Study on the influence of joint spacing on rock fragmentation under TBM cutter by linear cutting test

Joint spacing is one of the most important geological factors influencing rock fragmentation by TBM cutters and TBM performance. In order to study the influence of joint spacing, full-scale linear cutting tests have been conducted for the Beishan granite samples with different joint spacing (i.e. one intact sample, two jointed samples with joint spacing of 100 mm and 400 mm). For different joint spacing, the influence of penetration depth on rock fragmentation was also explored by varying the penetration depth with an interval of 0.5 mm. During the test process, the three directional forces acting on the TBM cutter were recorded, and the rock chips formed by each cutting pass were weighed, respectively. By analysing the cutting force, crack initiation/propagation and rock chips, the influences of joint spacing on rock fragmentation process by TBM cutter were investigated. The test results showed that the increase of penetration depth cannot improve the TBM breakage efficiency after reaching a certain value for the intact rock sample, and the normal force for intruding the intact rock is larger than that for intruding the rock jointed samples. It is also found that the sample part below the joint plane is intact, thus joint can restrain the crack propagating cross the joint plane and facilitates the chips formation on the cutting surface. For the rock sample with joint spacing of 100 mm, two rock fragmentation modes were found during the cutting process. One mode is that the cracks initiate from the crushed zone under TBM cutter, and the cracks propagate to the joint plane, consequently form large rock chips. The other one is that the cracks initiate from the joint plane and then propagate to the rock cutting surface, and the cracks initiate before the formation of the crushed zone under the cutter. For the rock sample with joint spacing of 400 mm, there are two rock fragmentation stages, i.e., the normal rock fragmentation stage and the joint-controlled rock fragmentation stage. There is a transitional process between these two stages, and also the median crack can be promoted to propagate vertically to joint plane due to the joint existence. This study can provide useful guidance for operation optimization and performance prediction for TBM operating in jointed rock masses.     

Results of Cerchar,LCPC, and equivalent quartz content from rolling indentation abrasion testing in plutonic rock

The rolling indentation abrasion test (RIAT) is a recently developed method for measuring rock abrasivity. In this study, RIAT tests were performed on 17 plutonic rock samples and the weight lost by the mini-disc cutter (mg) after testing (RIATa), the mean value of 10 evenly distributed measurements of the cutter penetration depth into the rock in 1/100 mm (RIATi), abrasion-penetration rate (APR), and penetration-time rate (PTR) values were determined for the samples. The Cerchar abrasivity index (CAI), LCPC abrasivity index (LAC), and equivalent quartz content (EQC%) values were determined for the samples. The relationship of APR and PTR to CAI, LAC, and EQC% was investigated using regression analysis, and the Fisher test and empirical equations between APR-EQC%, PTR-EQC%, APR-PTR, PTR-CAI, APR-LAC, and PTR-LAC are proposed. The proposed equations were validated on three control samples and were found to be valid for plutonic rock. The RIAT test was used at different rotations speeds to determine their effect on the samples, and an optimal rotation speed has been proposed for each sample using the APR parameter. Comparison of the current results and those of previous research on sandstone showed that the trends of PTR-EQC%, APR-PTR, and PTR-CAI were similar. An experimental relationship has been proposed for these types of rock for APR-EQC%. For hard and highly abrasive samples, the trends for PTR-EQC%, APR-PTR, and PTR-CAI were similar for plutonic rock and sandstone, but for medium-to-high abrasivity samples, the penetration rate of plutonic rock was less than for sandstone in terms of abrasivity.

     

Hard rock tunnel boring machine penetration test as an indicator of chipping process efficiency

The transition from grinding to chipping can be observed in tunnel boring machine(TBM) penetration test data by plotting the penetration rate(distance/revolution) against the net cutter thrust(force per cutter) over the full range of penetration rates in the test.Correlating penetration test data to the geological and geomechanical characteristics of rock masses through which a penetration test is conducted provides the ability to reveal the efficiency of the chipping process in response to changing geological conditions.Penetration test data can also be used to identify stress-induced tunnel face instability.This research shows that the strength of the rock is an important parameter for controlling how much net cutter thrust is required to transition from grinding to chipping.It also shows that the geological characteristics of a rock will determine how efficient chipping occurs once it has begun.In particular,geological characteristics that lead to efficient fracture propagation,such as fabric and mica contents,will lead to efficient chipping.These findings will enable a better correlation between TBM performance and geological conditions for use in TBM design,as a basis for contractual payments where penetration rate dominates the excavation cycle and in further academic investigations into the TBM excavation process.     

Assessment of brittleness using rock strength and density with punch penetration test

Brittleness fracturing of rock is one of the most popular research areas in rock engineering, since some rocks show brittle fractures under loads. Direct standard testing method for measuring rock brittleness have not available yet. Therefore, rock brittleness is indirectly obtained as a function of rock strength. The aim of this study is not only to introduce direct method to measure rock brittleness as an index via punch penetration test, but also to investigate the relationship between intact rock properties (uniaxial compressive strength, Brazilian tensile strength, and density of rock) and the brittleness measured from the test. To obtain these objectives, rock cores were gathered from 48 tunnel projects throughout the world. Followings the sampling, the samples were prepared and relevant rock tests were carried out to establishment of dataset at the Earth Mechanics Institute of Colorado School of Mines in the USA. Consequently, using generated dataset, new brittleness index (BI_m) and rock brittleness classification was introduced base on type, strength and density of rock together with result of punch penetration test. Further, the rock brittleness index was predicted as a function of the uniaxial compressive strength, Brazilian tensile strength and density of rock with correlation coefficient of 0.94.     

Approaches to modeling coupled thermal, hydrological, and chemical processes in the drift scale heater test at Yucca Mountain

A large-scale underground thermal test (Drift Scale Test–DST) in fractured volcanic tuff resulted in changes to water and gas chemistry as well as mineral precipitation and dissolution in fractures. Thermal, hydrological, and chemical (THC) processes in the DST were modeled by Lawrence Berkeley National Laboratory “LBNL” and Japan Nuclear Cycle Development Institute “JNC” as part of the international working group DECOVALEX. Predictions of THC processes in the DST for the 4-year heating and 4-year cooling periods were initially performed by the LBNL group, with the current model reflecting a revised heater operation history and model. JNC used primarily the original data from the prediction and created a new model to evaluate a selected set of data. The approaches taken by the groups differed in several ways and a comparison of the methodologies and results of the simulations allow for a better understanding of modeling coupled processes in unsaturated fractured rock. The LBNL model represented the fractures and rock matrix as a fully interacting dual-continuum (in terms of fluid, heat, and chemical transport) with the local mineral–water–gas reactions treated by kinetic and equilibrium reactions. The JNC model represented the fractures and matrix as a single effective continuum, with equilibrium mineral-water reactions controlling the chemical evolution. Both models considered aqueous species transport, with gas phase CO₂ transport only considered in the LBNL model. Comparisons to data collected from the DST illustrate the behavior of the models and their ability to capture the relevant THC processes. Overall, both models capture the temperature evolution in the rock quite closely, although the JNC model gave a closer match to the initial temperature rise in the rock, likely owing to the use of site-specific thermal data as opposed to average properties used for the LBNL model. Both models showed the contrasting solubility effects of increasing temperature on calcite and silica solubility; yet the dual-continuum approach better represented the effects of boiling and condensation on aqueous species chemistry and the distribution of mineral precipitation.     

A specific upscaling theory of rock mass parameters exhibiting spatial variability: Analytical relations and computational scheme

In this paper the representation of geological conditions in a numerical simulation model is considered. By the expression “geological conditions” we mean the 3D volume geometry of the geological formations, the spatial variability exhibited by the rock parameters inside each of these geological volumes and the necessary upscaling of the rock deformability and strength parameters that are determined in the laboratory from cores collected in the field. A specific theory is outlined of how to go from laboratory tests, geological information and field measurements and observations to the full-scale numerical or “ground model” that includes, apart from initial and boundary conditions and ground water, the rock constitutive laws and associated material parameters for use in simulation models. The term “specific” used in the title of this paper stems from the fact that other possible approaches for the same problem may be applied; i.e. empirical rock mass classification systems, explicit modeling of joints in the rock by the distinct element or finite element methods, homogenization techniques, etc. The method used to take into account the spatial variability of rock mass properties by virtue of Geostatistical Theory and 3D modeling tools is also outlined, with an example case study.     

Particulate forms of radium and barium in uranium mine waste waters and receiving river waters

A method of selective dissolution was used for analysis of particulate forms of radium and barium in a system consisting of uranium mine waste waters purified by coprecipitation with barium sulphate and of adjacent river waters. Four particulate forms of both the elements were distinguished: “loosely bound”, “acid soluble”, Ba(Ra)SO₄ and “in crystalline detritus”. It was found that the distribution of radium and barium between dissolved and particulate forms in waste waters depended on the time interval elapsing between the sampling and membrane filtration of the waters. No such dependence occurred in river water. The main particulate form of radium and barium in the system was Ba(Ra)SO₄. River water upstream of the mine water discharge contained radium mainly in “acid soluble” form or “in crystalline detritus” and barium as BaSO₄ or “crystalline detritus”. In unpurified mine effluents, a large part of radium and barium was present as “crystalline detritus”. Abundance of the “loosely bound” form was very low in all the samples analyzed. The bond of radium in bottom sediments was approximately the same as that in the solids suspended in waste waters. Suitability and accuracy of the selective dissolution method for analysis of surface and waste waters has been demonstrated by the analysis of the results and by radiotracer experiments.     

Stability analysis of an underground power cavern in a bedded rock formation

An underground power cavern situated in bedded sandstone rocks was evaluated using the finite element method. The rock formation had a set of joints vertically with an opening of less than 0.1 mm. A “bedded model” was used to analyze the stability of the cavern excavation. The calculations were then checked by an “imitative model”. The results from these two models were consistent with each other. The results from the “bedded model” were similar to the displacements from the field measurements. The paper describes details of the numerical model, presents the results of the numerical calculations and discusses possible reasons for the similarities between the field measurements and results of the computations.     

掘进机刀盘滚刀间距对北山花岗岩破岩效率的影响实验研究

掘进机(TBM)开挖隧道过程中,其刀盘上滚刀间距设计的合适与否关系着破岩效率的高低。由于岩石非均匀、非连续、各项异性的特性,使用数值模拟方法研究滚刀破岩过程存在局限性。现场掘进实验主要是针对特定的掘进机做出机械运行参数优化,无法研究不同刀间距对破岩的影响。全尺寸滚刀破岩实验可以人为调整刀间距,且实验中采用大体积岩石可以避免尺寸效应的影响,因此受到了广泛的关注。采用北京工业大学自制的机械破岩试验平台,安装17英寸(432 mm)盘形滚刀,选取尺寸为1000 mm×1000 mm×600 mm的北山完整花岗岩试样,进行了5组刀间距的线性切割试验。实验中采集滚刀三向力,分层收集岩片且对其进行称重。对不同刀间距作用下的平均法向力、平均滚动力和比能进行了分析研究。当贯入度较小时,刀间距对平均法向力和平均滚动力的影响都不明显,随着贯入度的增加,刀间距对平均法向力和平均滚动力的影响增加。对于所有的刀间距而言,增加贯入度会产生更多的岩片,但并不一定会提高破岩效率,对于北山花岗岩而言,当刀间距与贯入度的比值为30左右时,比能值最低,此时破岩效率最高。     

Natursyns model: A conceptual framework and method for analysing and comparing views of nature

This article presents a conceptual framework and methodology by which stakeholders’ views of nature can be investigated, explained, compared and ‘ideal types’ distilled based on qualitative interviews and, plans, laws and other texts analysed. The aim of such studies is to increase the knowledge about personal, social and cultural aspects of landscape and their relations in general to improve the basis of countryside planning and management in particular. Within the Natursyns model (the Danish word ‘natur’ corresponding to “nature” in English and “syn” implying perceived, imagined, cognized and culturally agreed interpretations) landscape is understood simultaneously as: ‘habitat’, unrealised sense impressions; ‘area’, all the ways in which nature is cognised; and as ‘symbol’, all types of representations of nature and its parts. The use of the model is illustrated; its epistemological foundation, the semiotics and phaneroscopy (phenomenology) of the American philosopher Charles S. Peirce, is described; the content of its fields explained; and benefits and shortcomings discussed.     

“Urban versus rural” no longer matches reality: an early public agro-residential development in periurban Santiago, Chile

The paper discusses the validity of the “urban versus rural” dichotomy in scientific literature, statistics and urban planning practice, especially in empirical studies developed around the issue of vegetable and animal farming inside and around cities. Santiago’s rural–urban interface is presented as a case study. Sample results extracted in early 2003 have shown that farming mixed with other land uses is even now a reality in Southern Santiago, supported in solidarity alliances and a characteristic life philosophy, giving researchers the possibility of exploring a living ecocity laboratory.     

Load testing, structural reliability and test evaluation

A brief review of the history and types of load testing is followed by an examination of the effects of load test and other information on structural reliability. Two aspects are studied. (1) Multi-mode proof testing is posed as a system relability problem with one or more inequality conditions on structural performance. After-test reliability can then be found using standard system reliability methods from the reliability of the system augmented in “series” with the test mode, divided by the reliability in the test mode alone. (2) Test evaluation procedures for several applications are analysed using simulation of destructive sample tests, including strength uncertainty discoverable by testing and other non-test uncertainties in strength and loading. Evaluation rules are found to have a significant effect on the achieved reliability of test-based design.     

The role of agroforestry networks in landscape socioeconomic processes: the potential and limits of the contingent valuation method

Agroforestry networks can be a means to achieve landscape amelioration. Some authorities of the Lagoon of Venice drainage basin (Italy) are planning, amongst other actions to control pollution in the Lagoon, to reintroduce agroforestry by means of a GIS-supported design procedure. The goals of this paper were to assess (i) the contingent valuation (CV) (willingness to pay and willingness to accept) of agroforestry networks and its relationship with socioeconomic and agroforestry role variables, (ii) the coherence between agro-economic policies and farmers expectations, (iii) the relationship between the value of agroforestry as a “shared good” and water quality (non-point source pollution). Respondents associate a positive value/preference to the agroforestry network implementation, although this value is strongly affected firstly by their identity with the landscape and secondly by their income. The motivations of farmers’ evaluation are precise and the agroforestry network is considered not only as an “ethical object” but also as a concrete element of their own cultural and economic world. In this case the contingent value (in particular, in terms of acceptance) increases with the farmer’s economic capacity, and the farmer’s valuation is not linked only to the “good” but also to the “service” offered for implementing it. The expectations of farmers regarding an agroforestry plantation were lower than European Union incentives at the time of survey, and a lack of results in this field is probably linked to poor information and to bureaucratic difficulties. Even if there is general knowledge on water quality, there is little awareness on the non-point source pollution control effect of agroforestry buffer plantations, either in the common people or in those who are environmentally trained (e.g. planning university students). In every case the agroforestry “shared good” evaluation is high enough to permit efficient and supported intervention policies. These results confirm that landscape choices strongly involve issues of identity, perceived rights and evaluation capacity that cannot be simply resolved in terms of preference cost benefit analyses, but a clever use of the CV allows an identification of these same limitations and a partial estimation of them.     

A continuum of organizations formed to carry out projects: Temporary and stationary organization forms

Projects are carried out by temporary organizations. These organizations can function independently or in cooperation with stationary organizations. To enable efficient project and program management, these differences in organization structure have to be considered. This paper therefore contrasts organizations formed to carry out activities at project sites based on forms of employment, work processes and resource networks used. Findings indicate that temporary organizations that are dominated by stationary “parent” organizations often rely on its abilities to secure access to crucial resources and to identify suitable work processes. “Pure” or virtually “pure” temporary organizations instead rely on their employees’ skills and contacts to develop suitable routines and gain access to resources.     

Use of the punch test for estimating TBM performance

This paper discusses the history of the punch test as a laboratory tool for estimating Raise Boring Machine and Tunnel Boring Machine penetration rates. Included are discussions of some of the methods that have been used to evaluate the test results for this purpose and how the test has been used to evaluate certain rock characteristics such as brittleness, bedding or cleavage, and porosity, which have been observed to affect machine performance. Also presented are some examples as to how the test has been used in an expanded form to evaluate the effect of certain machine parameters such as cutter spacing and geometry on excavation rates. Based on this, it is concluded that the punch test has proven itself to be a powerful laboratory tool for evaluating rock boreability and that it has the potential of becoming a stand alone test for this purpose.     

Applications of an explicit solution for the transversely isotropic circular disc compressed diametrically

This paper focuses on the Brazilian test configuration of anisotropic rocks. The proposed methodology follows that of Pinto (Proceedings of the Fourth ISRM Cong, Montreux, 1979); however, it is more accurate since we adopt Amadei's method of analysis (Int. J. Rock Mech. Min. Sci. Geomech. Abstr. 33 (1996) 293) that accounts for the influence of anisotropy on the stress distribution. In a first step, explicit expressions for stresses and strains for the anisotropic circular disc compressed diametrically are presented by employing Lekhnitskii's formalism. It is shown that the proposed analytical solution can be effectively used as a “back-analysis” tool for the characterization of rock elasticity and strength properties. This is illustrated both in the case of published experimental results on schist and gneiss rock types, and finally in the case of specially designed Brazilian tests on Dionysos marble.     

Rapid enumeration of water bacteria

The research reported in this paper is devoted towards the development of a rapid bacteriological test for water. The proposed technique consists in measuring “Cold T.C.A. insoluble portion” of metabolized phosphorus in multiplying bacterial cells with recourse to radioactive phosphorus-32 as a tracer and enumerates bacteria in 1 h incubation time. A linear correlation (coefficient of correlation = +0·989) has been shown to exist between this portion of phosphorus and cell population for bacterial species of public-health significance, thereby providing a point d'appui for this approach of enumerating water bacteria.The data reported in the paper reveal a promise for the differential enumeration of Grams positive and negative cells by incorporating suitable chemical inhibitors in appropriate concentrations in the test portions for rapid test.The technique has been exhibited to be applicable to field samples drawn from surface and underground sources of water. Its reproducibility and economics are comparable with “Standard Method” procedures.     

IHAS at Exeter 1982. First Scientific Assembly. Exeter, England, 19–30 July, 1982

This study contains the results so far of tests which have been carried out on samples of sedimented municipal effluent stabilized by means of simple preservation methods by the working party on “stabilization of samples” from the German Chemists Association's hydrochemistry team and evaluated with a view to providing recommendations on methods of preservation. It was assumed that the recurrent standard deviation of the test methods applied is less than ± 10%. Consequently a deviation in the measured concentrations by more than 10% in terms of the initial concentration after a given storage period of the preserved sample was to be regarded as a real change in the corresponding contents of the sample. Accordingly the datum “storage period of preserved sample” means that the samples must on no account be preserved for longer than the stated time, and that the actual storage period should, if appropriate, be shorter depending on the accuracy requirements.     

Improved rotatory-flow technique applied to Cod (Gadus morrhua L.)

An improved version of rotatory-flow apparatus is described, allowing tests of fitness with fish of different size at constant temperature. Cod (Gadus morrhua, L.) was used as experimental animal, and its treatment and behaviour during different phases of the test are described in some detail. Each test results in determination of the “critical rev min⁻¹” at which the fish is just brought to rotate with the water. The mean of a series of 10 critical rev min⁻¹ with the same fish, multiplied by the interior circumference of the rotational tube used, gives the “critical peripheral velocity” of the specimen. Critical peripheral velocities of a sample of fish, plotted against the standard length of the fish, arrange themselves along a straight line which intersects the vertical axis near the origin. Divided by the corresponding standard lengths the critical peripheral velocities give “reaction quotients”, the mean of which describe the reaction of the whole sample of fish.Optimal experimental conditions have been found by investigating the effects of systematic variation in streaming velocity, relationship between rotational tube diameter and fin-breadth, temperature, and effects of repetition of test-series on successive days etc. on the results of testing.     

Pollution of the river rhine with halogenated organic compounds an investigation during a “Fliessende Welle”

In August 1982 and between 13 September–1 October 1982, during two “Fliessende Welle” surveys, about 400 R. Rhine water sample were taken. The total organic halogen contents of about 200 samples were analyzed by different methods. In waste water samples, as well as in river water samples, there were considerable differences in the analytical data depending on the method used. Some discharge points for organic halogens into the Rhine are identified.