Hasil untuk "Engineering geology. Rock mechanics. Soil mechanics. Underground construction"

Junjie Zhao, Diyuan Li, Jian Zhou et al.

Abstract Rock fragmentation is an important indicator for assessing the quality of blasting operations. However, accurate prediction of rock fragmentation after blasting is challenging due to the complicated blasting parameters and rock properties. For this reason, optimized by the Bayesian optimization algorithm (BOA), four hybrid machine learning models, including random forest, adaptive boosting, gradient boosting, and extremely randomized trees, were developed in this study. A total of 102 data sets with seven input parameters (spacing‐to‐burden ratio, hole depth‐to‐burden ratio, burden‐to‐hole diameter ratio, stemming length‐to‐burden ratio, powder factor, in situ block size, and elastic modulus) and one output parameter (rock fragment mean size, X50) were adopted to train and validate the predictive models. The root mean square error (RMSE), the mean absolute error (MAE), and the coefficient of determination ( R 2) were used as the evaluation metrics. The evaluation results demonstrated that the hybrid models showed superior performance than the standalone models. The hybrid model consisting of gradient boosting and BOA (GBoost‐BOA) achieved the best prediction results compared with the other hybrid models, with the highest R2 value of 0.96 and the smallest values of RMSE and MAE of 0.03 and 0.02, respectively. Furthermore, sensitivity analysis was carried out to study the effects of input variables on rock fragmentation. In situ block size (XB), elastic modulus (E), and stemming length‐to‐burden ratio (T/B) were set as the main influencing factors. The proposed hybrid model provided a reliable prediction result and thus could be considered an alternative approach for rock fragment prediction in mining engineering.

Gianpiero Russo, Ilaria Esposito, Massimo Ramondini et al.

The Continuous Flight Auger (CFA) piles, also known as Auger Cast In Place piles (ACIP), have a widespread use in the world market of replacement concrete piles. The installation of such piles is generally made by equipment which records several significant installation parameters, as the torque Mt and the axial force N, applied during the auger advancing step. In the auger retrieval stage other parameters that can influence the load-settlement performance of the pile are monitored. The paper presents a case study dealing with the CFA piles adopted as a foundation for a water treatment basin. In the paper first the equations governing the kinematical analysis of the augering and concreting stages of the pile construction are introduced. After the description of the test site with the subsoil conditions and the presentation of a typical sets of parameters recorded during pile installation the results of two pile loading tests to failure are reported. A new approach for determining the depth of the soil layers boundaries, based on the statistical analysis of CPT profiles with depth, is proposed and successfully applied confirming the qualitative geological analysis of the site. A further statistical analysis is carried out to find a robust correlation between the qc of the CPT and the torque Mt needed to screw in depth the auger for pile construction. Finally, virtual CPT profiles generated from the torque Mt recorded during the tested piles installation are used for piles bearing capacity calculations which are compared with the results of pile loading tests. The successful comparison reported in the paper is a first step to validate the proposal to use parameters recorded during augering to calculate and/or to confirm design values of the bearing capacity.

LIU Shuang 1 , LIU Hanlong 1, 2, 3, XIAO Yang 1, 2, 3

The soil-water characteristic curve (SWCC) is an important constitutive relationship of unsaturated soils. The temperature and void ratio obviously affect the SWCC of soils. By combining the adsorption and capillary water models for soils with the introduction of a capillary condensation factor, a SWCC model is proposed. Moreover, an analytical solution for wetting coefficient considering temperature is obtained by considering the non-isothermal water-air interfacial tension and enthalpy of immersion per unit area. Then, a temperature-dependent matric suction and SWCC model is established. Additionally, the distribution curves of pores at different void ratios can be obtained by shifting and scaling the curve at the reference state. Then, a void ratio-dependent capillary model is proposed. On this basis, a capillary-adsorption decoupling SWCC model considering temperature, void ratio and capillary condensation is established. The parameters can be determined from two series of test data with different void ratios at the same temperature and one data of different temperatures. The comparison between the predictions and measurements indicates that the proposed model is precise in predicting the SWCCs under different conditions.

Osamu Kusakabe

This contribution is part of a series of invited papers on “A Review of the Author’s Own Seminal Contributions”. The paper describes the author’s 45 years of research experiences with a focus on foundation studies with physical modeling. Following some general statements on physical modeling, the facilities that the author utilized are described; and subsequently, the selected foundation problems that he tackled are explained mainly from physical modeling viewpoints. The selected problems cover shallow/ deep foundation stability problems and a few geoenvironmental issues, such as ground vibrations and piling at post-closure waste disposal sites. The outcomes of his research offered engineering solutions that society needs. The paper emphasizes the usefulness of the methodology of combining the theory of plasticity and physical modeling.

Zhang Cun, Ren Zhaopeng, Lan Shiyong et al.

Coal seam mining causes deformation, fracture and migration of overlying rock, further leading to the surface subsidence and ecological damage, which are the main manifestations of mining damage.Quantitatively characterize mining damage is the key to analyzing the stability of surrounding rock, designing mining parameters, and the premising of roadway support parameters.According to the finite element and discrete element simulation methods commonly used at this stage, this paper proposes a quantitative index(damage degree)to characterize mining damage: the proportion of zone plastic volume and the proportion of contact fracture length(number).On this basis, this study carried out the optimization of high-intensity mining parameters of the western mining area, the stability analysis of the coal pillar under the condition of mining and water immersion, and the progressive damage characteristics analysis of the roadway surrounding rock in the water-filled fault structure area by using the damage degree index.The quantitative relationship between the damage degree of the overlying rock and the mining parameters is obtained, which can realize the reasonable optimization of the mining parameters.This paper revealed the progressive damage characteristics of mining water immersion in coal pillars.We deemed that there is a danger of water seepage in the mined-out area as a water storage area under the existing coal pillar conditions.This study quantified the damage distribution characteristics of the surrounding rock in the roadway in the water-filled fault structure area, and proposed the corresponding? solution of dredging the fault through the roof aquifer, grouting reinforcement of the original fault fracture and strengthening the support.By comparing with common indicators such as the height of the water-conducting fracture zone and the width of the plastic development of the coal pillar, this research found that the damage degree indicators are more sensitive to the characterization of mining damage, and could realize continuous mining damage characterization.

Shuai Chen, Xiangchao Shi, Leiyu Gao et al.

To study the drillability and microscopic damage changes of granite after high temperature exposure and to study the influence of different cooling times on drillability after high temperature exposure, granite for high-temperature heat treatment was cooled by different times (2 h, 4 h, 24 h, and 48 h). Through the drillability experiment and the cast thin identification of the processed rock samples, the influence law and mechanism of high temperature on the drillability of granite were obtained, and the influence of different cooling times on the granite drillability was also investigated. The research results show that granite always maintains a high drillability index under the constraints of heat treatment not exceeding 500℃ and natural cooling for 2 h. After cooling 4 h, 24 h, and 48 h, the impact of high temperature on drillability shows three stages (First degradation stage, strengthening stage, second degradation stage). The location and number of microcracks affect the difficulty of rock resistance to crushing. After 400℃ heat treatment, the internal microcracks of the granite begin to increase significantly. When the microcracks generate a large number of microcracks inside the quartz particles, the drillability of the granite is significantly reduced. After heat treatment at 100℃, cooling for no more than 4 h at the same time will significantly affect the drillability of granite. After heat treatment at 200-400℃, the drillability index of granite will increase significantly as the cooling time (4-48 h) continues to increase. The damage caused by 500℃ to granite is irreversible, and 600℃ has completely degraded the granite. Understanding the influence of high temperature and cooling time on the drillability of granite can provide basic theoretical support for the efficient exploitation of hot dry rock resources.

Ramin Mardani, Hossein Montaseri, Mehdi Fazeli et al.

IntroductionDrought is considered a complex hazard, whose severity depends on the climate and weather conditions of each region. In fact, drought is caused by dry and unusual weather conditions, among other things, lead to a change in vegetation characteristics. Since this dangerous phenomenon is caused by the lack of rainfall for a long period of time, it slowly and gradually leads to a natural disaster and conquers the environment compared to other environmental hazards. Therefore, it is not noticed and taken less seriously by people and authorities. Undoubtedly, the occurrence of drought and as a result the crisis of reduction and shortage of water resources is one of the main and most important risks of the natural environment that humans have faced since the past. Therefore, it can be stated that the possibility of this natural phenomenon also exists in humid areas. Drought causes unfortunate and in some cases irreparable damage to human life as well as the natural ecosystem which is very different from other natural events such as floods, storms, and earthquakes. So that it has caused wide and big problems in the economic, social, political, and cultural fields. Therefore, the impacts it causes are not only structural and the damage it causes affects different areas. Drought is one of the destructive phenomena of the natural environment that affects a significant number of countries and causes problems. Simultaneous droughts with the period of vegetation growth cause environmental ecosystem consumption, which results in biological compounds such as land surface, soil amount, and plant growth rate, that we need proper management and planning in order to deal with this phenomenon. Materials and MethodsIn the present study, drought in Marvdasht city was analyzed using remote sensing technology and satellite imagery as a time series. For this purpose, during the statistical period of 20 years (2000-2019), out of 460 satellite imagery of land surface temperature (LST) and vegetation cover (NDVI) were used in conjunction with the MODIS sensor of Terra satellite, from which to estimate the temperature condition index (TCI) and vegetation condition index (VCI) was used. The optimal index indicating the state of drought from satellite imagery, the SPI was also used. In this way, using the rainfall data recorded by synoptic and rain gauge stations in the study area, the SPI was calculated using MATLAB software for the period of 3, 6, and 12 months. One of the other goals pursued in this study is to determine the basic and optimal index, indicating the state of drought in the study area, which is based on TCI and VCI satellite drought indices. Thus, after calculating the SPI and its intervals for each station, the points of each ground station were placed on the maps produced from TCI and VCI satellite indicators. Then, by taking the numerical value of the corresponding points for each of the years of the investigated period, the obtained values were entered into SPSS 22 software and the amount of correlation coefficients between SPI and its intervals with TCI and VCI values was calculated. Results and DiscussionAccording to the drought maps extracted from the TCI, the highest amount of land area with very severe drought in 2016 was 118.90 km2, and then in 2018 with 112.25 km2, and in 2017 with an amount of 101.66 km2 has happened. On the other hand, the least amount of extreme drought area in the first place is related to 2006 with an area of 46.10 km2, and then 2002 with an area of 48.21 km2. In terms of the severe drought category, 2009 with an area of 433.71 km2 experienced the largest area and 2007 with an area of 45.78 km2 experienced the lowest amount of drought. According to the maps obtained from the TCI, a very severe drought situation is observed in the southern and southwestern parts, especially in 2016 and 2018. It is also consistent with the results of the different intervals of the SPI in 2016 and 2018. They are considered as the years in which the highest amount of drought occurred. In addition, the year 2013 has less drought than other years in all three ranges of the SPI. From the comparison of the average SPI values for the studied years with the values obtained from the two indices, TCI and VCI obtained from satellite imagery, the highest amount of correlation coefficient between TCI and six-month SPI was equal to 0.65, which indicates that the TCI satellite index is the optimal index to indicate the drought situation in Marvdasht city. ConclusionAccording to the maps obtained from the NDVI, the studied area has normal and semi-dense vegetation density, which is scattered in all its different areas, so it has more density in the central and northwestern parts. The results of the VCI for the studied area, in none of the years, has not faced very severe drought. In terms of medium aridity, they have experienced the highest amount of drought in 2010 with an area of 62.98 km2 and after that in 2019 with an area of 50.04 km2. In contrast, the lowest drought in this layer was in 2002 with an area of 5.09 km2. According to the maps showing the drought condition of VCI, the studied area has almost the same distribution pattern in all areas and except for a small part of the southern part of the area which has a medium drought condition, the other areas have a mild drought condition and are not dry in most areas.

Huaizhong Liu, Jianliang Pei, Jianfeng Liu et al.

A reasonable evaluation of unloading deformation characteristics is of great significance for the effective analysis of deformation and stability of surrounding rocks after underground excavation. In this study, the damage-controlled cyclic triaxial loading tests were conducted to investigate the pore compaction mechanism and its influences on the unloading deformation behavior of red sandstone, including Young's modulus, Poisson's ratio, volumetric strain, and irreversible strain. The experimental results show that the increases of volumetric and irreversible strains of rocks can be attributed to the compaction mechanism, which almost dominates the entire pre-peak deformation process. The unloading deformation consists of the reversible linear and nonlinear strains, and the irreversible strain under the influence of the porous grain structure. The pre-peak Young's modulus tends to increase and then decrease due to the influence of the unloading irreversible strain. However, it hardly changes with the increasing volumetric strain compaction under the influence of reversible nonlinear strain. Instead, the initial unloading tangent modulus is highly related to the volumetric strain, and clearly reflects the compaction state of red sandstone. Furthermore, both the reversible nonlinear and irreversible unloading deformations are independent of confining pressure. This study is beneficial for the theoretical modeling and prediction of cyclic unloading deformation behavior of red sandstone.

R. Witasse, S. M. Kashfi, K. P. Iman

This article aims at demonstrating how the use of advanced numerical methods such as the Finite Element Method can provide a reliable prediction of the different ground formation behavior and development of structural forces during tunnel construction. It will particularly illustrate how the challenges associated with TBM excavation in mixed faced conditions could be efficiently dealt with using the finite element analysis. More specially detailed numerical analysis techniques for dealing with the construction of closed twin tunnels in mixed face conditions will be provided using the FEA software PLAXIS 2D. With the ongoing advancement of Tunnel Boring Machine (TBM) capabilities, the ability to tunnel through mixed face conditions has been improved dramatically and the risks have been reduced significantly. Still, mixed-face ground encountered in TBM tunneling presents great design and construction challenges for the tunnel engineers. From a geological viewpoint, the mixed-face condition is defined as the simultaneous occurrence of two or more geological formations with remarkably different properties in rock/soil mechanics, engineering geology as well as hydrogeology, or the same geological formation with different weathering grades. This paper aims at demonstrating how the use of advanced numerical methods such as the Finite Element Method can provide a reliable prediction of the different ground formation behavior along with development of structural forces and remarkably help geotechnical engineers to reach cost-effective and reliable tunnel design and construction. One of the first challenges is the consideration of the specific in-situ stress conditions with a large variation of initial orthotropic stresses from one geological formation to the neighboring one with possible significant initial locked stress in certain rocky layers that must be accounted for. The soft soil at the top of the face and the hard rock at the bottom makes it difficult to maintain a proper face-support pressure and face stability, and increases the risk of excessive cutter wear, face collapse, sinkholes, or damage to surrounding structures. This is another challenge that should also be properly addressed. To avoid undesirable ground surface settlement as well as provide appropriate safety measures and limit impact on existing assets, tunnel engineers must also be able to reliably predict the amount of settlement under all given ground conditions. The ground movement around the excavated ground mass will lead to stress changes (arching) the extend of which will define the effective load on the tunnel lining and will greatly condition its design. The mixed-face ground conditions will also induce uneven loading on the segmental lining that must be accurately assessed with the proper consideration of segment-to-segment non-linear contact interaction.

F. Yue, Z. Wu, Zhiqiang Fan et al.

The issue of soil–structure interaction (SSI) is essentially to analyze the influence of complex media on the mechanical behavior of supported structures. With the development of underground space, geological structures and space constraints put forward higher requirements for foundations and buildings. In this paper, the effects of soil heterogeneity and embedment depth on the bending of finite-length beams embedded in two novel Vlasov elastic foundations are investigated. Firstly, the constitutive relations of subsoil are simulated by Gibson and transversely isotropic soils, and the type of elastic foundation is described by the modified Vlasov model. Then, based on variational principles, the governing differential equations for the deformation and attenuation parameters of beams embedded in elastic foundations are derived by taking the variation of the minimum potential energy of the system, and the characteristic coefficient related to the embedment depth is introduced. Finally, the mechanical performance of the beam and foundation is obtained by an iterative technique and the Fourier series method, and an extensive parametric study is performed to examine influence of some basic parameters on the deformation and internal forces of the system. The results show that the mathematical expressions of two refined elastic models are in good agreement with those of the traditional Vlasov foundation after degradation. The iterative technique based on the principles of solid mechanics can be employed to obtain more reliable model parameters. More importantly, with the increase in the embedment depth, the mechanical responses of the beam and subgrade forces decrease. The main reason is that the restraint effect of the soil media around structures, which leads to the reduction of the characteristic coefficient affecting the displacement of beams. Moreover, the heterogeneity of soil, including Gibson characteristics and transverse isotropy, should be considered according to specific working conditions in civil engineering.

Sreenivasulu Sunkara, M. Sreenivasa Reddy

Gold is one of the valuable metals and an important asset class for investors. People in India are emotionally attached to gold. Thousands of tonnes of idle gold are lying with Indian temples, trusts, and individuals. Investors consider capital appreciation; interest income and safety are major factors that influence buying of gold [1][4][7]. India is one of the biggest importers of gold every year. The government of India has introduced a few gold-related schemes to reduce gold imports. Sovereign gold bond [2] scheme and Re-vamped gold deposit scheme are introduced in the year 2015 under the Swarna Bharath initiative [9]. The present study is an attempt to find the association between awareness of investors and demographic factors towards gold ETFs, gold bonds, and gold deposits. The results reveal that there is a significant association at a 5% significance level between awareness of investors and all demographic factors used in the study except the gender of the respondent.

Hui-feng Yang, Rui-fang Meng, Xi-lin Bao et al.

The Beijing-Tianjin-Hebei Plain (BTHP) is the political, economic and cultural center of China, where groundwater is the main source of water supply to support social and economic development. Continuous overdraft of the resources has caused a persistent decline of groundwater level and formed a huge cone of depression at a regional scale. This paper addresses current groundwater situation over the BTHP area. The paper also delineates the groundwater flow field, using groundwater level data, in order to provide an effective method for the restoration of groundwater level and associated water resources management. Based on the analysis of multiple factors, such as groundwater level, soil salinization, ground subsidence, groundwater recharge and storage, urban underground space security, formation of fractures, and seawater intrusion, the threshold for groundwater level restoration is defined, and some measures for groundwater over-exploitation management are accordingly proposed. The study shows that: (i) Since the 1980s to 2020, shallow groundwater level in the western part of the BTHP area has dropped by 25 m to 60 m, while the cumulative decline of deep groundwater in the central and eastern regions is in the range of 40–80 m; (ii) The water table of the shallow groundwater within the depression zone over the Western Piedmont Plain should be controlled in the range of 15–30 m below ground level (mbgl), while the depth of groundwater level in large and medium-sized urban areas should be controlled within 20–30 mbgl. The groundwater level in the resource preservation area should be controlled within 10–15 mbgl, and the groundwater level in the area with identified soil salinization in the central and eastern plain should be controlled within 3–10 mbgl. However, for the deep groundwater in the central and eastern plainwater, the main focus of the resources management is to control the land subsidence. The water level in the severe land subsidence area should be controlled within 45–60 mbgl, and in the general subsidence area should be controlled within 30–45 mbgl; (iii) Based on the water level recovery threshold and proposed groundwater overdraft management program, if the balance of abstraction and recharge is reached in 2025, the shallow groundwater abstraction needs to be gradually reduced by about 2×108 m3. Meanwhile, the ecological water replenishment of rivers through the South-to-North Water Transfer Project should be increased to 28.58×108 m3/a, and the deep groundwater abstraction needs to be gradually reduced by 2.24×108 m3. To reach the target of shallow groundwater level in 2040, surface water replacement is recommended with a rate of 25.77×108 m3/a and the ecological water replenishment of rivers in the South-to-North Water Diversion Project should reach 33.51×108 m3/a. For deep groundwater recovery, it is recommended to replace the deep freshwater extraction with the utilization of shallow salt water by 2.82×108 m3 , in addition to the amount of 7.86×108 m3 by water diversion. The results are of great significance to the remediation of groundwater over-exploitation, the regulation of water resources development and utilization, and ecological protection in Beijing-Tianjin-Hebei plain.

Miguel Angel Benz Navarrete, Pierre Breul, Roland Gourvès

Among the geotechnical in situ tests, the dynamic penetration test (DPT) is commonly used around the world. However, DPT remains a rough technique and provides only one failure parameter: blow count or cone resistance. This paper presents an improvement of the dynamic cone penetration test (DCPT) for soil characterisation based on the wave equation theory. Implemented on an instrumented lightweight dynamic penetrometer driving with variable energy, the main process of the test involves the separation and reconstruction of the waves propagating in the rods after each blow and provides a dynamic cone load-penetration (DCLT) curve. An analytical methodology is used to analyse this curve and to estimate additional strength and deformation parameters of the soil: dynamic and pseudo-static cone resistances, deformation modulus and wave velocity. Tests carried out in the laboratory on different specimens (wood, concrete, sand and clay) in an experimental sand pit and in the field demonstrated that the resulting DCLT curve is reproducible, sensitive and reliable to the test conditions (rod length, driving energy, etc.) as well as to the soil properties (nature, density, etc.). Obtained results also showed that the method based on shock polar analysis makes it possible to evaluate mechanical impedance and wave velocity of soils, as demonstrated by the comparisons with cone penetration test (CPT) and shear wave velocity measurements made in the field. This technique improves the method and interpretation of DPT and provides reliable data for shallow foundation design.

Hongju Chen, Shunkang Fu, Shuai Chai et al.

With the exploration and development of oil and gas fileds going towards into deep-water fields, high waxy reservoir has much more flow assurance issues of encourage complex solids depositions in the transportation system, especially hydrates and wax. Applying risk management such as hydrate slurry technology to control hydrate blockage, has much more economic and technical advantages, comparing to the traditional methods. It is significant to understand the viscosity of the waxy-hydrate slurry using hydrate slurry technology in high wax content reservoir. In this work, based on a simplification idea by coupling the wax content effect into the viscosity, volume and density of the water-in-waxy oil emulsion, a new viscosity model of waxy-hydrate slurry is established according to the Einstein effective medium theory, based on the experiments carried out in a high-pressure rheology system with different wax contents ranging from 0.5 wt%∼2.0 wt%. The effect of the complex aggregate coupling wax-hydrate-water is considered by function the non-Newtonian coefficient by four dimensionless parameters. Well-fitting results within an improved deviation of ±15% indicate the feasibility of this method is feasibility. This work can provide a valuable reference for the application of hydrate slurry technology in deep-water fields with high wax content reservoir.

ZHANG Jian-cong, JIANG Quan, HAO Xian-jie et al.

Columnar jointed rock mass with unique joint network structure is a special type of jointed rock mass, which is a binary structure composed of high strength ‘basalt block’ and specific ‘dominant joint’. Relaxation, opening and slippage of columnar jointed surfaces and disintegration of columns occur easily during excavation under high ground stress, which eventually lead to disastrous collapses in columnar jointed rock mass. The construction safety of underground engineering under high stress is severed restricted by it. By combining acoustic wave, borehole camera and other integrated in-situ testing technology and numerical simulation, the mechanism of stress-structural collapse in columnar jointed rock mass under high stress is studied based on multiple columnar jointed rock mass collapses at left bank tailwater connection pipe of Baihetan hydropower station. The proposed controlling measures of excavation and support are also provided. The key of columnar joined rock mass collapse is the redistribution of stress in surrounding rock mass after the excavation and the strong unloading relaxation of columnar joined basalt, which causes the opening of its internal joint surfaces and structural deterioration, result in the disintegration of basalt columns. Thus, the chain catastrophic process of continuous unloading relaxation and progressive collapse of columnar jointed rock mass is induced. The research can provide reference for the prediction and control of deformation and failure of jointed rock masses in underground engineering under high geo-stress.

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A. Radkevych, V. Petrenko, O. Tiutkin et al.

Junling Qiu, J. Lai

Recently, the water environment, especially the investigation on the influence mechanism of high water pressure or water seepage on the tunnel stability is not thorough. In this study, based on the theory of seepage mechanics and elastic-plastic theory, the stress state of tunnel rock mass under the coupling of seepage field and stress field is analyzed, the formula for calculating the radius of plastic zone, the stress and displacement of the rock mass in the elastic-plastic state are derived. The stress and displacement of tunnel surrounding rock and the mechanical characteristics of the supporting structure are analyzed under the condition of seepage. Introduction With the rapid development of underground engineering, groundwater is almost always accompanied by underground engineering, groundwater preventing problem has plagued engineering field. Underground work in the confined water, groundwater control is more complex, the problem becomes more and more prominent. In recent years, our country built a large number of mountain tunnel, cross river tunnel, mine tunnel and all kinds of underground engineering, the tunnel will be excavated with complex geological environment. These tunnels have most of the groundwater with a certain pressure. In order to ensure the construction safety of tunnel, the tunnel construction encountered in the process of high pressure groundwater must be controlled and grooming. For the water hydraulic tunnel, tunnel lining structure is subjected to the hydrodynamic pressure load inside tunnel and water pressure outside tunnel liner. For the non-hydraulic pressure tunnel, water pressure does not exist, there is only the external water pressure. Because the sealing impervious tunnel liner is not absolute, so the effect of water pressure on tunnel liner is the liner surface force and liner seepage volume force. Because the tunnel liner and the rock mass are permeable media, it can be considered that the movement of water seepage between the liner and the rock mass is continuous. In many cases, the tunnel liner and rock mass is not completely closed, there are pores, due to the existence of pores in the volume force of tunnel rock mass will not be directly transferred to the tunnel liner, this part becomes an independent structure to withstand water pressure. At present, the water environment, especially the investigation on the influence mechanism of high water pressure or water seepage on the tunnel stability is not thorough. The high pressure tunnel with complicated hydrogeological conditions or river tunnel construction under the influence of seepage field and stress field coupling model is not perfect, which cannot fully reflect the seepage field and the stress field in the high pressure. In this paper, based on the coupling theory of seepage field and stress field, the interaction between rock mass and tunnel liner was analyzed. The research results can provide important guidance for underwater tunnels and mountain tunnels. Model Establishment In this study, the circular tunnel is taken as the research object. The following assumptions are considered in this model: tunnel diameter is a, the pore water pressure of the tunnel wall is P1, the vertical distance from the tunnel center to the riverbed is b, and the far-field water pressure is P0. It is assumed that the initial stress of rock mass is the self-weight stress, the lateral pressure 5th International Conference on Machinery, Materials and Computing Technology (ICMMCT 2017) Copyright © 2017, the Authors. Published by Atlantis Press. This is an open access article under the CC BY-NC license (http://creativecommons.org/licenses/by-nc/4.0/). Advances in Engineering, volume 126

Korzeniowski Waldemar, Skrzypkowski Krzysztof, Zagórski Krzysztof

The basic type of rock mass reinforcement method for both preparatory and operational workings in underground metal ore mines, both in Poland and in different countries across the world, is the expansion shell or adhesive-bonded rock bolt. The article discusses results of static loading test of the expansion shell rock bolts equipped with originally developed deformable component. This component consists of two profiled rock bolt washers, two disk springs, and three guide bars. The disk spring and disk washer material differs in stiffness. The construction materials ensure that at first the springs under loading are partially compressed, and then the rock bolt washer is plastically deformed. The rock bolts tested were installed in blocks simulating a rock mass with rock compressive strength of 80 MPa. The rock bolt was loaded statically until its ultimate loading capacity was exceeded. The study presents the results obtained under laboratory conditions in the test rig allowing testing of the rock bolts at their natural size, as used in underground metal ore mines. The stress-strain/displacement characteristics of the expansion shell rock bolt with the deformable component were determined experimentally. The relationships between the geometric parameters and specific strains or displacements of the bolt rod were described, and the percentage contribution of those values in total displacements, resulting from the deformation of rock bolt support components (washer, thread) and the expansion shell head displacements, were estimated. The stiffness of the yielded and stiff bolts was empirically determined, including stiffness parameters of every individual part (deformable component, steel rod). There were two phases of displacement observed during the static tension of the rock bolt which differed in their intensity.