泉店煤礦0.9 Mta新井設(shè)計(jì)含5張CAD圖-采礦工程.zip

泉店煤礦0.9 Mta新井設(shè)計(jì)含5張CAD圖-采礦工程.zip,泉店煤礦0.9,Mta新井設(shè)計(jì)含5張CAD圖-采礦工程,煤礦,0.9,Mta,設(shè)計(jì),CAD,采礦工程 英文原文The optimal support intensity for coal mine roadway tunnels in soft rocksC. Wang*Mining Engineering Program, Western Australian School of Mines, PMB 22, Kalgoorlie WA6430, Australia1. IntroductionThe 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 modellingA 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 modelThe effective size of a physical model is 1000 mm wide, 1000 mm high and 200 mm thick.2.2. Three dimensional active loading capabilitySix 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 capabilityA 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 testsPhysical 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 scaleA 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 4:096 105 ;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 modellingDue 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 surroundingrock 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 modelThe 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 mixturesAccording 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 roadwayThe 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 rocksRequirements 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 designof 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.References1 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. Supports 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(hù)強(qiáng)度優(yōu)化C. Wang采礦工程專業(yè)，西澳礦業(yè)學(xué)校，港口及航運(yùn)局22卡爾古利WA6430，澳大利亞1引言地下巷道支護(hù)的實(shí)質(zhì)是給巷道圍巖提供支撐以實(shí)現(xiàn)應(yīng)力應(yīng)變平衡，并最終使變形穩(wěn)定。為達(dá)到這一目標(biāo)，需通過錨桿支護(hù)加固巖體或注漿（內(nèi)部巖石穩(wěn)定）或?yàn)閲鷰r提供被描述為支撐強(qiáng)度的具有有一定數(shù)量級的支撐阻力（外部巖石穩(wěn)定）。當(dāng)?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?yàn)橛龅剿畷r(shí)巖體滲透性或巖體惡化施加的限制。因此，外部巖石支護(hù)如鋼棚支護(hù)，成為了巷道穩(wěn)定控制的唯一選擇。在這種情況下，支護(hù)強(qiáng)度是指單位巷道圍巖表面積的支撐力。在軟巖工程實(shí)踐中，地下煤礦巷道支護(hù)模式設(shè)計(jì)通常是基于經(jīng)驗(yàn)法則。在大多數(shù)情況下，采用支護(hù)強(qiáng)度大的支護(hù)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(shí)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(yàn)和設(shè)計(jì)規(guī)范所致。因此，巷道失穩(wěn)是必然的。在隨后進(jìn)行巷道維修或重建時(shí)，又需支出額外的費(fèi)用。這兩種情況的關(guān)鍵問題在于最佳的支護(hù)強(qiáng)度，與巷道的斷面形狀和巖土工程條件，包括巖性，應(yīng)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(xué)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(yīng)力條件下施加一定的支護(hù)強(qiáng)度到巷道表面。在這份說明中描述的三維實(shí)體建模方法，展示了軟巖巷道支護(hù)戰(zhàn)略設(shè)計(jì)方面定量計(jì)算的方案。通過一系列相似實(shí)驗(yàn)的結(jié)果，支護(hù)強(qiáng)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(hù)強(qiáng)度的討論也由此展開。圖1 地下軟巖巷道支護(hù)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(hù)失效2.三維實(shí)體模型的特征在中國礦業(yè)大學(xué)巖土力學(xué)與地面控制中心實(shí)驗(yàn)室進(jìn)行的關(guān)于支護(hù)強(qiáng)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(shí)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(xué)巖土力學(xué)與地面控制中心實(shí)驗(yàn)室三維加載實(shí)體模型系統(tǒng)2.1實(shí)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(shí)時(shí)加載能力六個(gè)千斤頂用于向長方體形式的物理模型的六個(gè)面加載。六個(gè)千斤頂設(shè)計(jì)能夠各自覆蓋一個(gè)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(shí)在前后上下左右六個(gè)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?dú)獠僮鞯囊簤悍€(wěn)定單元是用來保持相同負(fù)載應(yīng)用到模型上，使物理模型試驗(yàn)?zāi)軌虺掷m(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(jìn)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(jìn)行，同樣的模擬材料重復(fù)使用六次來興建六個(gè)物理模型。對每個(gè)巷道模型提供不同程度的支護(hù)強(qiáng)度。3.1原型和模型比例的巖土工程條件為進(jìn)行模擬研究，假定一個(gè)指定的軟巖巷道為原型。巷道和圍巖詳細(xì)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(qiáng)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(hù)強(qiáng)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(qiáng)度相似不變：Cs ClCg 0:256;負(fù)載相似不變 CF CgC1 4:096 105 ;時(shí)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(qiáng)度 Rm=RcCs=0.512;模擬巷道直徑: Dm=DCl=180 mm;模型各面加載強(qiáng)度 pm=s0Cs=0.32 MPa;模擬支護(hù)強(qiáng)度: pam=paCs=0.00256, 0.00516, 0.00768, 0.01024, 0.0128 0.01536 MPa; 3.2物理模型支護(hù)強(qiáng)度的實(shí)現(xiàn)由于小尺寸模擬巷道在支護(hù)結(jié)構(gòu)上的限制，支護(hù)模式和結(jié)構(gòu)不能被模擬。相反，相同的支護(hù)強(qiáng)度被模擬并施加到模擬巷道圍巖。專門設(shè)計(jì)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(jī)制是用4個(gè)單獨(dú)的水膠囊向巷道頂板，兩幫和底板的表面提供支護(hù)強(qiáng)度。連接膠囊的并充滿水的四個(gè)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(shí)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(hù)強(qiáng)度，通過改變橡膠管水的高度來實(shí)現(xiàn)模擬支護(hù)強(qiáng)度的變化。每個(gè)水膠囊的體積變化可以通過在適當(dāng)時(shí)候收集并測量溢出水量來獲得。來自每個(gè)水膠囊的水的體積用來計(jì)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(shí)現(xiàn)建議的支護(hù)強(qiáng)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(shí)驗(yàn)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(qiáng)度（MPa）試樣1試樣2試樣3平均100:20.0330.0300.0290.307100:30.05540.0530.0530.0538100:40.08640.08420.08520.0853100:50.100.1070.1120.106100:60.1280.13040.1240.1275100:70.13860.13800.14240.1397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(jìn)，支護(hù)安裝和圍巖隨時(shí)間變形的真實(shí)過程是在實(shí)驗(yàn)室物理模型中模擬的。模型冷卻后，預(yù)加應(yīng)力到模型上，帶壓掘進(jìn)巷道，安裝SWSDMS設(shè)備，測量巷道圍巖變形。建模的全過程嚴(yán)格按照時(shí)間相似常數(shù)進(jìn)行，每個(gè)物理建模步驟在實(shí)驗(yàn)室持續(xù)10-25天，相當(dāng)于約50-125天的真實(shí)時(shí)間。4支護(hù)強(qiáng)度和巷道變形的關(guān)系比較相同材料和巖土條件下進(jìn)行的六個(gè)物理模型實(shí)驗(yàn)結(jié)果表明，支護(hù)強(qiáng)度在地下巷道或隧道支護(hù)中的重要性。4.1支護(hù)強(qiáng)度對巷道變形特征的影響相同巷道不同支護(hù)強(qiáng)度下的巷道變形特性以圖的形式展現(xiàn)在圖4（a）和（b）。可以看出，支護(hù)強(qiáng)度對巷道變性特性的影響很大。在0.1 MPa的支護(hù)強(qiáng)度下，巷道開掘完成并提供支護(hù)強(qiáng)度后118天，巷道經(jīng)歷了大的變形。在此期間，累計(jì)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(dāng)提供給同一巷道0.6 MPa的支護(hù)強(qiáng)度時(shí)，開挖后變形僅僅持續(xù)了36天，累計(jì)收斂40 mm，緊接著是0.08 mm/d的流變，且隨時(shí)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(hù)強(qiáng)度的負(fù)指數(shù)關(guān)系可以從圖5中所示變形速率和支護(hù)強(qiáng)度曲線推導(dǎo)出來，數(shù)學(xué)表達(dá)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(hù)強(qiáng)度，MPa。圖4 一系列支護(hù)強(qiáng)度下的巷道變形(a) 巷道變形隨時(shí)間的變化 (b)巷道變形速率隨時(shí)間的變化圖5 軟巖巷道流變速率和支護(hù)強(qiáng)度的關(guān)系4.2軟巖巷道支護(hù)強(qiáng)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(hù)軟巖巷道達(dá)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(jì)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(hù)強(qiáng)度從0.1增加到0.5 MPa，可以顯著減少圍巖變形速率。支護(hù)強(qiáng)度進(jìn)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(shí)大幅減少。這意味著合理支護(hù)強(qiáng)度范圍的存在，若實(shí)際支護(hù)強(qiáng)度在這個(gè)范圍內(nèi)，支護(hù)強(qiáng)度的增加會帶來巷道變形的顯著減少。進(jìn)一步增加支護(hù)強(qiáng)度，只會帶來極少的變形減少。因此，從技術(shù)和經(jīng)濟(jì)兩方面進(jìn)行考慮， 0.3到0.5 MPa的支護(hù)強(qiáng)度范圍適合大多數(shù)臨時(shí)隧道如煤礦巷道。在這個(gè)支護(hù)強(qiáng)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?jǐn)?shù)年到十年。5總結(jié)三維物理模擬方法為軟巖巷道支護(hù)提供了“定量化設(shè)計(jì)相關(guān)方法”。由于缺乏本構(gòu)關(guān)系的知識，特別是流變機(jī)制，在巖土工