009-156

ISRM International Symposium on Rock Mechanics - SINOROCK 2009

Industry:

- Transportation > Passenger (1.00)
- Transportation > Ground > Rail (1.00)

SPE Disciplines: Reservoir Description and Dynamics > Reservoir Characterization > Exploration, development, structural geology (0.69)

A three-phase medium model was proposed for describing wave propagation across filled rock joints in the paper. Parameters in the three-phase medium model were identified by a series of modified split Hopkinson pressure bar (SHPB) tests, where a sand or clay layer was used to represent an artificial filled rock joint. Two granitic pressure bars with the sandwiched sand or clay layer were used to represent the filled joint to simulate longitudinal stress wave propagation across such geological discontinuities. With the parameters fitted from a number of SHPB tests, the closure-pressure relation based on the three-phase medium model were compared with other test results and very good agreement was observed. Then, the three-phase filled joint model is adopted to carry out analysis of the longitudinal wave propagation through a single filled rock joint. The wave transmission coefficients were derived and compared with the test results. Finally, parametric studies with respect to the properties of filled joints and the incident wave on wave propagation through a single filled joint were carried out.

ISRM-SINOROCK-2009-129

ISRM International Symposium on Rock Mechanics - SINOROCK 2009

SPE Disciplines:

A three-phase medium model was proposed for describing wave propagation across filled rock joints in the paper. Parameters in the three-phase medium model were identified by a series of modified split Hopkinson pressure bar (SHPB) tests, where a sand or clay layer was used to represent an artificial filled rock joint. Two granitic pressure bars with the sandwiched sand or clay layer were used to represent the filled joint to simulate longitudinal stress wave propagation across such geological discontinuities. With the parameters fitted from a number of SHPB tests, the closure-pressure relation based on the three-phase medium model were compared with other test results and very good agreement was observed. Then, the three-phase filled joint model is adopted to carry out analysis of the longitudinal wave propagation through a single filled rock joint. The wave transmission coefficients were derived and compared with the test results. Finally, parametric studies with respect to the properties of filled joints and the incident wave on wave propagation through a single filled joint were carried out.

ISRM-SINOROCK-2009-029

ISRM International Symposium on Rock Mechanics - SINOROCK 2009

Reliable assessment of caving behavior of strata and support capacity requirement has been an issue of great demand for reducing the strata control risk while planning of longwall workings specially in difficult to cave strata conditions. This paper describes the findings of an integrated modeling approach for assessment of roof capability and estimation of optimal support capacity for longwall workings in a given geo-mining and strata condition. The modeling approach for support selection is suggested for regular as well as en masse caving conditions integrating the results of numerical modeling and field observation of 23 longwall panels worked in different coalfields of India. A mathematical approach is used to assess the effect of dynamic loading due to en masse caving and to estimate the design requirement of rapid yield valve. The modeling results of a case study of Churcha mine, a mining site well known for its difficult caving strata characteristics in Sonhat coalfield of India is also described.

Although, a number of models and approaches have been developed in different countries for prediction of caving behavior and support requirement, their applicability in Indian geo-mining condition is limited and suffers from considerable error resulting in inconsistent results (Sankar and Singh 1979, Sankar and Dhar 1993, Singh 2004). Experience shows that although the existing approaches offers important contributions towards understanding strata-support interactions, but they do not provide effective means of support specification (Trueman et al 2005). Further, the recent studies conducted by Singh (2007) as well as the Barczak (2006) strongly suggest that bigger the better consideration of support selection is not a good practice in support selection for ground control.

ISRM-SINOROCK-2009-168

ISRM International Symposium on Rock Mechanics - SINOROCK 2009

Industry:

- Materials > Metals & Mining > Coal Mining (0.53)
- Energy > Coal (0.53)
- Energy > Oil & Gas > Upstream (0.35)

SPE Disciplines:

Although a number of numerical simulation models were developed and improved in the theory and programs for jointed rock mass, there are many drawbacks to the simulation techniques, such as discontinuity modeling and free expansion. Instead of the spring model of discontinuity, a new numerical model is developed based on the essences of deformability and mechanical characteristics of discontinuity. Discontinuity is considered as a nonrenewable and volumechangeable plastic medium. In addition, Numerical errors between the linear displacement functions and the exact solutions can accumulate when the block rotates continuously. This cause a change in block size called the free expansion phenomenon. Here, the finite rotation theory is adopted to address the drawback of free expansion. Finally, jointed rock mass is considered as a two-media model. The coupling effects between blocks and discontinuities are established. These developments of simulation techniques can reveal the essences of rock mass and improve analysis accuracy for simulation.

In order to overcome the reaction force indeterminacy, one needs to introduce the deformability of the discontinuities. For example, DEM, DDA and BSM use normal and tangential springs at the intersection point between a discontinuity face and a block’s vertex. And they consider the thickness of discontinuity as 0. The interactive forces between discontinuity and block are based on the ‘invasion’. Although this discontinuity model can address the problem of discontinuity simulation, it does not reveal the essences of discontinuity, such as discontinuity deformability, mechanical characteristics.

ISRM-SINOROCK-2009-127

ISRM International Symposium on Rock Mechanics - SINOROCK 2009

Industry:

- Information Technology > Software (0.55)
- Energy > Oil & Gas > Upstream (0.31)

SPE Disciplines:

It is very difficult to predict accurately non-linear deformation time series of surrounding rock using general methods expecially under complex geological condition. A new method based on Gaussian Process (GP) machine learning, which is a newly developing machine learning method with excellent capability for solving highly nonlinear problems with small samples, is proposed. The method was verified by modeling deformations of surrounding rock of Yangzong tunnel in Yunnan Province, China. The monitoring nonlinear deformation time series of surrounding rock during excavation are taken as learning samples for GP machine learning. Non-linear relation of the deformation time series can be obtained by learning process of GP. Then, the future nonlinear deformations are predicted by using time series analysis based on GP. The results indicate that GP can appropriately describe the evolutionary law of non-linear deformation of tunnel and provide accuracy predictions. Furthermore, the results also show that the method is feasible, effective and simple to implement.

Gaussian process (GP) is a newly developed machine learning technology (Rasmussen and Williams, 2006) based on strict theoretical fundamentals and Bayesian theory. In recent years, GP has attracted much attention in the machine learning community, there are a lot of successful applications in the field of solving for nonlinear, small samples and high dimensions problems (Seeger, 2004; Girolami, 2006; Gramacy, 2007). GP is moderately simple to implement and use without loss of performance compared with ANN and SVM (Xiong, 2005).

In this paper, a new model based on GP is proposed to model and predict non-linear deformation time series of surround rock of tunnel. The model is verified by its application to study non-linear deformation time series of Yangzong Tunnel in China.

ISRM-SINOROCK-2009-109

ISRM International Symposium on Rock Mechanics - SINOROCK 2009

SPE Disciplines: Management and Information > Information Management and Systems > Artificial intelligence (1.00)

Technology:

- IT > AI > Machine Learning > Statistical Learning (1.00)
- IT > AI > Representation & Reasoning > Uncertainty > Bayesian Inference (0.87)