泉店煤礦0.9 Mta新井設(shè)計含5張CAD圖-采礦工程.zip,泉店煤礦0.9,Mta新井設(shè)計含5張CAD圖-采礦工程,煤礦,0.9,Mta,設(shè)計,CAD,采礦工程 英文原文 The optimal support intensity for coal mine roadway tunnels in soft rocks C. Wang* Mining Engineering Program, Western Australian School of Mines, PMB 22, Kalgoorlie WA6430, Australia 1. Introduction The essence of underground roadway support is to provide the surrounding rocks of an underground roadway with assistance to help them achieve stress and strain equilibrium and ultimately stability of deformation.The approaches to this goal are either to reinforce the rock mass by rock bolting or injection(internal rock stabilization) or to provide the surrounding rocks with a support resistance with a magnitude being described as the support intensity (external rock stabilization). When an underground roadway is located in soft rocks which are too soft to be reinforced by bolting and/or unsuitable for rock injection because of restraints imposed by either the rock mass impermeability or rock mass deterioration when water is encountered, external rock support, such as steel sets, therefore becomes the only option for the stability control of the roadway. Under this circumstance, the support intensity means a support force acting per unit surface area of the surrounding rocks of the roadway. In soft rock engineering practice, the design of a support pattern for a roadway in underground coal mining is normally based on rules of thumb. In most cases, heavy support measures are adopted to secure a successful roadway. Fig. 1(a) demonstrates the excellent condition of a sub-level roadway within soft rocks at an underground coal mine in north China, where an excessive capital cost was applied for the achievement of roadway stability. In some cases, such as a service roadway driven in soft rocks at the same mine (Fig. 1(b)), insufficient support intensity was specified as a result of a lack of relevant experience and design codes. Consequently, failure of the roadway stability was inevitable and an extra cost was incurred when the subsequent roadway repair or rehabilitation was undertaken. The critical issue in both cases lies in the determination of an optimal support intensity which is the function of the geometry and dimension of a roadway and its geotechnical conditions including rock mass properties, stress conditions and hydrological status. Physical modelling using simulated materials based on the theory of similarity provides a direct perceptional methodology for mining geomechanics study [1-6].Using simulated materials of the same composition to construct a roadway and its soft surrounding rocks, applying a certain magnitude of simulated support intensity to the surface of a roadway under simulated stress conditions, the three-dimensional physical modelling method depicted in this Note emonstrates a quantitative solution for strategic design of roadway support concerned with soft rocks. A relation between the support intensity and deformation of the surrounding rocks of a roadway has been established after a series of simulation tests had been conducted. A discussion on the optimal support intensity for a roadway in soft rocks is also given. Fig. 1. Examples of successful and unsuccessful support of underground roadways within soft rocks: (a) Good condition of a sublevel roadway, (b) Unsuccessful support of a service roadway. 2. Features of the three-dimensional physical modelling A physical modelling study of the interaction between support intensity and roadway deformation was carried out using the three dimension physical modelling system (see Fig. 2) at the Central Laboratory of Rock Mechanics and Ground Control, China University of Mining and Technology. Features of this system are described in the following sub-sections. Fig. 2.Three-dimensional loaded physical modelling system at the Central Laboratory of Rock Mechanics and Ground Control, China University of Mining and Technology.2.1. Size of the physical model The effective size of a physical model is 1000 mm wide, 1000 mm high and 200 mm thick. 2.2. Three dimensional active loading capability Six flatjacks are used to apply loads to the six sides of the physical model in the form of a rectangular prism. Each flatjack was designed to cover the full area of one of the six sides and be capable of applying a pressure of up to 10 MPa on to the surface of the simulated rock mass. This means that the flatjacks are capable of applying an active load of up to 1000 tonnes and 200 tonnes simultaneously on the front and back facets, the top and bottom, and the two side facets of a model, respectively. 2.3. Long-term continuous loading capability A high-pressure, nitrogen-operated, hydraulic pressure stabilising unit was employed to maintain a consistent magnitude of load applied to the model so that the physical modelling test is able to last continuously for weeks, months or even years without interruption. This feature ensures that the study of the long-term rheological behaviour of soft rocks can be carried out. 3. Physical modelling tests Physical modelling of an underground roadway/ tunnel within soft rocks with a hydrostatic stress condition was carried out. The same simulated materials were repeatedly used six times to construct six physical models. Each roadway model was provided with a different magnitude of support intensity. 3.1. Geotechnical conditions for the prototype and the modelling scale A specified underground roadway within soft rocks was assumed to be the prototype for the modelling study. Detailed geotechnical conditions of the roadway and its surrounding rocks are: circular roadway with a diameter (D) of 4.5 m and cross-sectional area of 16 m2; UCS (Rc ) of the surrounding rock was 20 MPa; bulk density of the surrounding rock was 2500 kg/m3; depth of the roadway location was 500 m below surface; rock mass stress (s0 ) was 12.5 MPa in all directions; support intensity(pa) to be applied to the roadway was 0.1, 0.2, 0.3, 0.4, 0.5 and 0.6 MPa, respectively. The geotechnical modelling scale (Cl ) determined was 1 : 25. The bulk density (gm ) of the simulated rock mass materials was 1600 kg/m3.Therefore, all the related simulation constants are: similarity constant for bulk density: Cg ? 1600/2500=0.64; similarity constant for strength: Cs ? ClCg ? 0:256; similarity constant for load: CF ? CgC1 ? 4:096 10?5 ; similarity constant for time: Ct ? C l:5 ? 0:2: Geotechnical conditions of the simulated rock mass and roadway were derived from those of the prototype rock mass as presented below: strength of the simulated rock mass: Rm=RcCs=0.512; diameter of the simulated roadway: Dm=DCl=180 mm; load intensity on the facets of the model: pm=s0Cs=0.32 MPa; Simulated support intensity: pam=paCs=0.00256, 0.00516, 0.00768, 0.01024, 0.0128 and 0.01536 MPa; respectively. 3.2. Realization of support intensity in physical modelling Due to the restraints of the small dimensions of the model roadway on the simulation of support structure, the support pattern and structure were unable to be simulated. Instead, an equivalent support intensity was simulated and applied to the surface of the surrounding rock of the model roadway. A Static Water Support and Deformation Measurement System (SWSDMS) was designed specially. Fig. 3 illustrates the SWSDMS being installed in the model roadway. The mechanism of SWSDMS is to use 4 separate water capsules to apply a support intensity to the surface of the roadway roof, two side walls and floor. Four rubber tubes, each of which was linked to a water capsule and filled with water, were used to generate a water pressure at the capsule/rock interface and measure it through the water level reading. A certain constant simulated support intensity was achieved by applying a certain height of static water pressure. A change to support intensity could be made by changing the water height in the rubber tube. The volume change of each of the four water capsules was measured at the due time by collecting and weighing the water overflow. The volume of water coming from each of the four water capsules was used to calculate the radial deformation of roadway surrounding rock, i.e., roof subsidence, wall-to-wall closure and floor heave. The proposed simulated support intensities, i.e., Pam ? 0:00256, 0.00516, 0.00768, 0.01024, 0.0128 and 0.01536 MPa, were achieved by adjusting the static water level to 256, 516, 768, 1024, 1280 and 1536 mm high, respectively. Fig. 3. Static Water Support and Deformation Measurement System (SWSDMS) being accommodated in a roadway model in the real 3-D loaded physical modelling system. 3.3. Construction of physical model The compositions and properties of materials to be used for the construction of physical models were studied prior to the physical model construction. Given the significant rheological deformation of roadways excavated in soft rock, sand and paraffin wax were chosen for the simulated soft rock. The properties of a series of sand/paraffin wax mixtures were studied in laboratory and are presented in Table 1. Table 1 Compositions and properties of sand/paraffin wax mixtures According to the geotechnical conditions of the prototype rock mass and the model scale, a mixture of sand/paraffin wax of 100 : 3 was selected to construct the rock mass model. The procedures involved in the model construction include cold mixing of the sand and paraffin wax, oven heating the sand/wax mixture and constructing the physical model using the hot sand/wax mixture. 3.4. Process of physical modelling The real process of an underground roadway excavation, support installation and deformation of the surrounding rocks with time was simulated in the laboratory physical modelling. After the model had cooled down, prestressing the model, excavation of the roadway under pressure, installation of the SWSDMS device and measurement of the roadway deformation were carried out step by step. The whole process of modelling was strictly conducted according to the time similarity constant. Each physical modelling step lasted for 10-25 days in the laboratory, which were equivalent to a real time period of 50-125 days approximately. 4. Relations between support intensity and roadway deformation Comparable results of the six physical modelling tests conducted with the identical materials and geotechnical conditions revealed the significance of the support intensity in underground roadway/tunnel support. 4.1. Effect of support intensity on the deformation characteristics of a roadway The deformation characteristics of an identical roadway with different support intensity is graphically presented in Fig. 4(a) and (b). It can be seen that the influence of support intensity on the deformation characteristics is significant. With a support intensity of 0.1 MPa, the roadway experienced a large eformation for a period of 118 days after the roadway excavation and the provision of support intensity. During this period, an average of 828 mm deformation was accumulated. Following this period, the wall-to-wall closure and roof-to-floor convergence stayed steady at a level of 4.4 mm/day. By contrast, when a support intensity of 0.6 MPa was provided to the identical roadway, its post-excavation deformation merely lasted for 36 days with an accumulative closure/convergence of 40 mm, followed by a rheological deformation of 0.08 mm/day, which was continuously reducing with Fig. 4. Deformation of roadway with a series of support intensities: (a) Deformation of roadway with time, (b) Deformation rate of roadway with time. time. The comparison shows that the deformation magnitude of the latter was only 4.8% that of the former. A negative exponential relation between the deformation rate and support intensity can also be deduced from the curve of deformation rate vs. support intensity presented in Fig. 5 and be mathematically expressed as: v ? 0:023pa2:4 : where v is the rheological deformation rate of the surrounding rock of a roadway in mm/day, pa is the support intensity in MPa provided to the surrounding rock. Fig.5 Relations between rheological deformation rate and support intensity of a roadway in soft rocks. 4.2. Optimal support intensity for a roadway in soft rocks Requirements on the control of roadway deformation depend on the usage and service life of the roadway. It is known that a zero deformation rate is impossible practically to target in supporting a roadway in soft rocks. A wise approach is to exercise a design principle that the roadway deformation is allowed to take place to a degree within an acceptable limit. Physical modelling results indicated that an increase of support intensity from 0.1 to 0.5 MPa can markedly reduce the deformation rate of the surrounding rocks. A further increase of support intensity from 0.5 to 0.6 MPa, however, did not bring about as much reduction of deformation rate as that created by the support intensity increase of from 0.1 to 0.2 MPa or from 0.3 to 0.4 MPa. This means that a reasonable range of support intensity exists and an increase of support intensity can be rewarded with a significant reduction of roadway deformation if the actual support intensity is within this range.Further increases of support intensity can only cause less reduction of roadway deformation. Therefore, if both technical and economical considerations are taken into account, a support intensity of from 0.3 to 0.5 MPa would be appropriate for most temporary tunnels such as roadways in underground coal mining. With this support intensity, the rheological deformation rate of the surrounding rocks can be controlled within a range of from 0.1 to 0.4 mm/day, with which an ordinary temporary roadway can be maintained safely for years to one decade. 5. Conclusions The three-dimensional physical modelling method provides a ‘conceptual approach to quantitative design’of roadway support associated with soft rocks. With lack of knowledge of the constitutive relations, especially for the rheological mechanisms, in rock engineering practice, the modelling results could serve as a foundation on which a scientific design of underground roadway/tunnel support is developed, particularly when a large amount of rock mass deformation is concerned. The experimental study conducted with a series of support intensities revealed that a reasonable support intensity exists. Its value depends on the geotechnical and geometric conditions of the underground roadway/tunnel concerned and the requirements applied by the roadway/tunnel safe use specifications and the roadway/tunnel service life span. The results indicate that a support intensity of 0.3 to 0.5 MPa can securely control the closure rate for the conditions tested within a magnitude of 0.1 to 0.4 mm/day for a medium size underground roadway/tunnel driven in soft rocks of around 20 MPa at a depth of about 500 m below surface. References [1] Internal Research Report. Study on the technology of large deformation control for roadways within soft rocks. China University of Mining and Technology, 1995 [in Chinese]. [2] Wang C. Study on the supporting mechanism and technology for roadways in soft rocks. PhD thesis, China University of Mining and Technology, 1995 [in Chinese]. [3] Internal reference (1993). Properties of simulated materials for physical geomechanical modelling. The Central Laboratory of Rock Mechanics and Ground Control, China University of Mining and Technology [in Chinese]. [4] Lin Y. Simulated materials and simulation for physical modelling. Publishing House of China Metallurgy Industry, Beijing, China, 1986 [in Chinese]. [5] Durove J, Hatala J, Maras M, Hroncova E. Support’s design based on physical modelling. Proceedings of the International Conference of Geotechnical Engineering of Hard Soils } Soft Rocks. Rotterdam: Balkema, 1993. [6] Singh R, Singh TN. Investigation into the behaviour of a support system and roof strata during sub-level caving of a thick coal seam. Int J Geotech Geol. Engng. 1999;17:21-35. 中文譯文 煤礦軟巖巷道支護強度優(yōu)化 C. Wang 采礦工程專業(yè)，西澳礦業(yè)學校，港口及航運局22卡爾古利WA6430，澳大利亞 1引言 地下巷道支護的實質(zhì)是給巷道圍巖提供支撐以實現(xiàn)應力應變平衡，并最終使變形穩(wěn)定。為達到這一目標，需通過錨桿支護加固巖體或注漿（內(nèi)部巖石穩(wěn)定）或為圍巖提供被描述為支撐強度的具有有一定數(shù)量級的支撐阻力（外部巖石穩(wěn)定）。 當?shù)叵孪锏捞幱谒绍泿r石中，巖石過于松軟以致錨桿加固或不適合注漿加固。這是因為遇到水時巖體滲透性或巖體惡化施加的限制。因此，外部巖石支護如鋼棚支護，成為了巷道穩(wěn)定控制的唯一選擇。在這種情況下，支護強度是指單位巷道圍巖表面積的支撐力。在軟巖工程實踐中，地下煤礦巷道支護模式設(shè)計通常是基于經(jīng)驗法則。在大多數(shù)情況下，采用支護強度大的支護措施，確保巷道穩(wěn)定。圖1（a）展示了在中國北方一煤礦為實現(xiàn)巷道穩(wěn)定投入過多資金成本的煤礦井下軟巖分段巷道的良好條件。在某些情況下，例如在同一煤礦軟巖中開掘的服務(wù)巷道（如圖1（b）），支撐力不足被指定為缺乏相關(guān)經(jīng)驗和設(shè)計規(guī)范所致。因此，巷道失穩(wěn)是必然的。在隨后進行巷道維修或重建時，又需支出額外的費用。 這兩種情況的關(guān)鍵問題在于最佳的支護強度，與巷道的斷面形狀和巖土工程條件，包括巖性，應力條件和水文狀況呈函數(shù)關(guān)系。 基于相似理論的相似材料的物理模擬為礦山地質(zhì)力學研究提供了直接感知的方法。[1-6] 利用組成相同的相似材料來模擬巷道及周圍軟巖，模擬應力條件下施加一定的支護強度到巷道表面。在這份說明中描述的三維實體建模方法，展示了軟巖巷道支護戰(zhàn)略設(shè)計方面定量計算的方案。通過一系列相似實驗的結(jié)果，支護強度和巷道圍巖變形間的關(guān)系建立。關(guān)于軟巖巷道最佳支護強度的討論也由此展開。 圖1 地下軟巖巷道支護成功和失敗的例子 a分段巷道的良好條件 b服務(wù)巷道支護失效 2.三維實體模型的特征 在中國礦業(yè)大學巖土力學與地面控制中心實驗室進行的關(guān)于支護強度和巷道圍巖變形間關(guān)系的物理模擬研究采用了三維實體模型系統(tǒng)（見圖2）。該系統(tǒng)的特征描述如下： 圖2 中國礦業(yè)大學巖土力學與地面控制中心實驗室三維加載實體模型系統(tǒng) 2.1實體模型尺寸 物理模型的有效尺寸為1000毫米寬，1000毫米高，200毫米厚。 2.2三維實時加載能力 六個千斤頂用于向長方體形式的物理模型的六個面加載。六個千斤頂設(shè)計能夠各自覆蓋一個面，并能夠向模擬巖石表面施加10MPa的壓力。這意味著千斤頂能夠同時在前后上下左右六個面動態(tài)施加1000 t到2000 t的力。 2.3長期連續(xù)加載能力 高壓氮氣操作的液壓穩(wěn)定單元是用來保持相同負載應用到模型上，使物理模型試驗能夠持續(xù)數(shù)周，數(shù)月甚至數(shù)年連續(xù)無間斷。此功能確保了軟巖長期流變行為研究的進行。 3物理模型測試 地下軟巖巷道或隧道的物理模擬在靜水條件下進行，同樣的模擬材料重復使用六次來興建六個物理模型。對每個巷道模型提供不同程度的支護強度。 3.1原型和模型比例的巖土工程條件 為進行模擬研究，假定一個指定的軟巖巷道為原型。巷道和圍巖詳細的巖土工程條件有： 圓形巷道，直徑4.5 m，截面積16 m2； 圍巖單向抗壓強度為20 MPa； 巖石體積密度為2500 kg/m3； 巷道位于地面以下500 m； 巖石各向壓力為12.5 MPa； 巷道支護強度分別為：0.1,0.2,0.3,0.4,0.5,0.6 Mpa。 巖土模擬比例定為1:25。模擬巖體材料的容重（gm）為1600 kg/m3，因此，所有相關(guān)模擬常數(shù)為： 容重相似不變：Cg ? 1600/2500=0.64; 強度相似不變：Cs ? ClCg ? 0:256; 負載相似不變 CF ? CgC1 ? 4:096 10?5 ; 時間相似不變 Ct ? C l:5 ? 0:2: 模擬巖體和巷道的地質(zhì)條件依據(jù)如下所示的原巖： 模擬巖體強度 Rm=RcCs=0.512; 模擬巷道直徑: Dm=DCl=180 mm; 模型各面加載強度 pm=s0Cs=0.32 MPa; 模擬支護強度: pam=paCs=0.00256, 0.00516, 0.00768, 0.01024, 0.0128 0.01536 MPa; 3.2物理模型支護強度的實現(xiàn) 由于小尺寸模擬巷道在支護結(jié)構(gòu)上的限制，支護模式和結(jié)構(gòu)不能被模擬。相反，相同的支護強度被模擬并施加到模擬巷道圍巖。專門設(shè)計了一種靜水支撐和變形測量系統(tǒng)（SWSDMS）。圖3說明了SWSDMS被安裝在模型巷道。SWSDMS的機制是用4個單獨的水膠囊向巷道頂板，兩幫和底板的表面提供支護強度。連接膠囊的并充滿水的四個橡膠管用在水膠囊和巖石界面生成水壓，并通過讀取水位來測量水壓大小。 圖3靜水支撐和變形測量系統(tǒng)（SWSDMS）被安置在真實三維物理模擬加載系統(tǒng)下的巷道模型 施加一定的靜水壓高度可以獲得某一數(shù)值的模擬支護強度，通過改變橡膠管水的高度來實現(xiàn)模擬支護強度的變化。每個水膠囊的體積變化可以通過在適當時候收集并測量溢出水量來獲得。來自每個水膠囊的水的體積用來計算巷道圍巖的徑向變形，即頂板下沉，兩幫移近和底板臌起。通過調(diào)節(jié)靜水位至256, 516, 768, 1024, 1280, 1536 mm 高度來實現(xiàn)建議的支護強度? 0:00256, 0.00516, 0.00768, 0.01024, 0.0128, 0.01536 MPa。 3.3物理模型的構(gòu)建 用于構(gòu)建物理模型的材料組成和性質(zhì)的研究優(yōu)先于物理模型的構(gòu)建。鑒于軟巖巷道出現(xiàn)的顯著流變，沙子和石蠟被用于模擬軟巖。在研究實驗室得出沙子石蠟混合物的一系列特性，列于表1。 表1 沙子石蠟混合物的組成和性質(zhì) 配比（質(zhì)量） 沙子：石蠟 單軸抗壓強度（MPa） 試樣1 試樣2 試樣3 平均 100:2 0.033 0.030 0.029 0.307 100:3 0.0554 0.053 0.053 0.0538 100:4 0.0864 0.0842 0.0852 0.0853 100:5 0.10 0.107 0.112 0.106 100:6 0.128 0.1304 0.124 0.1275 100:7 0.1386 0.1380 0.1424 0.1397 根據(jù)巖體的原型和模型比例的巖土工程條件，選用配比為100:3的沙子石蠟混合物構(gòu)造巖體模型。模型的建設(shè)所涉及的程序包括冷混合沙子和石蠟，烘箱加熱沙子石蠟混合物，使用熱沙子石蠟混合物構(gòu)建物理模型。 3.4物理模擬過程 地下巷道掘進，支護安裝和圍巖隨時間變形的真實過程是在實驗室物理模型中模擬的。模型冷卻后，預加應力到模型上，帶壓掘進巷道，安裝SWSDMS設(shè)備，測量巷道圍巖變形。建模的全過程嚴格按照時間相似常數(shù)進行，每個物理建模步驟在實驗室持續(xù)10-25天，相當于約50-125天的真實時間。 4支護強度和巷道變形的關(guān)系 比較相同材料和巖土條件下進行的六個物理模型實驗結(jié)果表明，支護強度在地下巷道或隧道支護中的重要性。 4.1支護強度對巷道變形特征的影響 相同巷道不同支護強度下的巷道變形特性以圖的形式展現(xiàn)在圖4（a）和（b）?？梢钥闯?，支護強度對巷道變性特性的影響很大。在0.1 MPa的支護強度下，巷道開掘完成并提供支護強度后118天，巷道經(jīng)歷了大的變形。在此期間，累計變形828 mm。此后，兩幫收縮和頂?shù)装迨諗糠€(wěn)定在4.4 mm/d 的水平。與此相反，當提供給同一巷道0.6 MPa的支護強度時，開挖后變形僅僅持續(xù)了36天，累計收斂40 mm，緊接著是0.08 mm/d的流變，且隨時間不斷減少。比較結(jié)果顯示后者的變形程度僅僅是前者的4.8%。 變形速率和支護強度的負指數(shù)關(guān)系可以從圖5中所示變形速率和支護強度曲線推導出來，數(shù)學表達為：v ? 0:023， pa 2.4 : 其中v指巷道圍巖變形速率，mm/day；pa指提供給圍巖的支護強度，MPa。 圖4 一系列支護強度下的巷道變形 (a) 巷道變形隨時間的變化 (b)巷道變形速率隨時間的變化 圖5 軟巖巷道流變速率和支護強度的關(guān)系 4.2軟巖巷道支護強度優(yōu)化 對巷道變形控制的要求取決于巷道用途和服務(wù)年限。眾所周知，支護軟巖巷道達到零變形速率是幾乎不可能的。明智的做法是行使此種設(shè)計原則，在允許范圍內(nèi)巷道發(fā)生一定程度的變形。物理模擬結(jié)果表明：支護強度從0.1增加到0.5 MPa，可以顯著減少圍巖變形速率。 支護強度進一步增加至0.5到0.6 MPa，巷道變形速率并沒有像在0.1到0.2 MPa或0.3到0.4 MPa時大幅減少。這意味著合理支護強度范圍的存在，若實際支護強度在這個范圍內(nèi)，支護強度的增加會帶來巷道變形的顯著減少。進一步增加支護強度，只會帶來極少的變形減少。 因此，從技術(shù)和經(jīng)濟兩方面進行考慮， 0.3到0.5 MPa的支護強度范圍適合大多數(shù)臨時隧道如煤礦巷道。在這個支護強度范圍內(nèi)，圍巖流變速率能夠控制在0.1到0.4 mm/d，普通巷道能夠安全維持數(shù)年到十年。 5總結(jié) 三維物理模擬方法為軟巖巷道支護提供了“定量化設(shè)計相關(guān)方法”。由于缺乏本構(gòu)關(guān)系的知識，特別是流變機制，在巖土工